Perkins 4-108 running hot

[Jerry Kimble]

Audrey, CD36 #086. The engine has always run hot, in the yellow on the temp. gauge. Anything over 1900 RPM puts it into the red. although 1800 RPM usually gives me 6.2 knots, there are times when I want more power.
Does anyone else have this problem? I would think the engine should stay at 160 Deg.



jkimble@mcn.org

[Jerry Axler]

Audrey, CD36 #086. The engine has always run hot, in the yellow on the temp. gauge. Anything over 1900 RPM puts it into the red. although 1800 RPM usually gives me 6.2 knots, there are times when I want more power.
Does anyone else have this problem? I would think the engine should stay at 160 Deg.

I have a 36 CD #137 and she runs at 2100rpm to yield 7-7.2 kts and the temp runs at 175-180. Check your water intake and strainer, it sounds as though you may have reduced water flow. Here on the Chesapeake there has been a lot of eel grass in the water and it has been blocking intakes and clogging filters.



cutter36@erols.com

[Jerry Kimble]

Audrey, CD36 #086. The engine has always run hot, in the yellow on the temp. gauge. Anything over 1900 RPM puts it into the red. although 1800 RPM usually gives me 6.2 knots, there are times when I want more power.
Does anyone else have this problem? I would think the engine should stay at 160 Deg.

I have a 36 CD #137 and she runs at 2100rpm to yield 7-7.2 kts and the temp runs at 175-180. Check your water intake and strainer, it sounds as though you may have reduced water flow. Here on the Chesapeake there has been a lot of eel grass in the water and it has been blocking intakes and clogging filters.

The water passages are clean. I've even replaced the hoses to be sure. This has been a long lasting problem. Thanks for the info. on your engine. It helps me know something is wrong with mine.



jkimble@mcn.org

[matt cawthorne]

Jerry,
My 1982 CD-36 runs at 160 all the time. I am told that it should have a new thermostat so that it will run at 180. You need to get to the bottom of this problem right away. The boat shuold be able to run with the engine wide open without overheating. You could have a problem with the intermal water pump, an internal blockage, a problem with the thermostat, or a blocked heat exchanger. I would start with the thermostat. Next check the heat exchanger. If you have the heat exchanger with the water cooled exhaust manifold which is rectangular and mounted on the side of the engine then you can pull then rubber ends off of it and get a good look inside. I have heard of impellers falling apart and blocking heat exchangers.

BTW: your tach may be reading low. I did a calibration of mine with a photo-tachometer and found it to be off by a large amount. On calm water with the original 15RH14 prop and 2:1 gearbox you should be at 7.2 knots when the true engine RPM is somewhere around 2800. (I don't run this way normally, that is the top end) I chose to reduce my prop pitch to 12 so that I could get more out of my engine when punching through choppy seas and it is more like 3250 rpm when the engine tops out in calm water. If you don't have the 2:1 box or 15RH14 prop ignore this note.

Good luck,
Matt



mcawthor@bellatlantic.net

[Steve Alarcon]

Jerry,

By coincidence, I was reading the operators manual for my 4-108 yesterday. It specifies that the engine temp should be between 160 and 200 degrees F. On my CD36, and also my previous CD30, I had similar problems to what you described. While on the hard, I noticed that multiple layers of bottom paint had caused restrictions at the little water intake cover. I cleaned out the holes with a pocket knife to return to the original size, and the overheating problem ceased.

Steve Alarcon
CD36 Tenacity
Seattle



alarcon3@prodigy.net

[Ron Miller]

I also had the problem with the 4-108 running hot at the higher RPMS and checked the more obvious stuff like pumps, inlet stainer, heat exchanger, etc. Lastly I flushed the cooling system using an automotive cooling system flush. This did the trick and the amount of scale removed was impressive!

Essentially (read the directions for the specific product you use) you mix the chemical and pour it into the fresh water system, run the engine for some time letting it heat up and then draining it out. After draining put in a new batch of proper coolant mixture.

I get the impressiion that after a few years the cast iron block of the 4-108 does corrode leaving scaly deposits in the cooling water passages!

Good Sailing,

Ron

Audrey, CD36 #086. The engine has always run hot, in the yellow on the temp. gauge. Anything over 1900 RPM puts it into the red. although 1800 RPM usually gives me 6.2 knots, there are times when I want more power.
Does anyone else have this problem? I would think the engine should stay at 160 Deg.

I have a 36 CD #137 and she runs at 2100rpm to yield 7-7.2 kts and the temp runs at 175-180. Check your water intake and strainer, it sounds as though you may have reduced water flow. Here on the Chesapeake there has been a lot of eel grass in the water and it has been blocking intakes and clogging filters.

The water passages are clean. I've even replaced the hoses to be sure. This has been a long lasting problem. Thanks for the info. on your engine. It helps me know something is wrong with mine.

rmiller@verizon.com