Coolant mystery

Grrrrrr · May 18, 2014

A puzzle for you. Checked the fluid levels a few nights back. All was well. Never ever needs any coolant adding. Never has since I got the car.

Yesterday (hot day) the missus gets 3 miles down the road and it overheats and then stalls. Loses 3.5 litres of coolant in 3 miles. RAC man arrives and refills with tap-water, missus drives back, I finish work and check ... and find nothing wrong at all. Car has driven fine since with no issues and no loss of coolant. No water on floor in car or outside that I can see. What the chuff just happened?

Only difference is that since then the temperature guage is smack bang in the middle whereas previously it was always a notch to the right of the last blue marker (in the white).

Theories?!

'95 DT.

Moreirinha · May 18, 2014

Termostat.

Saint.V8 · May 18, 2014

Water loss could be down to the fact it overheated and then the Expansion Tank cap relieved pressure and expelled water in the process....3.5l is quite a bit to expel but yer never know...

Check thermostat and also do you know if the water pump has the plastic or metal impellor??

Datatek · May 18, 2014

As the others said, thermostat sticking or pump impeller slipping. Worth checking the viscous fan too.

jt_armstrong · May 18, 2014

Quick question that may be related to this thread. Will a faulty viscous fan have any impact on the cooling when the vehicle is driving?

Datatek · May 18, 2014

jt_armstrong said:
Quick question that may be related to this thread. Will a faulty viscous fan have any impact on the cooling when the vehicle is driving?

That will depend on ambient and what you are doing. At idle a duff viscous will certainly cause overheating, same going up hill at low speed.
On the motorway the car will run with no fan unless it's very hot.

ShaunPDisco · May 18, 2014

Kept having issues with mine and it has been the viscous fan and expansion cap. I have now done the Datatek mod and replaced the cap and havent had any issues since.....well apart from/the door lock, transmission cooler leaking.....but not sure they are related!!!

Grrrrrr · May 19, 2014

OK. Of course, the weather would have to be 15 degrees hotter than it has been all year but the needle is resolutely 2 lines higher, I reckon. It is loosing about 3/4 of an expansion tank of coolant over 2 days but there is no sign of it anywhere! I looked under the tank where the overflow goes - nothing. Checked hoses - nothing. I'm beginning to consider the possibility it might be a small hole in the rad and it is leaking where I cannot see it and evaporating before it gets where I can see it.

No idea if the pump is plastic or metal as I've never had it out. Assume the former.

I think as preventative maintenance I might replace the pump and the thermostat. I'm planning on heading down to the South West in the summer and I don't want to be sat on the side of the M5 waiting for the RAC.

Cheers,

J

Datatek · May 19, 2014

Grrrrrr said:
OK. Of course, the weather would have to be 15 degrees hotter than it has been all year but the needle is resolutely 2 lines higher, I reckon. It is loosing about 3/4 of an expansion tank of coolant over 2 days but there is no sign of it anywhere! I looked under the tank where the overflow goes - nothing. Checked hoses - nothing. I'm beginning to consider the possibility it might be a small hole in the rad and it is leaking where I cannot see it and evaporating before it gets where I can see it.

No idea if the pump is plastic or metal as I've never had it out. Assume the former.

I think as preventative maintenance I might replace the pump and the thermostat. I'm planning on heading down to the South West in the summer and I don't want to be sat on the side of the M5 waiting for the RAC.

Cheers,

J

Check the expansion cap is screwed down tight, mine goes tight long before it's sealed.
Check the viscous with the news paper test, check the RAD is hot all over.

Grrrrrr · May 19, 2014

Seemed to be spinning fine and speeded up when the engine did. I'll try the newspaper when the missus gets back.

No issue with making sure things are screwed up tight. Quite the opposite. I have previous in overtightening and stripping threads.

Grrrrrr · May 21, 2014

Tried the newspaper test and damn nearly shredded it. That was right, wasn't it?

If I get to see it before it is warm I'll check the viscous isn't running all the time.

Coolant mystery

Grrrrrr

Technician, Bodgit & Scarper Ltd

Moreirinha

Member

Saint.V8

Dyed-in-the-wool 100% RR Junkie

Datatek

Well-Known Member

jt_armstrong

Well-Known Member

Datatek

Well-Known Member

ShaunPDisco

Active Member

Grrrrrr

Technician, Bodgit & Scarper Ltd

Datatek

Well-Known Member

Grrrrrr

Technician, Bodgit & Scarper Ltd

Grrrrrr

Technician, Bodgit & Scarper Ltd

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