overheating

[JRHI]

I have an 87 Century cabin cruiser with a mercruiser 260. I have not until this point had an overheating problem. It began when I was ready to drop it in the water after the winter. I replaced the impeller, housing and tube. I replaced the thermostat and also the water pump on the motor. It is still overheating.

 

[JRHI]

Re: overheating

I have an 87 Century cabin cruiser with a mercruiser 260. I have not until this point had an overheating problem. It began when I was ready to drop it in the water after the winter. I replaced the impeller, housing and tube. I replaced the thermostat and also the water pump on the motor. It is still overheating.

 

[JRHI]

Re: overheating

Also last year I had a small leak behind the motor in the Y-pipe. I pulled the motor, replaced the Y-pipe and elbows. I ran fine after this but even today when I took it out it began running hot and I turned back for home. Is it possible inside the check valve/"plastic balls" are hanging up?

 

[freddyray21]

Re: overheating

did you check the new thermostat in a pan of water? Is it a marine thermostat? An automotive thermostat will run a lot hotter than the marine one.

 

[JRHI]

Re: overheating

yes i checked the new thermostat. It is a marine thermostat.

 

[hullofalottatrouble]

Re: overheating

if you didnt have an overheat problem before doing all this.. perhaps something didnt go right along the way..

so did you replace all this stuff and find the overheat? or find the overheat and then replace all the stuff?

how did the impeller look that you replaced? was it all broken up? did you find all the pieces? how did the housing look? Are you getting good water flow throw the engine?

 

[Don S]

Re: overheating

Old, plugged up risers or manifolds?

 

[JRHI]

Re: overheating

I didn't have the problem before storing it for the winter. I found the problem when I put it back in the water this year. The impeller and housing were both in good shape, so were the thermostat, circulating pump (water pump on the front of the motor) but i replaced them all anyway. I just got back from taking apart the risers and they seemed ok, I also checked the "flappers" check valves in the Y-pipe and they were fine, actually replaced them, the Y-pipe and the elbows last year. I also check the hose from the sterndrive to the transom and that wasn't kinked. I pulled off every possible hose, started the engine and had flow thru them all. I am really at a loss for words on this.

 

[hullofalottatrouble]

Re: overheating

have you verified the gauge temp with an IR thermometer?

 

[JRHI]

Re: overheating

yes the temp. gauge is correct. The only thing I'm coming up with is what every dealer and mechanic is telling me, they have all said the same thing, that the manifolds and risers are bad. I am going first thing this morning to buy both manifolds and risers. This has to be it? There arent any other parts left to replace!

 

[Don S]

Re: overheating

Why don't you pull the riser off and LOOK at it before ordering a bunch of parts?

 

[JRHI]

Re: overheating

Well the risers had their normal amount of rust in them. I replaced the manifolds, risers and gaskets today. Still running hot. Although I replaced it last year, I am going to pull the circulating pump off and check this. I spoke to the dealer, parts guy and a marine mechanic and none of them had an answer.

 

[northvanwatertaxi]

Re: overheating

my new impeller went, as well as the 140f thermostat tested full open @ over 200f both new!! just wanted to pass that along.

 

[Reel Poor]

Re: overheating

How hot is the guage showing? How did you verify the guage is correct? Are the risers hot to the touch? Is the engine hot to the touch? Are you getting water out of the exhaust?