Exhaust valves. Are these salvageable?

[Junker]

I'm attempting to lap these valves and as it's my first time I'm not sure what is normal wear.

02 sierra 4.8L 360k km truck ran fine, great actually. Heads were pulled for a coolant leak. Never overheated. Serviced regularly, all other engine components are in remarkably good shape

The first 3 pictures are the exhaust valve I've started on, the second 3 are an example of one I haven't touched yet

The seats look polished because I already cleaned the head and it was unavoidable. I used a rubberized abrasive rotary brush specifically for cleaning aluminum heads (name escapes me, gasket surface cleaning tool)

The burr at the edge of the valve concerns me so I stopped before I potentially damaged the seat

Looking for suggestions on how to proceed

Thanks in advance

 

[Packard V8]

Yes, they could be reground, but lapping old valves is a last century bad idea.

You're spending the big bucks/time to R&R the heads. While they're off, have them surfaced, seats cut, new valves and seals. You'll be glad you did.

jack vines

 

[cvairwerks]

New set of intake and exhaust valves are about 100$ retail.

 

[four.cycle]

not worth messin' around.
have 'em press new seats in.

like Jack said - just have them reworked properly. seats/valves/guides/seals/

we always put new springs in. some guys will re-use them if they're "within tolerance" but that doesn't make sense on a production line.

 

[APEowner]

It's always hard to tell from pictures but both the seats and the valves look salvageable but you're not going to do it with lapping.

 

[ycgoat]

I take my heads to the local machine who will do a 3 angle valve job and resurface deck for $400 a pair. Are they leaking now?

 

[Spareparts]

flip the heads face up and level drop a little water in the chamber, if it disappers they are not sealing. Grind the valves and cut thr seats
lap them in done. You are not building a race motor or a complete rebuild it's a driver

 

[nadogail]

When I worked in an Automotive Machine Shop, 1956-1959, we reground valves and seats. Valve lapping had become only a check to determine that the contact areas were within specifications. Valve stem and valve guide wear should be checked before valve and seat reconditioning is started.

 

[four.cycle]

"...for $400 a pair...."

WOW!
Last time I sold cylinder heads we were pushing Chevrolet V8 heads out the door for $150 a pair exchange.
New valves, springs, guides, seals, seats, and resurfaced.

I'm showing my age for sure now.

 

[finn]

They’re worn and need grinding, not lapping.

That said, it’s probably not much more expensive to just replace them as others have said. Grinding is fas becoming a lost art.

Definitely have the seats touched up. Your scotchbriting didn’t do anything to address seat wear. Have the machine shop replace any worn guides.

 

[charbar]

What casting # are the heads? Being an 02 it probably has 706s that had issues with cracking and burning coolant. If you haven't yet I would get them crack checked before I spent any time trying to redo them.

 

[Junker]

I appreciate everyone's input. I'm going to call around but I'd be very, very surprised if i can get the job done for less than $1000CAD. Id be livid though if i wasted my time. Money is tight unfortunately at the moment so id like to assess all my options. I can be pretty resourceful

If you were flat broke, is there a gamble you'd consider taking? Time not being an issue, I have a 2nd vehicle

 

[Junker]

flip the heads face up and level drop a little water in the chamber, if it disappers they are not sealing. Grind the valves and cut thr seats
lap them in done. You are not building a race motor or a complete rebuild it's a driver

How long should tge liquid stay? I used old mix gas because it's freezing

 

[Junker]

When I worked in an Automotive Machine Shop, 1956-1959, we reground valves and seats. Valve lapping had become only a check to determine that the contact areas were within specifications. Valve stem and valve guide wear should be checked before valve and seat reconditioning is started.

Not too late to check, I should have thought of that. From 0 I have 10 thou at the edge of the valve on open. I have no other way to measure the guides

 

[Rusted Nut]

My guess is those leak. Agree with others, new valves/valve grind, and new valve seats. Heads are off, why not fix ‘em. Now if you do that, how’s the lower end? Hard to check compression with heads off, but I’d inspect for signs of wear in the cylinders. Maybe run a dial bore gauge and check specs. Pour a little very light oil over a ring, see if it disappears; not super scientific, but can tell you if you have a big ring seal problem. If it ran good and it’s been well taken care of, lower end should be good with that mileage on it.

 

[Junker]

What casting # are the heads? Being an 02 it probably has 706s that had issues with cracking and burning coolant. If you haven't yet I would get them crack checked before I spent any time trying to redo them.

862. I was afraid of that but it turned out to be gasket failure. It has the graphite gaskets but no tab on the block. Seems to be made in the middle of the design change and got lucky on the heads. They're perfectly flat still

 

[Junker]

My guess is those leak. Agree with others, new valves/valve grind, and new valve seats. Heads are off, why not fix ‘em. Now if you do that, how’s the lower end? Hard to check compression with heads off, but I’d inspect for signs of wear in the cylinders. Maybe run a dial bore gauge and check specs. Pour a little very light oil over a ring, see if it disappears; not super scientific, but can tell you if you have a big ring seal problem. If it ran good and it’s been well taken care of, lower end should be good with that mileage on it.

