Cost to rebuild GM pushrod 3.1L V-6 heads?

Originally Posted by atikovi
How many miles and why do you think they need to be rebuilt? Why not just replace the oil seals and maybe lap the seats yourself?

They are probably interference fit machined to enable the valves to fit correctly when operating. I think for example Toyota has .5 degrees difference on the seat and valve. Lapping is what I worry about rebuilders may do, and if not, how well they can achieve the precision of .5 degrees with their equipment and skills.
I would get a good straight edge and check flatness myself or have a shop do that and check for cracks. If no cracks and still flat reinstall the heads.
 
I have seen Fel-Pro sealant screened head gaskets fail so I use this and swear by it. Used it on everything, even the Cometic gasket for a Weisco 1314 resleeve overbore on a Yamaha FJ1100.

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Originally Posted by IMSA_Racing_Fan
This place can be pretty retentive so not arguing but personally if its straight and I would gasket spray and reinstall.



Yeah, I bet you would do that. Probably why you dont do this for a living
 
Originally Posted by IMSA_Racing_Fan
This place can be pretty retentive so not arguing but personally if its straight and I would gasket spray and reinstall.


There's a right way, and a slapped-together way. You'll generally have a better outcome, if things are done the right way.
 
Originally Posted by Farnsworth
Originally Posted by atikovi
How many miles and why do you think they need to be rebuilt? Why not just replace the oil seals and maybe lap the seats yourself?

They are probably interference fit machined to enable the valves to fit correctly when operating. I think for example Toyota has .5 degrees difference on the seat and valve. Lapping is what I worry about rebuilders may do, and if not, how well they can achieve the precision of .5 degrees with their equipment and skills.
I would get a good straight edge and check flatness myself or have a shop do that and check for cracks. If no cracks and still flat reinstall the heads.


Lapping is using abrasive between the valve and seat is to get a better seal. What is a .5 degrees difference for? Maybe just for initial break-in?
 
You guys are hilarious. I'm glad my dad taught me and my brother that when we were real young. He still has that machine to this day
 
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Local automotive machine shop finda a good one and you are good .Should be under 250-300 with a resurface, couple replaced valves, seals and new sets cut and lapped.
 
Originally Posted by Farnsworth
Originally Posted by atikovi
How many miles and why do you think they need to be rebuilt? Why not just replace the oil seals and maybe lap the seats yourself?

They are probably interference fit machined to enable the valves to fit correctly when operating. I think for example Toyota has .5 degrees difference on the seat and valve. Lapping is what I worry about rebuilders may do, and if not, how well they can achieve the precision of .5 degrees with their equipment and skills.
I would get a good straight edge and check flatness myself or have a shop do that and check for cracks. If no cracks and still flat reinstall the heads.

.5 degree for break-in.
 
Originally Posted by IMSA_Racing_Fan
If there's no cracks then get a head gasket set, spray with copper gasket paint and go. Why waste money?


This engine (and most other dissimilar metal engines) uses graphite/steel head gasket. This type of gasket allows for a small amount of movement due to different thermal expansion rates of the iron and aluminum. Using a spray or any other sealer for that matter can prevent the gasket from doing its job properly resulting in a blow out of the gasket in a short time.

What you describe is fine for all iron or all aluminum engines using a non coated shim stock HG and using a composite gasket is not desirable as it will lower the compression ratio.
 
That copper spray is meant for old style GM copper gaskets with iron heads/block, or the old flat head engines. It's especially a big no no on elastomer MLS gaskets, and engines with aluminum heads/iron block. It's really designed as a band aid for the cheap and lazy, but that's JMO.
 
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Originally Posted by mattd
That copper spray is meant for old style GM copper gaskets with iron heads/block, or the old flat head engines. It's especially a big no no on elastomer MLS gaskets, and engines with aluminum heads/iron block. It's really designed as a band aid for the cheap and lazy, but that's JMO.


You are absolutely correct.


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There are lots of shops and/or shade-tree mechanics that do half-axxxd work. That doesn't mean it's a good way to go about fixing anything correctly.
 
Another thing, after cleaning and oiling the threads I dial in an extra 5 ft/lbs of final torque on used head bolts. The horror! Its amazing how the cars don't come back spewing white smoke.
 
Originally Posted by IMSA_Racing_Fan
Another thing, after cleaning and oiling the threads I dial in an extra 5 ft/lbs of final torque on used head bolts. The horror! Its amazing how the cars don't come back spewing white smoke.



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Originally Posted by IMSA_Racing_Fan
Another thing, after cleaning and oiling the threads I dial in an extra 5 ft/lbs of final torque on used head bolts. The horror! Its amazing how the cars don't come back spewing white smoke.




TTY by chance?
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Originally Posted by IMSA_Racing_Fan
Another thing, after cleaning and oiling the threads I dial in an extra 5 ft/lbs of final torque on used head bolts. The horror! Its amazing how the cars don't come back spewing white smoke.


Just because you've gotten lucky hacking things over the years doesn't mean what you do is the industry standard. And that copper stuff will not seal actual cracks. It MAY fill in MINOR surface imperfections.
 
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I did a head gasket job on a Grand am for a co worker several years ago. Had a 3.1 or 3.4 can really remember, but same engine family. It had a leaky lower intake gasket and the co worker never checked his fluids and ran it low on coolant and overheated it.
Before I even agreed to do the job, I advised him we should sent the heads to the local machine shop, they would clean them and pressure check for cracks for $100.
Didnt even get to that stage, once removed, one had a visible crack between the valves.
Got a pair of junkyard heads, sent to machine shop for cleaning and inspection. They got a clean bill of health from the machine shop. They went on with a set of Felpro gaskets and new tty bolts. No sealer or goo on the head gaskets, and a set of the improved design Felpro lower intake gadkets.
Car ran well afterwards and the engine outlasted the rest of the car!

Moral of the story is, dont trust the heads on a car that was overheated! Call a local machine shop and see what they will charge to clean and pressure test them and check for cracks. In my area, it runs about $50-80 per head.
 
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