vettenuts

Well, I took advantage of being at Carlisle to look at some L-98 exhaust manifolds. I was surprised to see how far the EGR tube and air tubes protrude into the exhaust flow. I plan to remove the manifolds and smooth things out. Has anyone removed their exhaust manifolds and any problems getting out the bolts. Looking to gain from other's problems/mistakes. :hat

Flame Red

Bob,

Just curious. If you are going to all the trouble of removing the manifolds, why not just go with headers?

Flame Red

65Z01

The manifold bolts go into Al heads so the same precautions as with spark plugs would be appropriate.

After hearing some horror stories here about stripped out Torx bolt heads on the EGR tube I used great caution getting out the two that hold the tube to the header pipe. I had to put the Torx bit on the end of an extension and rap sharply several times on the end of the extension before they would break loose. Even then I had to lean on the wrench and slowly apply torque to get em free. The two bolts into the manifold were no problem. Of course I used antisieze on their threads before they went back in. I would think that antisieze on the stock header flange bolts would be a good idea too. In fact use it any place where a steel bolt goes into Al.

I'm surprised to hear this about the stock exhust system design. I found similar problems with a set of Edelbrock TES and had to "massage them" with a Dremel before installation.

You have come up with a good tip for those of us that want to retain that stock look and/or Ca residents. Thanks for the tip.

vettenuts

Want to keep the stock system if I can. The amount of protrusion is unbelievable, so I figure for the few bucks a gasket costs, I can probably pick up a nice little gain.

65Z01

I hear that. Wish I'd checked it out while there too. I had no idea it was even an issue.

If you compare the cross section of the exhaust with and without the protrusions sounds like you will see quite a restriction. Now I've got to check mine out, I'm always looking for another tenth.

Aggravated4life

Hey Bob,
If youre going to remove the manifold, do so with the egr pipe still intact.I believe you have 2 bolts holding the egr tube pipe at the middle.

These bolts tend to seize/snap off and I advise to heat the 2 small bolts up first before attempting removal.
You can do so with it still on the engine or put in a bench vise(my preference) and torch them up nice and hot til they glow a bit and they should come right off.

I bought a pair of '90 manifolds and it had the same issue, the egr pipe connection bolt were snapped off in there and I needed to drill them out.

As far as the bolts go for the manifolds to the heads, they arent usually torqued down very much from the factory and should come off pretty easy.
Mine came off with 90 k Miles with no problems.

Just Hope the hot and cold cycles didnt make them a permanent residence in there. :(

As always, use anti seize on them when re installing.
I did mine before and the next time I needed them off, they came off easily with no thread damage.
Didnt have any problems with them needing to be re torqued.

BTW, I dont like the GM gaskets for the manifolds...fel pro makes a long silver one piece gaskets for the exhaust manifolds and ive used them for 4 years now.
The GM 3 piece set can be a pita to align up when threading the bolts back through by hand.

However the fel pro gasket isnt D ported on the bottom like the GM ones are but they dont get in the way either of the exhaust ports itself from what I saw.
Keep us posted.

lareauxr@yahoo.com

I am sure someone delt with this issue egr tube at exhaust manifold the two torx bolts stripped can I drill them out tryin to do valve guide seals getting off to bad start any suggestions thanks vette7

WW7

If Im not mistaken you can just drill straight through both sides then put a nut, bolt and lock washer in to hold it together...As long as it's held together it shouldn't matter how it's done..Those bolts do snap off often, because of the extremely hot/cold cycles....WW

Next time maybe start your own thread instead of digging up a 14 year old one....
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Vic'89

from 2001

blackozvet

apparently vettenuts is still in his garage, and has nearly got the last exhaust bolt out !!

WW7

If you take your time you don't make as many mistakes......WW

Joe C

just pulled the exhaust manifolds on my iron head 85. bolts came out without issues, but then again, "iron heads." agreed, the AIR tubes do protrude into the manifold a bit. trimming them down may or may not provide you with any performance gains - nothing you'll feel by the seat of your pants anyway. not to go OT, but if you pull these things, inspect the exit flange studs. mine were in pretty bad shape. GM/OEM are crazy expensive (about $12 EACH!), but a box of 10 from amazon is less than $20 (got mine for $5.83 - before they realized the price typo - )



BTW, the on-line application data says otherwise, but they are a perfect fit. ...and finally, anti-seize the pi$$ out of the hardware when re-assembling! this is some really high temp stuff -




(edit) DAMN - just realized it's a 14 year old thread -

WW7

Joe, Go get another cup of coffee to wake yourself up...Then come back......This is why I hate when people revive these old threads, it really messes with your mind and wastes your time........WW

Joe C

WW - on cup three already. not so much the coffee, but it's the killer margaritas last night. that's the problem -

I heard he gave up, threw in the towel, sold the car, and moved on to the dark side (C5 forum)

WVZR-1

I believe the "more recent poster" and most anyone that is an "infrequent poster" attempts to likely use the search function looking for "solutions" and they see the "new reply" button and assume NEW IS NEW overlooking the REPLY aspect.

Some forums if you attempt a "reply" to an older thread display a "pop-up" asking if you realize what you've done and ask you to consider a new thread. I believe the "NEW TOPIC/THREAD" button can only be accessed by a return to the GENERAL, PERF or SALE ETC. headers.

There's so much that is way better than "what was" - I don't know that it's beneficial to fuss much. It's pretty easy for software guys to screw up way more than they fix when asked to change things. Perhaps some of that isn't by accident. Perhaps a "NEW TOPIC" button alternative next to the "NEW REPLY" button BUT at what cost?

WW7

WVZR-1
I've gotten myself in the habit of now looking at the dates of threads before progressing, but a lot of times if you don't look, you spend time ( Like Joe did) replying to an old thead which is useless ...We use to have a rule not allowing threads over 45 days old to be revived...I really think this rule should be brought back.....But until the rule is brought back, I will continue to let the Noobs know they have screwed up.....WW

WVZR-1

I can't agree to the 45 day thing BUT perhaps the "POP-UP WARNING" and giving the option to start NEW

- WE implies "ownership" and that WE don't have. Like I mentioned there's way more good than bad to the newer format and I ain't gona fuss

Joe C

- it would be easy - search old and start a new thread. not sure I "totally" wasted my time though - feel I provided some, somewhat, useful info - maybe not to vettnuts but maybe others. in retrospect, vettnuts has move on to the C5 forum, so my reply most likely is useless info to him -- if he even sees this. there lies the problem.

WW7

Sorry, didn't mean your info was a waste of time, just that he can't use it now........You always give good information.. Well, except maybe when you've had to many killer margaritas .....WW
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Joe C

well, that's contrary to popular belief -

- la fiesta, ormond beach - a couple large frozen, and to the 20,000, or so, dead brain cells, RIP -