Starboard Engine Steaming

[mitchconsult]

I have just rebuilt my Crusader 454 , new manifolds, risers etc
Engine has less then an hour on it. I dipped the heat exchanger, changed impellers, etc.
At about 2000 RPms it starts steaming, it is running at 160 degrees so I know it is Ok but have exhaust steam .
I have ran it at the dock and checked it with a heat gun.
anybody have any ideas?

[djmarchand]

You have twins, right? Put a bucket under the exhaust and catch the water on the port engine at 2,000 rpm and time how long it takes to fill. Then do the same thing on the starboard. If there is a significant difference, that is your problem- low raw water flow.

I realize that you say that you replaced everything in the raw water circuit. But if one side pumps x and the other side pumps 1/2 x then you have to look for why.

David

[mitchconsult]

Thanks David,
The boat is in the water and it would be difficult to disconnect the exhaust to perform the test.
I think there must be something in the pump assembly itself, I changed the impellers etc, maybe its a shim in the pump slipping.
Im confused because there are not hot spots in the exhaust system

[CPseudonym]

Have you checked the line from the pump back to the seacock yet for obstruction?

[chrisjs]

Or a blockage in the external inlet strainer?? Apart from plastic bags we have pretty agressive barnacles here in the Northeast. Totally blocked my holding tank outlet a couple of times!!

[donradcliffe]

Fire up both engines, and use your heat gun to check for differences in temperature at various spots, especially the raw water inlet to the injection elbow and the fresh water inlet and outlet of the heat exchanger.

[foggysail]

The OP's post tells us his engine is operating at 160 degrees. I don't see an over temperature condition here.

[chrisjs]

Au contraire, perhaps!!
The engine should run at a higher temp - about 185. The lower temp may mean inadequate coolant causing error with temperature gauge. Other reasons for low temp???

[mitchconsult]

Thanks everyone, I have some blockage between the strainer and pump, it resolved some of it, but under load at 2300 rpms and above, it is still steaming.
I have shot the manifolds and risers and there doesn't seem to be any hot spots.
There must be some blockage in a house after the pump, mystery continues

[foggysail]

There are things that can cause water vapors in the exhaust such as a blown head gasket. Is the reservoir for that engine maintaining full coolant?

[foggysail]

Originally Posted by chrisjs

Au contraire, perhaps!!
The engine should run at a higher temp - about 185. The lower temp may mean inadequate coolant causing error with temperature gauge. Other reasons for low temp???

My 454's run around 165. At one time they did operate at higher temperatures before I changed the oil coolers, water pumps, risers & elbows and finally rodded out the heat exchangers

[mitchconsult]

yes, maintaining coolant and has good flow.
Im starting to think there is an internal problem, it is a new rebuild, but it would not be the first time something was not put back together right

[chrisjs]

I guess I would start by checking the "new" impeller.

[mitchconsult]

I looked at again yesterday and it looks brand new, it doesn't have an hour on it

[chrisjs]

Couple of thoughts:
Did the old impeller have any missing vanes ??
If the new impeller connects to the shaft with a key, make sure the key did not slip out during installation. Unlikely, but impeller may be slipping on shaft.