Valve jobs

[bmwpower]

What constitutes a valve job on a cylinder head?

I need to get 2 valves fixed on a good used BMW head I bought. All the machine shops I've gone to are telling me it needs a complete valve job. The head is only 89k old...young for a BMW.

Why can't they just swap 2 valves over from the old head and redo the guides and seals on those 2 valves? Shouldn't the other valves be okay?

The one shop wants to charge me $699 for a "reconditioning" of the head...full radius valve job using Serdi equipment, new valve guides, balance and blueprint valves, balance springs, resurface. Does that sound like a lot? Plus $100 for removing/reinstalling the cams on the new head, so $799 total.

Having never bent any valves myself, I've never had to get a head redone, so this is new to me.

Any guidance?

 

[jimvannoy]

If you swap out valves at the least they need to be "reseated". It's easy to do yourself with some lapping compound and a lapping tool. While the head is off and apart I would go ahead and take out all the valves clean all the carbon off them and the head, put in new seals and lap them all. It would be better to grind all the seats and valves then lap them. Anyhow that's what I would do on Chevy or Ford heads.

 

[bmwpower]

If you swap out valves at the least they need to be "reseated". It's easy to do yourself with some lapping compound and a lapping tool. While the head is off and apart I would go ahead and take out all the valves clean all the carbon off them and the head, put in new seals and lap them all. It would be better to grind all the seats and valves then lap them. Anyhow that's what I would do on Chevy or Ford heads.

I wish I knew how to do all that. So you're saying a complete valve job is not required?

I'm not even sure what it means to "lap" them or "grind all the seats and valves".

 

[MXtras]

What they are suggesting is standard. It might not be what you want to hear, but it's standard procedure to recondition the entire head, not just one cylinder.

Scott

 

[jimvannoy]

I wish I knew how to do all that. So you're saying a complete valve job is not required?

I'm not even sure what it means to "lap" them or "grind all the seats and valves".

Grinding them, lapping them, cleaning them, and replacing the seals is pretty much a complete valve job. At least it is on Chevy and Ford heads.

Lapping them is matching the angle on the valve edge with the angle on the seat. You spread compound around the valve insert it in the head all the way to the seat and place a suction cup tool with a handle on it on the flat bottom part of the valve then spin the tool around in the palms of your hands until you have an even surface on the valve and seat.

Grinding them involves taking out the valves and placing them in a machine to regrind the angle on their face. You then regrind the angle on the seats in the head with another tool that sort of looks like a big angle drill with a stone on the end of it and a pilot in the valve guide hole. The stone and stone holder slide over the pilot and the stone rests on the seat

 

[Steve in Mi]

"$799 total" That must be one of them 24 cylinder BMW's

I'm kidding but if you want the bragging rights.... you just have to pay for them.

 

[timgr]

It's been a while since I worked in the trade, but this is what I recall.

Your typical valve job includes dissasembly, cleaning, inspection, and reassembly. They should test the springs for proper height and tension. Sometimes magnaflux or dye penetration (for aluminum heads) to check for cracks is included, sometimes not. Grinding of the valves and seats is also included. Any new parts needed are extra - you may need springs, valves and/or guides.

Additional machining operations can include surfacing, crack repair, and valve guide replacement or refurbishment.

I think lapping is no longer done - the lapping process uses a seating compound (fine paste abrasive) to grind the valve and the seat against each other. This is usually done with a suction cup on the end of a dowel, while turning the dowel between your palms - very 'old school'. Today, a modern multi-angle valve job should have a thin and accurate contact between the seat and valve, so no lapping is needed or desirable. The seat and valve have an angle difference of a few degrees, so the contact line is supposed to be very fine and seal tightly.

A good-quality job will have 3 angles (3 different angles on the face of the seat), though I think modern performance grinds have more. A smoother transition with more angles should make the air flow better... but it's more labor and more tooling (stones).

Don't regret not being able to do this yourself - the machinery needed is way out of the realm of the hobbyist. It's something you have to farm out.

Yep, $799 seems like a lot - ask your local BMW enthusiasts who's good and what you can expect.

