Replacing exhaust manifold

[jlinder]

Removed the exhaust manifolds and found a crack. Suspect it had some water that did not drain properly last winter.

Came off pretty easy but have a question on the replacement

1. Anyone know how tight to torque the bolts? This is a 1988 GM 5.0L engine.

2. Any tips on installing the new manifolds?

 

[Diggerpine]

Re: Replacing exhaust manifold

IMHO, If you plan on working on your boat, motor, etc, I would highly recommend you get a service manual for it. It will have all the information you asked for and more. If you are planning on purchasing another manifold, there are instructions usually included which will give you the torque specs you want.....my 2 cents worth.

 

[littlebookworm]

Re: Replacing exhaust manifold

One little trick for installing the manifolds. Get a bolt slightly longer than the ones used to mount the manifold. Cut the head off so that you have a long stud. Thread that stud into the block on one end of the manifold mount. Slide the gasket on and then slide the manifold onto that headless bolt. This will now support one end of the manifold as you catch the bolt on the other end. Then catch a bolt through the hole next to the one with the headless stud sticking out. Remove the headless stud with a pliers and then thread in the other bolts. Tighen and you're all set. This eliminates trying to hold the manifold with one hand as you try to catch both bolts through to the block, an impossible task. Before you mount the risers, check that the mounting surfaces of each riser and manifold are perfectly flat by drawing a file across each. Check some previous threads on details. The whole question of using a sealant or not is still up to discussion. Mercruiser recommends dry mount for most manifolds and risers. Again, check threads. Good luck. Hy

 

[jlinder]

Re: Replacing exhaust manifold

Thanks guys.

I have an after market manual (SELCO) but it does not list the torque. Hopefully the Sierra manifolds I ordered will have them.

This manifold hs studs sticking out of the block and uses nuts to hold the manifold on. Nice in that I have built-in locating studs tos slide the manifold on and rest until I get the nuts on.

It is also nice in that the nut end of the bolts never gets hotter than the water in the manifold. As a result the bolts were very easy to get off.

 

[Diggerpine]

Re: Replacing exhaust manifold

FYI

The manual I have states that for a (93') 5.0L (305 cid) GM motor, the exhaust manifold attaching nuts are 20-26 ft.-lbs and the high rise elbows are 10-12 ft.-lbs torque. If the attaching nuts on your exhaust manifold have an elastic stop on them, you can't use them more than twice.

 

[jlinder]

Re: Replacing exhaust manifold

Thanks Diggerpine

 

[borz170]

Re: Replacing exhaust manifold

Just get 'em tight. I have never torqued manifold bolts, I just snug them down equally with a 3/8" drive rachet.