Overheating when driven

[KatnDougal]

Hi, I am a new (hopefully proud owner) of a watercooled 1.9 Petrol T25. I purchased the van last month and it has been in the garage ever since. It turns out my purchase was not very wise as there has been a few 'bodged jobs' according to my mechanic. The main issue at the moment is it overheats when driven but doesn't when in idle (although it does get warm and the dial is just beyond the red light). The garage couldn't originally bleed the coolant as the radiator was blocked so we had that replaced with a new one from JustKampers. The garage could then bleed and replace the coolant in the system. On testing, the fan still did not kick in (but did when they bipassed the thermoswitch) so we replaced the thermo switch thinking this may help but still it does not kick in. It appears that the radiator is not actually getting hot even though the expansion tank is bubbling away. The pipe from the thermostat is warm but not as warm as expected and there is a slight drip from the thermostat housing - could the thermostat be faulty? Also, looking at a very useful schematic of the cooling system from another post, I have identified a part - a coolant distributor - that is normally hidden to the back right of the engine bay that has been exposed on my van and 'glued' together at the top (I don't know if someone tried fixing it and failed), but could this be stopping coolant flowing to the radiator?

My garage have said it could be both or one of or even the head gasket but say they can't do a head gasket test as when you rev it at 2500 it overheats... I do not know what step to take next and any advice would be extremely welcome!

[ghost123uk]

Well firstly, from the symptoms I would put a known good thermostat in it.
If you have the plastic thermostat housing at the front left of the engine be very careful with the 4 screws that hold the top on and in fact the whole assembly as they break easily and are hard part to find.

Then I would get it properly bled of air = a bit more complicated on these vans than most other types - all the info on how to do it right is in our "wiki" information store, see link at top of every 80-90 page. (E D I T = here is a link to the relevant bit = https://club8090.co.uk/wiki/Co ... ing_system" onclick="window.open(this.href);return false; )

Try that and let us know what happens.

Don't drive it if it is still in an overheating state as this can easily kill these engines

Keep fingers crossed it is not a head gasket as that can be a big can of worms on the flat 4 engine
By the way, any garage worth it's salt can do a sniff test (with a special sniffer tool) that tells if there are combustion gasses in the water tank = blown head gasket. Bearing this in mind I would be very cautious of taking much notice of what your current garage is telling you !!!

[Ian Hulley]

If you have the plastic thermostat housing at the front left of the engine be very careful with the 4 screws that hold the top on and in fact the whole assembly as they break easily and are hard part to find.

Not any more John ... http://www.brickwerks.co.uk/shop?page=s ... ory_id=118 Not cheap but cheaper than the ebay hawks were flogging them for but very much still available.

Our new friend would be best advised to deal with Brickwerks than Just Kampers or GSF ... they sell good quality parts which is more than can sometimes be said for the other 2.

Ian

[Novice in need]

Hi when i first purchased mine the thermostat had been taken out (obvious overheating problem prior) some people would
rather bodge than fix it properly. So what i found was that the Dalek cap was malfunctioning which was the case of the overheating their about £8-£10 well worth changing.
Or you can take it off and it should allow you to blow through it but be hard to suck back through (hope i got that the right way round?) however i hope you get my point in that its a non return type of function valve in the cap.

Hope this helps... O and defo change thermostat but before putting it in the van put it in boiling water to make sure it opens

Good luck fella

[ghost123uk]

Our new friend would be best advised to deal with Brickwerks than Just Kampers or GSF ... they sell good quality parts which is more than can sometimes be said for the other 2.

Ian

Agreed

And good to know the plastic stat housing is at least available from them

[KatnDougal]

Thanks All, particularly on Brickwerks, a big difference in price to JustKampers... I was wondering if I should look at getting a second hand thermostat housing or just get a brand new one, any thoughts?

Thanks ghost123uk about the sniff test, I shall press that with my garage (the main owner has his own vw and used to repair lots of them in the '90s apparently so I think he is genuine, i hope!)

I shall let you know how the new thermostat goes.

[Ian Hulley]

Brand new is the way to go, old ones split where the steel bolt collars run through the plastic.