 

[bmwpower]

"$799 total" That must be one of them 24 cylinder BMW's

I'm kidding but if you want the bragging rights.... you just have to pay for them.

Only 16 valves on this 4 cylinder...

 

[jimvannoy]

I have lost count of the number of 3 angle valve jobs I have done in my home shop. It is something you can do at home if you have the equipment. I have a Sioux valve grinding machine that I got for $75.00 and a Sioux seat grinding set that I got for $100.00. Granted it's not up to date modern/expensive equipment but it does the job for me. I still lap the valves by hand when I do a 3 angle valve job. It insures a near perfect seal of the valve to the seat. I am sure more modern (expensive) equipment will grind to closer tolerances and probably has some step where machines do the final seating (lapping) of the valves to the seats. I also have never done any forigen heads though and I only do US stuff from the teens to the 1970's.

Before I shelled out almost $800.00 for a valve job I would consider trying it myself first. You can buy lapping compound, a lapping tool, and valve spring compressors at most any parts store. If it were me I would take 2 valves out of your old head, replace the 2 in your new head, lap them, and replace all the seals.

 

[bmwpower]

What they are suggesting is standard. It might not be what you want to hear, but it's standard procedure to recondition the entire head, not just one cylinder.

Scott

I don't mind paying it if that's my only option. I'm really interested in knowing WHY the other valves have to be done at the same time, I mean when it was running they were fine.

Is it one of those "you're in there, might as well do the whole thing" deals or is it something else?

 

[bmwpower]

I have lost count of the number of 3 angle valve jobs I have done in my home shop. It is something you can do at home if you have the equipment. I have a Sioux valve grinding machine that I got for $75.00 and a Sioux seat grinding set that I got for $100.00. Granted it's not up to date modern/expensive equipment but it does the job for me. I still lap the valves by hand when I do a 3 angle valve job. It insures a near perfect seal of the valve to the seat. I am sure more modern (expensive) equipment will grind to closer tolerances and probably has some step where machines do the final seating (lapping) of the valves to the seats. I also have never done any forigen heads though and I only do US stuff from the teens to the 1970's.

Before I shelled out almost $800.00 for a valve job I would consider trying it myself first. You can buy lapping compound, a lapping tool, and valve spring compressors at most any parts store. If it were me I would take 2 valves out of your old head, replace the 2 in your new head, lap them, and replace all the seals.

Seriously thinking of it.... I can have them do the cam off/cam on deal then resurface for $160 or whatever it is since I really don't want to mess with that since I don't have the right tools for that job.

 

[russlaferrera]

Considering the labor rate to swap out 2 valves and re cut them.

How about replacing the 2 valves with new, lap them in. Replace all the valve seals, clean and check the head with a straight edge Have the machine shop R & R the cams and be done.

 

[timgr]

Is it one of those "you're in there, might as well do the whole thing" deals or is it something else?

I'd say that's part of it - a lot of the expense is the stuff that involves the whole head - cleaning, inspection, assembly and so forth. There's an overhead involved with the setup, so doing 2 of the valves likely won't be much less expensive than doing all 16.

There's an element of CYA too ... I expect the shop won't guarantee its work unless you go for the "complete" job. A hi-po or specialty shop might be very careful of their reputation. What kind of damage does this head have? A local garage or machine shop might be willing to patch it up, if you make it clear that's the kind of job you want.

 

[Stuart in MN]

I just had a BMW M30 (big 6) head rebuilt a few months ago. It was a used head and I just wanted them to check it out and make sure it was in good condition.

A special fixture is needed to remove the cam on that particular head, and then once the head was disassembled they found three or four of the valve seats were a little beat up so they needed to be ground, and then of course it made sense to replace the valve seals as well. Along with disassembly, cleaning, inspection of the bare head and all the parts, grinding the worn seats, and reassembly it came to a little over $400.

This was at one of the best machine shops in town but I think they gave me a fair deal - I bring all my business there, and I told them the head was real low priority so they only worked on it in between other projects.

 

[Aceman]

When we lapped the valves on one of our tractors we used a drill on the valve stem rather than a suction cup tool. Seemed to work fine...............

