50hp Perkins won't rev past 1900rpm

[Hoohaa]

Does anyone know where the thermostat might be hiding on this engine?


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[DeepFrz]

Originally Posted by Hoohaa

I didn't take the rubber boots off then of the heat exchange. It could be possible that there is some crap blocking things. But wouldn't there need to be a significant amount of blockage tty of effect things? Or are heat exchanges a bit sensitive and precious.

There are many threads on CF documenting that the cooling system on the 4-108 is marginal. A number of people have installed larger heat exchangers. They seem to just work okay. I don't think it takes much of a blockage or buildup of crud in the exchanger to cause a problem.

[Hoohaa]

Thanks. Its actually an after after market heat exchanger so I am not shore if thats a good thing or A bad thing.
I will be removing the boot next time I am onboard. Hopefully it will reveal some blockage.
On another note. This engine is also known as A Volvo Penta D2-55.

[DeepFrz]

Sorry about that. I "assumed" it was the 4-108.

[Hoohaa]

Originally Posted by DeepFrz

Sorry about that. I "assumed" it was the 4-108.

No need to apologise. I appreciate any help you can offer.
The Perkins version is A 104-19.

Just got some great pica of my heat exchanger.


PE122-5009.pdf

[Hoohaa]

Well. The heating problem is fixed. Before I tell you what the culprit was I will go over what I did.
Firstly I have run Barnacle Buster through the heat exchanger for 16 hours. Reassembled and tested it. Still got hot.
I then bought new rubber boots and a thermostat in preparation for checking the rubes inside the heat exchanger.
Armed with all this I arrived on board this morning and got stuck into the repairs including running a wire through all of the tubes. Put it all back together and checked for leaks. All good.
forgot to mention that I refilled the freshwater side of the cooling system with the good Stuff.
When doing all of this I did note that there was not allot of fresh water cooling fluid coming out of the heat exchanger.
Took it for a test run, ran it pretty hard couldn't get it to overheat. So I am a very happy camper.
Boats back on the mooring and looked over things to check there were no leaks or anything else.
Here's a shot of the panel during the test.
When I was going over the engine before shutting down. I saw this split hose at the cap on top of the heat exchange. ##@*.
Turns out she has just been short of water the whole time. . Could have fixed it in 10 minutes, a screwdriver and pocket knife.
Boats are so much fun.
Gunna chalk it up to experience .
Here's couple more fun picks.


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[SkiprJohn]

Originally Posted by Hoohaa

Well. The heating problem is fixed. Before I tell you what the culprit was I will go over what I did.
Firstly I have run Barnacle Buster through the heat exchanger for 16 hours. Reassembled and tested it. Still got hot.
I then bought new rubber boots and a thermostat in preparation for checking the rubes inside the heat exchanger.
Armed with all this I arrived on board this morning and got stuck into the repairs including running a wire through all of the tubes. Put it all back together and checked for leaks. All good.
forgot to mention that I refilled the freshwater side of the cooling system with the good Stuff.
When doing all of this I did note that there was not allot of fresh water cooling fluid coming out of the heat exchanger.
Took it for a test run, ran it pretty hard couldn't get it to overheat. So I am a very happy camper.
Boats back on the mooring and looked over things to check there were no leaks or anything else.
Here's a shot of the panel during the test.
When I was going over the engine before shutting down. I saw this split hose at the cap on top of the heat exchange. ##@*.
Turns out she has just been short of water the whole time. . Could have fixed it in 10 minutes, a screwdriver and pocket knife.
Boats are so much fun.
Gunna chalk it up to experience .
Here's couple more fun picks.


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I'm really glad you got it sorted out. Now you really know your cooling system and can't wait for it to happen again. : ) Just kidding.

[SkiprJohn]

Do you still have the rpm problem or did I miss a post or two?

[Hoohaa]

Yep. Still won't rev high. It will do 7 nkt at 1600rpm. So I am thinking of not opening that can of worms and just excepting it. It's running well. I think it's time to take her sailing for a change. Before I get started on the next project. Stay tuned. Thanks for all the help.

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[lancelot9898]

I also have that hose at the top of the Bowman H/E under the cap. My hose drains down into the bilge whereas it looks like your hose goes up. I thought about installing a coolant recovery tank so that the coolant would not empty into the bilge and be lost, but because of lack of space I have not done so. My point is that as the coolant heats up and expands, there is loss of coolant in my engine too(Perkins 4-108), but even with this loss of coolant which I do not replace the engine has been running at 180 degrees F for the past few years. (Only recently after draining all the engine coolant and then replacing...I'm running at 190.....although that reading was taken tied to dock under load whereas I may be back to 180 underway and in slightly cooler water)

[Hoohaa]

Originally Posted by lancelot9898

I also have that hose at the top of the Bowman H/E under the cap. My hose drains down into the bilge whereas it looks like your hose goes up. I thought about installing a coolant recovery tank so that the coolant would not empty into the bilge and be lost, but because of lack of space I have not done so. My point is that as the coolant heats up and expands, there is loss of coolant in my engine too(Perkins 4-108), but even with this loss of coolant which I do not replace the engine has been running at 180 degrees F for the past few years. (Only recently after draining all the engine coolant and then replacing...I'm running at 190.....although that reading was taken tied to dock under load whereas I may be back to 180 underway and in slightly cooler water)

My hose does go to a bottle. You cans see it in the background. We used to top it up fairly frequently. For some strange reason this hasn't been necessary for a while. Hmm. The indications where there all I had to do was look, my wife kept asking me why there was green liquid in the bilge..

[DeepFrz]

You never disregard a question like that from your wife. I remember, a long time ago, an investigator working on failed electronic components was musing over the problem at dinner one day. His wife said "I bet you its the bag" referring to the type of bag the components were packaged in. Some length of time later he "discovered" it was the bag.

[SkiprJohn]

Originally Posted by Hoohaa

Yep. Still won't rev high. It will do 7 nkt at 1600rpm. So I am thinking of not opening that can of worms and just excepting it. It's running well. I think it's time to take her sailing for a change. Before I get started on the next project. Stay tuned. Thanks for all the help.

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Might just be a tachometer calibration anomaly?

[Hoohaa]

Originally Posted by SkiprJohn

Might just be a tachometer calibration anomaly?

Yep. I might have a look at that. Just need to find some sort of gouge or device that can tell me? or would I have to get hold of a second tacho?

[SkiprJohn]

Originally Posted by Hoohaa

Yep. I might have a look at that. Just need to find some sort of gouge or device that can tell me? or would I have to get hold of a second tacho?

I have a handheld electronic tach that is easy to use. You put a white dot on your front crank pulley and then start the engine, point the tach at the dot and pull the trigger and the thing gives you a digital rpm. Pretty neat and is about $30. Maybe higher now that it's 2015 instead of 2000.

Remember each of the pulleys off the crank will be a different rpm depending on their size so you have to measure the crank pulley.