Yamaha 43 V6 stern drive OVERHEATING

"Ok - just joined this forum a

"Ok - just joined this forum and Im having a heck of a time diagnosing the problem with my EBBTIDE boat with 4.3 Chevy V6 stern drive,

PROBLEM : Submerge lower unit in a 35 gallon bucket of water. Engine starts right up - but heats up to 190 within 5 minutes, And theres no stream of water peeing out the lower unit weep holes like it should I get just spitting of air .

WHAT IVE DONE :
Checked ALL belts ( tight )
New Impeller
New circulating pump
New Thermostat (even tried with no thermostat)
Checked Risers (fine)replaced gaskets
Checked all coolant lines for implosions

Flushed weep holes in lower unit with garden hose from the RISER ( nice flow )

Removed output hose from impeller pump and she's pumping.

Removed coolant hoses from both sides of power steering oil cooler and flushed it AND the hoses . Checked the screen on the cooler as well - all clear.

Circulating Pump is pumping.
Bypassed the impeller pump and ran a garden hose right to the thermostat housing - engine temp was NORMAL and weep holes in lower unit were weeping.

QUESTIONS :
Is my power steering oil cooler clogged ?

My thermostat housing has 3 pieces
the cover - the middle( that the therm sits in)
and another block that two houses connect and run to UNDER the risers.... could this be blocked ??

What are the symptoms when the impeller pump fails ?? Leakage ???
I noticed that the impeller pump pumps at different speeds.

Look guys - I wasnt that familiar with these stern drives but in the past week Ive had quite the crash course - any help at all will be appreciated . Rob from Plymouth Ma."

"Sounds like the "Curse of

"Sounds like the "Curse of the Pilgrims" had returned!

I suggest that you disconnect the hose going to the raw water pump and put your garden hose there (and it needs to have really strong flow). Run at idle, and the flow should be okay out the tell tale. If not, there's a blockage downstream of the pump, one you'll have to locate by the process of elimination: Take one thing out of the circuit at a time until you find the problem.


Jeff"

"did you say you Bypassed the

"did you say you Bypassed the impeller pump and ran a garden hose right to the thermostat housing? if you did than you ran the impeller dry
replace that. Also how hot did the water in 35 gal. bucket get, do you have a pair of muffs to run on hose? Its a must have if you own a boat.
By the way you can't force water through impeller
it has to pump it."

I checked the impeller after d

I checked the impeller after doing my "test" and its fine ... Right after my test I hooked the hoses back up ..and pulled outlet hose on the impeller pump and she was pumping good.

The water in the bucket did not get hot. I have muffs but Ive been advised by every marine mechanic Ive asked to always try to submerge the lower unit in water as if were in the lake while running the boat on the trailer.

Maybe theres a clog in the manifold ?? I didnt check it out when I had the risers off- but the risers were extremely clean.

Im going to try what Jeff said and garden hose the inlet hose to the impeller pump .

Anyone know the symptoms of a worn out impeller pump ?

I can hear the pump chuggin like a vacuum pump when the engines runnin.Im assuming thats a good sign.

Hey heres a thought - when I replaced the circulation pump ... the new one had the back plate already bolted to it with the gasket in between - I checked and made sure the plate bolts were tight from the factory ( they were ) but should I have added gasket cement to the plate ??

Im really grabbing at straws here hahaha
Im determined to fix this problem before I give up and send her down to the marine guy at 75 bucks an hour.

"Those impellers are not ment

"Those impellers are not ment to run dry at all, it will kill it quick. There needs to be a gasket on that circ. pump.
Try hooking up water to lower unit and take off hose going to therm. housing and run motor only for a short time you should have 6'' to 8'' head of water and try to stop with hand should be all most impossable to do, if so impeller is good look for problem someware else.
Risers could be clogged but not so clogged that you don't get any water back out gimble ring and hub."

Problem solved Thanks alot guy

Problem solved Thanks alot guys - There was a clog in the lower unit in between the water inlet covers and the raw water pump.

That's allways the case yo

That's allways the case you look for some thing complex and it ends up being some thing simple.