 

[Lloydthumper]

I don't mind paying it if that's my only option. I'm really interested in knowing WHY the other valves have to be done at the same time, I mean when it was running they were fine.

Is it one of those "you're in there, might as well do the whole thing" deals or is it something else?

That is exactly what it is half of the labor for doing the whole head is done by the time they are at the machine shop and cheap insurance if they do two valves and you have a couple more that is fixing to burn or leak or other valve seals that are ready to crack then you just waisted the money you spent because it will have to be done again. It is just a good practice to do the whole head if you already have it off and apart.

 

[Charles (in GA)]

Removing all the valves and at least looking at them, and for sure replacing all the seals, is probably the bare minimum I'd want to do, but even given the special tooling needed to get the cam out, $799 sounds steep...... Then again I had to pay $60 just to get my Ranger flywheel surfaced last summer, and I thought that was a ripoff for what it takes to do the job. If this is a no rush kinda deal, I'd see if you could find other capable shops in other nearby towns and see what they say, it might be worth driving a few more miles.

Charles

 

[Stuart in MN]

The lion's share of the cost is going to be labor, and I imagine the typical labor rate for machine shops in New Jersey is pretty high.

 

[Junkman]

...... Then again I had to pay $60 just to get my Ranger flywheel surfaced last summer, and I thought that was a ripoff for what it takes to do the job. If this is a no rush kinda deal, I'd see if you could find other capable shops in other nearby towns and see what they say, it might be worth driving a few more miles.

Charles

I find it interesting that Charles (in GA) finds it a rip off to do a surface job of a flywheel that costs $60, when he works in a similar industry that also has high expense for repairs.... the airline industry. I doubt that he is working for minimum wage, or just slightly over that. In fact, I would guess that he has full health insurance benefits and is making a very good wage that many of us would be envious of. The same goes for the people that are doing the machining of his flywheel. They need to pay more than minimum wage to get qualified personnel to do the work, and offer other benefits. That $60 represents the cost of the machine that does the job, the wages of the person to operate the machine. The wages of the person that takes the part in, and writes up the work order, and then takes the money and delivers the finished product back to the customer. Then there is the costs that many people never see, such as insurance, taxes, rent, heat, etc. All this has to come out of that $60 job. Today, most shops can't operate charging only $60 for that job because of all the cost of doing business. In 1973 when I went into business for myself, I was paying $0.30 per month per square foot of space. When I closed my business in 2000, the rent for the same location was costing $20.00 per square foot per month. This is one of the reasons I closed, because I couldn't afford the rent any longer. If a man can't make a reasonable profit on his investment, he can't continue to provide the service. The same goes for employees... If they are not rewarded enough, then they go to another job where they can make more money for the same amount of time spent.

The lion's share of the cost is going to be labor, and I imagine the typical labor rate for machine shops in New Jersey is pretty high.

This is exactly the reason that the costs are so high.

Now, to address the original question. To do only two valves doesn't make economical sense to the shop, because a lot of the work that has to be done to do two vs all, is just about the same. The disassembly and cleaning is for the whole head, whether it is 2 valves or all the valves. The same for the rest of the operations. Once you have the tools out, and are working on the head, the others aren't going to take that much longer. Today, no one wants to do a half fast job, so they either do it right, or they don't want to do it at all. There reputation is too important to them, and if they only do a half a job, and it fails and ruins the engine, then they are afraid that you will come back at them. I know that I wouldn't do it if I owned the machine shop. You might consider checking with the local BMW dealership. They might be less, since they are used to doing this type of work, and they might be able to get the job done in less time as a result. Just remember, that when you tighten up the top end, if the bottom end is worn, then you will have additional problems to contend with. I know this first hand from the past "valve jobs" that eventually lead into doing complete engine rebuild jobs because of bad rings....

 

[bochnak]

You can check the condition of the valves by removing them, marking the seat with a sharpie marker, and then manually open and close the valve (simulate it's motion as if it were running). Check to see that the entire circumference of the seat has a "wear mark", which indicates a good seal.

I also have used a rubber fuel hose on the valve stem to lap valves instead of the suction cup tool (forgot to buy one).

