Running hot

I drive an 89 Atmo and recently I've been having some cooling problems (no surprises there then) I've looked through quite a few threads though and can't find one that matches the problems I'm having so would appreciate any advice.

It started with a burst water pipe which was mended but I couldn't get a replacement so ran it for a bit longer. Eventually the temp started rising when sitting in traffic, surprisingly this didn't really happen before, but cooled down again when driving. It started getting more serious when it overheated and I lost all the coolant. I managed to get a piece of replacement hose and had to clear out a blockage when trying to bleed the system which I thought must have been the cause of it all. Since then however the car has been gradually running hotter and hotter. It gets up to 90 and as long as its a short journey or you take it really easy it'll only go just above that. If your on a longer drive or want to get there a bit quicker though its been running hotter. Last week was about 100 - 110 but now its almost in the red. Strange thing is it will sit there for the whole journey and not actually overheat and lose coolant. When I arrive the coolant is bubbling up in the expansion tank but not pouring out and I don't have to replace any. Radiator looks ok, the fan wasn't working but having bypassed the temp switch and got it running all the time there is still no change. Don't think its the head gasket as I would have expected it to completely overheat as before if this was the cause and I'm not getting any white smoke as I've seen discussed in other posts.

Any advice would be great as taking it easy is boring me to death

Don't discount the head gasket,but it may just need flushing and bleeding thoroughly .Does the heater blow hot and cold ?

Have you tried bleeding the radiator again? Mine use to do this sort of thing. It was a small leak in one of the front hoses. The space was being taken up by air in the Rad that couldnt escape because of the position of the hoses - so the coolant level never really dropped much until it got so hot that it all spat out. Same symptoms - just got gradually worse as the days wore on until I bled the rad and topped it up again.

If your rad is old then the problem is probably exacerbated by the bottom half of the rad being full of crud. You can do the maths - top half full of air + bottom half full of crud = not much cooling effect.

I had similar symptoms on my Turbo and were certainly down to the radiator.
Mine had got to the point where lots of the fins had disappeared so it wasn't surprising.
However, unless you've had the radiator worked on recently, I think it sounds like that is still your culprit. Summarising what you've said, basically, the cooling system isn't cooling the engine down, especially when it gets hot and you've bled it and are not losing coolant.

You mentioned that you had a blockage in the system and we all know about the sludge that builds up in there over time blocking up the bleed hose and so on. I reckon a close inspection of the radiator may show that the pipes (that the fins are attached to in the core of the radiator) are bulging. Not sure whether this is from sludge or what but if they are bulging, the radiator won't be doing what it's supposed to.
When I had mine re-cored, the guy at Serck pointed out the bulging pipes (never mind the copper snow-storm of cooling fins all over the place!) straight away as a reason why the radiator wasn't working properly. Symptom-wise mine was OK if you pootled about but at higher motorway speeds and 'enthusiastic' driving, the temperature went up and up.

One last thing to try before getting the radiator out is what Paul Sage did on my radiator a couple of years before I got it re-cored. He back-flushed it to try to get a lot of the sludge out of the radiator. Improved things for a bit until the radiator got beyond serviceable use.

Hope this helps.

Jon

I'll have a closer look at the rad and try flushing it out / getting it re-cored as this sounds the most likely from what you've said.

Thanks, with any luck I'll be driving enthusiastically again soon.

Could be a stuck thermostat in the water pump...

[Alpineandy]

does the water flow easily from the rad bleed?

Do you have Aircon? I was having overheating problems, so took out the radiator to flush it out. The aircon radiator was bolted onto the front of the cooling radiator and when I separated the two there was a layer of crud that had built up over the years, (grass, leaves, feathers etc), it was like a layer of cardboard over the front of the radiator so no wonder no air was getting through to aid cooling. I did flush the system as well but not had a problem since.

Easiest way to know if you have airlocks or HG problems inducing airlock is by looking how quickly the temp gauge rises. It takes an extreme amount of energy to heat water up quickly, so if you see the temp rising quite quickly all of a sudden, then this is localised boiling or the temp sensor running dry due to an air lock in the thermostat housing where the sensor is.

I'll be taking the rad out this weekend to check it as its the first chance i'll get but I don't have aircon although a lot of the pipes seem to be there (I'm sure I read this was the same on most vehicles).

David, from start up the temp rises gradually to 90 but form here it rises quite sharply if you take it up to motorway speeds etc. Its fine when you can drive along in 4th or 5th doing 30-50mph which is ok as my drive to and from work is pretty much like that. Anything faster and it heats up pretty quick but like I said it doesn't actually overheat and lose coolant. I had to drive about 10 miles the other day with the temp just below the red but the air was blowing hot all the time and although the water was boiling up in the expansion tank it didn't lose any.

It would sound to me like you have a slight HG problem, and the increased load on the M'way is causing a airlock\hotspot.

One thing you could try flush the system as much as possible first, then try an additive/block sealer to the coolant to try and see if it rectifies the problem. There's nothing to lose and it costs next to nothing. You might find the rest of the system is so blocked as somebody might have done alot of this in the past, to try and cure an underlying problem.

Right, got the rad out ......eventually bumper was a pain, probably made worse by the fact that the car appears to have had a bump at some point. One of the plastic blocks that hold it on was badly damaged so the bolts just kept spinning.

The water in the rad was dirty but I don't think it was bad enough to cause the overheating. There was hardly any water in it though suggesting an airlock and an HG problem after all. Can anyone recommend a decent additive or sealer as I've heard they're not always successful.

I now have a sealer/additive to have a go at the HG problem but am a bit stuck trying to re fit the bumper. The badly damaged block that joins the bumper to the chassis is unusable and Renault say they haven't got any here or in France. Does anyone where I could source one, or better still, does anyone have a spare one for sale?

I got one from Simon Auto in Germany - but David Gentleman usually has all these weird and wondeful bits stashed away somewhere. Have you checked for any leaks at the front end while the trays are off? You should see some tell-tale rusty stains on the inside of the undertrays if there are. Remember that its a sealed system so if the pressure during hot running forces water out then there will be a vacuum when it all cools down again and that could draw air in. If it gets drawn in after the low point of the pipes at the front, the only place for it to go is into the radiator.

Overheating probs turned out to be a dodgy thermostat that had failed shut instead of open. No water was getting into the radiator at all so the only thing cooling the engine was me having the heaters on I think. Thanks for all the advice.