9 replies to this topic

[Irn Bru Cooper]

Hi

 

I'm new to here, only just found the site. Loads of excellent info and very knowledgeable folk.

 

My Mini is a 98 Cooper Sports Pack

 

My problem is;

 

Took her out for first run of the year yesterday (about 15-20 mins around the town) and when I pulled up back at the house it was blowing steam from the expansion tank cap.

 

Hoses were very hot but the gauge was only showing about half way, so hadn't gotten any indication it was overheating when out for the run.

 

Suspected maybe a dodgy thermostat. Managed to get two from local garage before they shut (82c and 88c) Got both as wasn't sure which should be in it but hopefully old one would have it stamped on.

 

Took thermostat housing off today only to find no thermostat!!

 

Have flushed out radiator and engine with clean water (water that came out wasn't bad, slight tinge of brown but not much)

 

So wondering:

Why it would be overheating with no thermostat?

Is there any reason not to fit a thermostat? (cant get in touch with previous owner to find out why not one in it)

And which would be best to fit? 82c or 88c?

 

Have had no problems with her before and doesn't do a lot of miles in the year.

 

Thanks in advance for any help.

Finlay

[Wise Old Elf]

Head gasket problem 

[Fast Ivan]

its the 88 degrees one you want, no idea why it doesn't have one, and it sounds like the expansion cap has failed, a common problem.

I don't suspect head gasket at this stage based on what you have said

[Dusky]

What makes you so sure its a HG? Could be vapour lock too,and probably loads of other things like.broken waterpump ertc etc.

[Irn Bru Cooper]

Didn't appear to have any water in the oil/oil in the water when I drained it. Still slight antifreeze colour but tinged with brown.

 

Just tried the thermostats but both just too big!!

 

Guy at the garage was slightly dubious that he had the right ones, said they didn't quite match the engine code on his computer.

 

Hopefully not head gasket! But i'll try Minispares for the 88c thermostat and a new expansion cap and see if that improves things.

 

Thanks for the replies and for any more info anyone might have.

 

Finlay

[pdaykin]

How long have you had the car ?

Taking the stat out used to be a common way of masking an overheating problem.

I'd first check that there are no air locks or the system is full of gunk - give it a good flush with the heater switched to the hot position.

Also, does the rad look damaged or blocked on the outside ?

Any signs of leakage at the hoses etc which may let air in ? If air is in the system the gauge often reads lower than it actually is

[Yoda]

if the temp gauge showed normal, then its most likely to be either expansion cap or head gasket. a leaky cap will not allow the system to pressurise properly therefore allowing the coolant to boil at a lower temp, or the cap is being blown by because a head gasket leak is pressurising the coolant system too much and pushing coolant out. I reckon that a previous owner has removed the stat because of one of these reasons. get a new cap first and hopefully thats the problem. If not, you need to get a leakdown test done to confirm a bad head gasket. A compression test may not show this up if it is a tiny leak.

[Irn Bru Cooper]

Had the car just under two years. Not done much running in it due to work, so not really had a chance to find out any issues with it. It's been fine until now though. Always starts first turn and runs good. 48,000 miles on clock.

 

Expansion tanks never dropped (or gained) in level in the time I've had it. Slight rusty staining to the inside though. Hoses all looked tight and think a new rad had been fitted not long before I bought it. (maybe to try and sort this problem?)

 

I'll go for the new expansion cap and thorough check/tighten of all hoses, and a flush with heater on hot first and then go for head gasket option if no resolution. 

 

Leakdown test? Is that a garage specific job rather than something I could try at home? And would a head gasket be a pricey fix by a garage?

[Wise Old Elf]

What makes you so sure its a HG? Could be vapour lock too,and probably loads of other things like.broken waterpump ertc etc.

 

Educated guess. Someone removed the thermostat suggesting the overheating problem is not a new thing. If it was a dodgy cap or air lock it would have been an easy fix so the previous owner would have fixed that rather than go to the trouble of removing the stat. Pumps generally leak water when failing although I did have a Vauxhall van once with a completely sheared impeller that did not leak a drop.

[MIGLIACARS]

If u take the thermostat out of a mini u need a blanking plate to put back in.

 

 

make sure the system is not air locked and you have enough water in it

 

 

is the fan coming on!

 

 

flush the hole system,

 

make sure rad isnt blocked

and the pipe to the expansion tank isnt blocked