When to replace exhaust manifolds

[foxriverat]

How many older supras still have original manifolds? The reason I ask. I have a small exhaust leak on the port side of engine where manifold attaches to block. (hearing a faint ticking noise) So I start looking around the internet. Some people say they only last 5 to 7 years in freshwater. Some people say they last a lot longer. I have always winterized the boat and filled with antifreeze the 3 years I have had boat. (1996 supra comp 400hours) I have no idea how the other 2 guys before me winterized. I dont see any signs of water or rust residue from outside of risers. When I flush them out at the end of the season. No flakes or residue come out. I am going to order a gasket kit and I want this to be a 1 day job. But when you hear some people saying you should replace every 5 to 7 years you start to wonder. Its about $550 for manifold and riser kit. So all you guys with older supras with original exhaust manifolds give me a little reasurance. Or I could live with the small leak till the end of the season. And if I run into a can of worms. At least my boat wont be down waiting for parts.

[wotan2525]

I would say that the exhaust manifolds are some of the only original parts on my boat. Still seem insanely solid (and almost everything else on my boat was neglected, so I wouldn't expect these to be any different.)

Gaskets is about an hour job. Get some longer bolts that are the same size as the exhaust manifold bolts.... Put one in the front and one in the back-most hole. This allows you to pull the manifolds far enough away from the block to slide the gaskets in without having to remove anything else or monkey around with trying to get them back into position. Make sure to give the bolts a good helping of antiseize when you reinstall.

[haugy]

I have never had to replace an exhaust manifold on any of my old Supras. Gaskets, yes, as a precaution, but not the whole cast manifold.

[riveredge]

Lots of original manifolds around here, on boats much older than yours. To put in new gaskets where the manifold meets the block I would separate the two completely and clean the surfaces really well to make sure there's no old gasket material stuck on there. Same if you were to separate the riser; I took everything apart a couple winters ago and flushed out thoroughly, then cleaned the surfaces and used new gaskets to reassemble.
But (as wotan said) you might be able just to slide the old manifold-to-block-gasket out and put a new one in; then tighten everything up and if you still have a leak, then go the extra mile.

If you listen to older (90's, early 2000's) Fords, especially those with 351's, lots of them have manifold leaks, at least up here in the salty Northeast.

[foxriverat]

Thanks guys. Thats what I figured. But I feel much more at eas now.

[cadunkle]

Mine is an '89 with what I believe are original manifolds.They're a little crusty inside but I've seen a lot worse. I just pulled hte plugs, cleaned as well as I could and flushed. I know a lot of people with 80s and 90s boats run in fresh water with original manifolds. Avoid salt water and they should last a long time.

[duckseatfree]

jb weld is your friend!

[lively]

Another thing , be sure not to let the bolt tighten up on it's way out ! I broke two off when I replaced my manifolds and risers ..
And then broke an easy out off after , but mine were rusty also .. Heat is a good friend of mine , I apply it to anything I'm going to loosen up .. Where did u find the new manifolds and risers for 550? Is that shipped ?

[haugy]

jb weld is your friend!

http://i0.kym-cdn.com/photos/images/original/000/276/790/bb9.gif

Never say that again.

[lively]

Ha ha! Specially on cast iron ..

[foxriverat]

Another thing , be sure not to let the bolt tighten up on it's way out ! I broke two off when I replaced my manifolds and risers ..
And then broke an easy out off after , but mine were rusty also .. Heat is a good friend of mine , I apply it to anything I'm going to loosen up .. Where did u find the new manifolds and risers for 550? Is that shipped ? http://bpi.ebasicpower.com/presto/index.php?ID=835&catname=PCM%20GM%20305%205.0L,%20350%205.7L%20V8%2 0-%20Short%20Riser%203-1/2%20inch%20Exhaust

[foxriverat]

http://i0.kym-cdn.com/photos/images/original/000/276/790/bb9.gif

Never say that again. I was thinking the same thing

[Scramblerone]

Are all the bolts tight? Just saying! I might use copper gasket prep on the new ones to for a positive seal between the block and manifold.

[duckseatfree]

http://bpi.ebasicpower.com/presto/index.php?ID=835&catname=PCM%20GM%20305%205.0L,%20350%205.7L%20V8%2 0-%20Short%20Riser%203-1/2%20inch%20Exhaust

$169 for the Manifold! That's pretty good!

[5akman]

I realize this thread is a few months old but for those with rusty iron parts, here is the fix. I recently took a rusty SBC block, bought a large Rubbermaid tub and 5 gals of molasses. Dump the molasses into the tub, add 5 gals of water and then place the iron into the solution. fill with more water to cover the part completely and cover the container as the water will evaporate and come back in a month. My engine block was a beautiful dull iron color, just like it was out of the foundry. Right now i have two sets of SBC marine manifolds/risers in the solution, works perfect! It will not however, take paint or grease off so prep the block correctly before putting into the molasses mix.

[crystal waters]

over 800 hours on my 89 conbrio and still in great shape--all original gaskets and manifolds.

[Blackntan90]

Mine are rather crusty inside, and I am a bit concerned. I guess I could pull them this winter and check them out. At least replace the gaskets and such.