Recent content by Coconuts

Well just for the update- it was the tstat housing and rusted tstat. I was able to get it all out, soaked the housing in muriatic acid/water mix, got it all cleaned up like new. Put a new tstat in and bingo - now getting 8+ PSI on water intake and idles at 1-2 psi and never gets above 160...

ok - pulled therm cover of and omg - well, think I found the issue - the system is massively rusted out... what do I do about this - doesn't seem like a flush is going to work?

I'll do a run test and if problem is not solved will dig thru the lines - I did check the gearbox cavity and everything real well and didn't find anything.

The rubber impeller I took out had zero damage to it - and I did not have this cooling issue until after I had changed the lower unit last summer. There was some very minor scoring in the old housing - and it looked like the housing wasn't made properly as the joint was not smooth.

Well, got the lower dropped, put an entire new OEM water pump assembly in, all new seals, etc.. The old one really didn't look bad - the pump itself is rubber so no way I could see these breaking apart and parts getting stuck in the cooling system - maybe it didn't have a good enough seal with...

ya - agree with you Scott - have a brand new impeller kit and the Merc Service manual... I've had outdrive off before and I think something got messed up putting it back together - it's a PITA to work on...

ok - if that's the case, can someone explain the basics of how this works then - does the raw water pump impeller (in the lower outdrive) actually spin faster when RPMs are increased the the boat is in neutral?

but it would explain why increase in RPMS in neutral increases water pressure just a bit.

ah yes - I figured as much. I'm guessing that pump is messed up... will look to replace that impeller too!

well - I'm hoping a new thermostat will fix it - ordered and will be here sunday. Still don't understand how revving up in neutral helps cool temps - almost like there's an internal water pump on the pully system that moves water???? no way the impeller on the lower outdrive moves when I rev...

Ya, I have the smartcraft guage - digital - it shows water temp along with water PSI. I have no poppet valve.

It will drop to the 150's - but idle, it only takes a few minutes and it's hitting 190 plus - and my PSI gauge shows 0.0 psi at idle - but only around 2-2.5 PSI at 1300rpm.

hmm - wonder how to clean the system out? any easy way?? So more info on the issue - idle, it overheats pretty quickly. If I leave it in neutral and rev engine up to about 1300 RPMs, the temps start to drop - it's not in gear so boat is not moving at all... what am I missing here?

Correct - my mistake on all this - so I have replaced that - it actually has a newer, rebuilt lower on the outdrive with all new pump assembly - and ever since, I have overheat problems on idle only.

There's a new impeller in the outdrive unit - that was just replaced. So I have the standard easy drain cooling system: https://www.marineengine.com/parts/mercruiser-sterndrive-parts/50l-mpi-alphabravo/0w310000-thru-0w649999/standard-cooling-system-alpha-single-and-3-point-drain