Logo
FULL SITE MENU

1994 Merc 175 HP runs hot ??

A

artie in miami

New member
I noticed that my port engine of my twin 175HP mercs runs about 20 degrees hotter than the starboard engine. I changed the impeller and water pump housing and it is still hot...the water coming out of the peehole is so hot at idle (with the earmuffs on) that it would scald your hand if you held it in the stream for any more than a second. At high RPM (around 3000), the temp drops down to about 140-150 degrees...at low RPM, it is right around 180-200 degrees. Has anyone else ever seen this situation ? The other engine runs about thirty degrees cooler when both are at low rpm.

I had the boat stored for about two years...before I stored it, I did not have this problem...it suddenly appeared when I started to use the boat again.

artie in miami
 
Bad thermostat(s) would be the leading contender.

Since the temp drops at higher rpms (when the thermostats are bypassed in favour of the poppet valve) it sounds like the waterpump and poppet is fine.

You can do the "easy test" - simply remove both thermostats from the "hot running" engine and take it for a spin. If the temp stays down where it should (actually might run a little colder than the "good" engine upto about 2000 rpms) then just get a new pair of thermostats.

Don't run for extended periods without thermostats in there - a day out for testing won't hurt, but continued use without thermostats will lead to problems...
 
Thanks...I will give that a try. I just thought of another wierd symptom...when the engine is running, the primer bulb clicks and pulses...I changed the primer bulb...same thing ! Only happens with the port engine which is the one that is running hot. It may not be related to the hot running problem...anyone know what causes that ?

artie
 
Back
Top