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  1. #1
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    Default Sabre Perkins still overheating

    Ok - new impeller, heat exchanger stripped, cleaned and refitted, oil cooler checked (clear), air charge exchanger stripped and cleaned. Thermostat tested and opening OK. Will run all day at 1200 rpm and 8 knots and is at 82 degrees. Take her up to 2100 revs and the temp creeps very slowly up to over 90 (over about 5 minutes) - I havent dared take her higher. Throttle back and within 10-20 seconds temp is back to normal

    My guess is now either a worn raw water pump (boat has about 520 hours) or a partial restriction on the raw water inlet. The latter is a pig to get at due to the way the strainers are fitted but that will be my next step. The boat doesnt come out for the winter so cant easily check from the outside. Any other thoughts? The other engine is fine.
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  2. #2
    penfold is offline Registered User
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    As you have already changed the impellor, the raw water pump seems unlikely at that age; do you sail on particularly muddy water as that causes accelerated pump wear? Other possibilities are the fresh water pump and Head gasket, although the fact that it runs fine a lower speed suggests not. Can you take the ground or get a lift out for a scrub? That would allow an external inspection.
    Grünkraft? - nein danke.

  3. #3
    Divemaster1's Avatar
    Divemaster1 is offline Registered User
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    Quote Originally Posted by stuartwineberg View Post
    Ok - new impeller, heat exchanger stripped, cleaned and refitted, oil cooler checked (clear), air charge exchanger stripped and cleaned. Thermostat tested and opening OK. Will run all day at 1200 rpm and 8 knots and is at 82 degrees. Take her up to 2100 revs and the temp creeps very slowly up to over 90 (over about 5 minutes) .......... Any other thoughts? The other engine is fine.

    Not knowing your engines it may be difficult to say, but;

    1) I do not see a cooling water temperature of 90 - 95 degrees C as overheating for a diesel engine. If she is stable as 95 degrees, then fine...
    2) Temperature gauge or sensor may be wrong ... once again, if she is stable, then fine... can you swap the cables on the instruments around to check the insrument? ... if same, it could be the sensor .... but once again is she stable after 15 min + ?

    What is your max RPM .... oh ... and are your RPM gauges correct, or do you have an un-even load on the engines ?

    Is one engine heating water as well as cooling the engine ? ... if so, you will have difference in temp as the one heating the water have more liquid circulating, thus more cooling capacity and thus cooler liquid....

    When we run at 1800 RPM (Max 2300), we run at about 87 deg C on port engine and about 93 deg C on Stb ...(Port engine is heating water).... at WOT we rise to just about 90 and 95 respective ... on the gauges that is.... but we have mechanical gauges near the engines, and they show 3 - 5 degrees less.... but all are stable once temp is reached..
    Last edited by Divemaster1; 03-01-12 at 00:43.
    Regards, Alf

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  4. #4
    Join Date
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    Have you looked to see if there's more steam from the overheating engine? That would be a visual indication. I had a similar problem on one of my engines and it turned out to be a blockage of seaweed/leaves etc in the pipe between the seacock and the raw water pump. I used my dinghy pump to sort of back flush it from the pipe connected to the pump. A few strokes of the pump later and the blockage was gone and engine back to normal. Worth a try, only takes a few minutes so nothing to lose.

  5. #5
    omega2's Avatar
    omega2 is offline Registered User
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    The book says 90c maximum, we have 180's and have suffered the same, one thing you can check, run the engine up to temp with the filler cap off the header tank, if you see needle bubbles in the water as it crosses the aperture then suspect head gasket. Or better still get a pickavant pressure tester. can you see the exhaust outlet on the transom? are both engines ejecting the same amount of water, is the generator belt tensioned correctly, have you drained down the fresh water, try disconnecting the pipe at the rear of the exhaust manifold and catch the water in a bucket look for dehbris. Also in the pipework from the raw water pump to the intercooler, this sometimes holds bits of broken up impellor. I am assuming that your Sabres are Ford based. Lastly is it your port engine giving problems? Soory misread the OP I see yopu have Perkins, but the advise may still be useable.

