Water leak : head gasket ???
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Thread: Water leak : head gasket ???

  1. #1
    1000+ Posts Beano's Avatar
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    Default Water leak : head gasket ???

    One of my cars is losing water. Only about half a litre a week (if that), but it's consistent.

    I have replaced the radiator (small crack in plastic tank) and top hose, but it still has the leak.

    When the car is hot and therefore the system is pressurized I cannot see anything leaking out. And no evidence of green-coloured coolant leak stains. Nothing where the heater hoses connect on back of engine or onto throttle body pre-heater.

    So I am starting to think it might be a head gasket getting old. But the car has only done 180,000 and I don't want to start thinking about head gasket leaks.....yet. Particularly since the engine does not get hot at all. But if I do go down that path and put a leak-stopper additive into the cooling system, I want to be sure it is a gasket and not something else which might suddenly let go after being bunged up for a long time.

    If I have a head gasket leak, as far as I know here is what happens : when I stop the engine, the pressurized cooling system forces water back into a cylinder. But there are head gasket leaks in which the engine does NOT get hot, aren't there ? How does the engine NOT get hot if there is a pathway from cylinder to water jacket, allowing water to travel back under something like 10 or 15 pounds pressure ?

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    The car is a Mitsubishi Magna 3.5 litre V6 (2000 model TJ ), but I hasten to add that I also own TWO Peugeots...

  2. #2
    Fellow Frogger!
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    Perhaps not a head gasket, but a leak into the intake manifold (I had a Subaru doing that and it wasn't easy to find).

    Recently had a subtle one on the 505. Turned out it was a fine pinhole in the heater hose which squirted straight onto the exhaust manifold and evaporated instantly. There was nothing to see each time I lifted the bonnet when the coolant level warning light came on. It didn't leak at all at idle, only when the revs were up.

    Have f un,

    Rob.

  3. #3
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    Yes, I had exactly the same thing in a 505 GTi.
    You need a pressure tester to find these leaks.

    Quote Originally Posted by robs View Post
    Perhaps not a head gasket, but a leak into the intake manifold (I had a Subaru doing that and it wasn't easy to find).

    Recently had a subtle one on the 505. Turned out it was a fine pinhole in the heater hose which squirted straight onto the exhaust manifold and evaporated instantly. There was nothing to see each time I lifted the bonnet when the coolant level warning light came on. It didn't leak at all at idle, only when the revs were up.

    Have f un,

    Rob.

  4. #4
    1000+ Posts geckoeng's Avatar
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    Check the water pump. My 19 was doing exactly the same no trace on the floor nothing. But close examination of the water pump showed small droplets coming out the body drain hole. Did the water pump and timing belt and idler, and all stayed full again.

    Ray
    Ray geckoeng

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  5. #5
    1000+ Posts Beano's Avatar
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    Thanks dudes.

    Sigh.

    I've been in denial about the possibility of the water pump. They apparently don't commonly stuff up at the mileage, and it's difficult to see in there in there with the timing belt, but I'll give it a go.

    Hoping it's a leak into the intake. Not sure how that'll show itself, even with a pressure tester. Maybe I'll have to take off the throttle body and leave it loose whilst it's getting tested....

  6. #6
    1000+ Posts driven's Avatar
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    Also check inside for leaks from the heater area/hoses/etc Wet underlay a giveaway

  7. #7
    Too many posts! JohnW's Avatar
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    "Only" half a litre a week!!!

    You'd expect something to be visible unless it really is an internal leak. Even if it is evaporating on something there'd be a big white mark by now. It would be awash inside and you'd smell the coolant I reckon, if it were the heater circuit. You could try jamming a tightly rolled rag or some cotton wool or something under the water pump drainhole - short run then it will be wet or not if that is the place and you just can't see it.

    Too big a leak to ignore, isn't it...

    Good luck with the hunt.
    JohnW

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  8. #8
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    Cracked head.