It's been almost an hour and one is empty now.

I'm in uncharted waters but I think the motor is in great condition. The cam has some wear, the cylinders are OK I think? I wouldn't know if this is glazed or not. As for the rings, I let coolant sit in them for a couple days and it never went down

Can I assume these are all good signs and its worth the investment?

 

[Jswain]

If you have more time then money, already have a lapping tool & compound then you don't have much to lose by lapping the valves then check and see if the leak improves. Start with the cylinder that emptied the fastest and see if it's worth your time to do the rest

If the engine ran fine before, it's not like your building a race car. I know this won't be the popular opinion

 

[drmarkr]

It's been almost an hour and one is empty now.

I'm in uncharted waters but I think the motor is in great condition. The cam has some wear, the cylinders are OK I think? I wouldn't know if this is glazed or not. As for the rings, I let coolant sit in them for a couple days and it never went down

Can I assume these are all good signs and its worth the investment?

You put coolant in the cylinders to check the rings??

 

[BillK]

I'm attempting to lap these valves and as it's my first time I'm not sure what is normal wear.

02 sierra 4.8L 360k km truck ran fine, great actually. Heads were pulled for a coolant leak. Never overheated. Serviced regularly, all other engine components are in remarkably good shape

The first 3 pictures are the exhaust valve I've started on, the second 3 are an example of one I haven't touched yet

The seats look polished because I already cleaned the head and it was unavoidable. I used a rubberized abrasive rotary brush specifically for cleaning aluminum heads (name escapes me, gasket surface cleaning tool)

The burr at the edge of the valve concerns me so I stopped before I potentially damaged the seat

Looking for suggestions on how to proceed

Thanks in advance

First of all take a look at this page from my web site:

Abrasive Disc Cleaner

The Abrasive Disc Cleaning tool can be very useful BUT also very distructive if not used properly.

www.enginerepairshop.com

That is what you most likely did to the heads no matter what type of tool you used, even the rubber bristle type that claims to be safe on aluminum.

If you are really broke just take the valves to your local machine shop and have them reface them. They will most likely clean up good enough. Let them resurface the heads while you are at it.

Throw the lapping compound away.

 

[four.cycle]

.010" ?!?!?!?!

 

[JeepYJ]

If the engine ran fine before, it's not like your building a race car. I know this won't be the popular opinion

I’m with you on this one. It’s a 20+ year old truck with a couple hundred thousand miles. It ran before and it will run again when reassembled. Once you start down the rabbit hole of “since I’m in here…” it gets expensive. Which is what the OP a said he doesn’t/can’t afford right now.

You put coolant in the cylinders to check the rings??

Is this coolant from pulling the heads? You should’ve cleaned that up right away and poured some oil in the cylinders to keep the lubricated and rust free.

.010" ?!?!?!?!

I’m not sure what he’s measuring there? Is that side to side lateral movement with the valve opened?

 

[OccupantRJ]

I use rubbing alcohol to check valve sealing, poured into the intake and exhaust ports with the head turned on edge. Any leakage will be immediately seen around the valve in the combustion chamber.

 

[four.cycle]

I’m not sure what he’s measuring there? Is that side to side lateral movement with the valve opened?

My comment was in response to BillK's post above - the link takes you to his webpage. Removing that much material from the mating surface of a cylinder head can bring about other issues.

 

[JeepYJ]

My comment was in response to BillK's post above - the link takes you to his webpage. Removing that much material from the mating surface of a cylinder head can bring about other issues.

Gotcha- I misread that. Changing cylinder head height does have effects on geometry. I’m always surprised that huge chunks of iron/aluminum can be machined that close in tolerances in mass quantities like engines.

 

[four.cycle]

^ Just requires a machine operator who knows what the hell he's doing and knows how to read a micrometer. No problem.

 

[JeepYJ]

^ Just requires a machine operator who knows what the hell he's doing and knows how to read a micrometer. No problem.

Still amazing that someone came up with the not only the design but also all the tooling and measuring devices long before computers were invented. 1/100 of an inch isn’t much variation across a 2’ long cylinder head.

 

[Rusted Nut]

It's been almost an hour and one is empty now.

I'm in uncharted waters but I think the motor is in great condition. The cam has some wear, the cylinders are OK I think? I wouldn't know if this is glazed or not. As for the rings, I let coolant sit in them for a couple days and it never went down

Can I assume these are all good signs and it’s worth the investment?

Judging from the photos, the cylinders look good. I guess if it we me, I’d replace/grind the the valves, install new valve seats , and put it back together.

 

[gregs]

It's a rabbit hole for sure. If they sealed up that good for that long I would call it good enough for your intentions. If you where completely rebuilding it with all new machine work and parts that would be a different story. You can do a quick lap on them just to make sure they are seating around the entire circle. Use a black sharpie on the valve seat and valve face. Then twist the valve back and forth a little and remove the valve and look at the areas the sharpie was removed from. If it looks even around 100% of the circle your good to go.