  6. #6
    Join Date
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    Default Thanks All

    To answer the questions. Have drained the fresh water side - no debris - also I know about the mesh debris trap on the sabres and have checked that.

    Doubt it is the gauges as the sboard engine doesnt mimic the behaviour - it stays at about 84 degrees at any revs and also the port engine isnt going hot and staying there, the temp changes are engine speed related and drop back as soon as I throttle back

    Like the dinghy pump idea - that is at the top of my list. Gen belt good question but the pumps are gear driven not belt. Divemaster - appreciate that 90 degrees is not "overheating" as such but it is the slow creep upwards which is a new event after three years use of the boat and not happening on the sboard side so I suspect something is amiss. The calorifier is on the sboard side so I accept port engine should be a bit hotter but again it is the change in behaviour I dont like.

    Talk of head gaskets is a bit scary. Would I get these symptoms - ie - no overheat at 1200 revs (max is 2500) and then slow creep up as revs increase. No loss of power, no coolant loss

    Thanks again
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  7. #7
    vas's Avatar
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    Quote Originally Posted by stuartwineberg View Post
    Talk of head gaskets is a bit scary. Would I get these symptoms - ie - no overheat at 1200 revs (max is 2500) and then slow creep up as revs increase. No loss of power, no coolant loss

    Thanks again
    filler cap of the header tank should help in clearing gasket problems, although gaskets can fail in different ways. Check oil cap for white creamy deposits for another type of gasket failure.
    Haven't come across a gasket failure that temps would drop as soon as load was reduced, usually the boiling that takes place has longer term effects even at idle speed. I'm sure someone will come along stating the oposite...

    Does sound more like a cooling pump/heat exchanger problem (ie not too expensive and boat lift out)

    good luck

    V.

  8. #8
    blueglass is offline Registered User
    Location : Greece (boat) Shropshire (home)
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    had exactly this issue on my Sabre Perkins 225Ti's - it was always an irritation, but never came to anything. Shortly after buying boat the problem arose when I first cruised at speed in my semi d atlantic 38 . Fine all day at displacement speeds but once above 14 knots - up the temp went on starboard engine. Had engineer strip everything down and he found nothing at all to cause problems. he said it was normal and just to carry on and reduce revs if temp crept towards 100deg.
    We cruise normally at displacement speeds so it was never a major issue until 5 years and many thousands of miles later we had the boat up for sale and the buyer was unhappy (understandably) At our expense, an engineer spent a week, stripping, sea trialling, part after part. Water pump housing backplate was found to be a little worn and replaced - made no difference. minor sludging around thermostat housing and themostat replaced - still no difference. Not an engineer myself , but the guy went through everything with a fine tooth comb and other than those very minor issues he found everything in tip top order and finally came to same conclusion as engineer #1. Perkins were consulted and they said the temp rise was within normal paramaters. Fair enough, but still didn't explain why the other engine allways ran cooler. Incidentally and paradoxically to me, the hotter engine in my case was the one runnning the calorifier!
    The buyer was satisfied and bought the boat and is still happy with his purchase.
    So OP, like you I was never happy with it, but learnt to live with it! If you don't get to the bottom of it try not to lose too much sleep.
    I will watch the thread with interest to see if a solution arises.

  9. #9
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    In re the head gasket, Mermaid (Ford) said if the gasket was blown the engine would reach a certain temp and then blow the cooling water out, and this would happen each time at a progressively lower temp. I had a new engine (Ford) which had the wrong thermostat and allowed a much higher temp than spec for marine use, still fine for a road engine, but it did blow the head gasket.

  10. #10
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    I have the 135's with a similar number of hours & every time I have had an increase in temp on one engine it has always been a blockage in the inlet strainer, which in my case are part of the seacock. This happens every year to me in the med at some point.

    It's surprising how little you need to block the flow to get a small increase like yours. Depending on the type of seacock/strainer you have I would remove hoses & check they are clear & see how the water flow is. In my case its easy & I can push something straight down through the strainer & seacock.

    At this number of hours the engines are all but new if they have been well cared for so it is most likely to be something simple.

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