What bolts can we re-use on an engine rebuild? (Page 1/1)
82-T/A [At Work] FEB 15, 08:09 AM
I tried searching the intarwebs... can't find anything. I did find a few things, but not the primary thing I'm looking for.

My daughter's rebuilding her 2.5L Iron Duke. It's a totally stock rebuild with many new (quality) parts. I'm not cutting corners on a lot of the wear items, and buying decent stuff. Still, I don't expect it to see the engine really pushed. That said, I want to make it as bullet-proof as I possibly can, so I'm not skimping on anything.

Big two questions for me are:
- Where can I get replacement bolts for the 2.5 Iron Duke?
- What bolts can I re-use on the engine in a rebuild?

I've already got a set of brand new GM OEM factory head bolts (including the bolt that has the sealant thread on it)... I know from decades-ago experience that these cannot be re-used. So... I'm good there. I also have a completely new set of waterpump bolts since I ordered them with the Bosch kit that I purchased.

Other questions though:
- Flywheel bolts. Can these be reused? They seem good.
- MOST IMPORTANTLY... bearing main cap bolts... I can't find these anywhere. I have our complete set, but is it OK to reuse these?
- Connecting rod end-cap bolts, again... I have these, is it ok to re-use these?
- Engine to transmission bell-housing bolts. The previous owner seemed to use a hodge-podge of different bolts with different head sizes. Can I order a new set?

Thank you!!!

Dukesterpro FEB 15, 10:16 AM
This is purely personal opinion. The only bolts I wouldn't reuse are the head bolts (obviously) and the flywheel bolts. Everything else should in theory be able to be reused.
sleek fiero FEB 15, 05:23 PM
the flywheel bolts and main bearing bolts can be reused along with the rod bolts. the only stretch bolts are your head bolts which should not be reused. Common sense says any rusted or damaged bolts should be changed with matching grade and length of bolt.
82-T/A [At Work] FEB 15, 05:48 PM
Thanks guys! I really appreciate it! I forgot to ask another question... should I be using blue thread-locker on these bolts, or any kind of thread-locker when I re-assemble these components?

It's been almost 20 years since I re-assembled an Iron Duke... and while it ran fine when I was done, I am QUITE sure it didn't last too long after I got rid of it... I did some ghetto **** back then.
theogre FEB 15, 06:06 PM
The Head Bolts for 2.5 is Not Torque To Yield but Should Not Reused because of other problems w/ factory ones.

Most to all of the rest can be reused unless:
Rust didn't rot the heads etc.
Never been Heated to remove them.

Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

[This message has been edited by theogre (edited 02-15-2024).]

Frenchrafe FEB 16, 03:53 AM
Yes, as the others have said, everything is reusable apart from head bolts and flywheel bolts.
That being said, how many of us have put a good dose of Locktite on a flywheel bolt and shoved it back into use?!

"Turbo Slug" - '87 Fiero GT. 3800 turbo. - The fastest Fiero in France! @turboslugfiero

82-T/A [At Work] FEB 16, 08:16 AM
Thanks Ogre, TurboSlug!

I'll order a new set of flywheel bolts... I see them on Amazon for fairly cheap by ARP... so small price to pay for better quality.

Do you guys use any thread locker or anything on any of these bolts when you re-install them? I know not the head bolts... but I only ask because the last time I did this... well... I managed to get it back together and running (in an 84 2m4 SE)... and the person I sold it to (gave it away to) never complained. but I know I could have done it better. I'll have my daughter actually torque everything to spec, rather than just tightening everything down with all my might like I did back in the day. Hahah...
theogre FEB 16, 09:36 AM

Originally posted by Frenchrafe:
Yes, as the others have said, everything is reusable apart from head bolts and flywheel bolts.
That being said, how many of us have put a good dose of Locktite on a flywheel bolt and shoved it back into use?!

Again, Flywheel/flexplate bolts are reused on nearly all vehicles including Fiero.

MOST "Pros" never replace these unless damage & Don't use locktite either. Most have Torque wrench & clean the parts then tight to spec & never has problems.

Most clutch problems are cause by Drivers & other fools & too long list of examples. Some clutch problems are cause by "wear" like TO Bearing binds for several reasons.

IOW when you see bolts gets loose/lost/breaking is 99% cause by morons don't torque flywheel &/or Pressure Plate right or think they can replace either w/ any bolt you find w/ same thread.

Related: Duke Intake Manifold will "hate" you if not having OE Bolts or don't torque right for same & other reasons. Examples (Some may only apply to 87+ dukes.):
Some or all bolts are "washer head" types that spread bolt load on the intake.
#4 cyl will suck coolant because gasket is loose.
Any cyl can leake vacuum for same.
If has "Engine hanger" bracket on #4 end & someone thinks to remove it, intake bolts can bend push rod(s) because now too long where in enters the head.
Intake can Break if the bolts are too tight because intake can't move right during heat cycling.
Dukesterpro FEB 16, 09:44 AM
While I will say that flywheel bolts are not torque to yield, most engine builder will tell you to replace them anyway. I worked with a NASCAR engine builder for a while flywheel bolt will always be replaced.. Built everything. For 12 dollar bolts, there no reason to risk having a 40lb Beyblade ricocheting around your aluminum bell housing.