Club 80-90 Forums

To recap:
* its overheating
* system has been bled
* the radiator fan works but temperature sensor in rad never switches it on
* the thermostat and rad sensor are new (have tested stat but not switch)
* rad gets warm (not hot) it also takes a long time to warm up... ie. the temperature gauge reaches max first!

The radiator send pipe (which goes from the top of the thermostat to the top of the rad) gets hot. But the rad return doesn't.

Both heater pipes get (very) hot. My heater fan switch isn't working but I'm pretty sure things could get nice and toasty in the van if it was!

So does this sound like a blocked radiator? ...next course of action remove the rad???

backflush the rad with as much pressure as you can get from a garden hose with a sock wrapped round it stuffed into the rad feed pipe. Guage by the crap that comes out what to do next, maybe some seek and seal has been used in the past. I understand this can clog the system.

did you use a genuine stat??
gsf ones are pants.
had the same prob on a mates bus and we changed rad and stat and cured it.

yeah the stat is genuine... the last one in the country according to VW

You will have to be a bit more specific ::

What are the symptoms of your overheating other than it showing HOT on the gauge ?

Is it boiling over/ 'Kettling' (water surging in pipes) Blowing steam /loosing water ?

Have you replaced the temp sender for the display (forward facing on the stat housing) if its a none diesel....
......................................................................................

The top hose of any rad will be piping and the bottom one will be a whole lot cooler, so your rad sounds like it is doing its job.....

And finally overheating problems can also be associated to duff expansion tank caps as some of us have found out in the recent past.....

does it still overheat if you open the bleed screw? I think the bleed screw open forces the thermostate to be open fully all of the time.

I assume your pipes are not almost bursting under the pressure, if they are it is possible that the head gasket is leaking hot air / flames into the water system

sounding like a rad or pipe blokage to me...... however, im guessing you are doing this testing stationary, as you say the heater fan isnt working so you cant tell the temp of the air coming out of the heater........

are the rad pipes connected the correct way round?
is the stat really opening?
the fan switch in the rad wont switch on till the rad is all well hot,
regaurdless of the engine temp......

have you bled it properly.......properly.

whay rev's are you doing this testing at, is the water pump working......

i had this prob years ago, and it turned out to be a hoofing gert lump of sillicon stuck in one of the pipes some muppet had used to seal a leak with...

Fritz wrote: Is it boiling over/ 'Kettling' (water surging in pipes) Blowing steam /loosing water ? Have you replaced the temp sender for the display

It was boiling over, huge clouds of steam everywhere coming out of the expansion tank - until I replaced the tank - the cap is fine, it was the thread on the tank that had gone. I have replaced the sender with a new one (but only from GSF, so I suppose it could be a false reading... I guess I really need a thermometer in there to be sure).

clartsonly wrote:does it still overheat if you open the bleed screw? I think the bleed screw open forces the thermostate to be open fully all of the time. I assume your pipes are not almost bursting under the pressure, if they are it is possible that the head gasket is leaking hot air / flames into the water system

If you mean the bleed in the engine bay, it still overheats regardless.
And no I don't the pipes are as pressurized as all that.

Mocki wrote:are the rad pipes connected the correct way round?
is the stat really opening?
the fan switch in the rad wont switch on till the rad is all well hot,
regaurdless of the engine temp......

have you bled it properly.......properly.

whay rev's are you doing this testing at, is the water pump working......

i had this prob years ago, and it turned out to be a hoofing gert lump of sillicon stuck in one of the pipes some muppet had used to seal a leak with...

Yep, I am testing stationary, don't want to lose my parking space outside the house!!!

I'm pretty sure the rad pipes are the right way round, as I have followed them underneath the van - top of stat to top of rad (via a solid pipe which goes up the driver's side of the rad) - is this how its meant to be?

The stat is new, genuine, and tested, so it must be opening!

I think I've bled it properly, have re-done it a couple of times now and only water has been coming out the rad bleed each time and I can't put any more into the tank. Haven't tried it on a ramp/hill yet tho...

Got no tacho, dunno what the revs are, its basically a fast idle from when it starts until about 15 minutes. After that I let it run at normal idle but I do try revving it a bit to see if that gets things moving (it doesn't seem to)... but by then then gauge is getting really near max and the red light comes on pretty soon, so I don't like to rev it that much.

I have removed, inspected and cleaned the water pump. Its a lovely genuine one with metal impeller blades. All looks like it should be working, but how can you test it? What about putting some sort of transparent plastic pipe (or something like a propeller which the flow would make spin) inline between the stat and rad hoses ???

So it hasn't turned a wheel yet.......

Yep, I am testing stationary, don't want to lose my parking space outside the house!!!

