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Unexplained Overheating ! Advice Needed


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#1 psoutzis

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Posted 23 July 2020 - 03:47 PM

Hi all.

I have recently, changed the following on my Mini to Resolve my overheating issue:
- Water pump
- thermostat (and housing)
- top and bottom rad hoses
- New aluminium Radiator
- electronic ignition
- timing chain
- Bypass water hose
- Engine flush, and added the blue Coolant afterwards
- Removed the heater (as I don’t need it)
And all the gaskets that are associated with.
I had the timing checked, and also the carb mixture was ok.
Now the Mini still overheats and I can’t find the source of it. It overheats really really fast, after 8-9 minutes from cold, the top hose is very hot to touch.
After this, I thought to replace the head gasket (which was the only thing left) and I removed the head today and the head gasket was in good condition!
Really frustrated by this, could anyone give any advice on this ? And also, now that the head is out, shall I skim it and replace the head gasket as well ?

Best
Panagiotis

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#2 johnR

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Posted 23 July 2020 - 04:39 PM

When you say 'overheats' how does this show? Does it boil over or is it just the gauge that shows it?



#3 psoutzis

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Posted 23 July 2020 - 04:46 PM

Yes, I have the nippon seiki 3 clock speedometer, which I know it’s working fine because I have done the mod with the voltage stabiliser. Also the water is boiling and it and spits out from the radiator. Thus the pressure in the system is building up

#4 johnR

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Posted 23 July 2020 - 05:18 PM

perhaps you could try a hot country fan - presumably yours is the right way round? 



#5 cal844

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Posted 23 July 2020 - 05:46 PM

Is the fan on the correct way around? Personally I'd have a leak down test done on the engine. Also have the coolant system leak tested.

#6 psoutzis

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Posted 23 July 2020 - 06:20 PM

Yes the fan is at the correct way. Ill try to do a leak test but I’m not loosing any coolant at the moment.. just the little bit from the radiator overflow when it gets really hot

#7 Algordo1100

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Posted 23 July 2020 - 06:37 PM

In my time I've had a bottom hose kinked enough to cause overheating, but not enough to see straight away. That took ages to find.
Also an incorrect pulley size for the set up, again took ages to diagnose. And a brand new thermostat that didn't open properly. And I've had ignition timing that was supposed to be set by a professional, be so wrong the car went ding ding ding down the road boiling away to itself.

#8 Moke Spider

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Posted 23 July 2020 - 08:10 PM

How clean is the Cooling Jacket on the Block and Head ?

 

If these are rusty, it really slows up the rate of heat transfer.

 

The other thing that comes to mind here is a crack in the head or the Block somewhere, you may need to have them pressure tested to find out, though, I feel it's possibly taking to long to get 'up there' in Temp for this, but I don't discount it.



#9 PACINO

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Posted 23 July 2020 - 08:31 PM

Hi friend! My advice is to fit a good cylinder head gasket. The black one for me is better than copper one. Then when you assemble everything, if it continues overheating, and if the antifreeze and radiator is clean and in good condition, is that you check the temperature with a laser gun.


20191227-132425-1.jpg

To me recently with this summer heat I was warming more than normal and you know what it was. Well, the Distributor timing was a little retarded. It was put the dizzy at right place and now it does not overheat.

Regards, Luis

#10 psoutzis

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Posted 24 July 2020 - 08:57 AM

Thank you for your answers guys !

 

I will skim the head and add a new head gasket on, and also check the ignition timing again.

 

Any advice on how to check if there is a blockage in the water jackets ? is it best when the head is out?

 

Also, could worn piston rings and combination with a bad air/fuel ratio and ignition timing cause overheating?

 

Best, 

Panagiotis 



#11 Pops_Guild

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Posted 24 July 2020 - 09:36 AM

I would agree with Moke Spider on cleaning the block water jacket. That was the issue with mine. The waterways furthest from the thermostat were totally blocked.

I cleaned mine when the head was off using degreaser, water, different size and length bottle brushes and eventually a rust converter. It took ages and you need to be very careful to not get any water etc in the bored but the crud that came out was shocking.

Never an issue since.

#12 psoutzis

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Posted 24 July 2020 - 09:42 AM

I would agree with Moke Spider on cleaning the block water jacket. That was the issue with mine. The waterways furthest from the thermostat were totally blocked.

I cleaned mine when the head was off using degreaser, water, different size and length bottle brushes and eventually a rust converter. It took ages and you need to be very careful to not get any water etc in the bored but the crud that came out was shocking.

Never an issue since.

 

 

Thats great ! I will try to do the same on mine tomorrow. Any chance you have a diagram to know which are the water jackets on the block ? and also i will try an block the cylinder bores and all the holes for the oil etc before cleaning.



#13 Pops_Guild

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Posted 24 July 2020 - 11:42 AM

 

I would agree with Moke Spider on cleaning the block water jacket. That was the issue with mine. The waterways furthest from the thermostat were totally blocked.

I cleaned mine when the head was off using degreaser, water, different size and length bottle brushes and eventually a rust converter. It took ages and you need to be very careful to not get any water etc in the bored but the crud that came out was shocking.

Never an issue since.

 

 

Thats great ! I will try to do the same on mine tomorrow. Any chance you have a diagram to know which are the water jackets on the block ? and also i will try an block the cylinder bores and all the holes for the oil etc before cleaning.

 

 

You need to map them to the ones in your head but the attached photo of when I did mine can give you a good idea. The holes that are visible are are the water ways and you can see I've put in some barriers for the bores and oil-ways but I can't stress enough that you need to be very careful doing this. When I put fluids into the waterways I did so with a syringe to limit spillage and seepage. A big capacity syringe allows you to rinse through with some pressure when you need it, helps to blast out the crud. Take your time, degreasing and/or rust conversion needs time to be effective. 

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#14 Woolfie 640

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Posted 24 July 2020 - 04:23 PM

Did you replace the radiator cap before you spent a lot of cash chasing the problem . Can you fit an expansion bottle to you set up to absorb any water coming out ?

#15 psoutzis

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Posted 24 July 2020 - 05:18 PM

Did you replace the radiator cap before you spent a lot of cash chasing the problem . Can you fit an expansion bottle to you set up to absorb any water coming out ?

 

Hi Woolfie, yes i did changed the rad cap before doing this, ive had this problem for a while now so i wanted to replace all parts associated with overheating.






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