Exhaust manifold bolts:Standard or Metric?

[Gray]

I have a '95 6.5 TD Suburban that I am restoring. I have hit a snag and can't seem to figure out what size the bolts are, they are too rusted. Can anyone give me a hand on this? Are they standard or metric?
Thanx

[More Power]

The exhaust manifold bolts are metric, but incorporate a slightly different thread configuration than other 10mm bolts used on the engine. Because the exhaust manifold bolt torque is less than that used with a typical 10mm bolt, the threads are made to be semi locking, which won't loosen easily on their own on a running engine. Using a typical 10mm tap & die will reduce the locking effect the bolt threads have. If a wire wheel & rust remover won't clean them up sufficiently, you may need new ones. They're pretty cheap when bought new from GM. ;)

The exhaust manifold bolts are torqued to 18-26 ft-lbs during assembly, where most other 10mm bolts on the engine are torqued to 25-37 ft-lbs. This lower bolt torque allows the cast-iron manifolds to move some against the cylinder heads due to expansion & contraction. The semi-locking bolt threads allow a lower bolt torque to maintain clamping load without working loose.

Jim

[ercaduceus]

I need new exhaust manfold bolts. Does anyone know the GM part # or where to find it?

Thanks,

Mike

[Gray]

Thank you for the assistance. It's appreciated. One more question. If it's a 10mm bolt, does that mean it has a 14 or 15 mm head, the bolts are so rusted both fit.

[john8662]

Thank you for the assistance. It's appreciated. One more question. If it's a 10mm bolt, does that mean it has a 14 or 15 mm head, the bolts are so rusted both fit.

It has a 15mm head on the bolts.

[Gray]

It has a 15mm head on the bolts.
Thank you very much:D

[Robyn]

There a a few diffrent lengths and types on these bolts as some have a stud on top some are shorter and so on.
The Ma General store should get you going right quick as these are readily available though GM parts. ( Take all your originals and count how many of each type, this will make the job easier for the parts man as the book gets a bit hinky in this area)
Use never seaze on the threads when you put them back in the head.

A standard tap will clean the threads in the head fine. The bolts as has been mentioned are a locking type and the threads are rolled and then a tricrimp is done to make then stay tight.

Once they get coroded and nasty new is better.
Note most all threads on the engines are metric. The tranny/ bellhousing bolts are 3/8-16 NC
There may be a couple other odd bolts but mostly metric inside and out.

Good luck
Robyn

[rustyk]

I need new exhaust manfold bolts. Does anyone know the GM part # or where to find it?

Thanks,

Mike

I got mine from a Chebby dealer. There are two lengths, and I don't remember how many of each is needed:

10137539 BOLT/SCRE C 3.275 $4.03 ea
14028922 BOLT B 9.173 $4.91 ea

Apparently, they're not commonly in stock. Because I coouldn't round up all the ones I needed, I got the equivalent heat-treated from a local fastener supply place; I can't find their invoice to give you the specs.

[ercaduceus]

Thanks for the info.

Mike

[bigredtruck]

5 of 10137539 stud 85mm long(2.55 per stud)9 of 14028922 65mm long(3.02 per bolt)4 of14928923 45mm long(5.89 per bolt) these are sold in packs of five at gm all for around 73.00 or you can go to gm partsdirect.com 34.50 plus ship for 60.00 double check part #s with dealerhope this helps