Overheating problems

[page3]

If anyone has any advice of what might be the problem with my poorly S I'd be grateful.

Full thread here http://www.pistonheads.com/gassing/topic.asp?h=0&a...

Apologies for repost, but though most of you won't see that thread as it wasn't a call for help.

What confuses me is that I can understand it overheating if the fan wasn't coming on, but not still having a problem once we hard wired that. It also wasn't gradual - absolutely no warning at all each time and not traffic induced. 70-80 deg one second, 120deg the next!

Cheers all.

[ChrisGadd]

Sounds like the cooling system is dumping the coolant out and isn't pressurising. Have you checked you don't have any leaks and that the pressure caps are sealing properly. Another problem I have had in the past with another car was a radiator leak which didn't appear until the system was heated

[chrischat]

First thoughts,I'm not going to get involved with the old argument about which cap goes where,but if either cap is not holding pressure it could be boiling at a lower temp.

[tvrgit]

Another thought - just a little one - when you hard wired the fan in, you did make sure it was turning the right way to blow (or suck) cool air in through the radiator, and not hot air OUT forwards? That would result in it seeming ok at reasonable speeds (the ram air effect through the rad would overcome the fan flow) but would heat up quickly at slower speeds when the fan could overcome air pressure at the front of the car and blow hot air through the rad.

Not doubting your wiring skills, but it's just a thought...

[jimed]

It sounds as if you may have some air in the system somewhere - once that gets hot it does blow it all out hence getting v hot quickly. Have another go at bleeding the air out - heater control on and also don't forget the little bleed valve on top of the radiator.
Jim

[Tant]

Hello sorry to hear about your troubles.

I suppose the first thing I would check, especially when you mention the "bubbling" noise, is for a blown head gaket, especially if it has happened suddenly with no "external" signs.

If the gasket has gone, it may be pressurising the system, and forcing coolant out of the swirl tank into the expansion bottle. I'd do a compression test before anything else, or look for an oily film on the water.
Does the car seem low on power at all, or run rough, or have any more white smoke in the exhaust than usual?

Hope you get it sorted...

Cheers
Anthony

[Dave_M]

Like tvrgit said, I once had an M with an extra Kenlowe in front of the spare wheel (which was mounted in front of the radiator, restricting air flow) that turned out to be turning the wrong way.

[page3]

Thanks everyone for the advice. I'm getting the car checked on Saturday so here's hoping.

I hope its not a gasket as both were replaced 6 months ago when I had the ACT manifold fitted. The car has also just been serviced and was driving the nicest it ever has!

[page3]

Well it looks like it was simply the sensor which had broken (which we diagnosed and hard-wired at the side of the motorway in Belgium). The other breakdowns were (probably) due to our fix not being 100% reliable and so the fan was still cutting in/out without me knowing.

I might replace the radiator cap anyway, just to be sure so this is good news!!!

[Roy C]

page3 said:

Well it looks like it was simply the sensor which had broken (which we diagnosed and hard-wired at the side of the motorway in Belgium). The other breakdowns were (probably) due to our fix not being 100% reliable and so the fan was still cutting in/out without me knowing.

I might replace the radiator cap anyway, just to be sure so this is good news!!!

I'm glad you got it sorted.
I didn't think it was serious, just a pain.

I've fixed the bonnet: had to adjust both hinges and pins, but it fits and works better now.

Will we see you at the R&C on Wednesday?

[page3]

Roy C said:

Will we see you at the R&C on Wednesday?

Hope so