Manifold Torque Settings?

[NorCal Boater]

This weekend I will be replacing the exhaust manifolds and risers on my port engine and realized I do not have the torque settings for either the manifold bolts or the riser bolts.

Anyone have those handy?

One more question....do you use a gasket sealer on the riser gasket?

Thanks Guys.

 

[Asureyez]

YEOW, a little late on that Q:


Use high temp anti sieze on the bolts.

 

[tobnpr]

Definitely gasket sealer on the riser gaskets. The only gasket I've ever dry-fitted was the stainless steel head gaskets.

 

[rondds]

Shawn
The guy who knows is Jon Levine. I'll see if I can get him for ya. He pops his on and off more often than I change the oil in my car. If you can, pls take pix and let me know how this goes?

I've never done manifolds but when I pulled the elbows for inspection, I did not use any gasket sealer on the elbow/manifold gaskets. I believe the torque on elbow bolts was 30 ft-lbs. But again, I defer to the Jedi Master for such specifics.

 

[J Levine]

I agree with Ron, you do not use any sealer with the Merc OEM gastkets and the torque spec according to an old 1994 Merc Technicians handbook I have here at home is 25 ft lbs. for both the manifolds to the heads and the elbows and or risers to the manifolds

 

[wileecoyote]

From the 89 7.4L Merc manual
1. Using new gasket, install exhaust manifold to cylinder
head. Torque fasteners to 25 lb. ft. (34 N·m).
IMPORTANT: See Section 7C if exhaust risers are
used.
2. Using a new gasket, install exhaust elbow to exhaust
manifold. Torque fasteners to 25 lb. ft.
(34 N·m)

Doesn't mention using any sealer except for perfect seal on all the block off plugs.

 

[Quint4]

Merc graphite imbedded gaskets, no sealer ( don't cheap out on the gaskets ).

 

[NorCal Boater]

You guys are great. Thanks for all the info.

I found OEM Mercruiser manifolds at Doug Russell's ebay site for $199.00 each. I considered that a pretty good deal as I was looking at $400 for each elsewhere. They came with the graphite imbedded manifold gaskets. I also bought new risers and they came with gaskets that have the slots cut on the side and small holes on the ends. This does not seem right to me for a motor with closed cooling. I know there has been a couple of threads about this but I can never find them.

Ron, I will take pictures for you. The one thing I am going to do is buy a couple of manifold bolts a bit longer than the actual bolts and cut the heads off. After I remove a couple of the middle/outside bolts I will thread these studs in. This will hold the manifold on, allow me to remove the other bolts and slide the old manifolds off. This also gives me a place to support the gasket and slide the new manifolds on. Those suckers are about 50 lbs apiece and even I won't be able to hold them with one arm.

Doing this job on Sunday (supposed to be like 90 degrees) and I will let you know how it turns out.

Thanks again for all the help. The worst part of this job is working in my spacious (not) engine room. It will take as long to get everything open as it will to actually change the manifolds.

 

[J Levine]

If you have a full closed cooling system you have the wrong elbow gaskets. You need block off gaskets that have no holes in them at all to keep the sea water and and cooling system water separated from each other. I use two bolts with the heads cut off to install the manifolds. Works great, you thread in the bolts one on each end, slide on the gasket followed by the manifold. You then install the remaining bolts and then back out the studs. I cut slots in the top of the studs so I can use a regular screw driver to remove them. I also recommend you use a tap and die to clean up the threads on the castings and on the fastners before you torque them down.

 

[rondds]

Shawn:

I did as the Jedi Master stated when I pulled my elbows, right down to the re-tapping. Very good advice.

You've alotted one day for this job, eh? If you can pull that off I'm buying you dinner next time you're back East!

Do you have risers too? Or just elbows?

You DEFINITELY have the wrong gaskets for the elbow/manifold junction. Someone somewhere on the board had a mechanic put those holey gaskets in his closed cooled engine and it F'd things up something fierce!

 

[flflatrate]

I'm not sure which closed cooling system you have. but I know there is two different ones. One incorporates the exhaust manifold which would have antifreeze running through it which would need the block off gasket, and the other just has antifreeze through the engine block and the exhaust is salt water cooled which would have the open gasket. also I've seen the gasket work better with using mercruiser perfect seal on them. on allot of them that you don't use it , you will start to see white salt deposits around the gasket surfaces. the perfect seal actually helps it out and usually you don'r see that.

 

[flflatrate]

also to tell which closed cooling system you have. the one that incorporates the manifold in with the antifreeze has 4 hoses going to the manifold extension and elbow. the salt water one only has 2 hoses.