Pennock's Fiero Forum
  Technical Discussion & Questions
  2.8L Exhaust Manifolds

Post New Topic  Post A Reply
Email This Page to Someone! | Printable Version


next newest topic | next oldest topic
2.8L Exhaust Manifolds by lyleap-gmc
Started on: 08-01-2020 09:29 PM
Replies: 5 (134 views)
Last post by: Patrick on 08-02-2020 08:43 PM
lyleap-gmc
Member
Posts: 28
From: White Bear Lake, MN, USA
Registered: Jun 2015


Feedback score: N/A
Leave feedback

Rate this member

Report this Post08-01-2020 09:29 PM Click Here to See the Profile for lyleap-gmcClick Here to Email lyleap-gmcSend a Private Message to lyleap-gmcEdit/Delete MessageReply w/QuoteDirect Link to This Post
Hi,
I have several cracks in the front exhaust manifold. I know they can be repaired, and at the same time the can be ported.

My question is are there any cast iron exhaust manifolds that can be used on the 2.8L?

Thanks to all,

Lyle
IP: Logged
PFF
System Bot
fierofool
Member
Posts: 11748
From: Auburn, Georgia USA
Registered: Jan 2002


Feedback score:    (13)
Leave feedback





Total ratings: 150
Rate this member

Report this Post08-01-2020 10:29 PM Click Here to See the Profile for fierofoolClick Here to visit fierofool's HomePageClick Here to Email fierofoolSend a Private Message to fierofoolEdit/Delete MessageReply w/QuoteDirect Link to This Post
3.1 and 3.4 manifolds will bolt to the heads, but they will not mate with the rest of the Fiero exhaust system.
IP: Logged
pmbrunelle
Member
Posts: 3465
From: Grand-Mère, Québec
Registered: Sep 2008


Feedback score: N/A
Leave feedback





Total ratings: 54
Rate this member

Report this Post08-02-2020 12:13 PM Click Here to See the Profile for pmbrunelleClick Here to Email pmbrunelleSend a Private Message to pmbrunelleEdit/Delete MessageReply w/QuoteDirect Link to This Post
You can say that the root cause of the manifold cracking problems is that the manifold seeks to expand with heat, but it is restrained from expanding from the rigid cylinder head.

The conflict between both parts is resolved with cracking...

I have bellows on my own car:
http://www.fiero.nl/forum/F...L/142133-3.html#p111

The intent of the bellows is to allow each part of the manifold to expand freely with the heat, stress-free (well, not completely free of stress, but far reduced).

Only a few thousand kilometres so far, so I cannot say that bellows are the final solution to 2.8 manifold problems, but so far things are looking good.

[This message has been edited by pmbrunelle (edited 08-02-2020).]

IP: Logged
fierofool
Member
Posts: 11748
From: Auburn, Georgia USA
Registered: Jan 2002


Feedback score:    (13)
Leave feedback





Total ratings: 150
Rate this member

Report this Post08-02-2020 07:26 PM Click Here to See the Profile for fierofoolClick Here to visit fierofool's HomePageClick Here to Email fierofoolSend a Private Message to fierofoolEdit/Delete MessageReply w/QuoteDirect Link to This Post
The odd thing is that the fro t and rear manifolds are almost identical and only the front one breaks. My theory has always been that the front one supports most of the weight and when support springs are missing too much weight is put on the front manifold.
IP: Logged
pmbrunelle
Member
Posts: 3465
From: Grand-Mère, Québec
Registered: Sep 2008


Feedback score: N/A
Leave feedback





Total ratings: 54
Rate this member

Report this Post08-02-2020 08:09 PM Click Here to See the Profile for pmbrunelleClick Here to Email pmbrunelleSend a Private Message to pmbrunelleEdit/Delete MessageReply w/QuoteDirect Link to This Post
I've only worked on Fieros in the "recent era", so after they've had recall work performed.

One difference between the front and rear manifolds is that one of them has elongated holes, while the other has smaller round holes. I don't remember which one was which.

There's also the dripping water factor; the instant cooling when a wet decklid is opened, pouring water on the front manifold.

[This message has been edited by pmbrunelle (edited 08-02-2020).]

IP: Logged
Patrick
Member
Posts: 30149
From: Vancouver, British Columbia, Canada
Registered: Apr 99


Feedback score: (1)
Leave feedback





Total ratings: 442
Rate this member

Report this Post08-02-2020 08:43 PM Click Here to See the Profile for PatrickClick Here to Email PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by pmbrunelle:

There's also the dripping water factor; the instant cooling when a wet decklid is opened, pouring water on the front manifold.


That's always been my suspicion as to why the front exhaust manifold is more prone to cracking than the rear one.

Even the original weatherstrip (removed as part of a recall) along the leading edge of the decklid was kind of useless, as water would still get dumped down on the front manifold if the decklid was opened when wet.

The best solution was/is this - read from Here (make sure to click the link in the first post) and continue on down to the bottom.

[This message has been edited by Patrick (edited 08-02-2020).]

IP: Logged

next newest topic | next oldest topic

All times are ET (US)

Post New Topic  Post A Reply
Hop to:

Contact Us | Back To Main Page

Advertizing on PFF | Fiero Parts Vendors
PFF Merchandise | Fiero Gallery | Ogre's Cave
Real-Time Chat | Fiero Related Auctions on eBay



Copyright (c) 1999, C. Pennock