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GaryMac

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Posts posted by GaryMac

  1. Hello

    A few years ago we had a truck come in with heaps of ongoing problems. It was a R model OSHKOSH, CAT 1674, RR gearbox, 4 speed SPICER on 55000lb ROCKWELLS.

    The fan vee belts would turn inside out, was always breaking fuel injector pipes, and the owner was about to remove the gear box as it was ready to blow up.

    Anyhow I can't remember what we were doing but were talking about all these problems and he said some one back into him many years previous and had to get a new radiator made. The boss said about the crankshaft, fan and crankshaft damper to which he said were all OK. We removed the damper and it looked OK, but suggest to replace it.  

    We cut the housing open as it was a viscous type and was dry as a bone. Well the truck was completely different, i.e. all the problems disappeared and drove better.

    I do remember you have replaced the damper but is it the right one? Vibrations are black magic and to control them is another science, but many thing generate them, i.e. engine components and adjustments. Timing and fuel rates.

    Gar

  2. Just some thoughts

    I like mechanical MACKS and CATS

    Last year i heard of a bloke with a Cummins electronic with similar problems.

    They checked everything with no luck, then started to renew the components,

    i.e. sencors, throttle pedal etc etc including the total on engine wiring loom

    with no success. With the progress bill for this work fastly approaching the

    trucks value things looked bleak. Finally the problem was found, being a

    input from the vehicles brake system.

  3. Most unit injector engines burn about 25% of the fuel circulating with the remaining fuel cooling the injectors and returning to the fuel tank.

    I have seen some engines, (8V92s etc) seizing injectors due to high fuel temperature especially when the tanks were low.

    Some engine manufactures would rate their engines performance @ 29degC fuel temperature with some losses due to temperature above, with a maximum

    alowable inlet fuel temperature of about 50degC.

    Therefore fuel cooler can be beneficial to the engines performance and component life.

    Best regards

    Gary

  4. Hello from Australia

    Yes I can remember several COE MACKs powered by 3406 CATS with 12 speeds fitted.

    They were owned by a farmer pulling fridge vans, factory fitted around about 1980s.

    Also of interest I can also remember three (3) R700s fitted with Cummins 400s

    in the mid 1970s, factory fitted for Wettennalls transport.

    Some early R700s V8s (865 & 866s?) were repowered with CAT 3408s especially

    those involved with heavy haulage (low loaders etc).

    Gary

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