FYI, I had a Chevy SB that needed a valve guide job (burning oil) and the shop quoted me for everything. I decided against it and just replaced the valve guide seals and dealt with a .5 quart oil loss between oil changes.

 

[VDubJoe]

If you need to have 2 valves replaced and plan on keeping the car it only makes since to ck everything. Valve guides, springs, valves, surface. Just because it was running fine dosen't mean its not ready for some work. I ve done a lot of heads that were working fine and found guides completly worn out. Witch causes a lot of valve self destruction. You could do most of the checking yourself but you would need a few tools. If you care to learn some look at getting the Sunnen engine machining book. Its very good.

Joe

 

[safetyfast]

Seems a bit high to me. Ask some hotrodders who they use locally. I found a good and affordable shop that way that wasn't even in the phone book. Turns out the guy has plenty of business so he doesn't pay to advertise.

 

[bmwpower]

Good recommendations.

I called a couple more places. One place wanted "around $800". Another place wanted close to $1k. Still checking...

 

[mike944]

I had a head done a few years ago, 16V Porsche head. Ii dissasembled it myself, and cleaned all the cams, springs, keepers, & stuff myself, and sent just the head and valves out. I had the valves and seats ground, the stem length trimmed, AND fly-cutting of the mating surface, and i don't think it was more than $250-300. This was a very reputable shop in central connecticut. I thought it was a pretty good deal. The only thing that didn't get done, by dissasembling it and reassembling it myself, was a spring pressure check. (i had the equipment to check the guides myself, per the factory manual)

I wouldn't "just lap" used valves into used seats. Most engines have a spec for maximum valve-to-seat contact patch width. By lapping without grinding, you increase that. If it gets too wide, over spec, it increases the likleyhood that particles will get stuck in that large area, and hang the valve open, which burns valves.

Do you have a factory rebuild manual, or spec sheet? Make damn sure the shop does. If the BMW's are anything like the Porsches, the factory specs are kind pf picky about certain things. My shop didn't have the specs, as my car is not a very common model, so i printed out the specific pages for them.

 

[malibu101]

I did not read all of the posts, but, here is my take on it (the head work). When I was younger and dumber with almost no money I took a set of SB Chevy heads to a machine shop because of a burned valve or two. The machinists advice was to also replace all the guides. I knew better: I said only replace the bad ones (remember very little money) he did and I was very happy with everything. A few months later I statred getting of then start-up puff of smoke which just kept getting worse.
I learned a valuable lesson from that.
Do it all and do it right- THE FIRST TIME. It's always cheaper.

 

[bmwpower]

I had a head done a few years ago, 16V Porsche head. Ii dissasembled it myself, and cleaned all the cams, springs, keepers, & stuff myself, and sent just the head and valves out. I had the valves and seats ground, the stem length trimmed, AND fly-cutting of the mating surface, and i don't think it was more than $250-300. This was a very reputable shop in central connecticut. I thought it was a pretty good deal. The only thing that didn't get done, by dissasembling it and reassembling it myself, was a spring pressure check. (i had the equipment to check the guides myself, per the factory manual)

I wouldn't "just lap" used valves into used seats. Most engines have a spec for maximum valve-to-seat contact patch width. By lapping without grinding, you increase that. If it gets too wide, over spec, it increases the likleyhood that particles will get stuck in that large area, and hang the valve open, which burns valves.

Do you have a factory rebuild manual, or spec sheet? Make damn sure the shop does. If the BMW's are anything like the Porsches, the factory specs are kind pf picky about certain things. My shop didn't have the specs, as my car is not a very common model, so i printed out the specific pages for them.

I don't have any of the tools to take the head apart. I'd need a special tool to remove the cams, plus the normal tools to remove the valves and seals.

The first shop does BMW stuff all the time, so I trust they have the right specs. I'd feel comfortable using them to do the work.

I did find another place (might be chancy) that said it would be around $400 to do the work. The guy sounded like a "tough" guy, but he came with a recommendation from another BMW guy online. Not sure about his quality or the specific on what he'd do (I have to get that still), but a BMW guy I talked to said he redid his bottom end on his M3, so he might be worth a shot. The only problem is he is somewhat far away.

