View Full Version : Cracked exhaust manifold HELP

03-12-2010, 09:23 PM
Found a crack in my exhaust manifold, will this make the engine run like it was suffering a carb or timing problem????

03-12-2010, 10:34 PM
very great possibility. it will have poor performance issues

03-13-2010, 06:02 AM
Thanks Brettj, appreciate the input.

03-13-2010, 08:49 AM
hmm maybe that's what's wrong with mine I know mine has a big crack in it, and I tried to wrap it up with some metal and hose clamp, and I also know I got an exhaust leak from the dounut gasket on that same side.

So this thing is gonna have bad performance because of a cracked manifold? Might be why I had to run my dist. timing past zero to get it to run decent, and still aint great.

03-13-2010, 08:59 AM
Years and years ago my Ex-girlfriend had a Geo that had a big crack in the manifold.
Her dad picked up on from a junk yard and asked if I would put it in just to find out the one he got had a worse crack in it then the original.
It would always run like the timing was off or the points were bad with very bad getup and go.

03-13-2010, 10:32 AM
Clean the crack with a file...Heat it up some and mig weld it...Iv done it 3 times in my life with out and come backs..

03-13-2010, 11:32 AM
Not sure what year your truck is, but exhaust manifolds are typically pretty cheap.
Replacement manifolds for my 95 5.7 are $50....

03-13-2010, 11:52 AM
^^ You lucky bastard! I shopped around and got the cheapest at $188! There are some days I wished I lived in America. The rest, I'm more than happy being to the North.

03-13-2010, 01:16 PM
agreed unless I find some used for my 88 k1500 there are about $90 a piece from lmc. For that price I'm gonna get some shorty headers to bolt in place of these.

Mines only on the pass. side and the freaking thing is cracked under the first tube, and then same side the counut leaks lol.

The Fiddle
03-13-2010, 01:21 PM
Throw some longtubes on it. Or if you are strapped for cash get replacement manifolds. Cracks can lead to performance issues.

03-13-2010, 01:39 PM
yea I'm worried about burning a valve or something, that's why I tried to seal it up as best I could.

Long tubes would be great but having to change my whole exhaust would not be.

The Fiddle
03-13-2010, 02:03 PM
Yeah I need to do something about mine. More of a gasket issue but I'd put money mine are cracked as well. Relatively rough idle, sluggish performance, etc etc.

03-13-2010, 02:44 PM
I think I may have cracked mine myself, they were fine when I took them off, but after the rebuild the holes would barely line up between the front and back so it took some work to get them back on, and once I did I noticed the big crack.

03-13-2010, 04:51 PM
Well it seems unanimous! Now how about a product called JB WELD? It comes in two tubes, one product and one hardener. Anybody ever use it?

03-13-2010, 05:06 PM
it is still holding a pulley idler stud onto the timing cover of my '96 Splaturn after two years. great stuff, but i don't know how well it will hold up to exhaust manifold temperatures.

03-13-2010, 05:31 PM
Good point. I just read the package and it says good up to 600 deg. Any idea how hot the exhaust man. gets?

03-13-2010, 05:59 PM
Jb weld sucks.....Iv used it...Id rather fix it right then to Rig it with glue....

03-13-2010, 06:10 PM
Ive heard good and bad things about it and I agree, proper fix is best. My problem is Im gonna have to wait a week before I can buy some "new" parts. Dont want to damage the engine in the process! Sucks to wait though.

03-13-2010, 06:59 PM
I don't think you're gonna damage anything. I thought exhaust temps can get at high as 1400F or something. I think o2 sensors work at about 900F, and they're far down the pipe.

03-13-2010, 07:13 PM
Yea i weld them while on the truck....Never had anything go wrong....

03-13-2010, 07:34 PM
Gonna have to try somthing, running bad. To many things going on at once, cant keep up!

03-14-2010, 02:36 PM
I have the same problem on my 88.. I got a new manifold from discountexhaust.com for 40. Have been spraying the bolts for 4 days with PB Blaster hope they come off.

