Volvo 850 1996 - Mystery of the Diasppearing Coolant

Discussion in 'Volvo 850' started by Chris, Apr 20, 2007.

  1. Chris

    Chris Guest

    850 with 20v 2.5l engine. 115,000km from new with full main dealer
    service history, Recently the collant light went on. Checked coolant,
    needed a litre of so to bring back to max line. After 150km city
    driving, needed another litre. Then went on 750km country trip. No
    coolant loss whatsoever. Think to myself, that was weird, but must be
    ok now.

    Now, another 200km later of city driving coolant light back on and it
    took 2 litres to bring back to max line.

    Is it leaking heater core? - don't think so as no wet carpets or other
    evidence of leak in cabin. No funny smell when heater turned on.

    Is it head gasket? - don't think so as engine runs smooth, no
    overheating at all when running (even when coolant was low guage bang
    slap in middle), and no white vapour from tailpipe).

    Coolant is clean, oil is clean.

    No evidence of any leaks under the bonnet.

    Radiator hoses are not pressurised (easy to squeeze together when
    engine running).

    Where is the coolant going?????
    Chris, Apr 20, 2007
  2. Chris

    James Sweet Guest

    I had a problem like this with my 740 years ago, ended up being a hose
    clamp with a slightly stripped adjustment screw, it was tight enough to
    not leak until the cooling system heated up and pressurized, but by that
    point it was hot enough and the leak small enough that it came out as
    invisible steam. I found it by pressurizing the cold cooling system with
    a sports ball hand pump, a few PSI is enough, it started pissing out
    around the clamp. I used the hose to the expansion tank but I've heard
    of installing a tire valve stem in a spare radiator cap. It's a trick
    worth trying before you do more drastic things, but if it doesn't
    visibly leak you should turn the engine over by hand to make sure it
    isn't hydrolocked from coolant leaking into a cylinder before you try
    starting it.
    James Sweet, Apr 20, 2007
  3. Chris

    blurp Guest

    Another point of leakage (for similar reasons as described above) is
    the water pump gasket. Mine only seemed to leak once the car was shut
    off and the engine temperature went up because the coolant has stopped
    flowing, further pressurizing the system.

    blurp, Apr 20, 2007
  4. Chris

    Chris Guest

    That is an interesting point, but would I not expect to see leakage on
    the engine or on the ground? There is no evidence of leaks at all
    (that I can see)

    Chris, Apr 20, 2007
  5. Chris

    Baz Guest

    If as you suspect the water is going into the engine and being "burnt" with
    the fuel, it is probably not in all cylinders. You should be able to see a
    difference in the condition of the spark plugs, the one with water entering
    should look cleaner than those without. If you can somehow get a view down
    the plug holes the piston top should also be cleaner.

    By the way I used to run water injection on another car, it pinged on 91
    octane unleaded - that cured it, and your water consumption is around the
    amounts I used, although it was going into all 4 cylinders. I had no
    evidence of white vapour from the tailpipe, although it's often very hard to
    see your own tailpipe while you're driving. So if it is going into the
    engine, you will probably see no ill effects in running from this amount.
    Maybe even an improvement.

    My 1996 850, upon refilling with coolant will often undergo a major drop in
    level overnight, some inches in the expansion tank, and it has emptied the
    tank on one occasion less than an hour after refilling. After a couple of
    days of this it stabilises and is then ok for a long time, until once again
    disturbed. I suspect air locks in the system, that bleed themselves out.
    I've gotten used to this and now expect it.

    You mentioned that your radiator hoses were not pressurised. Perhaps the
    expansion tank cap is not sealing. Buy another one. I had one on an
    earlier 740 Volvo (cap looks the same by the way) and although it looked ok
    and the valves and gasket seemed ok, a new one cured the leak on that car.
    But there were stains around the cap indicating a leak.

    Coolant leaks often do not reach the ground, but will always leave a residue
    on something showing its path on the way out. If enough leaks out, you can
    generally locate it with careful examination. That is if you are using the
    proper coolant and not just water (If you're losing enough $$$, perhaps
    you're down to just adding water?)

    Lastly I had heard that some 850s had problems with porous cylinder heads.
    It was aggravated by not using proper coolant. Perhaps someone else can add
    some information here.