Another thing that is throwing a monkey wrench in this whole process is the fact that I'm temped to do an engine swap on this car. I could get a used M3 engine for around $2k-2.5k. By the time I'm done with this other engine, I will probably have close to $1K+ in it. If I sell the head as is, the block and the transmission, I could probably get $1k or more. If I fixed the head and then sold it, I'm not sure I could get my money back on the engine.

This would be my first 4 cylinder BMW, so I'm not sure I'm gonna be happy with the power.

 

[Kevin54]

I did find another place (might be chancy) that said it would be around $400 to do the work. The guy sounded like a "tough" guy, but he came with a recommendation from another BMW guy online.

You had better take it to a reputable place to begin with instead of a place that cuts everyone by half. Usually when you find someone that does it for half of what everyone else charges, it cost you three times as much in the longrun. If something goes wrong would he stand behind it, or would he start in with "what the hell did you expect for $400?". That $400 could easily turn into $2400. Like was stated above, "Do it right the first time". Find a reputable machine shop, ask a lot of questions of them, ask them what all is involved, look at the workers and look at the place of business. Guaranteed you will be satisfied on the end.

Kevin

 

[bmwpower]

You had better take it to a reputable place to begin with instead of a place that cuts everyone by half. Usually when you find someone that does it for half of what everyone else charges, it cost you three times as much in the longrun. If something goes wrong would he stand behind it, or would he start in with "what the hell did you expect for $400?". That $400 could easily turn into $2400. Like was stated above, "Do it right the first time". Find a reputable machine shop, ask a lot of questions of them, ask them what all is involved, look at the workers and look at the place of business. Guaranteed you will be satisfied on the end.

Kevin

I hear ya. I probably won't go with him. Something didn't jive right with me when I talked to him.

 

[bmwpower]

So the one guy at the shop tells me that the $799 price might be more if they take off the cams and the lifters look worn. So I said, ok take the cams off since I needed the cams off anyway.

Then I get a call back today and he said the machinst didn't take the cams off but he looked "around" the cams (which I don't see how it is possible) and advised to replace them at the cost of an additional $316+.

Does this sound like BS? I took a look at the cams and they were the cleanest cams I've seen. Doesn't this mean the lifters should be fine? Then he started to talk about how the engine was overheated and that probably affected the lifters, etc. I'm not buying it. If the lifters were bad, why didn't he tell me this when he cleaned and checked the other head since he knew I was going to be swapping the cams, etc. over.

 

[Junkman]

Sounds like he is trying to take you for a ride. Go there and ask him to show you how he can tell without disassembly. My guess is that he thinks that you don't know any better, and he will take advantage of you as a result. My experiance tells me that when you show up, he will probably say something like....... "I haven't time to do this now, and come back later", hoping that you will just say to go ahead with the work.

 

[bmwpower]

Sounds like he is trying to take you for a ride. Go there and ask him to show you how he can tell without disassembly. My guess is that he thinks that you don't know any better, and he will take advantage of you as a result. My experiance tells me that when you show up, he will probably say something like....... "I haven't time to do this now, and come back later", hoping that you will just say to go ahead with the work.

My thoughts exactly. The phone guy (not the machinist) might be pulling one over on me or it might be the machinist himself, but I only ever talk to the phone guy (who has been gerenally nice). I pretty good at figuring people out when they're lying..usually.

He called like 15mins to 6 (they close at 6), so there would be no way I could have gotten down there in time to take a look. I wouldn't be surprised if he forgot to ask the machinist and just called me to try to rap things up.

Next thing I know he's gonna say the cams are no good.

I hate being at the mercy of other people.

 

[wrenchr]

I'm not saying to pay that big amount. But you have it apart, Do it right the first time and your engine will run super!!!!

 

[bmwpower]

I'm not saying to pay that big amount. But you have it apart, Do it right the first time and your engine will run super!!!!

Yea, the price keeps getting more and more everytime I talke to the shop. I may just take it elsewhere. Maybe the other place for "about $800". They came with good recs.

More questions:

Q1: Can't they just swap over the lifters as is? I'm not sure why they have to be taken all apart and cleaned.

