problems with cooling system

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ewenmaclean
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Re: problems with cooling system

Post by ewenmaclean »

Feardana,

just to go back to the original questions! I agree with the other helpful comments you've had so far from andyb and Nicola&Tony et al. - lots of good advice there. I would add though (can't see if it's already been mentioned) then under certain situations when the red light flashes and the gauge goes to maximum it is because the coolant level is low, as regulated by module 43 (looks like a relay)- it doesn't necessarily mean you're overheating.

Also - the interesting bit of anecdotal evidence here which I find interesting is that the fan came on all of a sudden when the engine was cold. I can't really understand why this would happen, but it does suggest potential electrical gremlins. The switch for that is in the radiator and is controlled (at least high speed) by a relay above the fusebox. I wonder if it's possible, given that you say you have blue antifreeze, that at some point original G12 has been mixed with G11 (which as has been mentioned, shouldn't be mixed) and you have sludge and airlocks in your cooling system. If it were me, I'd be inclined to flush the entire system out including the radiator and refill. If you have access to a hose in a garden this isn't too painful a process to do.

If you disconnect the switch for the radiator fan, which you can do by removing the lower grill and just unclipping the electrical connector, you should be able to check the function of the slow/fast fan speeds by bridging the pins briefly. It is indeed possible someone has tinkered with the electrics to make the fan come on some other way, but you'd have to go investigating to try and find this. The switch itself isn't very expensive (£12ish from brickwerks assuming you have the later type with two speeds as it's originally 1985) and if you flush the coolant system you could think about changing this - easy job.

I certainly agree with kit and andyb about the dipstick. Drain the oil - refill with 4.5 litres, and see where the level is then. You might find it's way above or below where your marks are and if so you'll need to go through the correct procedure for marking it up.

In the wiki there are some good sections about how the cooling warning system works and how to test the correct operation too. Hope you manage to get it all sorted.

Ewen

82JEW75
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Re: problems with cooling system

Post by 82JEW75 »

Thinking from a different angle, do you have children? Does one sleep in a bunk across the cab? If so, have a good look to make sure someone hasn't installed a "chicken switch" to switch the fan on manually.

feardana
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Re: problems with cooling system

Post by feardana »

Well i reckon i know a little more about thermal expansion now :lol: - thanks for all the info folks, it's been incredibly helpful and thanks for the pointer to the wiki source tony, i should have looked there to begin with

i haven't experienced any loss of coolant to my knowledge but that's probably because i wasn't filling the header tank, just making sure that it stayed above the minimum mark on the tank - i did top it up the other day but haven't driven the van yet so if it does pour out all over the battery i'll let ya know :wink:

i need to say that i drove the van quite a bit, on long journeys and often over hilly terrain for a month ever before we went to france without any issues and when in france the weather was really hot most days and never in all that time were there any overheating issues, it was only the last day couple of days there and then the drive home that we experienced problems so the cooling system seemed to be working fine up to then and i don't know how long the last owners had this set up andy, the van had been laid up for quite a while before we bought it that's all i know

To summarize the situation and just to check that i understand correctly:

1. the rad fan is running all the time and since it's running when the the engine is cold it's probably an electrical problem either with the switch or some kind of short circuit/bypass

2. the gauge and red light is telling me that the engine is overheating but there are indications that the engine isn't actually overheating so does this indicate a second electrical problem and are these two electrical problems, ( the rad fan and heat sensors in the engine), happening independently or are they connected on a circuit? if they are occurring independent then is it likely that both systems would fail at exactly the same time?

3. the coolant in the tank was kept above the minimum mark but is this too low generally, everyone seems to agree that you keep the main tank close to full? could this alone have caused the overheating problems?


finally, what can be done about fixing the dipstick problem both in terms of getting a better fit and making sure that the stick will give an accurate reading of the oil level?

many thanks and regards

ps, as i was writing this a couple more comments came in - yes we do have kids and the younger guy has a button/switch fetish and he'd definitely be in the frame for this one if he had been in the area but he was comatose up in the rock n roll bed at the time the fan came on so unless the chicken switch has been installed up there! - by the way, what would a chicken switch look like/likely to be placed ?! we did have a problem with the heater/cooler in the cab where the fan switch went and it was stuck on full power for most of the trip - could that be somehow related to the rad fan? showing my ignorance now :oops:

as for mixing the coolant, i didn't mix them before or during these problems though i'm not sure what the mechanic did in the service just before we left - when i asked him what coolant to get he recommended the G12 so if he did top it up he would have used that i reckon

regards
1985 Hi-top caravelle 1.9D

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ewenmaclean
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Re: problems with cooling system

Post by ewenmaclean »

Hello again,

Just to reiterate a couple of points:

The rad fan circuit should be entirely separate from the gauge. The gauge temp is read from the head and the fan sensor is in the radiator.

