How hot should we be???

[TheTransborger]

Hello everyone - just joined 80-90 (already on JK) as apparently you guys are the ones to ask about the T25... I've had a look through the wiki and although there was some good stuff in there it hasn't quite answered my question...sorry it's a bit of an essay

We have a 1985 1.9l petrol watercooled. When we bought it the temp gauge didn't work, we finally got around to having it fixed about 18 months into our ownership, although we'd never had an overheating problem, even stuck in traffic on hot summer days. The fan had kicked in occasionally though so we at least knew that was working. With the gauge fixed (we got it from GSF), under normal 'cruising' and running the needle sits slightly above (to the right of) the warning light. She'll cruise quite happily like this (e.g. down the motorway), when running round town in relatively clear traffic she might get a bit hotter but not much more. The fan doesn't ever kick in like this.

As soon as we get stuck in traffic the needle will start to climb - not too rapidly but quite steadily. My last experience was being stuck on the M4 on the second May bank holiday - quite a warm evening. Needle climbed pretty close to the top of the scale (was getting a bit panicky by this point), then after about 20 mins of stop-start in traffic the warning light started flashing. No fan though. I decided to carry on, the needle didn't get much higher but the fan then started kicking in. Finally got through the traffic after about 35mins, back to cruising, the needle went back down to a bit above where it normally sits but the light kept flashing until I stopped for petrol and had the engine off for 10/15 minutes.

Last Saturday - not a particularly hot day but quite a bit of stop-starting round town and up a bit of a slow hill, we also left it idling for 5/10mins, needle climbed again to over 3/4 and the light came on, but then went back down again to more or less normal with a bit more running (light stayed flashing again).

We regularly check the expansion tank water levels (all fine, very rarely needs topping up) and coolant mix, and have had the coolant changed completely since we bought it as well, but we don't know the history of coolant changes before us. I wanted to know if these running temperatures are 'normal' or if we should be concerned. I read an old post on another website that said if a van runs like this it's likely to be internally corroded and you should walk away from buying it!!

Any advice on how 'normal' this is would be appreciated - we haven't had a problem yet but should we be worrying about the needle climbing like this and the light coming on so frequently? Especially as it then has to go even higher before the fan actually kicks in??

Thanks everyone

[CovKid]

Maybe investitage the thermostat switch on the fan. Cheap and easy to replace too. Cured mine.

[syncrosimon]

The difficulty is that you don't know if the temp gauge is working properly.

If the temp only goes up when the fan is'nt running then suspect the thermoswitch as above.

If it is not that then you can try these two.....

It sounds to me like you have a blocked radiator or as above a restricted (partially closed) thermostat. A blocked rad would have poor flow except on faster roads where airflow and engine speed is sufficient to keep things cool. I would be tempted to pull the rad and flush it, after you swap the thermostat for a genuine VW one.

You can test this theory by using the internal heaters. When you get stuck in traffic and the needle goes up, put the heating (and fans) on full, and the back one if you have one. If that brings the temp down, then there is a blockage in there somewhere, and the favorites are radiator and thermostat.

Happy hunting.

Simon.

[TheTransborger]

Thanks for the prompt replies CovKid and Simon.

Simon - as you say, we're unsure whether the actual gauge is working properly, but yes, the temp does always go right up when the fan isn't on, so we'll check out the thermoswitch/stat for the fan first. Just out of interest, how long does it normally take your fan to start up when you're stationary/stuck in a jam? A few minutes or more like 20-25 like ours?

I did try putting the heaters on when I was crawling along the M4 a few weeks back, but it didn't seem to be making any difference. Maybe I didn't leave it on long enough so will also give that another try.

Thanks again
Heather

[syncrosimon]

My fan will come on about a full needle width from the little red light. It will normally sit on the red light, but everyone's seems to be different. In traffic the fan will be on off all the time, but as soon as you hit second gear, or even fast in first the airflow will be sufficient to cool the engine. If when your van gets too hot you can drive it up to a good speed, the needle should drop very fast, within a minute or two max.

If your van is overheating then it will be blowing coolant into the top up tank when hot, so have a look, it then sucks it back in as it contacts and cools.

In the winter the fan wont come on at all, so depends on the weather. In 20 deg C your fan will be on in the traffic, but not in winter, especially with the heater. I drove the bus 8 miles in the winter, and the rad was still not hot, all heat going through the heater.

[TheTransborger]

Hmm, interesting. Def going to check out our thermoswitch!! Ours never comes on that quick, always takes a while of sitting in traffic. The gauge does drop pretty fast as soon as we get moving again, just always stays riding a touch on the high side (with the little light blinking away). Might also let it idle and check the expansion tank too.

Thanks again...off to dream about fans and rads now...might post again in a couple of weeks and let you know how we get on.

[toomanytoys]

Early vans the fan doesnt come on as quick......
I would prob agree with Si in that the rad could be blocked/low flow or the pump is poor..
2 tips when sitting in traffic is.. if you aint going to move for a bit, switch off....
and raise the idle speed a bit with the throttle.. this spins up the pump and pumps coolant around a bit faster... thus getting the hot water to the rad quicker... heater takes a hell of a lot of heat out of the engine too...

Oh... and can you fill out your profile with location, that way we know what part of the country you are in and may have someone locally to help you..