Was replaced last year along with the water pump and viscous fan, seems to open when the engine warms up. Today the temperature shot up so that the light came on, i whacked the heater on full which brought it back to normal and then it didn't do it again all day even with the blower off. The coolant is a bit low but the new cap came apart, the cooling system seems to be cursed.
There isn't a lot to it!
There's the jacket around the engine, it comes out and through the rad, through the thermostat pushed by the water pump and job's a good un. Dogleg out for the heater matrix. Viscous for when forward air-flow not good enough.
So to summarise:
Expansion cap is new.
Pressure test OK.
Thermostat new.
Collant flushed several times.
Rad weeping?
Have you checked the baffle in the rad? Water pump is the other option. The metal ones are about £35 off Island so not a lot. I have my old one in the shed. I kept it as backup as I replaced it as a precautionary measure. Could see how much it would cost to post it down if that would help you troubleshoot?
There's the jacket around the engine, it comes out and through the rad, through the thermostat pushed by the water pump and job's a good un. Dogleg out for the heater matrix. Viscous for when forward air-flow not good enough.
So to summarise:
Expansion cap is new.
Pressure test OK.
Thermostat new.
Collant flushed several times.
Rad weeping?
Have you checked the baffle in the rad? Water pump is the other option. The metal ones are about £35 off Island so not a lot. I have my old one in the shed. I kept it as backup as I replaced it as a precautionary measure. Could see how much it would cost to post it down if that would help you troubleshoot?
Hi, sorry for late reply, your summary is correct yes, that is very kind of you to offer, the pump is a plastic one unfortunately as I didn't see the advice on here until after I had it. I think if I replace the rad first and go from there, the temperature shot up again yesterday, would it be unusual for these parts, i.e the pump and thermostat, to go so quickly? Many thanks.
Littelwill
Well-Known Member
Depends on what make they where.... Not to start another this part is better than that part but if you need to rely on it don't buy the cheapest...
Quick check, get the engine hot stat open and feel the bottom of the rad, should also be hot. If it's cooler at the bottom but hot along the top baffle maybe missing. Baffle forces coolant down right hand side of rad and up left hand side, if it's not there, hot coolant just goes along the top. Looking from front of engine.
And if the top is hot and the bottom cold as above, after that it is rad off, turn upside down and try and roll a marble in one side and out the other. The baffle should stop it. If it doesn't there's no baffle and you've got the wrong rad.
Would say thermostat opened or the engine burped. Airlocks on these can kill the cylinder head.
brianp38dse
Well-Known Member
Make sure the thermostat has a bleed hole in it as well and the hole is at the top, when the temp gets hot can you hear the viscose fan roar?
Ok so there was no crud around the rad however it has split on the plastic part right along the top, now the man at the shop said that only happens due to overpressure, however we have ruled that (at the expansion tank) out so I'm wondering how that has happened. Is it worth taking the water pump out and having a look or not? Many thanks.
Bollocks. The cap is designed to relieve pressure above 15 PSI and fail completely at 22 PSI to prevent system damage. Unless you have a defective cap. Not unknown ( BMW did a recall in the late nineties reference incorrect caps causing system fails). Also there seem to be a lot of cheap and cheerful rads about at the moment.
brianp38dse
Well-Known Member
The rads cracking along the top is not uncommon at all, heard of quite a few on here.
That is more down to cheap crap plastic being used to make cheap rads than anything to do with pressure.
ok so I replaced the rad which has solved the issue of coolant dribbling out of the overflow however now the car hardly gets up to temperature, whereas before it was always exactly in the middle of the gauge now it is more to the cooler side. The thermostat stays closed and then opens so maybe not that? Many thanks for your continuing help with this saga.
Littelwill
Well-Known Member
Hope you get to the bottom of it!
