1990 Mariner 175hp overheating issues....HELP!!

[bwest0615]

I have a 1990 Mariner 175hp serial number OC254550 that is getting hot at higher RPMs ONLY. I have a solid beep alarm going off. She will run fine all day at an idle and lower RPMs (anything below about 3k). I have installed a water pressure gauge but I don't get a pressure reading at all at anytime. I know there is water getting to the gauge and that the gauge is good. I have also done the following:

1. Replaced water pump and housing in January
2. Replaced T-stats in July
3. Replaced temp sensor in July
4. Replaced poppet valve and torqued to specs in July
5. Moved my jackplate all the way down and up and no changes.

I have been told that my poppet valve needs to but hooked up to the exhaust port. Currently the hose coming from the top of the block is going directly to the poppet. Any other thoughts or ideas??

[JOE54]

all 3 gaskets on pmp ????? DO NOT MOVE HOSE not the problem , possible exhaust plate gaskets leaking, recheck pump, go up from there

[bwest0615]

Yes I replaced everything yesterday with a new water pump kit. Where is the exhaust plate gasket?

[leonreno]

Exhaust plate gasket is between the exhaust plate and power head, power head has to come off. Where is your water pressure gauge connected to the block? Maybe a picture?

[bpicinc]

Do you get a pee stream?

[bwest0615]

I will check my new impeller today and follow up. I always had a pee stream before, just for sure ruling that out by replacing everything (impeller, housing, gaskets, pic shows old impeller). The gauge is now tied into the line running from the port side t-stat down to the tell-tale. I had it in the hose running from the top of the block(fitting just behind the fly wheel) to the poppet valve. I am getting the same results in either location.

[lpugh]

^^^^^^^^^ Then:
Compression test is in order, look for a abnormally clean plug and look at the piston tops. Water in the cylinders will have a steam cleaning effect.

[bwest0615]

All my plugs look like the ones in the pics. I will do a compression check and check back in.

[JOE54]

put wpsi hose back on top of block tee into hose to poppet , at yellow circle, there 2 gaskets below powerhead , check rubber grometts each end of copper tube and make sure poppet is closed and seated