Universal engine overheat

[jeagles]

1987 ODay with original engine.
Engine starts out cool but after 1 hour temp starts rising until overheat at about 2 hours. Seems to be lots of water coming out the exhaust - so assume raw side is oK. Freshwater side has full coolant. Fresh pump appears to be spinning.
Is this a heat exchanger or manifold problem? If so why so long to show up?
Any ideas?
Jim

 

[Stu Jackson]

What engine?

 

[Sail7cc]

Universal overheating..

The heat exchanger maybe your problem but you may as well go through the whole system to just to be sure.

Here are a few things that maybe overlooked. Check the prop shaft for anything wrapped around it, make sure there are no air bubbles in the fresh water side of the system, no broken vanes on the impeller.

Happy sailing!

 

[westbaydude]

It's probably broken vanes on the impeller if everything else is OK. If you do have broken vanes, make sure you can account for all the pieces of the impeller.

 

[Barnacle Bill]

If you have water coming out the exhaust, then your "vanes" on the impeller are ok, or you wouldn't have water coming out. Did you do any work on your fresh water heater of late? Like install a new one, or change hoses, etc.? If so, you may have to bleed the system to remove air which may be the culprit.

 

[Richard19068]

I had the same problem last year.

What's "lots of water"? Buildup inside the heat exchanger can reduce the flow slowly over time so the reduction in water flow is subtle. That could result in the symptom you are having. If I had to guess I would say the problem is probably calcium (or whatever it is) buildup in the heat exchanger. Have you cleaned it out in the last few years? You can use some diluted muriatic acid and a wooden dowel to clean out the tubes (be cautious with the acid).

Is the engine an M-18?

 

[Stu Jackson]

I don't know what is causing it to take so long to heat up.

But the only way to figure out what is happening is to check each and every COMPONENT of the system in a thorough manner. This also includes avoiding doing two or more things at the same time, 'cuz you won't know what the real solution was.

Think of the parts: inlet (you could simply have picked up a couple of plastic bags absolutely coincidentally two trips in a row); seacock; strainer; hoses; rw pump impeller; hoses; HX; exhaust riser; muffler. Anything I missed?

Take the HX off and check the inlet and outlet ports - they can get significantly reduced in diameter as the salt precipitates out.

Good luck.

PS - again, what engine?

 

[Charles Erwin]

The symptoms you describe point to the seawater intake hose/strainer assembly. This is just about the only part of the system that can change cooling water flow during motor use.

So -- ultra clean strainer. Inspect/replace all seawater intake hose which leads: seacock (intake) ---> strainer---> seawater pump. These hose sections need to be correct construction (ie Trident helix wire reinforced hose) thus it cannot collapse under vacuum. Also - double check the hose clamps to make sure you have doubles and that they are tensioned. Suggest discard old clamps in favor of new.

Check also there is no growth/debris blocking outside of the seacock mushroom head.

Charles

PS Observe/check drive belt tension to assure it does not change when the belt(s) warm up. When you acquire replacement/spare try to obtain Gates brand belt - as quality is excellent.

Stu?