68 replies to this topic

[mullet]

Hi all.  I drained the coolant.  I took the radiator out, and the thermostat-valve out.  Observations:

 

 - The coolant was rusty in colour, but liquid.  But the dregs (about the last 20ml) of the coolant was really thick, almost blood-thick.

 - thermostatic value was hard to remove, but I think that was just because some of the old housing gasket had it stuck. It was in the closed position as I expect is expected on a cold engine.

 - I tested the thermostatic valve in a saucepan.  It should open at 88 degrees, but only started opening at about 93 degrees.  Going up to 96 degrees, it really only opened about 2mm at the most.  Is this a healthy valve, or defective?  Should it open more?

 - there's no "wobbly freeplay" movement in the fan to assess if the water pump is defective, so based on this external test alone it may be in good condition(?).

 

I wonder if I should go the whole hog now and do the extra work getting the pump out and replaced given I am halfway to it now, or if there's enough, above, to suggest a good flush, new thermostat valve, and good quality coolant should do the trick? 

Edited by mullet, 31 May 2025 - 05:47 PM.

[lippo]

 It sounds like the thermostat needs replacing. I have just done a full flush for my Mini, I had some overheating and I noticed the heater wasn't hot. I ended up removing the heater and flushing it through, loads of gunk came out and I found one of the heater pipes was blocked with crud. It's all clean now and the car is rock solid for maintaining temp now.

 

 I flushed mine out (Holts flush - horrible stuff) and then cleaned out with a garden hose and a hose pipe connector connected to the heater pipe. I used Bluecol coolant as recommended on here.

[mullet]

 It sounds like the thermostat needs replacing. I have just done a full flush for my Mini, I had some overheating and I noticed the heater wasn't hot. I ended up removing the heater and flushing it through, loads of gunk came out and I found one of the heater pipes was blocked with crud. It's all clean now and the car is rock solid for maintaining temp now.

 

 I flushed mine out (Holts flush - horrible stuff) and then cleaned out with a garden hose and a hose pipe connector connected to the heater pipe. I used Bluecol coolant as recommended on here.

Thanks!   I read somewhere that for models without a lower drain plug, the lowest point is then the heater.  Makes sense to me to flush it too, especially as the dregs were already thick like blood from a higher level.  Was it a big job to remove?  Any new pieces needed?  I ask as about to order the new thermostat and don't want the engine "dry" for too long.  Thanks for the advice.

[lippo]

 My radiator has a drain plug, so I got most of the coolant out before dropping the heater. I have read that people remove the lower rad hose to remove most of the coolant and that this can be a little tricky due to space.

I had a bowl under the heater and removed the lower hose and let it drain. Dropping the heater is easy, two screws at the front, remove the 2 coolant hoses to the matrix (mine were located on the right as you look at the heater), remove the trunking to the heater, unhook the heater from the metal hooks on the bulkhead and I think there was a bullet connecter on top of the heater to separate, then the whole heater came out. The 

I didn' bother removing the matrix as I wasn't replacing it, I attached the hose pipe to the matrix and flushed both ways. Only took around 30 mins of actual work.

[mullet]

 My radiator has a drain plug, so I got most of the coolant out before dropping the heater. I have read that people remove the lower rad hose to remove most of the coolant and that this can be a little tricky due to space.

I had a bowl under the heater and removed the lower hose and let it drain. Dropping the heater is easy, two screws at the front, remove the 2 coolant hoses to the matrix (mine were located on the right as you look at the heater), remove the trunking to the heater, unhook the heater from the metal hooks on the bulkhead and I think there was a bullet connecter on top of the heater to separate, then the whole heater came out. The 

I didn' bother removing the matrix as I wasn't replacing it, I attached the hose pipe to the matrix and flushed both ways. Only took around 30 mins of actual work.

Thanks for the advice.  It's a shame the Haynes manual always assumes a full dismantle is required, instead of explaining how to remove things as a complete unit like you described it.  I put your text into practice and just flushed it in the backyard.  One thing I'll add, after I flushed both in/out lines until water came out clear, I just had a gut feeling to turn the unit upside-down and do it again; about the same amount of rust water came out as the first flush!  I did it again a couple more times, right way up and upside-down until all combinations had the water come out clear.  I will reattach the unit now.

 

Then with the radiator already removed, I will also do this kind of right-way-up then upside-down flush.

 

Hopefully tomorrow the new thermostat-valve arrives and I will do the saucepan test and compare with the old one.  Put all back together, do some extra chemical flushing with recommended chemical products, then fill up with good coolant.  I REALLY hope this does the trick and it wasn't always the pump at fault.  At least now I see what was a daunting job as one I should be able to handle, even if I have to replace the pump.

 

More to follow....