    Had a '95 Magna wagon with a recon motor which always used a consistent amount of coolant. (Recon motor went in after wife cooked original motor due to leaking radiator hose). Mechanic eventually replaced the cracked head, but returned the car with stuffed big-end bearings .

    Next recon motor was better, but then the auto started giving trouble (at (300,000km). Was saved from wasting more money by a hail storm .

    EDIT: Of course my TS had a Japanese V6, and your TJ has an Australian made motor, but hey - it's just as valid as comparing it with a Subaru, Pug 505 or Renault 19 !

    Cheers

    Alec
    Last edited by Armidillo; 23rd December 2016 at 03:36 PM.

  9. #9
    1000+ Posts schlitzaugen's Avatar
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    Quote Originally Posted by Beano View Post
    Thanks dudes.

    Sigh.

    I've been in denial about the possibility of the water pump. They apparently don't commonly stuff up at the mileage, and it's difficult to see in there in there with the timing belt, but I'll give it a go.

    Hoping it's a leak into the intake. Not sure how that'll show itself, even with a pressure tester. Maybe I'll have to take off the throttle body and leave it loose whilst it's getting tested....

    You'll see the pressure drop?

    If it is that big and it leaks at all engine regimes, you might be able to catch a whiff of coolant at the exhaust.
    ACHTUNG ALLES LOOKENPEEPERS

    Das computermachine is nicht fur gefingerpoken und mittengrabben. Ist easy schnappen der springenwerk, blowenfusen und poppencorken mit spitssparken. Ist nicht fur gewerken bei das dummkopfen. Das rubbernecken sightseeren keepen hands in das pockets-relaxen und watch das blinkenlights.

  10. #10
    1000+ Posts Beano's Avatar
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    Problem found !

    It is a leak from the heater coming down into the passenger footwell.

    I rationalized the water I found there, telling myself it was a window I left open during the recent rain. And it didn't really smell like coolant.

    I was losing about half a litre a week when the radiator's plastic end tank was cracked, but actually only about half THAT now I've replaced the radiator. Slow enough to not be seen under the plastic passenger-side foot mat. Then when I DID see it, and thought it had been rain, slow enough to dry out on hot days.
    I did wonder about the stain on the carpet though.....thought it was from the underfelt.

    The whole thing has been an exercise in self-deception : I was unwilling to admit the reality of the situation and wanted the problem to conform to my preconceived ideas about what it might be.

    I need to re-think my problem-solving processes.
    Last edited by Beano; 24th December 2016 at 09:51 PM.

  11. #11
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  12. #12
    1000+ Posts Peter C's Avatar
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    A much better result than head gaskets etc. As someone often says to me, looks for the simple things first! I have trouble applying this myself.

  13. #13
    Too many posts! JohnW's Avatar
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    Quote Originally Posted by Beano View Post
    Problem found ! It is a leak from the heater coming down into the passenger footwell. I rationalized the water I found there, telling myself it was a window I left open during the recent rain. And it didn't really smell like coolant. I was losing about half a litre a week when the radiator's plastic end tank was cracked, but actually only about half THAT that now I've replaced the radiator. Slow enough to not be seen under the plastic passenger-side foot mat. Then when I DID see it, and thought it had been rain, slow enough to dry out on hot days. I did wonder about the stain on the carpet though.....thought it was from the underfelt.

    The whole thing has been an exercise in self-deception : I was unwilling to admit the reality of the situation and wanted the problem to conform to my preconceived ideas about what it might be. I need to re-think my problem-solving processes.
    Actually, your problem solving process evolved correctly, so that side is OK now!!

    Bloody nuisance nonetheless, but at least it ain't the engine. Nice result, in its way.

    Happy Christmas to you and yours.
    JohnW

    Renault 4CV 1950 (R1062)
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    Renault Scenic Series II 2005 (wife's)
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    CitroŽn CX Pallas 1980 (moved on to new custodian)

    National Co-ordinator, Renault 4CV Register of Australia

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