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Unexplained Overheating ! Advice Needed


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#16 sonscar

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Posted 24 July 2020 - 06:33 PM

If you are serious I would knock out the core plugs from the block and using some tough stranded wire in an electric drill poke it about in as many places as you can,regularly flushing the debris.Replace plugs afterwards.This worked for me.I would also recommend checking/changing the radiator cap,it must seal on the bottom of the radiator neck,some don't.Good hunting.Steve..

#17 Spider

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Posted 24 July 2020 - 06:36 PM

As Pops has suggested, depending on what you find, you may have to clean them first by mechanical means and then use a chemical cleaner.

 

For mechanical cleaning, I have used old drill bits, starting smaller and working up to the size of the holes I'm going through. I try them by hand first, but even in a cordless drill is OK. You can blunt them if you are worried about drilling in to things that you shouldn't. These won't reach everywhere though. As well as going in through the deck, there's also the drain plug on the back of the block, and in through the water pump too. You can follow this up with circular wire brushes or if you can find them, Boil Tube Cleaners, which you can also use on a cordless drill.   This mechanical cleaning will only get you so far though.

 

Once you have the car re-assembled, fill the cooling system with water and so a couple of heat cycles so you can retorque the gasket down then drain the water and flush as there'll be a fair bit of crud that will come out from the mechanical cleaning. I found that all the off the shelf 'Radiator Flushes' are next to useless, however I've had great success with a product you can get from the hardware called CLR (Calcium Lime Rust), mix so up in about a 30 / 70 mix with water and fill the cooling system with that (be sure to turn the heater on) and run with it for a few days, up to a week. Again, depending on how bad it is, you may need to repeat this a few times, flushing with clean water in between until you get little discolouring of the fluid after it's been in for a few days.

 

If however, you find there's oil in the cooling jacket, you'll need to clean that out first before using the CLR.

 

After you get it clean and if the temps seem to be behaving, flush the system out for a good 20 minutes with clean water, then fill he system with a good quality coolant / inhibitor.



#18 viz139

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Posted 25 July 2020 - 09:36 AM

Looking at the photo of the head it appears that cylinders 3+4 are much leaner than 1+2, are you running twin carbs?

When you say overheating in 8 minuets is this at idle or being driven ?



#19 psoutzis

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Posted 01 August 2020 - 06:29 AM

Thank you all for your comments. The engine head will be skimmed on Monday and i will replace the head gasket. I will also do the mechanical and chemical cleaning of the cooling system this weekend to make sure we have no blockage. Another possible problem to overheating is my HS4 carburetor, too lean or too rich. 



#20 Ethel

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Posted 01 August 2020 - 08:30 AM

Most heat is generated in the head. If you're going to get it skimmed, maybe you can find somewhere with a big enough ultrasonic bath to take it first?

 

At the more mundane level, how's it plumbed in? It's possible for a fair bit of water to bypass the radiator depending on how the heater & other ancillaries are connected.



#21 psoutzis

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Posted 24 August 2020 - 08:41 AM

Ok, I have the headgasket replaced and the head skimmed, all back together now. I have done the mechanical and chemical cleaning of the cooling system and i am now sure there is no blockage. Changed all the gaskets (exhaust, inlet, carb etc..) adjusted the air/fuel mixture on the HS4 carb and runs ok now. 
​The car still overheats and am so frustrated ! any other possible reasons? 


#22 cal844

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Posted 24 August 2020 - 09:00 AM

Get an infrared gun on it so you can check the temperature of your engine and system

#23 beardylondon

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Posted 24 August 2020 - 09:12 AM

Make sure your infrared gun is working correctly, as I bought a cheap one off Amazon and it’s 8 degrees off!

#24 sonscar

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Posted 24 August 2020 - 10:24 AM

If it is really overheating checked by temp gun over 100degrees and your cooling system is OK an unlikely problem I once had was the water pump impellor was loose,a replacement pump caught on the cylinder in the jacket and another caused the radiator to empty.Converting the rad to a pressurised header tank system cured it.If all else fails retarded timing,weak mixture and hopefully not cracked block or head.Keep looking,you will cure it.Steve..

Edited by sonscar, 24 August 2020 - 10:24 AM.


#25 psoutzis

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Posted 24 August 2020 - 10:57 AM

Hi Steve thank you for your answer. I will keep looking yes. Is there any chance worn piston rings are the problem here ? Ofcourse that would mean engine out.

#26 sonscar

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Posted 24 August 2020 - 07:57 PM

Piston rings will cause other problems but not overheating I would have thought.Steve..

#27 InnoCooperExport

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Posted 24 August 2020 - 08:28 PM

I´m with Pacino on this, have you checked the radiator itself yet? I see a lot of great suggestions here but I don't see anyone mention the radiator core itself. We had terrible overheating problems with our MGA, everything was fine and new but the stupid thing kept getting far too hot. Turned out the new core was flowing too well. All the coolant was just whizzing through it and not dissipating enough heat. New core as per original design fitted, hey presto cooling is instantly fine. Is your radiator new by any chance?



#28 psoutzis

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Posted 24 August 2020 - 08:40 PM

Hi innocooperexport! Yes the radiator is New, bought it a month ago and the brand is Fletcher. I’m sure the rad is okay..

#29 cal844

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Posted 24 August 2020 - 09:36 PM

I have constant overheating (but no boiling over) on my Clubman Estate, it turns out that the engine and electrics to the gauge are good, the gauge is simply inaccurate. I just run the car.

Cal

#30 Tornado99

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Posted 25 August 2020 - 04:38 PM

I think you need to put a thermometer on the block to actually confirm it is too hot. Dont rely on dash gauge. Having some amount come out the rad overflow might just mean there is too much coolant present. Having a hot rad hose within ten minutes could be normal or could indicate a stuck thermostat valve. Even new these can be bad. I always check mine in a pot of water on the stove with a thermometer to confirm when they open.




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