overheating light comes on, but needle only halfway??

Post by **herby** » 03 Apr 2008, 21:23

Hi all.

OK, so I've been having some problems with the cooling system in my 1.6 TD T25. Briefly:

A hose conecting the top up tank to the exp tank (see pics in this thread: https://club8090.co.uk/forum/viewtopic.p ... highlight= perished a few weeks ago, and it had a temporary repair. All seemed fine, but I knew I had to get the hose replaced eventually. I drove the van around with the temp repair a few times and everything was OK, until one day the dashboard warning light started flashing after I'd been driving for about 15 mins. Pulled over, cooled down, drove home.

Booked into a garage 2 days ago and they replaced the hose. They also said there was a bearing loose in the fan assembly unit, but that it was fine to drive for now - although I'd have to get a replacement fan assembly at some point.
They said that the overheating light on the dash definitely won't come on, the cooling system was working fine, and the fan was kicking in at the right temperature.

I drove it home (a journey of about 15 mins) and everything was OK. Temp guage went up to a shade over halfway as it always used to, no warning light.

Just taken it out tonight for another 15 min drive - warning light came on, but the temp gauge had only just hit the halfway mark.

I'm supposed to be taking my family out for a camping trip this weekend (2 hour drive), and don't know what to do. The temp gauge is saying the temp is OK, the light is saying it isn't.

Any clues? Is it safe to drive with the warning light on but the gauge only at halfway? Tbh I am tempted to take it back to the garage tomorrow morning but a) they probably won;t be able to fit me in, and b) if they can, it might not be fixed before I have to go away.

Post by **amazingdave** » 03 Apr 2008, 21:49

The flashing light indicates low coolant level in the resevoir not overheating, sounds like you have air in the works and need to bleed the cooling system asap...

Post by **Mocki** » 03 Apr 2008, 22:06

the flashing light indecates low coolant level AND over heating, if the gauge says not hot, then it is low coolant level, open the engine lid and top the header tank up..... it could be they have not bled it correctly, and the level had dropped........ the header tank should be full to the rim, and the top up tank should be full to overflowing, and make sure the small hose between them is connected

Post by **Plasticman** » 03 Apr 2008, 22:14

Mocki wrote:........ the header tank should be full to the rim, and the top up tank should be full to overflowing

Nah shouldnt the top up tank be filled between the hi-lo marks?

Mike

Post by **Mocki** » 03 Apr 2008, 22:18

ok, so 1/2 inch lower than overflowing......whatever

Post by **herby** » 03 Apr 2008, 22:27

Thanks Mocki, that's really useful. The garage said the coolant level was a bit on the low side and they filled it up 2 days ago so i didn't think to check it. Will do so first thing tomorrow and top up to the max if it's a bit low.

Apologies for this thread btw - I did do a search earlier and couldn;t really find anything quite the same, but having refined my search terms I now see this is quite a common problem.

Could it not also be a dodgy sensor in the exp tank? If I check the coolant level and it's fine, is it more likely to be this?

amazingdave - the garage did a full bleed so hopefully it won't need another. They're supposed to be quite a reliabel garage too - Volkspares in Sydenham, S london.

*waits for horror stories about Volkspares*

Post by **Plasticman** » 03 Apr 2008, 22:27

NO, more than 1/2 inch !

Sorry only being pedantic
Mike

Post by **Mocki** » 03 Apr 2008, 22:32

if the header tank is full, check the connections on the sender plug, and the condition of the wirs, follow it back untill it goes into the tricity box, see it isnt damaged or melted, then suspect the sender........ it could also be the multiplug on the bottom of the dash assy, just above your right knee(RHD) give it a wiggle, sometimes they need a wiggle if they have been disturbed any.........

Post by **herby** » 03 Apr 2008, 22:41

Yet again, thanks Mocki!

Am very much a novice so am not sure what the sender plug or sender look like, but I'm sure it'll be pretty obvious when I have a look. (i.e. the thing with the wire(s) in it in the exp tank). Ditto multiplug, but again I'll look under my, in my case left knee (LHD!) and wiggle away.

Club 80-90: invaluable, as always.

Post by **Plasticman** » 03 Apr 2008, 22:44

Yep, I think this is one of the perenial problems, Mine doesnt overheat and is sufficiently full of water but the light does occasionally flash, and days can go by and then it will have a flash, , as mocki says check things and if all is well then its a case of getting top know the vagaries of your own motor
Mike

Post by **Mocki** » 03 Apr 2008, 22:47

still your right knee, the dash pod is the same ........ but im not sure if you can reach up there on a wrong hand drive!!!
i doubt it is the dash end anyway, more likely engine bay end in your case........ good luck!

Post by **herby** » 03 Apr 2008, 22:48

metalmick8y wrote:Yep, I think this is one of the perenial problems, Mine doesnt overheat and is sufficiently full of water but the light does occasionally flash, and days can go by and then it will have a flash, , as mocki says check things and if all is well then its a case of getting top know the vagaries of your own motor
Mike

Fair point. I've had her for 2 years and this is the first time the warning light has played up - am really hoping it's the sender wotsits or the multiplug thingummies.

Post by **herby** » 03 Apr 2008, 22:50

Mocki wrote:still your right knee, the dash pod is the same ........ but im not sure if you can reach up there on a wrong hand drive!!!
i doubt it is the dash end anyway, more likely engine bay end in your case........ good luck!

Heheh - ta, that's saved me groping around for hours, that has.

'Wrong hand drive'. Tsk. :p