Anybody got the part number for the donut gasket

03-14-2010, 03:05 PM
I found out today my pass. side is junk, the big crack in the front I covered up before, dounut leaks on that side and maybe up top on the head not sure, but the air tube fitting I bent shut is leaking air out too.

03-14-2010, 03:54 PM
At this point Ive spent the day looking for headers. My cheapest price on the pass. side manifold has been 101.95 and I can pick up summit headers for 113.00. Of course Im totally leaving out the fact Ill have to go duel exhaust probably for around 200.00 through summit but who can say no to headers!!!!!!

03-14-2010, 04:01 PM

03-14-2010, 04:32 PM
It all starts with that first purchase then its all downhill from there. Ill be eatin Mac & Cheese every day for the next year so I can sink another nickle into my truck!

03-14-2010, 06:14 PM
you don't have to do an exhaust system ebay has headers for around the same price that bolt to stock pipes, and the shorties from summit can fit with some lil modification.

As for manifolds I found one last night on ebay for $42 actually found a couple for around that price new and shipped.

03-14-2010, 06:32 PM
Hey Swims350, You remember if they were all on e-bay or did you find somewhere else?

03-14-2010, 06:38 PM
yea the manifolds were all on ebay, just done a search for 88 chevy manifold, came up and I said lowest price first on the top right, came up some for about $42 shipped.

As for headers, same deal 88 chevy but said truck this time and then headers.

03-14-2010, 06:44 PM
Thanks, Ill go check it out.

03-14-2010, 06:51 PM
I cant believe it, but they were there. 53.00 for them. Looked quick at the headers and there are hundreds so thats gonna take a few to go through. Gotta find out who makes headers that bolt up to stock exhaust. You know off hand?

The Fiddle
03-14-2010, 07:48 PM
IMO, get coated headers or none at all. Doesn't matter if they are shorties or longtubes, they'll rot within a year out there in Mass.

03-14-2010, 07:49 PM
here ya go....

http://cgi.ebay.com/ebaymotors/EXHAUST-MANIFOLD-chevrolet-K2500-88-00-99-98-97-96-95_W0QQcmdZViewItemQQhashZitem20afde9370QQitemZ140 389553008QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAcces sories

http://cgi.ebay.com/ebaymotors/88-89-90-Chevy-Pickup-Truck-5-0L-305-Exhaust-Manifold-R_W0QQcmdZViewItemQQhashZitem3caa310b00QQitemZ2605 53378560QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccess ories

http://cgi.ebay.com/ebaymotors/EXHAUST-MANIFOLD-chevy-gmc-C-K-PICKUP-TRUCK-88-95-350-R_W0QQcmdZViewItemQQhashZitem19b6e7edf9QQitemZ1104 42835449QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccess ories

those are the ones I pulled up last night.

http://cgi.ebay.com/ebaymotors/1988-95-Chevy-Truck-SBC-350-Pacesetter-Headers-70-1318_W0QQcmdZViewItemQQhashZitem27b00102b1QQitemZ1 70456580785QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAcc essories

http://cgi.ebay.com/ebaymotors/WOW-NEW-SBC-CHEVY-GM-GMC-88-95-TRUCK-HEADERS-4x4-OR-2_W0QQcmdZViewItemQQhashZitem2c538ae124QQitemZ1903 80171556QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccess ories

http://cgi.ebay.com/ebaymotors/SBC-Chevy-88-95-Truck-Chrome-Headers-305-350-5-7L-GMC_W0QQcmdZViewItemQQhashZitem58869b2580QQitemZ38 0215436672QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAcce ssories

http://cgi.ebay.com/ebaymotors/Stainless-Steel-Header-Small-Block-Chevy-Truck-88-95_W0QQcmdZViewItemQQhashZitem5190f06d4dQQitemZ350 324026701QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAcces sories

http://cgi.ebay.com/ebaymotors/Chevy-GMC-88-96-97-Truck-305-350-5-0L-5-7L-JDM-Header_W0QQcmdZViewItemQQhashZitem2a0533968eQQitem Z180475893390QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fA ccessories

http://cgi.ebay.com/ebaymotors/Chevy-GMC-Truck-5-7L-88-97-305-Stainless-Steel-Header_W0QQcmdZViewItemQQhashZitem27afcfc889QQitem Z170453354633QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fA ccessories

The ones with the rounded over/ball end on them are supposed to bolt right in place of stock manifolds. The ones with reducers should come close but you'll have to cut the flange off the stock pipe and maybe more mods, not sure. The last ones I think are the exact ones I want, polished stainless, ball end and o2 bung all ready to go.

