Exhaust Manifold Warped? (Page 1/2)
jazz4cash FEB 18, 07:48 PM
I have the typical exhaust manifold leak on the left (firewall side). I think the leak is not too serious because it is barely detectable after the engine warms up. From what I've read here, I expect the manifold could need to be reworked (e.g milled flat, cracks welded, etc.)

Question: Has anyone experienced a manifold that was warped beyond rework or unusable for some other reason?

Thanks in advance
FieroJimmy FEB 18, 08:37 PM
Well, just about anything CAN be fixed. The question would be whether or not it is WORTH fixing. If the repair cost gets too high, replacing it may be more cost effective.

Since you don't hear it much when it's warmed up, it is likely repairable.

Other possibilities include one or more broken manifold bolts, and there is a heatshield between the head and manifold that can rust out.
Patrick FEB 18, 10:54 PM

quote
Originally posted by jazz4cash:

I have the typical exhaust manifold leak on the left (firewall side).



"Left"? By "firewall side", I assume you mean the front bank?

The biggest challenge might be the need to drill out broken exhaust manifold bolts. Not a fun job.
pmbrunelle FEB 18, 11:33 PM
The design of these factory 2.8 manifolds is essentially marginal from the factory; they will always be prone to cracking / leaking problems, and prone to broken bolts.

I guess you're finding this out now.

Really bad warping (the three flanges no longer aligned with each other) could be repaired by cutting the manifold into three sections, bolting each section to a spare head (or Rodney Dickman's jig if you don't have a spare head), and then re-welding the sections into one piece:


Resurface each flange first:


I went a step further and installed bellows in my 2.8 manifolds:

By installing bellows, you address the root cause of all the damage that occurs (cracking, broken bolts, leaks): stress caused by thermal expansion of the manifold relative to the head. You don't necessarily have to go this far.

If you have broken bolts stuck in the heads, save yourself the time and pull the head(s); these problems are better dealt with on a bench.


quote
Originally posted by Patrick:
"Left"? By "firewall side", I assume you mean the front bank?



Left and right conventions come from the traditional longitudinal front-engine, rear-wheel drive layout... imagine the pulleys as being the front of the engine, and the bellhousing as the rear end of the engine. Left and right follow on from there.

[This message has been edited by pmbrunelle (edited 02-18-2020).]

Patrick FEB 19, 03:39 AM

quote
Originally posted by pmbrunelle:

Left and right conventions come from the traditional longitudinal front-engine, rear-wheel drive layout... imagine the pulleys as being the front of the engine, and the bellhousing as the rear end of the engine. Left and right follow on from there.



I'm aware of that. You're aware of that. So now perhaps you can explain how the statement I quoted and asked for clarification makes any sense then... unless the trunk is the firewall.


quote
Originally posted by jazz4cash:

I have the typical exhaust manifold leak on the left (firewall side).


pmbrunelle FEB 19, 12:23 PM
I don't see any contradiction in OP's statement.

Camaro 2.8:


Fiero 2.8:
Patrick FEB 19, 01:15 PM

quote
Originally posted by pmbrunelle:

I don't see any contradiction in OP's statement.

Camaro 2.8:...



The picture of the Camaro's engine bay would make more right-left sense if taken from the perspective of looking forward from the driver's seat, but okay, I understand your point. Still say it's a confusing way to describe a rear transverse-mounted engine.

jazz4cash FEB 19, 02:55 PM

quote
Originally posted by Patrick:

The picture of the Camaro's engine bay would make more right-left sense if taken from the perspective of looking forward from the driver's seat, but okay, I understand your point. Still say it's a confusing way to describe a rear transverse-mounted engine.



The left/right convention is how the parts are identified on several parts lookup sites I found. I added the "firewall" description for clarity.
jazz4cash FEB 19, 02:59 PM
Thanks to all for the replies and feedback. I do not want to do the work myself and the shop I'm using does not want to tie up a bay if the manifold is not reusable or needs to be re-worked. Or, maybe they really just don't want to do the job. I think I have located a set of manifolds that I can have on hand for backup.

[This message has been edited by jazz4cash (edited 02-19-2020).]

pmbrunelle FEB 19, 06:42 PM
For information, Rockauto sells "FAMOUS BRAND" remanufactured cylinder heads, in case there is some sort of broken bolt disaster that cannot be easily reworked in a short time span.