Q2: As far as vacuum testing goes (as some shops said they would do this as part of a check), does that test the ability of the vlaves to hold vacuum and not leak? And does this negate redoing the whole entire valve job?

 

[wrenchr]

Vacuum, Simply tell's you the over all health of your motor, Mainley your piston / ring seal. I would do the work myself, unless this is your daily driver and you need it on the road quickly. There are manual's that you can purchase to help you along in your project. I would change the lifter's. Again it is all torn down, why not. I firmly believe in doing it right. If it is a project that you can take your time on you can buy the parts here and there, and you will be happier after it is all said and done.

 

[thefairlaneman]

I don't mind paying it if that's my only option. I'm really interested in knowing WHY the other valves have to be done at the same time, I mean when it was running they were fine.

Is it one of those "you're in there, might as well do the whole thing" deals or is it something else?

Its because the customer wants it fixed and expects a garantee thAT IT IS FIXED, iF YOU PIECE IT BACK TOGETHER and then another valve blows you will blame the mechanic AND SAY why didnt you inspect it and know there was a micro-sized crack hidden behind the carbon on the other valves,,,,,,,,the mechanic doesnt have time to see your car back in 3 months with you wanting it fixed again for free,no offense

 

[wrenchr]

Its because the customer wants it fixed and expects a garantee thAT IT IS FIXED, iF YOU PIECE IT BACK TOGETHER and then another valve blows you will blame the mechanic AND SAY why didnt you inspect it and know there was a micro-sized crack hidden behind the carbon on the other valves,,,,,,,,the mechanic doesnt have time to see your car back in 3 months with you wanting it fixed again for free,no offense

Good point

 

[bmwpower]

Vacuum, Simply tell's you the over all health of your motor, Mainley your piston / ring seal. I would do the work myself, unless this is your daily driver and you need it on the road quickly. There are manual's that you can purchase to help you along in your project. I would change the lifter's. Again it is all torn down, why not. I firmly believe in doing it right. If it is a project that you can take your time on you can buy the parts here and there, and you will be happier after it is all said and done.

How am I going to grind/cut/whatever to the seats, etc.? I don't have the equipment to do the entire job. I don't have the special $1000 tool to remove the cams from the old head. Sure, I believe I can pop the lifters in. I would need a valve compressor. I could put the seals in if I had the tool. I don't have a way to check the springs and or ballance the valves, etc. I obviously can't do the resurfacing either. Seems like most of it I can't do.

 

[wrenchr]

How am I going to grind/cut/whatever to the seats, etc.? I don't have the equipment to do the entire job. I don't have the special $1000 tool to remove the cams from the old head. Sure, I believe I can pop the lifters in. I would need a valve compressor. I could put the seals in if I had the tool. I don't have a way to check the springs and or ballance the valves, etc. I obviously can't do the resurfacing either. Seems like most of it I can't do.

I'm not sure I'm getting this, What is holding the cam's in place? This is a overhead cam correct? These usualy are secured like main cap's.
You should strip the heads down compleatly, the engine shop will charge you for disassembly, that is a way to save coin. Pay to have the 3 angle V/J, I would buy new valve spring's. What is your engine size / liter's, Year as well. I can look around and see what the going price is for recond, heads.

 

[RAYJAY]

I'm not sure I'm getting this, What is holding the cam's in place? This is a overhead cam correct? These usualy are secured like main cap's.
You should strip the heads down compleatly, the engine shop will charge you for disassembly, that is a way to save coin. Pay to have the 3 angle V/J, I would buy new valve spring's. What is your engine size / liter's, Year as well. I can look around and see what the going price is for recond, heads.

A GREAT WRITE UP ON HOW TO STRIP THE HEADS ON BMW'S

http://www.pelicanparts.com/BMW/techarticles/E36-Camshaft-Removal/E36-camshaft-removal.htm

 

[Junkman]

After reading the information on how to do it with out the proper tool, I can honestly say that I wouldn't want to be trying this on anything other than a junk engine that I didn't care about the cams. What I can't understand is why the tool couldn't be mass produced and sold at a much lower price. My only guess is that there is very little call for the tool, and they are made to order.