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  1. #1
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    Aug 2004
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    Default Perkins 4108 coolant flow problem

    My refurbished 4108 is up and running ( in the garage). I have installed some 'raw water plumbing' so I can do a proper test.
    There is an overheating issue as follows. The coolant water gauge climbs rapidly towards the 100 degree mark but the raw water coolant is not getting even warm.
    Water in the header tank is getting very hot but not flowing through the heat exchanger jacket.
    I had installed a new hot water 'valve' and actually checked that it was opening as required.
    It would seem that the coolant water is simply not being pumped around the system. I am going to give it some though but am minded to remove the header tank and check the valve ( possibly I will try running the engine without it first.
    Thought I would give the experts a 'call' first to see if I am missing anything obvious?

  2. #2
    Join Date
    Nov 2009
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    Default Re: Perkins 4108 coolant flow problem

    I assume that the hot water valve is the thermostat? That would be my first thought but as it's new then it should be fine, assuming that it's the correct heat range.

    My second thought would be that the impeller in the water circulation pump, assuming this engine has one, is spinning on its shaft and not actually pushing any water around.

    Richard

  3. #3
    Join Date
    Jul 2001
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    Weybridge, UK
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    735

    Default Re: Perkins 4108 coolant flow problem

    The fresh water pump is usually driven from the alternator belt. Do you have this fitted?
    Dave Seager
    Weybridge UK

  4. #4
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    Jul 2002
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    Default Re: Perkins 4108 coolant flow problem

    Quote Originally Posted by RichardS View Post
    I assume that the hot water valve is the thermostat? That would be my first thought but as it's new then it should be fine, assuming that it's the correct heat range.

    My second thought would be that the impeller in the water circulation pump, assuming this engine has one, is spinning on its shaft and not actually pushing any water around.

    Richard
    Regarding your second thought and the fact that I have an overheating problem , not yet investigated, with one of the cars It was suggested to me, by my MOT tester, that the impeller of the coolant pump could be corroded ... like a sacrificial anode !

    Anything you've come across ? Could, of course, be spinning on the shaft

    Obviously will check the thermostat and give the rad a good flush but I am reluctant to disturb the water pump without good reason.

  5. #5
    Join Date
    May 2007
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    37,716

    Default Re: Perkins 4108 coolant flow problem

    Is the block warming up or just the head?
    Have you checked the head is actually getting hot?
    Sounds like either faulty thermostat or coolant impeller not spinning?

    But if the raw water is flowing through the heat exchanger, why is that so much colder than the header tank? Airlock?

    If the head is not getting hot, then the thermostat will remain closed and the header tank and HE will be heated by the exhaust.
    Can happen, idling at zero load!

  6. #6
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    Jul 2002
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    Default Re: Perkins 4108 coolant flow problem

    Quote Originally Posted by lw395 View Post
    Is the block warming up or just the head?
    Have you checked the head is actually getting hot?
    Sounds like either faulty thermostat or coolant impeller not spinning?

    But if the raw water is flowing through the heat exchanger, why is that so much colder than the header tank? Airlock?

    If the head is not getting hot, then the thermostat will remain closed and the header tank and HE will be heated by the exhaust.
    Can happen, idling at zero load!
    There is a note in the mnaual for the 4.108 which says to make sure the correct type of thermostat is fitted. "Certain engine applications have an external bypass which incorporates a thermostat with a bypass blanking valve. This valve closes the bypass port as the thermostat opens ."

  7. #7
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    Default Re: Perkins 4108 coolant flow problem

    Quote Originally Posted by VicS View Post
    Regarding your second thought and the fact that I have an overheating problem , not yet investigated, with one of the cars It was suggested to me, by my MOT tester, that the impeller of the coolant pump could be corroded ... like a sacrificial anode !

    Anything you've come across ? Could, of course, be spinning on the shaft

    Obviously will check the thermostat and give the rad a good flush but I am reluctant to disturb the water pump without good reason.
    The only similar thing I have direct experience of is a plastic impeller slipping on the shaft although I would guess that the OP has a metal impeller and I've never had any problem with those although I have read about it happening with metal impellers.

    However, in a situation with a thermostat definitely working, or perhaps even removed entirely, if the block is getting hot and the temp gauge is registering but the top inlet hose to the radiator/radiator matrix still feels cool it's difficult to think of any other possibility other than the pump failing to circulate the water.

    Richard
    Last edited by RichardS; 25-08-19 at 08:17.

  8. #8
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    Aug 2004
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    Default Re: Perkins 4108 coolant flow problem

    Thanks all. Yes, by valve I did mean thermostat (senior moment!) The fan belt is in place and the pulley turning. I propose to try again but will more carefully feel which components are getting hot and report back.
    Just looking at my set up again: the coolant is in the header tank at the front of the engine and directly connected to the heat exchanger at the back and returns via the exhaust manifold. I can confirm that the exchanger and the manifold are clear so why are they not getting as hot as the water in the header tank? are senior moments at work again?

  9. #9
    Join Date
    Jun 2001
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    Corfu - mostly
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    5,343

    Default Re: Perkins 4108 coolant flow problem

    When my 4108 had this problem it turned out that the manifold had corroded internally, on a heat-exchange system, dumping rusty sludge through the cooling passages in the engine block and preventing the coolant flowing freely. (Also it meant that raw salt water was flowing through the engine). I managed to flush it clean by first removing the outlet plug and rigging my dinghy pump to blow into the system, then turning the engine over with the plug still out, continually adding fresh cooling water. But I was lucky, any more blocked and this wouldn't have worked.

    That having been said, there are numerous other possible reasons for your problem, as previous replies suggest.

  10. #10
    Join Date
    Aug 2004
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    Default Re: Perkins 4108 coolant flow problem

    A BUMP up on this one please!!
    Many thanks for the responses to date. I have been waiting delivery of a remote heat tester ( the gun type) so that I can get real figures on what is going on with the plumbing.
    I now have the gun, it will go into my boat tool kit as I can see it could be quite useful.
    I propose to do some more testing and will value any advice.
    As stated the 'raw water' plumbing is circulating water well though it is not getting water. The heat exchanger and manifold were all checked for water flow. The header tank is full and there are no internal or external leaks from that. The fresh water pump has been off and looked fine and the belt is in place.
    when running and despite the raw water coolant remaining cool the water temp from the head sensor is getting hot quickly as is the water in the header. By hand I could not detect any real heat in the pipes on the header-exchanger-manifold 'circuit' ( I am not sure just what should push water round this 'circuit'.) also I am not sure if the block was getting warm.

    I assume that on start up the thermostat will be closed so the 'circuit' above will not be required, then as the water in the block and head warms up the thermostat will open and the water in the header 'circuit' can start to flow?

    I propose to run the engine up again, switch off when it gets too hot and record the temps at the header, outer of exchanger, manifold, block, head and for good measure the oil filter.

    Any advice on the general situation and on testing will be welcome.

    This engine is identical to the one installed on board and this exercise has been very instructive ( and the advice invaluable!)

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