Conference terri::cars_uk

    ..................OVERHEATING...........................
    
    I dont want to worry you but the use of two head gaskets is unlikely to
    last very long. The seal between the pistons will probably fail and the
    oilway joint between the block and head will not be very effective
    (known problem on these engines.)
    
    Back to the original problem, I suggest you check the timing is not
    over advanced and  that the radiator waterways are clear.
    Disconnect top and bottom hoses from rad and flush with hosepipe until
    clear water emerges or use proprietary cleaner for cooling systems. 
    
    Adrian
    

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Note 2.8                            DIRECTORY                             8 of 8
KIRKTN::LDICKHOFF                                    18 lines  21-NOV-1990 09:27
                            -< HELP!! Polo coolant >-
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    Moderator,
    
    I've got a problem with loosing coolant and don't know where to look in
    this file (new noter you see). Can you point me in the right direction?
    
    Make: VW Polo C
    year: 1986 (D)
    milage: 40,000
    Problem: level of coolant in external tank drops significantly; been to 
             the garage (A Clark, Edinburgh) where I bought it 2nd hand a year
             ago. They pressure tested the system, but couldn't find anything. 
             As far as I know, it is supposed to be a closed system; it
             should not loose anything. 
    Is there anybody out there............
    
    Thanks in advance,
    Leon
    South Queensferry Mfg

Do you get any white smoke (steam) out the tail pipe?  You could have a leak
through the head gasket (or block) into the engine itself.  With 40k on it,
it's not normal, unless it's been overheated or otherwise abused.

Dave

    Re: .4

    Leon, when you say the level drops significantly in the expansion tank,
    how often do you need to top it up ? The cars I've had with this sort
    of cooling system have still needed to be topped up from time to time.
    Ensure that you always check the level when the engine is cold.

    It is unlikely to be head gasket problems if the system has been
    pressure tested.

    Also, when the car is running normally is the temperature gauge showing
    a normal reading all the time or does it vary at all ?

    - Roy (Whose had head gaskets go before)

    >It is unlikely to be head gasket problems if the system has been
    >pressure tested.
     
    Since when did running diagnostics always find the problem :-)
    
    A quick check for something like this is by examining the oil. 
    If you have a mixture that is not unlike Bailey's Irish Cream, you
    have a problem.
    
    What do you mean by "external tank" ?  Shouldn't you be checking
    the radiator, did you mean the radiator.  My Fiat has an external
    plastic tank connected to the cooling system which is for overflow,
    it shouldn't really have anything in at all, as far as I know.
    
    TP

    I'm impressed by the speedy replies..................
    
    Oil doesnot look like Bailey (might become an addict otherwise)
    Temp Gauge: gets to normal and stays there.
    External tank: is really a plastic tank and as per the handbook should
    contain fluid up till the MAX mark.
    
    However; I phoned A Clark (to moan) and much to my surprise they offered to
    double check everything free of charge!! I'll keep you noters posted...
    
    Cheers,
    Flying Dutchman
                                       

If the Polo is anothing like the Golfs and Foxes, there is no 'radiator cap', 
per se.  The expansion tank has a cap on it and that's how you top off the
system.

For complete refills it's easier to disconnect the top radiator hose and dump
most of it in there.

It might be worthwhile steam cleaning the entire engine.  This makes looking for
leaks easier.

Dave

    The plastic "external tank" is known as an expansion bottle. On
    sealed systems they are connected to the top of the radiator
    underneath the cap. When it builds up pressure the vent under the
    cap opens to release the coolant. On the old systems it just overflowed
    hence the need to top up regularly. With the sealed system the coolant
    goes into the expansion tank. So when you've been on a long run
    and you check the exp. tank the level will be higher than when the
    engine is cold. 
    
    The problem comes as Trevor says, when the level in the radiator
    drops but there is still coolant in the exp. bottle. As you may
    think all is hunky dory but in fact have hardly any coolant in the
    system. This happened to me on a TR7 where you needed to top up the
    coolant at the thermostat housing, I didn't know this, there was
    coolant in the exp. bottle, but hardly anything in the system and
    it overheated.
    
    - Roy

This sounds like an internal leak in the head gasket.

"Old" style expansion tanks work as described in a couple of earlier replies.
Newer cooling systems ahve no radiator cap; the pressure cap is on the expansion
bottle.  This bottle is connected directly to the cooling system (ie there is
no valve restricting fluid flow in either direction).  It may be connected to
the radiator, or in my case (Sierra 1769cc CVH engine) to the water-cooled
inlet manifold.  I suppose it could connect anywhere really...

With this sort of system, the expansion tank should be kept topped up to the
line marked "Max".  If the level drops quickly or regularly then there is a leak
somewhere.

So to summarise: an old style system has a radiator cap with pressure-relief
valve, with the overflow pipe going to an expansion tank with an ordinary cap.
This sort of expansion tank should normally be empty.

A new-style one has no radiator cap, the expansion tank being connected
directly to the cooling system.  It may or may not have a pressure-relief valve
on the cap.  This type of tank should be kept full.

Now my own question:

I have been told that having the radiator too high or too low in relation to the
engine can cause the head gasket to fail.  I presume this is because pressure
builds up in the wrong places, or air pockets form, etc.  How can you (or
rather I) work out the correct position for a radiator, given that:

a) the radiator isn't the standard one for the engine (it's tall and thin
   rather than short and wide)
b) I don't know the position of the original, although I could find out if it's
   essential...

Scott

    Picked the car up on Friday nite, awaiting final quote. Would this
    stuff called Leak Seal (from Halfords) be any good? I feel it might be
    worth a try. Anyone has experience with this stuff??
    
    This morning I checked the coolant level and found the tank empty. That
    however is not the only thing I found:
    
    The hose from radiator to tank was disconnected and another hose hung
    down from the radiator!!!! First thing tomorrow I'll be kickin' some
    ......!
    
    As I'm not confident as all on car mechanics, the Sunday afternoon
    solution is a nono. I would do much more damage!!! ('ow 'bout this fer
    'onesty???)
    
    Flying Dutchman