Nearly Boiled Over

[Guest robinj66]

Was still losing coolant (albeit a little), even though the temperature was stable and being cooled by the mega fan.

 

The system on my car has 2 radiator caps, one on the rad and one on the GBS water rail. Fitted seals to the caps and this stopped coolant being lost around the cap (as opposed to through the overflow), although there was still the minor loss from the overflow.

 

Have fitted a plastic expansion tank from CBS to catch the coolant (thanks for the heads up Bob). But the engine filled this up last Saturday afternoon while out for a little drive, capacity of this tank is 1.5 litres! Nothing was being drawn back into the cooling system while the engine etc was cooling down (via vacuum caused by hot coolant contracting in a sealed system).

 

So looked at the cap on the rad. I thought that maybe air is being drawn through this cap, bypassing the expansion tank. So located and fitted a 20lb cap to rad yesterday (have kept the 15lb cap on the water rail). Ran the car up and no coolant weas observed flowing into the expansion bottle, (it would have usually done this just before the fan first kicked in).

I kept the car running for 30mins or so, and there was no coolant loss into the expansion tank. I let the car cool down for a couple of hours, and the coolant level was still the same!!!

 

So it looks like the coolant loss was caused by a 15lb cap on the radiator letting air in. I now have a engine that not only can maintain it's engine temperature but also hold on to it's coolant!!

Early days yet and miles will prove this theory, but the indication is that the problem has been put to bed at long last

 

excellent news

 

Now come round and sort mine out

[Al Milton]

Saturday or Sunday Rob??

Will give you a shout - get the Hob Nobs in!!

 

Only if you need your problem sorting over a couple of months of course

:D

[Guest kent zero]

Hi mate,have you checked to see that to top edge of the aluminium thermoste housing where the cap sets

against is completely fat and doesnt have a casting make left around it? my housing did faced of with

new cap sorted problem.

What temperature thermostate are you using? try 84-88 degree may make run a bit cooler.

 

John.

[Al Milton]

Hi John,

 

Yes, checked the housing. All is good, no casting flash or lip.

Thermostat starts opening at 85 degees and has additional 5mm holes around the circumference to aid flow.

 

Al