    Baz, Apr 20, 2007
  6. Chris

    Chris Guest

    I looked at the filler cap - no evidence of any leakage whatsoever.
    The date of manufacture is 2003, so I presume the original failed and
    was then replaced.I have cheked all the water connections. Some have a
    white powdery type of residue (such as the heater pipes on the
    firewall) but nothing tha appears to be a current leak.

    I don't actually suspect the water is entering the combustion chambers
    - I believe it must be a leak of some sort.

    I have just come back from a 200 mile drive and the car used no
    coolant whatsoever. Ehat really do not understand is why it consumes
    water in city driving, but not on the highway. On a long drive the
    engine gets a good rev, I a not scared of redline. My wife thnks the
    coolant los correlates with her use of he airconditioning, but surely
    the systm are completel independent?????
    Chris, Apr 22, 2007
  7. Two clues in that:
    *long drives keep the cooling system pressurized, while a succession of
    trips (maybe typical of city driving?) causes the coolant to be pushed into
    the reservoir when the engine heats up and slurped back up when the engine
    cools. If the recovery hose is split, like at the radiator neck, the coolant
    can be lost in the transfer. I've also had grief from the seal at the
    radiator cap leaking, causing the system to pump coolant into the reservoir
    when heating and sucking air back in when cooling. That causes the reservoir
    to get overfilled, though. Regardless, if the radiator cap is more than a
    couple years old this is a good time to replace it with a new Volvo cap -
    aftermarket radiator caps and thermostats are unreliable.
    *The A/C affects part of the cooling system: the radiator. Since the A/C
    condensor is in front of the radiator, using the A/C raises the radiator
    temperature and in that way raises the temperature of most of the coolant in
    the system. That means more expansion and more cycling into and out of the
    reservoir (previous paragraph).

    Michael Pardee, Apr 22, 2007
  8. Chris

    Chris Guest

    Good suggestions - I will purchase a new radiator cap at Volvo dealer
    today - can't be that many $$$ (I hope!) and will at least discount
    one potential issue. However, if there was loss between engine and
    expnsion tank I would have thought it would be visible - I can't see
    any loss.

    Chris, Apr 22, 2007
  9. Chris

    moster Guest

    Chris, I hate to be the bearer of bad news, could very well be your
    head gasket. You may NOT see anything at all on the outside as far as
    evedence is concerned because it may be getting compressed and burned. Start
    your car and remove the coolant cap. Watch for about thirty minutes or until
    you see coolant come bubbling out of reservoir. If the the temperature is ok
    and coolant comes out of reservoir what is happening is your head gasket is
    blowing compression into the cooling system. When that happens, and chances
    are that it will happen at higher speeds, your cooling system cannot handle
    that much pressure and releases coolant as you are driving down the road.
    Happened to my Chrysler LHS and it, like yours, had no symptoms anything was
    moster, Apr 23, 2007
  10. What makes me think elsewhere is that the coolant holds up well in highway
    driving. That is usually worst case for head gasket coolant consumption.

    Michael Pardee, Apr 23, 2007
  11. Chris

    bfiske Guest

    I had the $ame problem on my '97 960.
    Replaced two radiator$, water pump, thermo$tat, ho$e$ and clamp$.
    Car would lo$e coolant after driving in heavy traffic.
    No sign$ on driveway or "under the bonnet".
    Drove me crazy.

    Defective temperature $ensor was not $tarting the electric cooling fan.
    Sometime$ the fan would come on, sometime$ it would not.
    Pre$$ure would build up and $pray out the coolant.
    Pre$$ure blew out two radiator$.

    Mystery $olved for me.

    Good luck.

    Bring back the 240!

    bfiske, Apr 23, 2007
  12. Chris

    Chris Guest

    I must admit I feel the same way as Mike. On long trips the car
    performs beautifully - smooth, fast, responsive, and NO coolant loss.
    And temperature guage at horizontal at ALL times. irrespective of
    speed, a/c operation etc. This is with sport mode, lots of full
    throttle, engine revs >4000rpm often. Me driving. In town (wife
    driving, careful, moderate throttle, what is a redline???) coolant
    lasts about 200km before below min line in expansion tank. It sems
    logical to me that it must be related to cycling of the coolant
    between the block and expnsion tank. Which says to me expansion tank
    leak of some sort. Dealer had no caps in stock this morning, Perhap I
    should just change the entire tank???? I am thinking of trying a crude
    pressure test before going down that path. If I remove the hose
    attachment to the thermostat housing and use a hand pump with a
    suitable fitting will I be able to sufficiently pressuise the
    expansion tank to etst its integrity.

