Mercrusier v8 overheating

[achris]

That looks like the right gasket. If the manifolds and elbows are flowing properly, then it may be time to start checking other things. What condition is the water pump impeller in (engine circ)... Check that all the hoses are clear. Also check the engine timing. Advanced timing can cause overheating....

One more 'easy' test is to put a section of clear hose in place of the water supply form the drive and the thermostat housing. You need to see a solid clear stream of water. Any bubbles indicate an exhaust leak into the cooling water somewhere...

Have a read of this -> http://forums.iboats.com/showthread.php?t=556903&p=3825409&viewfull=1#post3825409

Chris........

 

[Thomas A Ross]

Timing is set at 6 degrees at idle and changes as rpm come up. never checked timing at higher rpm. Do you know what timing advance should be maybe my distributor ir advancing to much? Water pump was brand new when i rebuilt the engine 6 months ago.

 

[achris]

Have you done the 'clear hose in the water inlet line' test yet?

 

[kenny nunez]

As Chris said about in coming bubbles from the out drive pump here is something else to look for. Watch which way the bubbles appear, if you have a combustion gas leak you will actually see the water completely stop flowing and disappear and the tube will be empty. What makes things even worse is when you slow down and the water returns the cold water can cause a crack when the steam bubble cools. The first time I witnessed this was on a 3.0 with a head gasket leak that would not show up doing the usual checks.

 

[Thomas A Ross]

I was told by another mechanic to do the clear hose after the manifold and i had no water flow out of the manifold. He said that my manifold is cracked internally. and i have a set a pressure tested center riser manifolds that i am going to switch to. So i plan on installing them this week and try that.

 

[Thomas A Ross]

Plan to use my original thermostat housing and plum it like this would that work. I will pull my risers off and check what gasket is installed to make sure it will work from what ive read. Is that picture good way to do it with the looped manifold hoses.