bolt hole repair on engine block

[JeepsAreBuilt]

I got myself in some trouble with my jeep motor

A water pump bolt broke off in the block. It is a steel block, a buick v6 motor. The bolt is a 5/16", and it holds the water pump on the timing cover though the block.

So, It snapped off.. I pulled the timing cover, attempted a easy out, no worky as the easy out was stripped(worn or whatever). I moved on and tried a splined type of bolt extractor, the kind where you drill a hole and tap it in, and wrench it off. And then what the heck ! It snapped off in there ! Next, I got a die grinder with a carbide grinding bit and grinded it some, and then was able to drill out the bolt extractor. Now I got messed up bolt hole at the start, and the remaining 5/16" bolt in there with a 3/16" drilled hole(not so straight) in here.

Now, I think I should stop trying to fix it myself without advice from a collective group of people(better than me). The remaining good threads in the block is about 3/8" deep(with the broken bolt still in there). I am hoping to save it, so I can still use a a bolt in there. What should I do ?

I have some ideas:

1. Drill it out more, and tap it out with a 5/16" tap.
2. Go next size bigger(may have to ream timing cover)
3. Weld the bolt hole up and drill tap(sounds good ?)
4. Helicoil(.47xx" would be the drill size required for a 5/16" helicoil, and may not be enough meat for that)
5. form a thread
6. New block

 

[Adam McLaughlin]

How about a left handed drill bit?

Adam

 

[JeepsAreBuilt]

How about a left handed drill bit?

Adam

I used a left hand drill bit when I tried the easy out..

 

[Steve from Socal]

You have to drill completely thru the part still in the block to relieve the tension on it. When you get it out even if the hole is really wallowed out it can usually be repaired. A threaded insert can be used with up to a 5/8 OD thread.

If you can't drill the broken remover try heating it to cherry red, that will soften the steel somewhat and try a cobalt left hand drill bit.

Steve

 

[Stick Figure]

If you still have good threads and want to keep them rather than repair them, why not make a quick drill jig based off of the other hole locations of the water pump, then use a drill guide to get the drill bit going straight.

 

[JeepsAreBuilt]

If you still have good threads and want to keep them rather than repair them, why not make a quick drill jig based off of the other hole locations of the water pump, then use a drill guide to get the drill bit going straight.

Interesting idea.. the point of this is to drill a good hole for a tap right ? Can you give me more of an idea how to make this jig ?

 

[Daedalus]

Use a shorter bolt? In general a bolt is good if you can bury it as deep as its diameter. Nearly all tension is carried by the first 3 "good" threads, and you assume the first thread isn't any good. You might have to shop around, but you can usually get bolts in increasing grip lengths of .063" (1/16"). Even with a coarse thread bolt you would get 5 threads of engagement. Make sure you don't bottom out on the broken shank so you get the proper preload when torqued.

 

[gorilla]

To make a drill guide you will need to find a piece of plate large enough to pick up two holes plus the one needing repair, if you can't find a plate 1/2" or thicker weld a thicker piece of material over the hole you need to repairl. Use the gasket as a template and drill the needed holes in the plate. The guide hole should be drilled the size of the tap drill you chose to use. After you drill the block remove the guide and redrill the guide to hold the tap strait. All the drilling should be done with a drill press or a mill.

 

[JamieK]

Do you have a mig welder? I've always had good success by welding a nut onto the broken stud. Heres a step by step tutorial...

http://4x4preservation.com/forums/showthread.php?t=382

 

[Stick Figure]

To make a drill guide you will need to find a piece of plate large enough to pick up two holes plus the one needing repair, if you can't find a plate 1/2" or thicker weld a thicker piece of material over the hole you need to repairl. Use the gasket as a template and drill the needed holes in the plate. The guide hole should be drilled the size of the tap drill you chose to use. After you drill the block remove the guide and redrill the guide to hold the tap strait. All the drilling should be done with a drill press or a mill.

Drilling w/ a drill press or a mill is going to be tough on the block unless he is going to do a LOT of extra work. i have had great success w/ these http://www.mcmaster.com/#drill-bushings-and-liners/=73c07j. I actually use them to in a jig to drill a couple of holes i have to drill in cylinder heads on a pretty regular basis. This is so tight that i can't even see straight on the thing, and have to use an 90° angle drill to even fit so i know they will hold the bit dead straight.

but otherwise thats pretty much what i had in mind.

 

[JeepsAreBuilt]

Sounds good.. I dont have any 1/2" plate laying around. How about some rectangle tubing ? I could make a jig and bolt it on the block. I have some 2x4x1/4" stuff.

too late for welding on a nut.. next time I'll try that.

And, I'm wondering.. what do you guys think of welding the hole back up and drill/tap it ?

 

[brownfoot]

use your water pump as the drill guide
bolt the pump to the block, press a bushing in the water pump bolt hole
that will center the hole properly with the hole in the pump
once the hole is centered it can be enlarged to the size needed for tapping
the pump without the bushing can be used to keep the tap straight

 

[e-tek]

If you still have good threads and want to keep them rather than repair them, why not make a quick drill jig based off of the other hole locations of the water pump, then use a drill guide to get the drill bit going straight.

Do This.......

You have to drill completely thru the part still in the block to relieve the tension on it. When you get it out even if the hole is really wallowed out it can usually be repaired. A threaded insert can be used with up to a 5/8 OD thread.

