New Engine - Same 4.107 over heating problem.

[jewt]

Just for the sake of discussion, what is the size of your exhaust hose. My '69 41 Morgan originally had a Perkins 4-107 and was factory equipped with an 1.5 inch exhaust hose. I corrected the problem when I repowered in '94 with a 4-108.

jewt
S/V Bifrost

[donradcliffe]

I just went through the overheating problem on another boat. Turned out the engine intake was partially blocked with crap. If you can, measure the GPM of wter coming out of the exhaust with a bucket when the engine is in neutral, both at idle and 2000 rpm.

[FionaJC]

I have a 4107. I would top up the coolant and run at 1800rpm with a temp of 193f. If I run at 2000 rpm plus it goes to 221f. And would stay there until I dropped the rpm. I did not have an overflow bottle so I was always topping up. I now have a bottle fitted and it stays full but the temp goes up and down as before. I talked to an old tractor engineers and he said that engine under load would go to 120c. So I'm not over bothered.i am using the same intake and oil cooler with my old engine and that had a massive heat exchanger and stayed at 80c. Just the thermostat temp. My exhaust temp is around 40c at the moment. The only time I had a problem with the weed on the intake. Check with jabsvo about the flow and take an inlet to a large bucket with a measured amount of water to check thst the flow is right and look at the temp at high revs. Keep spare measured water to keep it topped up.

[joesail]

Thanks for all of the great advice. Let me answer some of your questions.

1. Thruhull Inlet size. I have a 3/4 inlet which is the same size as the input port on the raw water pump so I believe that should be OK. My strainer is a Groco and I never see bubbles in the glass so I assume it is not starving for intake water flow.

2. Pressure: If you watch my video you'll see the steady flow of bubbles out of the radiator cap. I used a radiator pressure tester and tested the cap fist. Then I started the engine with the pressure gauge attached. Immediately on start the pressure started rising and I shut the engine off when the pressure reached 17 pounds. Perkins calls for a 7 pound cap and Trans Atlantic Desisel recommends a 10 pound cap which I am running now. The pressure overwhelms the cap limit within a few minutes of start.

The coolant circuit holds this pressure after shutting the engine down too. Coolant gets pushed into overflow tank and never returns to the engine. After the engine cools I have to break the seal on the cap to let the pressure off to drain the coolant back into the system.



Crimped hoses: All hoses are new and not crimped.

Combustion test: I did test the coolant for combustion gasses using the blue fluid. I really had to strain to see a color change but I think there was a slight shade change of green. It did not give me a dramatic change in color like the manual showed.

Prop. I think I was mistaken about the prop. I think it's 15" and not 12". The PO had an 18" prop on the boat and I was afraid the larger prop may have been causing a high load on the engine. I called Michigan prop and they selected the prop and pitch based on my boat dimensions.

Normal Temps. All gauges are new and my gauge matches my laser thermometer so I believe the temps are correct.


I am planning to pull the head, have it tested, and replace the gasket. Thats my only thoughts unless someone here can think of another possibility.

[TNRivers]

Make sure your seawater inlet hose is wire reinforced...otherwise the pump can collapse the cooling water feed.
Terry
sv Privateer III
Islander 41 ketch

[joesail]

Originally Posted by TNRivers

Make sure your seawater inlet hose is wire reinforced...otherwise the pump can collapse the cooling water feed.
Terry
sv Privateer III
Islander 41 ketch

Not sure about that. I'll check

[NorthCoastJoe]

How far of a run is the intake hose? If it is a long run the friction loss within the hose could be a problem solved with a larger hose. Is it possible to load the engine at the dock with a wide open garden hose feeding the raw pump? If it still over heats it would eliminate the raw side of the cooling from the problem. Then look toward the engine.

[Ken Z]

I would lean toward pitch of prop, repitch, check cooling intake , hoses.

[jimbunyard]

There are two numbers relating to prop size; diameter and pitch. Without both, either number is essentially meaningless.

You can (generally) check if your prop is causing an overheating problem with an rpm check.

First make sure that the engine reaches maximum high idle speed, usually about ten percent over rated maximum operating speed. Then check that the engine will reach maximum rated operating speed (preferably a little over) in gear. If not, then you are overpropped and this could cause, or be contributing to, an overheating problem.