Also - low coolant warning is a flashing red light and on some circuits causes the gauge to move all the way to the right - it might not be overheating. That sensor is in the expansion tank.

I like the chicken switch suggestion! If it were that it would just be some sort of on/off switch - impossible to say what it would look like.

Hope you find the problem

Ewen

Ewen

feardana
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Re: problems with cooling system

Post by feardana »

Many thanks for that Ewen - if low coolant can get the red light flashing which in turn causes the gauge to go to max as you say then i think you could be right about the possibility of the problem being caused simply by low coolant levels as the header tank was way below full and as i mentioned in an earlier post the gauge warnings happened more frequently when on a moderate but long incline which could have affected the level of coolant in relation to the sensors in the tank even more - i'll probably take it for a spin over the weekend and see what happens, sort out this problem first and then tackle the radiator fan - i certainly understand alot more about the problem now after all the posts and it's good to be aware of the oil/dipstick problem also and at least i can pass that on to a mechanic when getting an oil and coolant change to make sure that it's done to suit the specifications of the engine and not just in a routine way, that information is invaluable really

regards
1985 Hi-top caravelle 1.9D

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Nicola&Tony
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Re: problems with cooling system

Post by Nicola&Tony »

feardana wrote:Many thanks for that Ewen - if low coolant can get the red light flashing which in turn causes the gauge to go to max as you say then i think you could be right about the possibility of the problem being caused simply by low coolant levels as the header tank was way below full . . .

Ooh, just noticed that your thread has been moved to Alternative Engines forum, I've never been in here before! :shock:

Cooling system might need bleeding as well to get any air out of the pipes, as that would affect the temp guage?

Tony
Looking for: window apertures for side windows, at the back of the van

T25; 1985; RHD; 1.9DG petrol / LPG; white Autosleeper high-top; Looking rusty again!

LT31; 1993; RHD; 2.4L petrol; high-top; diy camper project.

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Nicola&Tony
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Re: problems with cooling system

Post by Nicola&Tony »

phil miller wrote:Its a 1.9 defo, mainly because VW never made a 2lt that looks like that :mrgreen:

Second, you dont need the over flow, i didnt fit one in mine and have ZERO problems of coolant loss

If this engine doesn't need an overflow tank (as you say, lots of other engines don't have them), does the dalek cap on the reservoir need changing for one that doesn't have an outlet, or make some sort of bung / stopper for the outlet, or is it fine as it is?

Tony

E D I T: oops, I missed this bit when reading the other replies:
ewenmaclean wrote: . . . I just use a Mk2 golf coolant tank cap, but the dalek cap is fine too. The tdi are thermally much more efficient than the idi engines and don't get as hot, which does allow this system to work well as the fluid expansion is somewhere in the order of 150ml.
Looking for: window apertures for side windows, at the back of the van

T25; 1985; RHD; 1.9DG petrol / LPG; white Autosleeper high-top; Looking rusty again!

LT31; 1993; RHD; 2.4L petrol; high-top; diy camper project.

feardana
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Re: problems with cooling system

Post by feardana »

Hi folks, just to let anyone know who contributed to this thread that the cooling system problems seem to be sorted - got the sensor on the rad replaced and that sorted the fan out, (it was running all the time regardless of the engine temp) and it now seems to be kicking in at the right time/temp and also replaced the old blue coolant with G12 and topped up the expansion tank and there hasn't been any more issues with the gauge and red light indicating overheating so 2 problems sorted in that dept - as for the possible issue with the dipstick being unreliable the current stick had actually been modified to take into account the new engine and it's position in relation to the sump so no problems there - think that was it - many thanks again to everyone for their help, it was great advice and much appreciated

regards
1985 Hi-top caravelle 1.9D

Dave Crowe
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Re: problems with cooling system

Post by Dave Crowe »

Hope I can get a bit help, another coolant thing my main coolant tank is leaking from the cap, I have an expansion tank, took the hose off the thermostat to see if that might have been blocked but coolant was clean, any ideas thinking maybe water pump, there’s no damage to filler cap I’ve tried thread tape but still leaks, it’s a T25 1988

RogerT
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Re: problems with cooling system

Post by RogerT »

Hi Dave
Start a new thread, saves us having to read all the guff in this ancient thread. And let us know what you’re driving, engine type etc by putting it in your signature.

And welcome to the forum!
Have you ever seen an unhappy fool?

88 Transporter with hitop camper conversion, 1.6td.

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