I own a Cape Dory 36 and have problems with my perkins 4108 diesel. It is a l984 model. The seawater compotent seems to be working well with the new impellor and thermastat. But, the engin still overheats under load,1800rpm. Could there be a problem with the heat exchanger. I do think that the problem may be in the fresh water cooling component of the system.Also, could a foulded 3 bladded prop cause overheating problems at cruising rpm's(below 2000). Is this a problem I can fix myself or do I need to call the Diesel Doctor. Thanks. joe
windwalker111@yahoo.com
overheating perkins 4108 diesel
Moderator: Jim Walsh
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Bob Pence
Re: overheating perkins 4108 diesel
Have owned 2 boas with this engine. 9 times out of 10 it is the heat exchanger. If the zinc on the exchanger has not been replaced on a timely basis it contributes to the problem. You can order a new one from Hansen Marine in Marblehead, Ma. or Foley. Cleaning the one on a 4-108 isn't worth the trouble.JMullins wrote: I own a Cape Dory 36 and have problems with my perkins 4108 diesel. It is a l984 model. The seawater compotent seems to be working well with the new impellor and thermastat. But, the engin still overheats under load,1800rpm. Could there be a problem with the heat exchanger. I do think that the problem may be in the fresh water cooling component of the system.Also, could a foulded 3 bladded prop cause overheating problems at cruising rpm's(below 2000). Is this a problem I can fix myself or do I need to call the Diesel Doctor. Thanks. joe
sixpence@dmv.com
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R Baker
Re: overheating perkins 4108 diesel
I own a 36' CD hull #18 built in 1979. I had overheating problems with "Solitaire" when I removed a larger heat exchanger that the previous owners had installed. I cleaned and replaced it with the old heat exchanger. The larger one did not fit properly and one of the cooling water hoses let go, we had to sail back in. Sailing in the Gulf the water temperature can get pretty high and I thought that this might be the reason of the overheating. The first time I took her out, after changing heat exchanges, I checked the prop and found it covered. After I cleaned the prop she ran allot better and overheating was not a big problem. I have ordered a new heat exchanger to replace the old one, because she still runs a little too warm. A fouled prop can make it overheat and run slower at higher RPM. Good luck and I hope this helps.Bob Pence wrote:JMullins wrote: I own a Cape Dory 36 and have problems with my perkins 4108 diesel. It is a l984 model. The seawater compotent seems to be working well with the new impellor and thermastat. But, the engin still overheats under load,1800rpm. Could there be a problem with the heat exchanger. I do think that the problem may be in the fresh water cooling component of the system.Also, could a foulded 3 bladded prop cause overheating problems at cruising rpm's(below 2000). Is this a problem I can fix myself or do I need to call the Diesel Doctor. Thanks. joe
Bob Pence wrote: Have owned 2 boas with this engine. 9 times out of 10 it is the heat exchanger. If the zinc on the exchanger has not been replaced on a timely basis it contributes to the problem. You can order a new one from Hansen Marine in Marblehead, Ma. or Foley. Cleaning the one on a 4-108 isn't worth the trouble.
rbaker3@tuelectric.com
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Ryan Turner
Re: overheating perkins 4108 diesel
I haven't got a Perkins but cleaning the heat exchanger on my 24 hp Universal did wonders for my engine temperature. I just used some muriatic acid to clean out the mineral concretions that accumulated inside the exchanger. After the acid bubbled and boiled awhile I rinsed it out, reinstalled it, cranked up the engine and marveled at how much cooler the engine ran. It was cheap and easy to do. Other things that will greatly affect engine temp, speed, etc. are barnacles on the prop and slime/barnacles, etc. on the hull. I just scrubbed all the slime off my hull and scraped a fresh crop of barnacles off my prop this weekend and picked up 0.5 knots of hull speed at 2200 rpm. These little things mean alot.
