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Exhaust manifold torque specs

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mike64646

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"great forum..I hope you all c

"great forum..I hope you all can help me. 1985 mercruiser 3.0 L 140
noticed water in the oil....ran a compression check and got close to 145-150 on all cylinders. I assume therefore that I dont have a cracked block, warped head or bad head gasket. It DID overheat for a VERY short period of time the first time I had it in the water due to a bad impeller which I subsequently had replaced. After some research I figured that the milk chocolate in the oil pan was due to a bad exhaust manifold gasket caused by the over heating. I have removed the exhaust manifold and riser and have a new gasket set at the ready.....two questions...1) does anyone think I am making bad assumptions, and 2) how can I find the torque specs for the manifold bolts? I am assuming around 25, but I dont want to be too far off...also, is there a blt tightening pattern? Thanks in advance."
 
"Did you have the manifold &am

"Did you have the manifold & riser leak tested? If not, you should. There may be an internal crack letting water into the engine thru an exhaust valve.
If OK, I would pressure test the entire block cooling system. If it wont hold, you have a leaky head gasket or a cracked head or block.
The water in your crankcase had to get there somehow.

Rod"
 
"Mike
My information shows 20

"Mike
My information shows 20-25 ft lbs for the manifold. As far as the tightening pattern, I imagine from centre out with 1/2 the value first then full.
Bert"
 
wouldn't the compression t

wouldn't the compression test rule out head gasket or block?
where do I go for a manifold test? a marine repair shop? or could an auto repair place do it?
this engine was rebuilt about 2 years ago and had been running fine before I noticed the water in the oil
I got the service manual downloaded. that tells how but not why...........
 
"Thanks Bert.. I was able to d

"Thanks Bert.. I was able to download the service manual from a link on this site...it confirms your estimate at 23 lbs for the manifold, tightening from the center out. and 25 for the riser. Thanks for your input."
 
milk chocolate in pan and comp

milk chocolate in pan and compression test have no connection - most engines with cracked blocks compression test fine.
I bought a motor once on eBay that had 160# across all 4 cylinders...block was all freeze cracked internally.
A brief overheat generally doesn't kill a 3.0...they are fairly resilient in my experience... but ice is another story
 
"Still need to pressure test i

"Still need to pressure test it.
common thing that happens on these 3.0's is people open the drains, the hot water comes steaming out so it looks like they are winterizing just fine, but then a chunk of rust comes floating by and plugs the drain, leaving the block or manifold half full of water.
I lost a manifold once to this on a 3.0.
Now I poke wire in all drains as I winterize."
 
"Mike
Any engine rebuild shop

"Mike
Any engine rebuild shop should be able to check your manifold for cracks, or know where a good NDT tester is in your area.
Bert"
 
"if it were a cracked block or

"if it were a cracked block or head gasket or warped head, would it still run well? without missing? the fact that it runs good makes me hope that its in the exhaust and not the main block. it ran great right up until I discovered the water in the oil, I havent started it since."
 
cracked engines run great...

cracked engines run great...

until chocolate milk starts blowing out the breather.

Having a crack from the cooling passages to the crankcase does not affect the suck/squeeze/bang/blow of a 4 stroke engine

Head gasket or warped head a totally different story..warped head or gasket failure would not usually compression test evenly
 
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