And like all things you should be ready to do 100% of the job. Because if you improve the compression on the top end and don't do anything to the bottom end, typical you will hear it knock. Everything wears out together especially at that mileage.

 

[CraigStu]

I am w/ Jswain. Money is tight. I remember being there. We all know what would be needed to completely rebuild the engine. OTOH, the thing ran 'great' but was leaking coolant. Fix the coolant leak. Lap the valves as best you can and put it back together. If you want to spend a little $ get the valves ground. Or spend that on a Christmas present for your wife.

 

[Junker]

You put coolant in the cylinders to check the rings??

The coolant left in the block that spilled into the cylinders, it's unavoidable. I have to flush everything anyway so I just left it a while

 

[Junker]

If you have more time then money, already have a lapping tool & compound then you don't have much to lose by lapping the valves then check and see if the leak improves. Start with the cylinder that emptied the fastest and see if it's worth your time to do the rest

If the engine ran fine before, it's not like your building a race car. I know this won't be the popular opinion

I'm not building a race car but she thinks I am.... still, to get the valves and seats ground is actually only 400 so less than I was expecting and I'm leaning that way

 

[BillK]

.010" ?!?!?!?!

That one was about the worse I have seen but they always take a couple of thou off between the cylinders. I tell them not to even try.

 

[Junker]

First of all take a look at this page from my web site:

Abrasive Disc Cleaner

The Abrasive Disc Cleaning tool can be very useful BUT also very distructive if not used properly.

www.enginerepairshop.com

That is what you most likely did to the heads no matter what type of tool you used, even the rubber bristle type that claims to be safe on aluminum.

If you are really broke just take the valves to your local machine shop and have them reface them. They will most likely clean up good enough. Let them resurface the heads while you are at it.

Throw the lapping compound away.

The bristle type? You'd have to be ****** daft to do that kind of damage no? I went low and slow with a drill and can pull a straight edge anywhere on the surface with a .001 feeler gauge. With a die grinder I can see it but not at 200rpm

 

[Junker]

I’m with you on this one. It’s a 20+ year old truck with a couple hundred thousand miles. It ran before and it will run again when reassembled. Once you start down the rabbit hole of “since I’m in here…” it gets expensive. Which is what the OP a said he doesn’t/can’t afford right now.

Is this coolant from pulling the heads? You should’ve cleaned that up right away and poured some oil in the cylinders to keep the lubricated and rust free.

I’m not sure what he’s measuring there? Is that side to side lateral movement with the valve opened?

Yes, I couldn't think of any other way to measure the play in the guides

 

[Junker]

It's a rabbit hole for sure. If they sealed up that good for that long I would call it good enough for your intentions. If you where completely rebuilding it with all new machine work and parts that would be a different story. You can do a quick lap on them just to make sure they are seating around the entire circle. Use a black sharpie on the valve seat and valve face. Then twist the valve back and forth a little and remove the valve and look at the areas the sharpie was removed from. If it looks even around 100% of the circle your good to go.

And like all things you should be ready to do 100% of the job. Because if you improve the compression on the top end and don't do anything to the bottom end, typical you will hear it knock. Everything wears out together especially at that mileage.

That's something I hadn't considered at all. If I go improving one area, well I thought about that but not in the sense that I could actually make problems for myself. Basically do it all or leave it alone

 

[BillK]

The bristle type? You'd have to be ****** daft to do that kind of damage no? I went low and slow with a drill and can pull a straight edge anywhere on the surface with a .001 feeler gauge. With a die grinder I can see it but not at 200rpm

I see them almost monthly. I tell people if they have to use anything a good sanding block with 100 grit sandaper actually does the best job. Did you check right between the cylinders ? Thats the part that usually gets it the worse. It rounds the eges and the MLS gasket cant seal.

 

[gregs]

That's something I hadn't considered at all. If I go improving one area, well I thought about that but not in the sense that I could actually make problems for myself. Basically do it all or leave it alone

Yep

 

[gregs]

I see them almost monthly. I tell people if they have to use anything a good sanding block with 100 grit sandaper actually does the best job. Did you check right between the cylinders ? Thats the part that usually gets it the worse. It rounds the eges and the MLS gasket cant seal.

I have a piece of granite thats about 5" x 12" that I use with good 3m wet/dry sandpaper for some items I need to flatten. And a bigger granite surface plate for others. I usually go at 180 and 320 depending on how low the spots are. I also found that some of the graphite composition gaskets seem to seal better and have less failures if the surface isn't polished super smooth.

 

[drmarkr]

The coolant left in the block that spilled into the cylinders, it's unavoidable. I have to flush everything anyway so I just left it a while

Get it out of there now. And spray it all down with WD40 and then a mist of oil while turning the crank over. It's surely already flash rusted...?