2006 200 Select overheating - Merc 5.0 MPI (305ci)

[Scott215]

I had a very good marina do my water pump so I not worried . But overheating at idle would be a concern

 

[Coconuts]

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 the tube to the uppper, not sure... Tried to make sure I got it back together all good - will see if it works...

 

[Scott215]

Please let us know how it goes running on the hose and see how it does

 

[Lazy Daze]

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 the tube to the uppper, not sure... Tried to make sure I got it back together all good - will see if it works...

How was the housing/plate? Any scoring, at all - even small?

If I may, what are you basing your assumption on that a broken vane won't clog the system? Parts of a rubber impeller ABSOLUTELY can get stuck in a system. Happens all the time.

 

[Coconuts]

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.

 

[Nater Potater]

Please go back and re-read post #36 and search for impeller chunks. I know you didn't find a broken impeller when you were in there, but that's not to say that your work wouldn't have dislodged something from prior. There's a large cavity up the back of the gearbox that could have been hiding something that then came loose when you R&R'd the lower unit.

 

[Coconuts]

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.

 

[Coconuts]

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?

 

[Lazy Daze]

No, there's nothing there in the t-stat housing that worries me at all. Certainly nothing "massively rusted" in the least.

You could, however, test your t-stat and/or just replace it.

 

[scoflaw]

Flush your block, probably filled with rust flakes

 

[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...