[stuart bowes]

not sure if you still have the rad out, when I cleaned mine I plugged the bottom hole and filled with Kilrock and hot water, left it for a while and then flushed, water flushed through lovely and clean both ways

 

yours may be fine now by the sounds of it but adding this anyway in case others are wondering what products work

Edited by stuart bowes, 03 June 2025 - 10:47 AM.

[mullet]

not sure if you still have the rad out, when I cleaned mine I plugged the bottom hole and filled with Kilrock and hot water, left it for a while and then flushed, water flushed through lovely and clean both ways

 

yours may be fine now by the sounds of it but adding this anyway in case others are wondering what products work

I still have the radiator out.  Literally just back inside having flushed it.  I don't think I can get my hands on this Kilrock product in time for when I really got to get the car back together.  However, what about white vinegar?  I assume any descaler is going to be acidic, so could white vinegar be used?  I also have a product from the UK I brought back called "Elbow Grease" that cuts through oils and limescale on kitchen surfaces and pots and pans. 

[PACINO]

I would be careful with what vinegar you put in there and how long you keep it there. Radiator cells are very fragile, and it's very easy to puncture a duct, as I've seen on several.

A few years ago, I cleaned my radiator with a specific product sold at auto parts stores. Mix this product with water, then run the engine until it reaches operating temperature. Turn off the engine, drain the radiator, and rinse thoroughly with distilled water.
This way, it will be very clean.

[mullet]

I would be careful with what vinegar you put in there and how long you keep it there. Radiator cells are very fragile, and it's very easy to puncture a duct, as I've seen on several.

A few years ago, I cleaned my radiator with a specific product sold at auto parts stores. Mix this product with water, then run the engine until it reaches operating temperature. Turn off the engine, drain the radiator, and rinse thoroughly with distilled water.
This way, it will be very clean.

Thanks Pacino.  I bought "Liqui Moly" and 10 litres of distilled water yesterday.  I am waiting for the new thermostat to arrive in the post which I will saucepan test with the original.  If it is clear the old one was faulty, then reassembly.  I'm in France and no one in the car shop knew what coolant should fill up the system once I've re-flushed it.  They narrowed it down to two bottles (but did they really know?), each with a list of car makes, none of which included an Austin/Rover classic mini.  One bottle had the code "G12EVO (VW TL-774-L) (>06/2018)" and the other "G11 (TL-774-C)".  I saw threads on here with different opinions as to what to choose.

 

EDIT: found an independent shop that said "yellow" is what is needed, very sure about it.  Whatever that means ;)

Edited by mullet, 05 June 2025 - 06:23 AM.

[mullet]

Hi all.  The problem persists.  I drove at 80kph (50mph) for about a mile, then 50kph for another mile.  The engine started losing power, became erratic, needle up almost to the 'H'.  Pulled over for 10 minutes, then limped it back home.

 

What I have done (and noticed):

  - I tested old vs. new thermostat/valve in a saucepan.  It is an 88 degree one.  New one started opening at 89.  Old one at 93.  By 97 degrees, new one was open about 10mm.  Old one about 1.5 - 2mm. 

  - I've flushed, fitted all back together, filled up with coolant.  2.5 litres of coolant (surprised it wasn't more(?)).

  - Took the opportunity to do an oil change. 

  - Turns over well if parked.  But overheats quickly on the road test.

  - After road test, pipes to&from internal heater equally hot.  Hottest pipe was the one at the top of the radiator leading to the thermostat value.

  - Internal heater blasts hot, but not scorching hot.

 

I want to take the car to get the timing looked at as I have my doubts it is set optimally (but there is no apparent 'pinking'). 

 

THEREFORE: is there anything else to check now, or time to buy a new pump?  My thinking is anyway, all the work draining and getting the pump out, why not just to replace at the same time.  Unless there is another possible issue here?  Thanks everyone!

Edited by mullet, 07 June 2025 - 11:47 AM.

[imack]

I would suspect the impeller may be loose on the water pump. In my experience, when the impeller is loose the engine will over heat when driving a short distance, but the temperature is OK at idle.

[mullet]

I would suspect the impeller may be loose on the water pump. In my experience, when the impeller is loose the engine will over heat when driving a short distance, but the temperature is OK at idle.

Thanks imack!  Does this mean replacing the pump as an entire unit? Please excuse the simple questions, my first time dealing with heating issues.

[imack]

The pump only comes as a complete unit. You'll need to remove the radiator and fan to access it. You may also have a small but fiddly bypass hose that fits between the pump and the cylinder head.

[mullet]

The pump only comes as a complete unit. You'll need to remove the radiator and fan to access it. You may also have a small but fiddly bypass hose that fits between the pump and the cylinder head.

Ordering now, thank you.  At least after all this work, the thermostat valve was on its way out it seems and replaced so happy about that.  Hoping the pump replacement solves the issue :)

[Earwax]

Just to cover possibilities thoroughly.  Does the fan face the correct way and is it nicely under the shroud and reasonably close to the radiator face.