My Diesel 75 is loosing coolant

[alanaslan]

Originally Posted by 75c

When I was a derv driver I had a problem with coolant loss. I spent a lot of time and money trying to get to the bottom of it (I have no mechanical skills) before finally buying a new coolant cap. The new coolant cap solved the problem. Embarrassed doesn't cover it.

I have to say don’t be embarrassed. I am coming around to that way of thinking myself. As the pressure tester uses its own expansion tank lid with the pressure relief valve and spigot lock for the pump.
So when I am pressure testing the system and getting no coolant loss or drop in pressure the cars own cap is out of the equation.
Bringing me back do I just replace the cap or the tank and the cap.
As I have said the cap is slightly distorted, I would venture to suggest the tank must also be distorted in the same way.
I can’t think of an easy way to check the tanks neck and seat.
Come on you engineers the question would seem to be cap or cap and tank.
I hate problems you can’t reproduce on the bench.
Alan


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[Jules]

We've not had to replace a tank yet.
You would see coolant around that area if leaking.

As for the cap just replace the two O rings
£4 posted.

Is radiator fan working on all speeds?

[alanaslan]

Originally Posted by Jules

We've not had to replace a tank yet.

You would see coolant around that area if leaking.



As for the cap just replace the two O rings

£4 posted.



Is radiator fan working on all speeds?

Hi Jules,
Yes your lovely new fan works very well I have not had the need of it except when pulling the van. Even in this hot wether I have not heard it running on except when the AC is on or when I had the overheating problem.
Jules do you stock the “o” rings if so can you send me a set please drop me payment details in a PM.
I guessed at 10psi for a hot car running pressure and left her in the workshop on pressure test overnight, under tray off and two large water wet pads under her not a drop of water on the pads and she had dropped less than 0.5 psi over night, I put that down to the pump seals over twelve hours.
Thanks Jules as always you have the part to solve the problem.
Alan


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[Jules]

Well if it's any cosolation Alan I've only heard of 2 cases of HGF pressurisation with the CDT (both behaved unless towing!)

The only other important thing to point out is the Renault 5 inline stat a lot of owners fit is NOT suitable for towing on hot days. (think yours is OEM)

The "Precision Engineering" inline type is fine.

Have you monitored the coolant temp via the built in OBD dash test no 7?

[alanaslan]

Originally Posted by Jules

Well if it's any cosolation Alan I've only heard of 2 cases of HGF pressurisation with the CDT (both behaved unless towing!)



The only other important thing to point out is the Renault 5 inline stat a lot of owners fit is NOT suitable for towing on hot days. (think yours is OEM)



The "Precision Engineering" inline type is fine.



Have you monitored the coolant temp via the built in OBD dash test no 7?

A I have to confess that I have both OEM stat replaced in October and a machined two piece aluminium stat holder in line in the top hose. But both are opening when they should. The temperature I am taking from my head up display that is connected direct to OBD2 bypass plug gives digital readout of revs, temp, voltage, speed, instant fuel consumption. And so on, much easier to read than silly little gauges on the speedo real numbers, that I can see.
Alan


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[slovcan]

Originally Posted by alanaslan

A I have to confess that I have both OEM stat replaced in October and a machined two piece aluminium stat holder in line in the top hose. But both are opening when they should. The temperature I am taking from my head up display that is connected direct to OBD2 bypass plug gives digital readout of revs, temp, voltage, speed, instant fuel consumption. And so on, much easier to read than silly little gauges on the speedo real numbers, that I can see.
Alan


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I don't think you should run 2 functioning thermostats together. I think it adds restriction to the system. If you have a new and reliably functioning OEM thermostat, maybe you should take out the inline one.

The temp sender gives you a temperature, but from where in the system in relation to the 2 thermostats - between them or after the second one in the direction of coolant flow?

Cheers,
Glenn

[SD1too]

Originally Posted by alanaslan

The temperature I am taking from my head up display ...

Alan; take Jules’ advice and use the built-in instrument pack diagnostics test 7.0. If your radiator fan is working correctly and is switched by the original control box then your coolant should not be reaching 104 degrees as you report. But read on ...

Originally Posted by slovcan

I don't think you should run 2 functioning thermostats together.

You definitely shouldn’t Alan. This is sometimes found on 1.8 engines with the PRT and it causes all sorts of baffling overheating symptoms. Use one or the other but not both.

Simon

[NigelOBB]

Originally Posted by SD1too

Alan; take Jules’ advice and use the built-in instrument pack diagnostics test 7.0. If your radiator fan is working correctly and is switched by the original control box then your coolant should not be reaching 104 degrees as you report. But read on ...









You definitely shouldn’t Alan. This is sometimes found on 1.8 engines with the PRT and it causes all sorts of baffling overheating symptoms. Use one or the other but not both.



Simon

Totally agree as one can open before the other, pressuring the system


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[alanaslan]

Originally Posted by SD1too

Alan; take Jules’ advice and use the built-in instrument pack diagnostics test 7.0. If your radiator fan is working correctly and is switched by the original control box then your coolant should not be reaching 104 degrees as you report. But read on ...









You definitely shouldn’t Alan. This is sometimes found on 1.8 engines with the PRT and it causes all sorts of baffling overheating symptoms. Use one or the other but not both.



Simon

Hi Simon, she only reached 104 degrees when she was low in coolant. Also the fan was running at high speed. ( thanks Jules your new fan works a treat.)
The reason for me fitting a second stat was the new stat was either failing to close properly or the stat was opening far to early.
A common problem I know. The engines own stat was open at 70 degrees three months after fitting. Had a choice of two guess I picked the wrong one. They were both brand new and still in their packaging. For this reason I made up an inline stat casing to fit in conjunction with the cars own stat. Since fitting this unit the car is running at the correct temperature checked both;by the cars OBD2 information. And from checking with my temp gun which is in calibration.
The difference is fantastic before fitting my new inline stat the car was getting 30.4 mpg. With the unit fitted she is now getting 35.3.
Just what the doctor ordered, when towing I select sports drive and she tows the Caravan with ease. Yes she is a 158Bhp Diesel, pulling the van in sports drive I find keeps the engine on cam with the turbo running nicely to give instant boost as required. With her in drive I find she has to change down to get the required boost. You could almost describe the feeling that she was pinking, I know she is a diesel just trying to describe the feeling. As she has the torque to easily pull the van with out being lumpy I just select sports mode and the slight lift in rpm by her being held in the lower gear for the extra 300 rpm makes all the difference.
Jules will send you the stuff in the morning.
Kind regards to all
Alan


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[alanaslan]

Originally Posted by alanaslan

I have just checked the cars own expansion tanks pressure cap in the lathe between two centres, it is very slightly distorted but less than 1mm. This now raises the question should I be fitting a new pressure cap or a new pressure cap and expansion tank.
I’ll buy a new cap to start with to see what it is like between centres, before fitting to the existing tank. I have to say I would have expected the rubber o ring to have taken that amount of play up.
Alan


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Fitted the seals supplied by Jules as the new expansion cap which came out a sealed Rover bag was 2.3mm off true worse than the existing cap.
So many of us buy and fit new parts then assume that the replaced part can be ruled out as being a potential problem.
Three years ago I fitted new front springs and dampers to the wife’s car the parts were delivered by a well known Factor as OEM parts three months later I had a pair of uprated coil springs made took off the units that I had fitted three months earlier. Standing together the uprated springs and the ones I had just removed looked, Panic..... fitted the uprated ones the ride height was up by 30mm or perhaps I should say 2mm higher than the microfiche said it should be.
The morel to this is just because you have fitted quality spares never assume that they are not faulty.
Alan


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