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).
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.
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.
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)
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.
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?????
*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).
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, I hate to be the bearer of bad news, but...it 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 wrong.
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$.
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
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).
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.
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
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 :-]
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?????
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
formatting link
, but you won't havethe 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 :-))
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 brittle.
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.
MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.