    Thanks for all comments - you are all most helpful

    Chris, Apr 23, 2007
  13. Chris

    Chris Guest

    The fan comes on regularly and temperature guage never varies position
    when warm but it is something I will also re-check. Thanks for the

    Chris, Apr 23, 2007
  14. Chris

    John Horner Guest

    I would start with a pressure test of the cooling system to see if it is
    holding pressure when stopped.

    On my '96 850 the heater core failed and I think there was a drain in
    the car which took the leakage away so that it didn't get the carpet
    wet. I'm not sure though and I have since sold the car (after fixing
    the heater core).

    John Horner, Apr 24, 2007
  15. That is often the way it works. The heater core usually shares the
    evaporator drain pan, so leakage from the heater core drains the same way
    A/C condensation does. It does add a lot of humidity to the passenger
    compartment, though, producing steam that smells like vanilla.

    Michael Pardee, Apr 24, 2007
  16. Chris

    Chris Guest

    There is no steam in passenger compartment and no funny smell,
    although being in Australia I don't have much cause to use the heater.
    If the heater controls stay constantly on coolest setting does this
    mean no coolant will cycle through the heater core? Whatever, when I
    tried the heater it blew very hot and no steam, no funny smell.

    After the a/c is operated and the car is stopped there is often some
    water pooled under the car. It is clear, certainly not coolant. I had
    assumed it was evaporation off some part of the a/c system. manual
    says perfectly normal to have water in car in this situation

    Chris, Apr 24, 2007
  17. That's a pretty good sign the leakage is not from the heater core. The core
    is pressurized with the rest of the system even when the valve is closed.
    You're right; the dripping water is perfectly normal when the A/C is
    operating. If it stops, you have trouble and the passenger gets wet feet :-]

    Michael Pardee, Apr 24, 2007
  18. Chris

    Chris Guest

    Mystery Solved!!!! (I think)

    I took the car to Volvo main dealer who did last service. Said it was
    losing coalant nad could they pressure test. Popped the bonnet.
    Mechanic went straight to the LHS of Radiator (facing towards rear of
    car) and found a TINY leak near where the upper hose enters the
    radiator. He said there was an aluminium bracket that runs
    longitudinally across the radiator, and leaks often occur where this
    bracket meets the end of the radiator. His view was that getting 11
    years out of the original radiator was very good going. Quoted A$800
    for R&R new radiator.

    I still don't understand the higher coolant leakage during city
    driving compared to long trips.

    However, my question now is, is is possible to seal the leak in what
    looks like a plastic radiator through some sort of adhesive. It such
    small hole, there is a TINY amount of coolant leaking You can't
    actually see the leak. It is only when you wipe a finger over the top
    of the radiator where this aluminium bracket enters the radiator that
    you can see any liquid.. For something so small surely there is a way
    to repair. rather than go through the time and expense to replace?????
    Chris, Apr 26, 2007
  19. Chris

    Baz Guest

    Hi Chris,

    I think you said you were in Australia, so am I (Sydney). I bought a new
    radiator from Volvo about 6 years ago for my old 740 (its very similar) and
    was surprised to find the cost at around AUD240-ish. So check on the price
    of a new one for the 850. DIY replacement should be a fairly straight
    forward job. Have a look at , but you won't have
    the turbo intercooler to worry about.

    Personally I wouldn't try repairing the plastic radiator parts, tried that
    with another car and had no success. I couldn't get the glues I tried to
    stick to the plastic. If it's the aluminium core, I wouldn't try either,
    there's probably more just around the corner at this age, and I'd be
    thinking reliability.

    Incidentally, mine is still the original radiator, I'll keep my fingers
    crossed :))

    Baz, Apr 27, 2007
  20. Tempting, isn't it? I've tried twice to repair cracked plastic headers, and
    it was always a feeling of "almost... now, if I just try a little twist"
    time after time. JB Weld seemed to adhere well enough but may be a bit too

    As for why the problem is worse in town than on the highway, well, that's
    part of the mystery, isn't it?

    Thanks for the feedback, Chris. Maybe we can help the next guy better.

    Michael Pardee, Apr 27, 2007
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