960 header tank boiling over.

It sounds as though, basically, your engine is overheating, causing the cap to lift, although this is inconsistent with the length of time it takes to warm up - my 960 temp guage reaches the 'normal' mark after only 2-3 miles from a cold start. Did you fit a new thernostat? As far as I know, the water/coolant mix isn't as critical as this in affecting the engine cooling efficiency - the system should cool the engine, in theory, with plain water. It sounds to me as though the radiator isn't doing its job - as if it's blocked - because you mention that even the bottom hose is too hot to handle. That means that the coolant isn't being cooled as it passes through the radiator. If the water pump wasn't working, that would also cause overheating, but wouldn't explain the hot bottom hose. The 'hardness' of the hoses is normal - they do feel hard at normal operating pressure. Was the 12 miles you did clear running, or was the car stationary a lot? Is the electric fan working? If it isn't, that would cause slow overheating and would explain why the bottom hose is so hot. But all this doesn't fit with the long warm-up period. Perhaps other members can explain it. Sorry if this doesn't help much - it's just my random thoughts, really. Good luck with it . . . Stan.

i would give the car back , if it IS the head then its going to be VERY expensive , you might consider buying it again if he gets it fixed . But there are sure to be more nice 960's around at bargain prices considering the cost of fuel and how much they use ... He or you need to be sure it is the head gasket leaking though or worse , It could still be something simple ..

The first 12 miles were clear running at speeds of 30 -50 mph and the last six were a mix of light and stationary traffic. The fan did kick in a couple of times for short periods when the engine ws ticking over after I got it home. I removed the thermostat completely for the second 'run up' to normal temperature on the guage to isolate the stat from the equation. Both top and bottom hoses are hot and so is the outer casing of the radiator. If I run the car from cold it seems to boil over after about 15 miles and I get a low coolant level warning light on the dash. If I look at the header tank with the guage at normal, I can see the water level rising and falling until it finally breaches the filler cap. Definitely a lot of adverse pressure there. At no time does the temperature guage move beyond half way. Is it possible for the head to be warped without the needle hitting the red?

firstly get a new cap they should hold about 20+ psi a faulty cap will cause this problem .. ok take the thermostat out to eliminate it or put a new one in . fill with plain water go for a short run of a mile or two to bleed the air and wait for it to cool and top up header tank again .. Go for your run again but stop after say 5 miles and park up with engine running , lift the bonnet and see if the radiator fan comes on .. when it does , is it blowing large quantities of hot air through the radiator? With a new cap it should not expell any water from the bottle unless there is a head or gasket problem .. I cant help feel you have inherited someone elses problem ... maybe you can fix it with a cap :-) Yes it is possible for the head to be warped if the previous owner has overheated it ... but as long as you keep it topped up with water it wont go in the red again but can still blow water out with a head or gasket problem ..

Hi Strapkass, I would make sure you don't have an air lock in the system as that would give exactly the symptoms you mention. Take a good bit of time squeezing the various hoses to try and displace any air. Does the heater give a good hot output?. If not then that might confirm it.

The heater is blowing hot and good. I have removed the stat. I'll fit a new cap, follow the procedure you recommend and see what develops. Is the cap from my 940se turbo diesel compatible with the 960? They look the same.

" When I originally test drove the car for 3 or 4 miles, I noticed that the temeperature guage was taking what I assumed was an unusual amount of time to register a reading. The previous owner told me that it would eventually kick in so I though nothing more of it." It does seem like the previous owner knew of the problem. I noticed coolant down the side of my header tank and on the strut pillar of my car after a run,i took the rubber seal off the cap and put the cap in a bowl of soapy water where i worked the pressure spring a few dozen times ,( got some crap out) turned the seal over and put it back on and its been ok since. By the way, my 4 cylinder 940 temp gauge starts to move after a few hundred yards and gets to normal operating temp after a mile and half ish

JUst had similar last Thursday night. My wife phoned (I work away during the week) to say that the car was spitting out steam/water from the expansion tank cap area. There was no oily residue in the header. My son took the expansion tank off the donor car in the garden and swapped it for the one in the 960. There is now no problem - even after some hard testing of the cooling powers of the system. It is possible that the release valve in the cap had jammed shut and the build up of pressure in the system had also caused damage to the float sensor in the tank.