At Idle My Engine Is Not Intaking Cooling Water

rpell1@msn.com · Aug 22, 2012

Might be debris in your raw water filter, or perhaps the pencil zinc deteriorated and either broke off the nut inside the exchanger. or maybe broke apart enough to cause an obstruction. I hope this helps...

Good Luck and Happy Sailing

digggs said:
Looking for some input while at idle my engine does not seem to draw cooling water or very little at that.When I increase the the throtle I get flow.I believe I have an obstuction as I have changed the impeller.Has anyone else come across this problem?

thanks,
Sean.

Bob4203 · Aug 23, 2012

I had the same issue, but started to heat up when increasing rpms for awhile. Start with the raw water strainer (is it clean?), move to the impellor (remove cover and inspect - any broken fins? brittle?), waht was the condition of the old impeller?, move to the heat exchanger (it can be clogged with debris (zinc, rubber fragments from impeller).

In my case the impeller had several broken fins and one got caught in the hose to the exchanger and in the exchanger. I had to replace the impeller and clear out the hose and exchanger. Pours out in buckets now! Do a flow diagram of the components and trace to the problem.

Bob
'88 Mark II (M-18)

shipwreck66 · Aug 24, 2012

Just a thought. I noticed something similar last week, panicked, returned to slip thinking water pump was broke. Spent a couple hours jacking with all things in the raw water intake including thinking I had a grocery bag on the intake. In the end I discovered the exhaust was leaking and somehow this disrupts the flow of water, will spend tomorrow replacing my 28 year old exhaust.

jrhamp · Aug 25, 2012

Perhaps the thermostat.

jrowan · Aug 25, 2012

I am inclined to agree with JR. Check your thermostat. Of course it will not open up until the engine is warm. The faster the rev's the faster the engine will warm up. You didn't mention what type of engine you have, which is kinda important when figuring out cooling problems. My 5411 doesn't even have a heat exchanger, but when the thermo is closed it wouldn't even exhaust any water out the exhaust until the the thermostat opens up to allow exhaust water to flow to the water muffler. I never liked this & use the valve that directs exhaust flow directly to the exhaust. The other place to check if the problem is not from a clog at the raw water strainer, inlet hose, impeller, etc. is to finally check the exhaust mixing elbow for heavy carbon or rust buildup which can obstruct flow as well. But if your engine has been pumping well until recently, then the problem is likely a clog in the intake line before the engine.

shipwreck66 · Aug 25, 2012

Replaced my exhaust today, and the mixing elbow was pretty gunky. The detachment occured directly at the rear of engine. Required two trips to Lowes for 1 1/4" galvanized pipe pieces, elbows, etc. Now all is well, until the next thing breaks of course.

jrowan · Aug 27, 2012

Of course that galvanized pipe is the real problem to begin with. It rusts like crazy in the inner wall of the pipe, creates rust scale & carbon buildup on the scale & hence an eventual clog. I know that this stuff is cheap, but why do all the engines manufactured from the 70's & 80's always use it on the exhaust? I've seen it on Yanmars, Universal, Perkins, you name it. Cheap = you get what they paid for. My Universal has a replacement mixing elbow from Westerbeke installed that is powdered coated steel & looks great (from the outside). Cheers.

shipwreck66 · Aug 29, 2012

The mixing elbow I have is bronze and very tender. Haven't seen replacements but would dearly love one.