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Thread: Manitou 634 overheating

  1. #1
    Member
    Join Date
    Mar 2013
    Location
    Yorkshire
    Posts
    43

    Manitou 634 overheating

    Morning all....we have yet anothe manitou fault😫

    She he has the Merc engine and has always tended to run warmer than I'd like.

    she had thermostats replaced under warranty to no avail but recently the fault has developed to the point where the hydraulically driven fan is totally in op in forward and reverse.

    the fault has been traced to a worn splined drive shaft on the independent engine driven oil pump(pretty poor at 1800 hrs)

    upon replacing that,I have pump flow and pressure in abundance but the fan is running in reverse all the time flat out,so there must be a control issues too.

    there are two electro magnetic solenoids/spools on the motor drive control block and whilst these are rated at 12v,the feeds to them are nearer 4-5volts and I'm unsure wether the machine steps voltage down or wether voltage drop has occured through a faulty relay or something.

    im also unsure as to where the control switch is in the cooling system.Ive located the temp guage sender unit(could this possibly do the job of both)

    just to add,there was evidence of broken o rings in the spools which was jamming them too😫

    Any advice appreciated as local dealers(bless them)are only interested in selling parts and swapping everything until it's cured.....not the way IMO.

    i don't seem to be able to get test data or advice from anywhere.....😕

  2. #2
    Junior Member
    Join Date
    Nov 2017
    Location
    Scotland
    Posts
    1

    Re: Manitou 634 overheating

    Hi

    Hopefully you find this helpful
    Merc engine is bullet proof

    The cooling fan pump drive shaft is a known Manitou issue and subject to your machine having a full dealer service history the replacement pump should have been covered by Manitou via a policy claim.

    I would almost be certain that your cooling fan is not running in reverse. The fan is a puller type meaning the air is drawn over the engine the out the front. The 2 solenoids you are trying to test are PWM and cannot be tested with a multimeter. The fan is controlled by the SPU ecu and pulling the plugs off the coils will just bring on (!) Warning on the SLI all electrical checks need to be done by a Manitou dealer with the Pad tool. if there is an electrical fault the fan will default to full speed.

    The only test I could suggest to you is with the plugs still connected to the coils remove the bottom coil from the control valve on the fan motor, the fan should go to full speed.

    If you still think your engine is overheating it will be more than likely the bottom of the radiator is blocked. The only real solution is to remove the radiator and powerwash it thoroughly and also powerwash the engine pod too.

    If your still having overheating issues the cylinder head gasket could be blown depending on how long the machine ran with the failed cooling fan pump?

    Cheers
    ManitouMan

  3. #3
    Senior Member ACE's Avatar
    Join Date
    Feb 2013
    Location
    Oxfordshire
    Posts
    1,503

    Re: Manitou 634 overheating

    Quote Originally Posted by ManitouMan View Post
    Hi

    Hopefully you find this helpful
    Merc engine is bullet proof

    The cooling fan pump drive shaft is a known Manitou issue and subject to your machine having a full dealer service history the replacement pump should have been covered by Manitou via a policy claim.

    I would almost be certain that your cooling fan is not running in reverse. The fan is a puller type meaning the air is drawn over the engine the out the front. The 2 solenoids you are trying to test are PWM and cannot be tested with a multimeter. The fan is controlled by the SPU ecu and pulling the plugs off the coils will just bring on (!) Warning on the SLI all electrical checks need to be done by a Manitou dealer with the Pad tool. if there is an electrical fault the fan will default to full speed.

    The only test I could suggest to you is with the plugs still connected to the coils remove the bottom coil from the control valve on the fan motor, the fan should go to full speed.

    If you still think your engine is overheating it will be more than likely the bottom of the radiator is blocked. The only real solution is to remove the radiator and powerwash it thoroughly and also powerwash the engine pod too.

    If your still having overheating issues the cylinder head gasket could be blown depending on how long the machine ran with the failed cooling fan pump?

    Cheers
    ManitouMan
    I was going to send you a PM but there not switched on yet as your new here If you need Manitou part number 224053 give me a shout

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