Ian

[kevtherev]

The pipe from the thermostat is warm but not as warm as expected and there is a slight drip from the thermostat housing - could the thermostat be faulty? Also, looking at a very useful schematic of the cooling system from another post, I have identified a part - a coolant distributor - that is normally hidden to the back right of the engine bay that has been exposed on my van and 'glued' together at the top (I don't know if someone tried fixing it and failed), but could this be stopping coolant flowing to the radiator?

Firstly welcome....
The coolant enters the system from the thermostat housing and is delivered to the waterpump... it does not leave the engine there
That pipe will always be cooler than the coolant leaving the engine at the coolant distributor

The thermostat is heated by coolant from the by pass hose that comes from the coolant distributor.

[KatnDougal]

OK, now I am getting very desperate! The van is still building up a lot of pressure in the coolant expansion tank and bubbling over as it overheats. The radiator is receiving only a small amount of water hence the fan is not turning on because no hot water is reaching the front. We have changed: the radiator, the thermo switch, the thermostat, the thermostat housing, the coolant distributor. The water pump was supposedly new last year but that has not yet been checked. The pipe from the engine is hot but cold when it reaches the radiator. When removed at the radiator water does come out so it is not blocked. If anyone can give us some ideas it would be greatly appreciated as even my mechanic is at a loss - he said the last thing to check is the impeller on the water pump. Oh, and he did do a sniff test on the head gasket and it was fine...

[kevtherev]

Only leaves the pump then

[KatnDougal]

I just popped down to the garage to chat with the mechanic and saw that they have reconnected the pipework from the coolant distributor as it was when they received it but according to previous posts, the way it is connected is not correct. On the diagram, a pipe comes from the coolant distributor to the top of the thermostat housing where the breather valve is, on mine it doesn't, this pipe goes straight into the coolant pump. The garage say that this could just be particular to the pump - is this possible or should a pipe always go into the top of the thermostat housing?

p.s. the radiator is now getting hot

[kevtherev]

This is a later cooling system isn't it
so the radiator by pass from the distributor goes to the thermostat housing.
There should be no physical way of attaching that pipe to the pump
does this mechanic know how t25's are plumbed?

[kevtherev]

[KatnDougal]

Hi kevtherev, I thought he did but maybe not... The bypass goes directly into the pump through a hole that (when compared to a similar pump on another van) should be a bolt (or at least that is what is on the other van). I don't know whether previous owners have taken out the bolt and drilled in a connector to avoid the valve on the thermostat housing (I think a couple of cowboys attacked the van in a previous life). Our mechanic thought it might just be a 'different sort' of pump.
Later today the garage have bypassed the heat exchanger as the pipes to/from it were not hot and said there may be a blockage there that was causing a back-up in pressure in the coolant preventing the thermostat to 'know' the coolant was hot, but on your diagram this is an unrelated circuit (or does it have a knock on effect?) By doing this the pipes were then hot and the van appeared to be ok but no test drive until the morning.
I am just a bit concerned that the piping for the main system still isn't right and I have a bad feeling that I am starting to know more than my mechanic...

[kevtherev]

Hi kevtherev, I thought he did but maybe not... The bypass goes directly into the pump through a hole that (when compared to a similar pump on another van) should be a bolt (or at least that is what is on the other van). I don't know whether previous owners have taken out the bolt and drilled in a connector to avoid the valve on the thermostat housing (I think a couple of cowboys attacked the van in a previous life). Our mechanic thought it might just be a 'different sort' of pump.
Later today the garage have bypassed the heat exchanger as the pipes to/from it were not hot and said there may be a blockage there that was causing a back-up in pressure in the coolant preventing the thermostat to 'know' the coolant was hot, but on your diagram this is an unrelated circuit (or does it have a knock on effect?) By doing this the pipes were then hot and the van appeared to be ok but no test drive until the morning.
I am just a bit concerned that the piping for the main system still isn't right and I have a bad feeling that I am starting to know more than my mechanic...

Right
I don't understand why this has been done, because now and very hot coolant is being pumped directly into the engine instead of being re-directed to the radiator to cool it down, when the thermostat opens.
I see a cooked engine on the horizon

the pump is correct for the 1.9 late cooling system ... it is late isn't it?
the bolt is for an oil cooler on the 2.1 which the pump also fits

What the blithering heck has a heat exchanger got to do with a watercooled engine???

take the van off them and run away