T25 Overheating

[isaune]

Hi there

I've had this T25 for 3 months now and have had no problems at all until this weekend when it started overheating.

Well - not exactly overheating - but the red light started flashing and the temp gauge settled at about three quarters - ie hot but not dangerous. That was on the motorway anyway - when there was plenty of air coming in.

When I checked the coolant level recently, I noticed it was a bit low - not much - but it needed about a pint - so I put in neat antifreeze. This is because I was told by the previous owner that it had no antifreeze in it.

Anyway, when the light came on I checked the levels in both the reservoir and the expansion tank and they looked fine.

Also, I could hear the fan at the front coming on and off like normal so it's not that.

Reading in the manual last night, I noticed that the procedure for draining the cooling system includes "bleeding the radiator at the front". Now I don't particularly want to drain the system but I did wonder whether maybe the rad needs bleeding??

Or does anyone have any other ideas please?

If you agree with me about bleeding the rad - should the engine be running or not?

And the manual mentioned something about a "bleed valve" in the engine compartment. Do I need to do anything with that or do I just need to open the bleed screw on the rad?

Or am I barking up the wrong tree completely - any other ideas please?

Grateful for any advice - as you can probably tell, I am a bit new to this game!!

Thanks

Ian

[jamesandtheopenroad]

Do a search for coolant change on here and the wiki, but the cooling system takes around 17litres (I think) and it must be at least 50/50 water to coolant otherwise it'll rust the inside of ur engine. Trust me, I found out the hard way.

As for the overheating - may well be rust or limescale type deposits clogging up the thermostat, stopping it from opening fully so no coolant can get to the rad in order for it to be cooled. Hence flashing light and high temp when running.

Not desperately difficult but if you're unsure how to do it, take it to a garage.

Kinda needs looking at pronto.

[Ian Hulley]

Obviously watercooled but petrol or diesel and year (early or late cooling system)? The header tank has a level sensor in it and that flashes the red light on the temp guage if it drops below the sensor prongs. You DO understand that the most important tank is inside the engine bay and not just behind the cat flap (which tops up the other one if it gets low).

Ian

[isaune]

Hi Ian

Yep I checked that tank aswell and it was full.

It's a 2.1 litre petrol automatic.

The way I see it, if the system is full and the fan is cutting in and out, then there must be some sort of blockage and I am hoping bleeding will fix it.

Especially as it has been fine for 3 months and just happened out of the blue last week.

But any other ideas, help, advice greatly appreciated - thanks

Ian

[California Dreamin]

The worrying thing here is you said the temperature went high (2/3rds) whilst on the motorway. This is very unusual as travelling at speed provides the 'best' cooling senario forcing lots of nice cool air through the radiator.
You are going to have drain and flush your system anyway as running these without a rust inhibitor (antifreeze) is not advisable.
You are going to need 8 litres for a 50:50 mix.
I suppose you need to cure your issue fist so it wouldn't hurt to bleed the system first and once you are happy that the overheating issue has been fixed dran FLUSH and refill afterwards. I know it's doing the job twice but you really don't want to be wasting expensive antifeeze with further work to the cooling system.
Martin

[Oldiebut goodie]

Who knows what problems there may be - I don't like the sound of 'have run it for 3 months without antifreeze' - we have had some seriously cold temps in the last 3 months.

[isaune]

Hi thereSorry forgot to mention it is 1986 Caravelle.

Also, I didn't go anywhere near it when the temperatures were down around freezing....because I knew there was no antifreeze.

Strange thing is, the van has been totally reliable, starts first time, steady idle, good on the motorway, steady oil pressure etc etc

Which makes this thing on Saturday so strange.

I am thinking that when I slapped a litre of neat antifreeze in it a week or so ago, I somehow "disturbed" the system and created an air blockage - hence I'm going to try bleeding it tomorrow.

Three quick questions

1) Which grill will I need to remove - the top one I guess?
2) When I get round to draining and refilling, is there any perticular type of antifreeze I need?
3) Does anyone know any good mechanics who "know" these vans around the Enfield/North London area?