03-14-2010, 07:52 PM
Take it you've been out here. Yea everything rot. Massachusetts, high taxes and high salt levels in our water! Dont know if I can afford coated pipes. They take a big jump in price when you go coated.

03-14-2010, 08:01 PM
HOLY S#*T!!! You work far faster than me! Thanks a lot. Going to check it out.

03-14-2010, 08:30 PM
no prob. man glad to help.

03-15-2010, 04:44 AM
Both of mine were cracked. One of them was cracked at both ends and nearly all the way around on one of them. I drill a 1/8 hole at the end of each crack to stop the crack, ground a 1/8 groove along the crack and brazed them up. I've only got about 300 miles since I did it, but they seem to be holding fine.

03-15-2010, 05:03 AM
$50 brand new!
http://www.partstrain.com/store/?PN=11921+5674&N=0&VN=4294967240+4294966993+4294966371+4294962826+429 4966426&Nr=AND(universal:0)

03-15-2010, 02:37 PM
Checked out the partstrain, cant beat that price yet. Thanks!

03-15-2010, 02:47 PM
uuummm isn't ebay cheaper since it's $42 shipped?

03-15-2010, 03:03 PM
Yes, cant find it for 1987!

03-15-2010, 03:06 PM
aaahhh my bad man didn't know it was for an 87. Shoot I had some from an 84 I scrapped and they were crack free.

03-15-2010, 03:09 PM
Im still lookin on e-bay, hard to sift through the junk and to expensive stuff.

03-15-2010, 03:18 PM
found em for ya buddy....

http://cgi.ebay.com/ebaymotors/87-91-Chevy-GMC-Truck-LH-Exhaust-Manifold-for-305-350_W0QQcmdZViewItemQQhashZitem2305d4ddd0QQitemZ15 0421691856QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAcce ssories

http://cgi.ebay.com/ebaymotors/LH-Exhaust-Manifold-305-350-V8-Chevy-Truck-1987-88-91_W0QQcmdZViewItemQQhashZitem439d952469QQitemZ290 406605929QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAcces sories

http://cgi.ebay.com/ebaymotors/1987-87-Chevy-Truck-5-0L-305-Engine-Exhaust-Manifold-RH_W0QQcmdZViewItemQQhashZitem3a583251bbQQitemZ250 587795899QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAcces sories

http://cgi.ebay.com/ebaymotors/1987-87-Chevy-Truck-5-0L-305-Engine-Exhaust-Manifold-LH_W0QQcmdZViewItemQQhashZitem3a583ca5f8QQitemZ250 588472824QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAcces sories

03-15-2010, 03:21 PM
Exhaust manifolds get cherry red when driving on the x way for a while. Thats far above the 600F the JB weld is good for. Any leak big or small affects the O2 sensor operation and will result in a lack of performance & economy.

03-15-2010, 03:31 PM
I like the price on the e-part ad. Free shipping is great especially on cast iron! And vette, I think im gonna save the five bucks for J.B. and put it towards the new manifold!

03-15-2010, 03:51 PM
Hey swims, know anything about cb antennas?

03-15-2010, 04:19 PM
not much bro but whatcha need? my old man has a cb in his 84 but can't get it to pick up anything.

03-15-2010, 04:24 PM
Lookin for some ideas on quality brand antennas. I know of Firestick just didnt know if you knew of more.

03-15-2010, 04:59 PM
we usually run the whip antenna's around here, and usually cobras and such or midlands. I aint sure what my buddy uses he's with the fire dept. and not sure what they use or preffer.

03-15-2010, 05:23 PM
Im back, outa beer! I have a Cobra, just trying to pick out an antenna. I guess ill post question for opinions on....interiors or electrical?