intermittent overheating

Hi All.
Haven't been on for a while, just moved house so up to my neck in it !!!
Any way here we go. Our 2.5 dse is overheating but only very occasionally. Friday night the other half went out and did about 15 miles then phoned me up to say the temperature gauge had gone up in the red, she got home and I checked the water level which was fine, the rad hoses were rock hard though. It has done this a about half a dozen times since we have had it which is just over twelve months now. I have got my own sniff test kit which i have used on it several times now but each time it doesnt change colour. It does use a bit of water with no signs of obvious leaks. I have changed the water pump, thermostat and viscous fan. I have thought about the radiator but cant really see this giving me the intermittent overheating. Anybody got any ideas ?????
Thanks in advance.
Luke

Theres a plastic baffle in the BMW radiator to force the water through the entire radiator. If this fails the water 'short-cuts' through the radiator. No real problem in the winter or on short trips but in summer can lead to itermittent overheating.

Yes, I had a cheapo nasty rad from Shi... I mean Britpart with a baffle that was broken/non-existent.

Had some of the same symptoms BUT I would always overheat when idling when the engine was warm - sequence went like this - engine started from cold and got upto temp (12 position) within about 3/4 mins which I thought was a little too quick. If I was sitting at lights or in a traffic jam for a prolonged period the gauge would suddenly creep a little past 12 and then slowly but steadily make its way further and further up the gauge.

I drove along with one eye on the temp gauge for weeks and luckily I always caught it before I actually overheated (needle in the red). Turning the A/C OFF and putting the heat up full inside the cabin could bring the temp down.

I eventually replaced with a genuine rad which was only a few quid more and all my problems with overheating disappeared.

The one thing I would have concern over is you say you have rock solid rad hoses. I had this when I had a cracked head. The crack in the head would only open up at high temps when the engine was working hard which made it difficult to diagnose. Are the hoses red red hot as well as rock solid?? I remember when my head went the hoses got so hot I couldnt touch them whereas normally you can touch them quite easily for a few secs.

How old is the rad you have, how is your water pump and stat??

-Wills

Replace the rad mate just had the same rock hard hoses and overheating. rad replaced and all is well. its a good place to start.

Andy........

p38owner said:

Hi All.
Haven't been on for a while, just moved house so up to my neck in it !!!
Any way here we go. Our 2.5 dse is overheating but only very occasionally. Friday night the other half went out and did about 15 miles then phoned me up to say the temperature gauge had gone up in the red, she got home and I checked the water level which was fine, the rad hoses were rock hard though. It has done this a about half a dozen times since we have had it which is just over twelve months now. I have got my own sniff test kit which i have used on it several times now but each time it doesnt change colour. It does use a bit of water with no signs of obvious leaks. I have changed the water pump, thermostat and viscous fan. I have thought about the radiator but cant really see this giving me the intermittent overheating. Anybody got any ideas ?????
Thanks in advance.
Luke

Click to expand...

I'd get it upto normal temp and the feel the bottom of the radiator (you might well need to remove the fan shield to do it, if it's cold (much cooler than the top) it could be a fooked waterpump (common failure, did you replace it with a new one?) a fecked radiator, or more lightly a head / gasket problem, I had very similar problems, even sniff testing was not conclusive as the crack only opened up under certain circumstances, is the sniff fluid fresh? have you sniffed it when it was overheating?

If your interested I'm selling a brand new (never been fitted) cylender head (well, reconditioned one, complete with valves, cam, I'll even throw in a new genuine head gasket (£88) and a new set of stretch bolts, all yours for £500, the head alone cost me in excess of £800 back in December, I replaced the whole engine in mine as I got so pi$$ed off arsing about with fault after fault with my old one (had only done 90k aswell!).

Well I have replaced the water pump and taken the guts out off the thermostat. Doesnt seem to be overheating at the moment but the hoses still seem to be to hard. Have tried sniff testing again and still no change to the fluid. Have tried shinning a light inside the rad to see if the baffle is broken but cant see any light. Think I will try the rad next as this could be blocked, I have found one on ebay that claims to oe for £125. Doesnt seem to be a bad price. Thanks for the offer of the head geek freak but I already have a head that I will probably recon myself. That will be the next thing to change. Has anybody come across block problems with the diesel engine that could be causing my faults ?

I had exactly the same problem - and the outcome wasnt pretty

It turned out that the O rings had gone - now these things only cost 50p each and are used to connect to the heater behind the dash for the climate control - all sounded cheap to fix but here's the catch.

They need to remove the entiure dash to get to them - cost about £1000.

The loss of fluid from the Orings contribnuted to the overheat and fooked the head gasket - £3000.

Good news is that as I was only 2 months out of landrover (approved used) warranty I wrote a complained and they stumped up 75% of the repair costs ........