thread: V6 water pump discovery!

  1. #1
    Woodsport Paul Woods's Avatar
    Mar 2005
    Durham, UK birthplace of the 1.5,v6 and v8 Mr2
    14,617

    V6 water pump discovery!

    We have made a bit of a breakthrough here!

    In doing a v6 conversion we have always fitted brand new water pumps as part of the job, but on some v6 swaps a few people have reported that if the engine is left to idle for long periods of time, especially after a bit of a thrash, they would start to very slowly overheat.A quick blip of the throttle and the temp would settle to normal again.

    Now it occurred to us that this was no normal fault, if the thermostat was faulty it would overheat all the time,or stay stone cold... if the radiator was partially blocked it too would give a constant problem.You also have to factor in the fact that not everyone has seen this little oddity with the coolant temp.Indeed all systems are checked for fan operation, rad switches checked and systems fully bled.

    So what was causing the odd V6 mr2 to heat soak around the engine if left to idle but not others?

    Well we put in a lot of time into this one, mainly because if we are fitting brand new water pumps,thermostats and doing everything by the book then what else can we do as mechanics?

    We have been getting our water pumps from our local parts supplier that i have been using for the last ten years, he only supplies good quality parts, none of the cheap rubbish you can buy off ebay or from china.Normally it is a QH (Quinten Hazel) water pump we would use, who are a reputable make of spurious parts, and it was only last month when we happened to have a QH pump on the bench, a genuine Toyota one and a Blueprint pump all side by side that we stumbled on something VERY important.

    It appears that different makers of spurious pumps have DIFFERENT designs of pump impellor blades!

    Take a look at the pic below....


    Notice anything odd? Both of these pumps are brand new 3vz-fe pumps, the one on the right is a QH pump and the one on the left is a Blueprint pump.You can see the impellor design is completely different between the two..... we compared them both to the genuine toyota pump which shared the same design as the Blueprint pump on the left.

    So, we then fitted the new Blueprint pump to a conversion we did that was having the mystery heatsoak issue and after a quick bleed up of the system it was 100% cured.

    What is basically happening here is that the QH pump impellor is not moving enough coolant at engine idle, probably fine for a camry with its short run to the radiator but on an Mr2 it was just lacking enough push unless it was given a little blip of the throttle now and then.

    We have spoken to QH directly about this, who were initially shocked that their pump design was not the same as toyotas, and they have promised to change the design.Wether they do or not remains to be seen!

    So this is an important find, you presume by fitting a brand new water pump that you are doing everything in your power to do a good job, sometimes you have to look into it a little deeper.

    Bottom line is if you do buy a QH pump make sure it has the same impellor design as the pump on the left.Otherwise buy a Blueprint one that shares the toyota design.

    To date we have no idea which conversions we have personally done have which design of pump, it may or may not have been one design or the other, who knows! All i do know we have been fitting new pumps to them all.Ironically if we left the old knackered toyota pumps on (presuming of course nobody ever changed it during its life on the camry) the issue would never have been spotted.

    So a bit of an important cooling system breakthrough this one, up to now it only applies to the 3vz, 1mz pumps appear to be all the same.

    Hopefully this new information helps you lads out.

    TB Quote of the month:"I split my ear open whilst masturbating" - Jasper Full story Here

  2. #2

    Aug 2008
    kent
    51
    Mine gets very hot at idle

  3. #3
    Woodsport Paul Woods's Avatar
    Mar 2005
    Durham, UK birthplace of the 1.5,v6 and v8 Mr2
    14,617
    Yours is a 1mz though chris,all of their pump designs appear to be the same..... are you seeing actual overheating if it is left to idle or just a constant higher temp?

    TB Quote of the month:"I split my ear open whilst masturbating" - Jasper Full story Here

  4. #4
    Lee's Avatar
    Nov 2005
    Kilmarnock
    587
    Hi Paul,

    Is there anything QH can do to help out owners with this problem?

    A change of design and a discount for a new pump as a gesture of goodwill seem fair?

    How much is the blueprint pump?

  5. #5
    antnkel's Avatar
    Jul 2008
    Littleborough
    611
    Yours is a 1mz though chris,all of their pump designs appear to be the same..... are you seeing actual overheating if it is left to idle or just a constant higher temp?
    Mine seems fine, hardly ever changes on the gauge

  6. #6
    Woodsport Paul Woods's Avatar
    Mar 2005
    Durham, UK birthplace of the 1.5,v6 and v8 Mr2
    14,617
    QH are not prepared to refund anyone in this case.Even though they have been told it is a problem, bottom line being the pump works ok in a camry so the buck stops with us having the V6 in an Mr2.All they have said is they will revise the design.... not much good to us now.

    The blueprint pump is around £60.

    As above it is not affecting everyone, but then we do not know who has one type and who has another.

    TB Quote of the month:"I split my ear open whilst masturbating" - Jasper Full story Here

  7. #7

    Aug 2008
    kent
    51
    Yours is a 1mz though chris,all of their pump designs appear to be the same..... are you seeing actual overheating if it is left to idle or just a constant higher temp?
    Just at idle if left for a long time it doesn't overheat because i stop it before it gets there, I had thought that it was because there was no air moving throught the rad because when the fans come on it is for a very short time only just enought to cool the water in the rad not long enough to get to the motor.
    It's not a problem because I know it does it.

  8. #8
    Woodsport Paul Woods's Avatar
    Mar 2005
    Durham, UK birthplace of the 1.5,v6 and v8 Mr2
    14,617
    Thats a good bit of info, looks like QH are using a cheap cast part.

    Another pump that uses the same design as the blueprint one is "First line", FWP1642 is its part number.
    Indeed Tone, it has taken us months to totally investigate this, good info on the First line part number too :thumbsup:

    It should be noted we have only heard of one or two cars even seeing this issue, but we needed to get to the bottom of it regardless.

    TB Quote of the month:"I split my ear open whilst masturbating" - Jasper Full story Here

  9. #9
    hmmmmm's Avatar
    Dec 2006
    Netherlands
    1,063
    Nice find paul, just checked my ebay water pump (not fitted yet) and looks like its the right design.

  10. #10
    tripod23's Avatar
    Mar 2009
    lancashire / preston
    611
    i know this is a little stupid but i read somewhere that in the swap over the coolant accually runs in the wrong direction , is this true or just an old wives tail. also iv got to say that the temp gauge in the n/a still factory standard at the moment touch wood has never moved away from halfway even when left to tick over for a long time. and i have done the same test with the camry donor car which is a 1mz - which i know is a shorter coolant run but same again it seems perfect even when left to idle . i would have thought that if the after market pump matches what toyota had in there to begin with we should be fine after all theres more coolant running in the mr2 surely over the camry . do we need a bigger rad for the n/a swap over do we think

  •