Ryan Turner
s/v Zenobia
CD33 hull no. 100
Oriental, NC
rdtsails@msn.com
Ryan Turner
s/v Zenobia
CD33 hull no. 100
Oriental, NC
rdtsails@msn.com
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Jim Roedel
Re: overheating perkins 4108 diesel
Check for any torn rubber impeller blades down stream of the pump. They will usually end up at the inlet side of the heat exchanger. jrJMullins wrote: I own a Cape Dory 36 and have problems with my perkins 4108 diesel. It is a l984 model. The seawater compotent seems to be working well with the new impellor and thermastat. But, the engin still overheats under load,1800rpm. Could there be a problem with the heat exchanger. I do think that the problem may be in the fresh water cooling component of the system.Also, could a foulded 3 bladded prop cause overheating problems at cruising rpm's(below 2000). Is this a problem I can fix myself or do I need to call the Diesel Doctor. Thanks. joe
marinerketch@aol.com
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Matt Cawthorne
Re: overheating perkins 4108 diesel
Joe,
Lots of things could be a problem here. One thing is certain. Your engine should not overheat at any loading. The 4.108 tops out at 4000 rpm if the prop is matched to the transmission and engine. The props that came with the boat in that era were typically 3 bladed Michigan Wheel 15RH14 on a 2:1 Hurth transmission. With that combination my 36 would make 7.3 knots at 2800 rpm. At higher throttle settings than that all you get is lots of black smoke. The fact that the engine does not reach max RPM at hull speed implies that there is too much pitch, but since the engine larger than the boat needs that is not really a major problem. Despite the overpitched prop my boat has never overheated since I have owned it. There were 2 or three heat exchanger configurations on the 4.108. One type was a thin walled cylinder that mounts across the back of the engine. This model had a zinc installed in it. The other model (the one that my CD36 has) is a Bowman model that is integrated with the exhaust manifold. This model is a very heavy design and has no zinc. Here is my recommended checklist.
1. Make certain that there is not a lot of growth on the strainer on the outside of the hull.
2. Check the strainer.
3. Check the impeller.
4. Pull the rubber caps off of the end of the heat exchanger and verify that there is nothing plugging it. (for the side mounted rectangular model only)
5. Check to make certain that there is plenty of water coming out the exhaust. Actually you should do this first. If there is plenty of water coming out then the problem is likely to be in the fresh water side.
Now with all that being said, a fellow cape dory 36 owner had his fresh water pump fail this summer. He ended up having to take it to the Perkins doctor to get that job done.
Matt
mcawthor@bellatlantic.net
Lots of things could be a problem here. One thing is certain. Your engine should not overheat at any loading. The 4.108 tops out at 4000 rpm if the prop is matched to the transmission and engine. The props that came with the boat in that era were typically 3 bladed Michigan Wheel 15RH14 on a 2:1 Hurth transmission. With that combination my 36 would make 7.3 knots at 2800 rpm. At higher throttle settings than that all you get is lots of black smoke. The fact that the engine does not reach max RPM at hull speed implies that there is too much pitch, but since the engine larger than the boat needs that is not really a major problem. Despite the overpitched prop my boat has never overheated since I have owned it. There were 2 or three heat exchanger configurations on the 4.108. One type was a thin walled cylinder that mounts across the back of the engine. This model had a zinc installed in it. The other model (the one that my CD36 has) is a Bowman model that is integrated with the exhaust manifold. This model is a very heavy design and has no zinc. Here is my recommended checklist.
1. Make certain that there is not a lot of growth on the strainer on the outside of the hull.
2. Check the strainer.
3. Check the impeller.
4. Pull the rubber caps off of the end of the heat exchanger and verify that there is nothing plugging it. (for the side mounted rectangular model only)
5. Check to make certain that there is plenty of water coming out the exhaust. Actually you should do this first. If there is plenty of water coming out then the problem is likely to be in the fresh water side.
Now with all that being said, a fellow cape dory 36 owner had his fresh water pump fail this summer. He ended up having to take it to the Perkins doctor to get that job done.
Matt
JMullins wrote: I own a Cape Dory 36 and have problems with my perkins 4108 diesel. It is a l984 model. The seawater compotent seems to be working well with the new impellor and thermastat. But, the engin still overheats under load,1800rpm. Could there be a problem with the heat exchanger. I do think that the problem may be in the fresh water cooling component of the system.Also, could a foulded 3 bladded prop cause overheating problems at cruising rpm's(below 2000). Is this a problem I can fix myself or do I need to call the Diesel Doctor. Thanks. joe
mcawthor@bellatlantic.net