Without being able to view the video and the nature of the 'bubbling', bubbles in the coolant could be caused by a leaking head gskt, a cracked head or, less commonly, block or exhaust manifold (depending on the engine).

A steady stream of relatively fine bubbles would be more indicative of head gasket than, say, an intermittent burst of large bubbles, which might be more indicative of trapped air being 'burped' through the system by uneven heating within the engine, but without firsthand experience we're all just guessing.

Pulling the head seems a little drastic at this point though, unless you have more information of which we're not aware...

[Rowglide]

We run twin VT903's in our fireboat. usually run right around 175-180... BUT 2 seasons ago the starboad engine was getting up to 190-195.
Not good .... until we replaced the temperature gauge. There was no overheat issue at all but a defective VDO Gauge.
Make sure your temperature gauge is accurate.

[Zhyachts]

Cooling water is injected into the exhaust manifold through a small section of threaded pipe. Once in a while this "half nipple" has an overly long threaded section that reaches into the manifold and blocks cooling water.

[DeepFrz]

What is your coolant comprised of? If straight deionized water then try running it with a 50/50 water antifreeze mix. One of the easiest things to try before going to more expensive things.

[donradcliffe]

[QUOTE=joesail;2406342
Combustion test: I did test the coolant for combustion gasses using the blue fluid. I really had to strain to see a color change but I think there was a slight shade change of green. It did not give me a dramatic change in color like the manual showed.[/QUOTE]

When I used the NAPA fluid, I got about the same result. I then stuck the tester in the exhaust pipe of my rental car and got an immediate dramatic change to yellow. The problem I was chasing was oil in the coolant, and it turned out to be a leak in the oil cooler. The bubbles I saw in the coolant turned out to be a normal startup phenomena.

[lifeofreilly57]

Might sound stupid, but on a previous boat I owned the yanmar 3gm would overheat if I went over 2800 rpm, I had one on an earlier boat that would run 3200 rpm all day long. After trying every trick in the book I looked at the through hull and the plumbing attached to it and realized that the intake through hull and fittings were too small. THe next time it was out of the water I changed the through hull to the next size up, along with the plumbing and the problem was solved.
On another boat it turned out to be the prop sizing, swapping to a similar prop with slightly less pitch solved the over heating issue and gained speed, since the motor was able to run in it's max power range.
This is assuming all other parts such as heat exchangers and the engine plumbing are in good shape.

[Uncle Bob]

Originally Posted by joesail

Thanks for all of the great advice. Let me answer some of your questions.

1. Thruhull Inlet size. I have a 3/4 inlet which is the same size as the input port on the raw water pump so I believe that should be OK. My strainer is a Groco and I never see bubbles in the glass so I assume it is not starving for intake water flow.

2. Pressure: If you watch my video you'll see the steady flow of bubbles out of the radiator cap. I used a radiator pressure tester and tested the cap fist. Then I started the engine with the pressure gauge attached. Immediately on start the pressure started rising and I shut the engine off when the pressure reached 17 pounds. Perkins calls for a 7 pound cap and Trans Atlantic Desisel recommends a 10 pound cap which I am running now. The pressure overwhelms the cap limit within a few minutes of start.

The coolant circuit holds this pressure after shutting the engine down too. Coolant gets pushed into overflow tank and never returns to the engine. After the engine cools I have to break the seal on the cap to let the pressure off to drain the coolant back into the system.



Crimped hoses: All hoses are new and not crimped.

Combustion test: I did test the coolant for combustion gasses using the blue fluid. I really had to strain to see a color change but I think there was a slight shade change of green. It did not give me a dramatic change in color like the manual showed.

Prop. I think I was mistaken about the prop. I think it's 15" and not 12". The PO had an 18" prop on the boat and I was afraid the larger prop may have been causing a high load on the engine. I called Michigan prop and they selected the prop and pitch based on my boat dimensions.

Normal Temps. All gauges are new and my gauge matches my laser thermometer so I believe the temps are correct.


I am planning to pull the head, have it tested, and replace the gasket. Thats my only thoughts unless someone here can think of another possibility.

The statement that the engine coolant pressure keeps rising well above the manufacturer recommended pressure says it all for me. I believe that you are on the right track with the plan to remove the head, test etc.