If you can't drill the broken remover try heating it to cherry red, that will soften the steel somewhat and try a cobalt left hand drill bit.

Steve

Then this.....

Then This:

 

[gorilla]

I'm sorry, I should of made myself more clear. I meant that the drill fixture should be drilled on a drill press not the hole in the block. Drill bushings are always a good thing but not really needed to drill one hole IMHO. Using the water pump as a fixture is a really good idea! Good Luck.

 

[Stick Figure]

gotcha, that makes more sense. Using the water pump w/ a bushing though sounds like the best bet, no drill press or mill needed.

 

[JeepsAreBuilt]

Thanks for all the tips.

Today, I got a tap in there and tap'ed the hole. It had a 1/4" drilled hole all the way though, and it was slightly off center. I thought If I tried to tap it, it would break away the old bolt and I'll be able to clean it out. Well, the tap just cut though the old bolt and I think put new threads on the side of the block. It did tap very easily and was not much material removed. After finishing, I can see what looks like I have tapped threads in the old bolt, and it is on the side only. I did fit everything, and it fits good. The bolt is 4.5" long as it goes though the aluminum timing cover and water pump.. there was a slight rubbing on the timing cover as the bolt is not perfectly straight.

Should I run it, or will it fail ? There are plenty of other bolts holding the timing cover on, and water pump on. I was able to get a 5/16" helicoil kit incase I needed it, but I am thinking I probably wont get the bolt much straighter than it is now.

For new bolts.. should I get some grade 8 bolts(it had grade 8) or some SS ? The old bolts have some rust pitting and the threads corroded away.

 

[rsanter]

I have had the same thing happen before where you tap the hold and there is still part of the bolt there and you tapped new threads right into it.
if the remaining threads were that stuck then they will stay.
I wouls worry a little about the new bolts rusting to the old bolts threads and then you have a cam-lock situation next time you go to take that bolt out.
I recomend that you use some anti-seaze or silicone on those threads to reduce the incident of future thread rusting
put a new bolt in and run it

bob

 

[moparmuscle88]

ive done the same thing and the old bolt that i tapped thru was still holding 3000 miles later when i junked the car

mine however was an intake manifold plug that i retapped the inside of it

 

[JeepsAreBuilt]

Ok sounds good.. I'm going to use some thread sealant.. as I need to seal this bolt as the bolt hole goes though to the water chamber in the block.

I certainly hope it'll last more than 3k !

 

[Pat]

Next time providing you have, or can borrow the equipment, I would give the Mig weld removal technique provided by JamieK a try. I have had excellent results with this method as long as the bolt broke off flush, or a little above the surface. If you break a bolt off below the surface try to get a hold of a few sticks of 3/32" ( good for bolts or studs up to 3/8" ) Messer MG600 welding rod. This type of rod was designed for broken bolt and stud removal. It is actually referred to as Stud Pull Rod. The reason this works so well is because it has a special flux that will fill in the threaded area and protect it from any metal adhering. It is also a lot stronger than normal mig wire which is about 70,000 psi. The MG600 is approx 130,000 psi and can work harden to about 180,000 psi. If you get a good weld, this stuff will not break very easily, and you can even use an impact to remove the broken bolt after you have welded a nut on the end.

 

[rsanter]

Ok sounds good.. I'm going to use some thread sealant.. as I need to seal this bolt as the bolt hole goes though to the water chamber in the block.

I certainly hope it'll last more than 3k !

it will last far more than 3K
the cause of the rust is the fact that it goes into the water passage.
wire wheel the snot out of the other bolts or replace them.
chase all the threads and apply sealant to all threads that will be exposed to coolant to help avoid rust on them in the future.
when you apply the sealant to the threads dont just put a glob on them. use your finger to apply a thin smear across all the threads. you want a coating of it between the bolt and the block, you dont want to push excess into the engine that could end up in the radiator.

bob

 

[JeepsAreBuilt]

Next time providing you have, or can borrow the equipment, I would give the Mig weld removal technique provided by JamieK a try. I have had excellent results with this method as long as the bolt broke off flush, or a little above the surface. If you break a bolt off below the surface try to get a hold of a few sticks of 3/32" ( good for bolts or studs up to 3/8" ) Messer MG600 welding rod. This type of rod was designed for broken bolt and stud removal. It is actually referred to as Stud Pull Rod. The reason this works so well is because it has a special flux that will fill in the threaded area and protect it from any metal adhering. It is also a lot stronger than normal mig wire which is about 70,000 psi. The MG600 is approx 130,000 psi and can work harden to about 180,000 psi. If you get a good weld, this stuff will not break very easily, and you can even use an impact to remove the broken bolt after you have welded a nut on the end.

I wish I knew about the mig method.. I would have done it. Next time.

Very cool about that MG600 stuff.. sounds like the best way to go. I did a google and found a thread on another msg board about it.. http://www.hobartwelders.com/weldtalk/showthread.php?t=14860



Bob - I plan on using some permatex thread sealant. 2 of the bolts go into the water passages. I thought of squirting some RTV in the hole, then putting coated bolts in.

Today I spent some time running a tap though all the bolt holes - lots of crud in there ! The thing is almost 45 years old.

 

[Daniel Dudley]

Do you have a mig welder? I've always had good success by welding a nut onto the broken stud. Heres a step by step tutorial...

http://4x4preservation.com/forums/showthread.php?t=382

Great link !