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  1. #1

    Default Wire inside coolant passages of head ??? Westerbeke 4-91


    I've been trying to sort out an overheating problem with a Westerbeke 4-91 (25 Hp diesel inboard, 1975) and after moving from raw water side (replaced impeller, flushed hoses etc) into the fresh water side I drained the heat exchanger and had it cleaned and tested, then pulled the fresh water pump and thermostat. At the thermostat housing I discovered a wire (solid steel, looks like an old coat hanger) rattling around under the thermostat. It had been in there at least 18 years and > 1000 engine hours but didn't look like it belonged so I tried pulling it out, the other end is stuck pretty good and all I managed was to break off about 10 mm of it.

    I brought my borescope webcam to the boat today to see if I could find out more, unfortunately the camera head is a bit fat to go in very far but I did get a glimpse of a couple more wires in deeper. I've uploaded a couple photos, in one you can see my finger pushing the original wire to one side, the other is a clearer shot of all three.

    Can anyone think of a valid reason why these wires might belong inside the cooling passages of the head ? I've been quoted $4.5K+ to have a head job done, doesn't seem worth it on an almost 40 year old engine (though other than this latest overheating it has been pretty good).

    Any thoughts appreciated, thanks.

    ... Niall
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  2. #2
    Join Date
    Jun 2008
    Island Heights, NJ,

    Default Re: Wire inside coolant passages of head ??? Westerbeke 4-91

    When things are cast from cast iron, cement like forms are used to "define" internal cavities. Often these forms have wire cores are reinforcement. After casting, these cores are supposed to be removed, i.e., broken and chipped out.
    I once had one runner on an aluminum intake manifold on a limited production high performance car I once owned be completely blocked from the port to plane under the carb with casting material and another car had remnants of wire in the water jack of the block. I would not think that the wire as it is would cause any problems other than the fact that your cooling water will always have some rust in it. Should a piece rust thru and break off, you might end up with a stuck T'stat.
    Capt Bob
    1969 23ft ChrisCraft Lancer
    Merc 5.7L 260HP/ Volvo 280
    1972 22ft Bristol
    Honda 7.5HP 4 stroke Long shaft

  3. #3

    Default Re: Wire inside coolant passages of head ??? Westerbeke 4-91

    Thanks for the insight, the two smaller wires may very well have been part of the cement forms and ended up too close to the surface during the casting. The other piece probably got stuck in afterwards but as you say is not likely to cause any trouble until it breaks off (pretty solid at the moment !) ... I'll leave it for now and see if I get another 1000 hours out of it

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