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Hot engine, but not overheating

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kierantrees95 PCGB Member
2019/06/11 21:28:27 (permalink)

Hot engine, but not overheating

the expansion tank on my s2 is getting really hot, to the point where I cannot keep my hand on it, but the car is not overheating at all, or the system isnt getting pressurised. Do these cars just run that hot or do I have an issue with cooling.

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    Guest of the Club
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    924Srr27l Guest of the Club
    Re: Hot engine, but not overheating 2019/06/11 22:17:46 (permalink)
    yes they do run hot, but is the temp gauge reading ok ? and the fan kicks in when hot?
    Do you have any leaks on the floor, when cooled down is the expansion coolant level going down and needs
    topping up regular ? 
    If all the above is ok, and your oil level's good with no discoloured white or cream on the dipstick?> don't worry. 
    The plastic tanks do tend to bulge and swell with use, age and the heat it's an extension to
    the radiator which you'd not be able to hold for long either...
    Guest of the Club
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    bmnelsc Guest of the Club
    Re: Hot engine, but not overheating 2019/06/11 22:21:50 (permalink)
    If you are confident in your gauge and your levels are OK then I wouldn't worry.  Remember that the system runs about 192F when fully warmed up (both fans running) and even the low temp when the first fan cuts in is around 180F so the expansion tank will be hot.  I don't recall if the expansion tank sees coolant before or after the radiator but even so...coolant is at or above 180 at the top of the radiator.  If you are not pressurized - the coolant will boil at a lower temp (pressurization raises the boiling point) - won't affect the operation of the fans, thermostat, etc. 
    I had some problems with my S2 running warm - turned out the fan temp switch in the rad quit working and also had a sudden coolant loss with no obvious source.  The source became obvious after a flush and refill - the O ring under the plastic hose neck on the water pump had disintegrated and coolant started streaming out.  I replaced both the neck and O ring as rumor has it the plastic neck can warp affecting the seal.  The factory O ring is small and fragile so the least bit of warping would cause a leak.  Not sure why a thicker O ring wasn't specified and not sure that you couldn't substitute a thicker one yourself and possibly get longer life out of it.

    Bruce Nelson
    91 S2 Guards Red, Blk Script, sunroof delete, no air bags, no cruise
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    kierantrees95 PCGB Member
    Re: Hot engine, but not overheating 2019/06/12 16:56:23 (permalink)
    Both the fans kick in when they are supposed to, no leaks, and not losing any water at all, no issus with the oil either.
    I'm just being paranoid I think. The car runs well.
    Thanks for your help both 
    Guest of the Club
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    Waylander Guest of the Club
    Re: Hot engine, but not overheating 2019/06/12 17:52:14 (permalink)
    Clean up the rugby balls and all the connections on the clocks to make sure they are working as expected,
    but with a thermostat at 94 degrees and a rad fan switch at 102 it get really warm in there

    1992 Cobalt Blue 968 Coupe
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    graham.webb PCGB Member
    Re: Hot engine, but not overheating 2019/06/13 11:41:50 (permalink)
    The plastic elbow off the front of the water pump leaked on my S2 when I first got it....just another optimistic use of plastic I'm afraid. It had lost quite a lot of water before I noticed. When I took it off I checked the plastic flange with a straightedge, and it was bowed, so I flatted it of with emery paper on a wooden'd hope that the O ring and its metal reinforcing ring would do the job but apparently not! It needs to be compressed, and a distorted flange is unlikely to do that well. Thoroughly cleaned and reassembled with a smear of Hylomar, and it was fine.

    '91 944 S2: Alpine white
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