A very different reason for engine overheating

[Bill Seal]

If the system is designed properly, no air can become trapped. On my MD11C, there are air bleeds at the high points on the circulating pump and fresh water side of the heat exchanger, but none on the raw water side. By reversing the connections on the raw side, any air is simply dumped into the injection point in the mixer elbow.
This kind of FUBAR can happen when a draftsman "simplifies" a design without asking the designer why it was designed the way it was . It happened to me many times back when I had a real job.

[RogerLloyd]

An exhaust elbow temperature alarm will tell you when the engine is too hot, but a low-flow cooling water alarm will tell you that the engine is about to get hot.

[Cadence]

Originally Posted by Bill Seal

If the system is designed properly, no air can become trapped. On my MD11C, there are air bleeds at the high points on the circulating pump and fresh water side of the heat exchanger, but none on the raw water side. By reversing the connections on the raw side, any air is simply dumped into the injection point in the mixer elbow.
This kind of FUBAR can happen when a draftsman "simplifies" a design without asking the designer why it was designed the way it was . It happened to me many times back when I had a real job.

If your a designer you sketch it on a napkin and take to the model make/ machinist and ask how it should be done. Design and practicality are two different animals.

[qwert]

Originally Posted by Bill Seal

If the system is designed properly, no air can become trapped. On my MD11C, there are air bleeds at the high points on the circulating pump and fresh water side of the heat exchanger, but none on the raw water side. By reversing the connections on the raw side, any air is simply dumped into the injection point in the mixer elbow.
This kind of FUBAR can happen when a draftsman "simplifies" a design without asking the designer why it was designed the way it was . It happened to me many times back when I had a real job.

At the risk of thread hijack this seems a good moment to point out to other MD owners another easily fixed idiocy in the MD11c cooling system.The gearbox has a water channel which runs around the box (like a vertical wheel in shape). It has four identical threaded entries at midnight, three, six, and nine o'clock. The engine is plumbed with raw seawater coming in at nine and exiting at three. the top and bottom holes have bronze threaded plugs. What happens is that the water takes the lower path and air collects in the top half. The mixture of wet air and heat causes rapid corrosion in the top of the water passage jacket which eventually cracks.

The cure is simple...........swop the plugs and make the bottom one at six the inlet and the top one the outlet and there's no more air pocket.

[captlloyd]

Originally Posted by Cadence

Jack posted a very comprehensive account and finding of the cause. It was an FYI.
Why am I reading what he should check.

Because some posters didn’t understand what the actual problem was.

[Searles]

Have seen similar problems with air getting into the seawater pump intake for many reasons,the simplest alarm is a bore water flow alarm in the intake after the seacock and before the raw water pump easy to fit and connect to most alarm panels or fit a tell tail in the raw water flow line. .⛵️⚓️

[Bill Seal]

Originally Posted by qwert

At the risk of thread hijack this seems a good moment to point out to other MD owners another easily fixed idiocy in the MD11c cooling system.The gearbox has a water channel which runs around the box (like a vertical wheel in shape). It has four identical threaded entries at midnight, three, six, and nine o'clock. The engine is plumbed with raw seawater coming in at nine and exiting at three. the top and bottom holes have bronze threaded plugs. What happens is that the water takes the lower path and air collects in the top half. The mixture of wet air and heat causes rapid corrosion in the top of the water passage jacket which eventually cracks.

The cure is simple...........swop the plugs and make the bottom one at six the inlet and the top one the outlet and there's no more air pocket.

Tank you! The MSB gearbox that came with our Formosa kept polluting the oil with sea water, and apparently had been doing it for years. After replacing it, the old one actually broke apart when I put down on my garage floor. That modification has just moved to the top of my "to-do" list.

[Iains boatyard]

Originally Posted by Cadence

Jack posted a very comprehensive account and finding of the cause. It was an FYI.
Why am I reading what he should check.

Cadence
Good pick up, also one of my little stressors, because very few people read all the words, they scan and figure they know it all. An outcome of people living their life off and or from a phone.:whistling

[Tillikum]

Originally Posted by Jack C

I checked the water strainer, the cap was loose. The scupper pipe runs alongside the strainer and I mistook its friction on the cap for the cap being tight.

And fortunately you noticed this the second time.

Things, even life, can indeed hang by such a thread.

I'm reminded of the sub that was lost because a flooding detection pinhole on a torpedo tube cover was accidentally painted over...

A lot of "bad luck" is not luck at all.

[smacksman]

Our 4236 (later M90) exhausted so close to the waterline it was difficult to see water flow under way. I fitted a 3mm telltale before the injection elbow and ran it into the cockpit. Worked well but made you wee a lot!

[MicHughV]

I go with (a) the strainer location....you could get air in it, because of it's location, this would cause a lack of coolant water flow ...air lock....and (b) the impeller...it's important that the outer seal plate completely rests on the rubber impeller..if there is any gap here for any reason, the impeller will just spin around without pumping water.....sometimes one of the impellor blades can break of and jam in there...

[Shaneesprit]

99C is a bit early to shutting down the engine, protective but when you need power you need it.
Would suggest 107C at least and in reality the oil temp is more important that the coolant if your going to shutdown at all.
I am sure most of us don’t have a shutdown at all
Oil is good for about 110C and then it breaks down quickly.
In reality the coolant is probably good for 150C if you could pressurise it enough. and the metal well a lot more than that.
Sorry I didn’t catch or read the engine type / Brand but I am assuming it’s a fairly modern engine.
Just lucky your not heading to the rocks as it switched off - some people have no sense of the word critical supply - Not aimed at the OP

[Jimmyhenry]

Raw water flow alarm is in my mind essential. We have a 4-236 also. Great engine. Aqualarm is what we have. It detects change in raw water flow. Easy to install.

[Jack C]

Originally Posted by Shaneesprit

99C is a bit early to shutting down the engine, protective but when you need power you need it.
Would suggest 107C at least and in reality the oil temp is more important that the coolant if your going to shutdown at all.
I am sure most of us don’t have a shutdown at all
Oil is good for about 110C and then it breaks down quickly.
In reality the coolant is probably good for 150C if you could pressurise it enough. and the metal well a lot more than that.
Sorry I didn’t catch or read the engine type / Brand but I am assuming it’s a fairly modern engine.
Just lucky your not heading to the rocks as it switched off - some people have no sense of the word critical supply - Not aimed at the OP

It was 99 when I had entered the slip. That when I shut it down. Its a Perkins 4236M. Can anyone tell me if there is an oil temperature sensor and where to find it?
My 4236 has an oil cooler heat exchanger cooled by the raw water flow. So low flow probably means higher oil temp.
I checked the cooling fluid. Nice and green although there is some sediment in the overflow bottle. The high temperature probably loosened some muck.

Thanks for the numbers.