I just had the heads re-conditioned on my 2.8 after 210,000 miles. The car ran great but a previous owner stripped out TWO exhaust studs on the forward head. I thought (erroneously) that the easiest fix would be to pull the heads off rather than drop the engine. Is it really necessary to replace the head bolts? GM also uses a sealer on the threads, Is this really necessary? I built many engines in the '70's without new head bolts and sealer, have things changed that much in the last 40 years?

Yes things have changed. The head bolts are designed to stretch when torqued. So when you remove them they are stretched. New bolts are HIGHLY recommended.
Sealer, some of the bolts go thru the water jacket. I would rather have sealant around the threads than engine coolant.

This is true for the 2.5L, but I am not sure about the 2.8. I reused the head bolts without an issue.

i dont know if they are TTY or not, but the torque procedure leads me to believe it is. On the new bolts, the last step is to turn 90 degrees. the set is 25 bucks at kragens, and head bolts are one of the places you shouldnt try to save money.

side note: i also used the perma torque severe duty head gaskets.

The 2.8 is TTY. Period. Get new bolts. Cheap insurance, and isn't doing it correct better?

Tony

GM service manual says to tighten to 90NM... nothing about replacing bolts or anything else. The 2.5L states to turn an additional degree (which would be a TTY bolt). I am not saying they can't be replaced, but does anyone have information that states they should be replaced?

I do not have the information in front of me, but when I blew out a lower intake gasket on my new build 2 years ago, TTY was the answer. I am sure of it.

A TTY bolt stretches to provide maximum contact with the internal threads. It is this frictional contact that holds a bolt in place, and even one torqueing can and does change the fasteners ability to hold.

I have worked in the robotics and automotive industry for a long time in the past. Never have I heard it is ok to reuse TTY bolts. Someone will always say "it is ok", but when the thing breaks, that person that claimed "it is ok" cannot be found.

Tony

How are TTY bolts installed? Don't you need to set an angle after torquing it down? The 2.5l has instructions for this, but the V6 doesn't (from the GM manual). Your experience with a broken bolt is not uncommon, but I am trying to determine if the 2.8 uses TTY, as the GM service manual doesn't seem to indicate it. I will check my V6 rebuilt book at home also.

I found this... https://www.fiero.nl/forum/A...050410-2-057224.html

So... if new bolts are TTY, what is the proper torquing sequence, as it seems the original ones are not TTY.

[This message has been edited by jaskispyder (edited 07-28-2011).]

The 2.8 Fiero motor head bolts are most definitely *not* TTY, not even in the slightest. About all you need to do is wirebrush the old sealer and any rust off the shafts and threads, oil the shafts, and install with new non-hardening teflon-based sealer. The only reason to replace a bolt is because it's broken or too corroded to use.

The key to telling if a bolt is TTY is the torquing instructions. TTY bolts require torquing to a low value, then tightening a specific number of degrees afterward.

quote Originally posted by Doni Hagan. Last summer, I got coolant in the oil/overheating/missing/white smoke/etc, all the classic blown head gasket symptoms. When I tore the engine down, I discovered the gaskets didn't blow.....a bolt snapped right at the thread on the front head. This I discovered AFTER I had all but the last three bolts out of the second head. I recalled that when I put the 3.4 in the car last year (64K on the block) I replaced the head gaskets (to be SAFE, right?) but DIDN'T replace the bolts... Moral? SAVE YOURSELF THE HEADACHE, SPEND THE $22 (Murray's) AND GET NEW HEAD BOLTS!! That's my 2 cents.

As is mine. Like I said earlier, listen to who you want. If the price of the bolts are an issue, then reuse the old bolts. It is only my personal experience that once a bolt is torqued, it can never be accurately retorqued. It may not say TTY, but even then, just how many hours are you going to have into replacing a broken bolt, or an improper torque hold from the one that cause you to need repair.

The consensous seems split, but piece of mind is worth much more than my advice. I have no issue on reusing a bolt that is not as important as a head fastener, but....

Tony

Edit: It seems that lately any advice I give gets scrutinized. Is it any wonder that so many of us are fleeing the Tech section? Use any advice that you choose. (Not directed at the OP. Just a very broad generalization.)

And FYI, this is how I do things...

[This message has been edited by Tony Kania (edited 07-28-2011).]

this has been flogged to death in the past. still no definite answer. I would wonder, "were they even useing torque to yield bolts in 1985 ? MY question would be: if a bolt is torqued to 100 lbs, & it stretches, if you took it out then retorqued it ot 100 lbs again, COULD YOU DO IT? or would the bolt just "keep stretching ?? all the descriptions of these bolts seems to "infer" that the TTY bolts will only get to the premade torque, then "go no more". in "theory, sounds good. Me, well, I'm old school, I "LIKE" good old fashioned "grade 8 "& above bolts !

quote Originally posted by Tony Kania: Edit: It seems that lately any advice I give gets scrutinized. Is it any wonder that so many of us are fleeing the Tech section? Use any advice that you choose. (Not directed at the OP. Just a very broad generalization.)

I hope that was not directed towards me, as I am only trying to discover the truth, so others don't have to have this battle. I am trying to use documented sources. Bolts breaking and such, happen, but does that mean the bolts are TTY or maybe they were overtorqued by someone or maybe they were defective.... who knows. Your suggestion to replace is a good one, but it would be helpful to know what GM intended their mechanics to do. Sometimes you don't have the money or the time to get new bolts, and if they are not required, then some grief can be spared. Rebuilding the top end of an engine can be expensive enough and for those on a tight budget replacing bolts maybe a call that has to be made.

Thanks!

I have always re-used my head bolts
I have rebuilt this motor at least 3 times, and beat it regularly. have yet to have a related failure.

the new bolts i got had torque specs different from the manual i have. the bolts i got were TTY im pretty sure, 30, 60, then 90 degrees. maybe the original bolts werent, but if you buy new ones they might now be tty.

quote Originally posted by jaskispyder: I hope that was not directed towards me, Thanks!

Not at all. You are very cool with me. I am mearly venting.

Tony

Per the 88 Service Manual Section 6A2-17

Clean cylinder head bolts

Coat cylinder head bolts threads with GM 1052080 Sealer, or equivalent, and install bolts.

Tighten bolts in sequence - 90N-m (66 ft. lb.)

I would like to thank everyone for their input. It has been over 30 years since I have built a motor and I know a lot has changed in that time; mostly for the better. I bought a set of Fel Pro bolts from the Fiero store, and Monday I will search for some thread sealant. When I have time and money I will do a complete rebuild. I need to get the car back on the road so I can start my '84 Duke to 2.8 transplant (my daughter spun a bearing and I have a 2.8 lying around from my '85 SE).

To me, its all a matter of taste. If your going to put 4000$ into an engine, replace them. Its just common sense.

Its like rebuilding the whole engine, and not changing the oil pump. Your there, so don't cheap out and disgard.

I like things 100% done right and new. Again, brand new engine & old spark-plugs...makes sense? No...not at all.

You can do it...but on my engine, I won't let that happen.

I'm not a cheap ass...

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fierogt28

88 GT, Loaded, 5-speed.
88 GT, 5-speed. All original.