Grateful for the advice

Thanks

Ian

[Oldiebut goodie]

Also, I didn't go anywhere near it when the temperatures were down around freezing....because I knew there was no antifreeze.


Ian

But you still had water in her without antifreeze! Freezing water doesn't need you to go near it to cause damage!

[California Dreamin]

Also, I didn't go anywhere near it when the temperatures were down around freezing....because I knew there was no antifreeze.


1) Which grill will I need to remove - the top one I guess?
2) When I get round to draining and refilling, is there any perticular type of antifreeze I need?
3) Does anyone know any good mechanics who "know" these vans around the Enfield/North London area?

With respect....It is clear from the first statement that you have know idea how freezing temperatures cause damage to engines. Infact not driving it is even worse as there isn't even any residual heat from the engine keeping the water above freezing.

Get a glass bottle..fill it with water and put it in the freezer..leave it over night and then take a look. It will look something like John Hurts chest in ALIEN after the little critter burst out his ribs!

When water freezes and turns to ice it expands and gets BIGGER splitting open anything that contains it (water jackets/engine blocks simply crack open).
If you are really lucky the pressure will just pop out the core plugs like those false eyes on springs...very comical looking but not very funny for the owner I can assure you.

1) Yes top one, bleed bolt on the top left side as you look at it)
2) Either genuine VW G12 Plus or equivelent spec..read the label for mention of G12 Plus spec)
3) Sorry no idea

Martin

[Ian Hulley]

I'd go with normal commercial blue anti-freeze cos sure as hell it'll be out again soon by the sound of this thread.

Ian

[jamesandtheopenroad]

Try Chris Cross Motors in Palmers Green or Beetlemania in Muswell Hill.

Similar thing happened to mine and when it was flushed and new coolant put in, annoyingly it went to work on the rust that had started and the engine developed leaks around the water jacket seals - eventually leading to a recon engine. Hope this doesn't happen with you.

[isaune]

OK - getting worried now.

A quick update.

The van started first time this morning as usual but, even when the engine was stone cold, the red temperature light started flashing.

I let the engine warm up and the radiator in the front got nice and hot.

I undid the bleed screw and coolant came out strongly so no problem there then.

I double checked coolant levels in both reservoirs at the back and they were fine.

And, whilst I didn't notice the fan at the front coming on and off, this was certainly happening the other day so I don't think that's the problem.

By then, I guess about 15 mins had gone by and the temp gauge was near the top. I turned the engine off and came inside but not before having one last look at the engine compartment - obviously it was really hot and making some not very nice gurgling noises.

So, we have:-

1) enough coolant in the system
2) a well bled system
3) a radiator in the front that gets hot which indicates to me that coolant is flowing around the system
4) a fan that comes on and off as expected

I just phoned Chris Cross - not very helpful - won't come out to look and can't even see it for a couple of weeks.

I obviously can't drive it in this condition so I'm a bit stuck.

Any ideas please on where to go next? Thermostat maybe? A pump somewhere? A fuse?

Remember the weird thing is that this happened suddenly - it was good as gold before Saturday.

And what does it indicate when that light flashed almost as soon as the engine was turned on? It's obviously trying to warn me about something - it's not simply telling me that it's overheating - because it flashes when it's stone cold.

Any ideas?

Please help.

Thanks

Ian

[jamesandtheopenroad]

Yeah, like I said before, sounds like your thermostat isn't opening.

So...

Go in to the wiki - read the post about flushing and bleeding the cooling system.

Go on to Eurocarparts and order 8 litres of blue coolant and a new thermostat.

Follow the wiki instructions of draining the system, flushing it (a good few times), put new thermostat in, refill 50/50 then bleed.

It's a straight forward job. Good luck.

[Cableguy]

How can it be the stat if the rad is getting hot?
Not that I can offer any words of wisdom:-)

[jamesandtheopenroad]

Dunno to be honest.

But when I had my recon fitted, after the 500 mile run in service, was driving home, the temp went up & van came on so turned round and drove back. They bled the rad (so there was some coolant getting there but clearly not enough) but was still over heating, took the thermostat out and it was all bunged with deposits. Changed thermostat - sorted.

It's a cheap materials though and if there isn't the correct mix in there already, it needs to be done.