12 replies to this topic

[marksbros6]

~~~~~Please delete this text before posting the topic~~~~~~
Please give your topic a title that quickly describes your problem. Just putting 'Help my Mini doesn't work' is useless to anyone trying to help.
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Model:MPi
Year:1997
Description of problem (please be as in depth as possible)Hello all you helpful Mini people!

Having a problem with my '97 MPi. (Stock, no mods)

On a recent trip up to Leeds it overheated quite badly around Leicester, curtailing the trip.

AA found lots of rust, crud and detritus in the cooling system and rinsed it all out as best they could. It was still boiling the water when it was re-assembled and pressurising the system.

Back home I took it to my friendly mechanic.

He's flushed through the cooling system several times, lots of brown water coming out. New head gasket, skimmed head. All back together and still boiling over and hydrocarbon's in the coolant after a sniffer test.

New radiator (old one crudded up). Still boiling over. Head went back to the engineers and one of the water channel plugs/jackets was corroded/damaged. This has been repaired and re-drilled. Back together and there no longer hydrocarbons in the coolant afterthe sniffer test.

Still running very hot though and relying on the cooling fan to stop it from overheating. with the expansion tank bubbling and boiling up.

The heater matrix has been disconnected, and thermostat taken out. Ran Ok, and didn't boilover/heat up overly. This was last night.

Today though he was getting ready to pop it back to me and put the thermostat back in. Started boiling up again though?

Basically running out of things to swap out now? Thinking there might be some of the 'crud' left in the water channels in the engine block and he's popping some detergent in to try and clean it out. Other then that a crack in the block maybe? The head has been crack-tested (for free) and passed.

Anyone had similar problems?

Or have any ideas what it might be?

Thanks in advance, any questions give me a shout

Mark:



Any non-standard parts that might be involved with the problem? None

[AndyMiniMad.]

I take it that before all this complicated work was undertaken.....Someone dropped the stat into a pot of hot water to make sue it works...

Edited by AndyMiniMad., 07 June 2011 - 05:00 PM.

[marksbros6]

I take it that before all this complicated work was undertaken.....Someone dropped the stat into a pot of hot water to make sue it works...

Isn't your motto 'if it's not broke, take it apart anyway?'

If it's that simple I'll kick myself. The chap is at his wits end though so I imagine it's been tested. Will mention it.

[charie t]

Is the water pump impellor still attached?
Although you have flushed the system have you tried a new radiator, they can gunge up and block galleries. My mpi was running super hot when i got it. I left it full of toilet cleaner for a week as a cheap fix which has helped.

[marksbros6]

Is the water pump impellor still attached?
Although you have flushed the system have you tried a new radiator, they can gunge up and block galleries. My mpi was running super hot when i got it. I left it full of toilet cleaner for a week as a cheap fix which has helped.

Cheers bud, new rad has been fitted, still overheating though...

[lawnmowercrap]

If when the stats out it has the ability to stay cool, but cant with it in then id say thats definetley a circulation / low pressure issue.

Id start by checking for play in the water pump, in fact id have it off incase the impellor has come off the shaft as already stated. If its shafted, fit a high capacity pump and a smaller pulley.
If you think there may be a crack in the block, remove the plugs and pressure the system manually and listen for a hissing.
I personally never run a thermostat during the summer.

Also, have you had a straight edge on the block to make sure its not warped?
Changed the radiator cap?
Coolant pipes all plumbed up correctly?

[AndyMiniMad.]

I take it that before all this complicated work was undertaken.....Someone dropped the stat into a pot of hot water to make sue it works...

Isn't your motto 'if it's not broke, take it apart anyway?'

If it's that simple I'll kick myself. The chap is at his wits end though so I imagine it's been tested. Will mention it.

Yeah! that is my motto right enough!!! Maybe I should get that changed.....I agree with marksbros6 about the water pump....It could be that....but I always look for the easy answer first....Im a lazy old git..

[marksbros6]

I take it that before all this complicated work was undertaken.....Someone dropped the stat into a pot of hot water to make sue it works...

Isn't your motto 'if it's not broke, take it apart anyway?'

If it's that simple I'll kick myself. The chap is at his wits end though so I imagine it's been tested. Will mention it.

Yeah! that is my motto right enough!!! Maybe I should get that changed.....I agree with marksbros6 about the water pump....It could be that....but I always look for the easy answer first....Im a lazy old git..

Your new motto works as well.

Got it back just now. Temporarily without the thermostat (which was a new one anyway and was working).

Impellor is still attached.

Temp gauge goes up to about halfway shortly after commencing journey and stays there.

However once I got home I popped the hood and the water in the expansion tank was boiling/bubbling and spluttering, took about 3/4 mins to stop and was still very hot afterwards. Gonna try the run to work tomorrow and remove the temp sensor on the fan to run it constantly, see if that has any effect. I presume the dash gauge takes it's readings from there as well?

Engine has been 'sniffer tested' (hydrocarbon check) and there are none in the coolant, so not likely to be a crack in the block? But that is all we can really think of?

Water is still pretty dirty though, and it's been flushed several times. Will be looking at it a bit further at the weekend myself and trying to flush it out some more.

[L400RAS]

Have you tried a new expansion cap? If they do not seal, it means the water system will not pressurise, and the water will start to bubble at around 88-92 ºc (this is when your thermostat opens). If the system is working correctly and is pressurised, then the waters boiling point is actually raised (can be around 110-115ºc), and as such, the water doesnt even start to bubble at 88

Edited by L400RAS, 08 June 2011 - 06:35 PM.

[marksbros6]

Have you tried a new expansion cap? If they do not seal, it means the water system will not pressurise, and the water will start to bubble at around 88-92 ºc (this is when your thermostat opens). If the system is working correctly and is pressurised, then the waters boiling point is actually raised (can be around 110-115ºc), and as such, the water doesnt even start to bubble at 88

Sounds simple, and cheap? I'll give it a go!

[marksbros6]

The Engine Coolant Temperature (ECT) sensor is pretty essential for the engine management system. I do not think you can simply disconnect it without affecting the ignition timing.
I am not sure what you will prove by running the fan constantly. I am also not sure what you mean when you say you are relying on the fan to stop it overheating. That is what it is supposed do. However I would not expect a need for the fan to come on unless you are in heavy traffic. If that is the case is it not coming on frequently enough? If so I wonder if the ECT sensor is faulty. I have heard they can become unreliable. A diagnostic test might identify an error. I am not an expert, just giving a few thoughts. My only experience with overheating in my MPi was because the fan connection was broken.

Basically the coolant in the expansion tank is bubbling and boiling,getting very hot without the fan coming on.

Have tried lots of things to remedy the situation (see above) and am just trying now to get the desired effect, (it running cooler) through whatever means at the minute. Will wonder then how to rectify things on a more permanent basis? (The 'Mythbusters approach')

Anyone know what temp the coolant should be before the fan cuts in?

Oil temp gauge is not showing hot at all. Climbs to half way and never goes above.

Cheers for all the advice so far.