............So rad fan switch doesn't work/Heater blower fan doesn't work and you are basically simulating being stuck in a traffic jam,,,




Regards

Fritz,,,,,,,,,,

ambivert wrote:

Fritz wrote: Is it boiling over/ 'Kettling' (water surging in pipes) Blowing steam /loosing water ? Have you replaced the temp sender for the display

It was boiling over, huge clouds of steam everywhere coming out of the expansion tank - until I replaced the tank - the cap is fine, it was the thread on the tank that had gone. I have replaced the sender with a new one (but only from GSF, so I suppose it could be a false reading... I guess I really need a thermometer in there to be sure).

clartsonly wrote:does it still overheat if you open the bleed screw? I think the bleed screw open forces the thermostate to be open fully all of the time. I assume your pipes are not almost bursting under the pressure, if they are it is possible that the head gasket is leaking hot air / flames into the water system

If you mean the bleed in the engine bay, it still overheats regardless.
And no I don't the pipes are as pressurized as all that.

Mocki wrote:are the rad pipes connected the correct way round?
is the stat really opening?
the fan switch in the rad wont switch on till the rad is all well hot,
regaurdless of the engine temp......

have you bled it properly.......properly.

whay rev's are you doing this testing at, is the water pump working......

i had this prob years ago, and it turned out to be a hoofing gert lump of sillicon stuck in one of the pipes some muppet had used to seal a leak with...

Yep, I am testing stationary, don't want to lose my parking space outside the house!!!

I'm pretty sure the rad pipes are the right way round, as I have followed them underneath the van - top of stat to top of rad (via a solid pipe which goes up the driver's side of the rad) - is this how its meant to be?

The stat is new, genuine, and tested, so it must be opening!

I think I've bled it properly, have re-done it a couple of times now and only water has been coming out the rad bleed each time and I can't put any more into the tank. Haven't tried it on a ramp/hill yet tho...

Got no tacho, dunno what the revs are, its basically a fast idle from when it starts until about 15 minutes. After that I let it run at normal idle but I do try revving it a bit to see if that gets things moving (it doesn't seem to)... but by then then gauge is getting really near max and the red light comes on pretty soon, so I don't like to rev it that much.

I have removed, inspected and cleaned the water pump. Its a lovely genuine one with metal impeller blades. All looks like it should be working, but how can you test it? What about putting some sort of transparent plastic pipe (or something like a propeller which the flow would make spin) inline between the stat and rad hoses ???

firstly, just how long does it take to overheat, stood standing, stationary?
secondly, imo, you cannot bleed these water systems any other way than with the front raised , the physical shape of the pipework means trapped air otherwise....others say different?

also, you should be able to see the water pump pumping the water round the header tank with a few extra revs it should "lower" the water level in the header tank.....

there are a few things you have to sort out here, the rad switch for one, and the temp gauge for another.

this time of year, i coould leave my van idling for literally hours on my drive and it would even think of overheating, the fan would maybe cut in, maybe not, they are not everso active the fans on the rads on these, even in mid summer its rare to hear one happening...

Hi Mocki,

Thanks for your help, I have answers to your questions below...
I have also discovered some new things today, as I removed the rad then and gave it & the main hoses a good flushing:

• * The rad and pipes do NOT seem to be blocked and didn't really have any gunk in them, just a bit of rusty water came out at first then it ran clear.
  
  * When I put a garden hose into the back end of the radiator hose, the engine bay bleed valve lets water flow from it back into the engine. Turning the valve has no effect on this. There is still a healthy flow of water out of the front end of the hose tho... so I don't think this could be the cause of the overheating - ?
  
  * The radiator hoses were connected the WRONG way round - the hose from the top of the thermostat was going into the bottom of the radiator! Could THIS be the problem - ?
  

Mocki wrote: firstly, just how long does it take to overheat, stood standing, stationary?
secondly, imo, you cannot bleed these water systems any other way than with the front raised , the physical shape of the pipework means trapped air otherwise....others say different?

Today it took about 25 minutes for the gauge to hit max and the red light to come on. I put it up on ramps, still only getting water out the rad bleed and no room for anymore into the tank.

Mocki wrote: also, you should be able to see the water pump pumping the water round the header tank with a few extra revs it should "lower" the water level in the header tank.....

Ah... thats a good test... and yes it passed, so the pump appears to be working

Mocki wrote: there are a few things you have to sort out here, the rad switch for one, and the temp gauge for another.

OK, I will test these in boiling water... ran out of time today... it will have to be the weekend.

Mocki wrote: this time of year, i coould leave my van idling for literally hours on my drive and it would even think of overheating, the fan would maybe cut in, maybe not, they are not everso active the fans on the rads on these, even in mid summer its rare to hear one happening...

Wow, there really is something amiss with mine then

BTW, I have left it up on the ramps (mainly so putting the rad back on will be easy) - is there anything else I should check now I have this opportunity?[/list]

ambivert,
You said.................

* The radiator hoses were connected the WRONG way round - the hose from the top of the thermostat was going into the bottom of the radiator! Could THIS be the problem - ?

You know........... I guess it could kinda spoil your whole darn day.

I can't get my head around the early thermostat/waterpump layout, (especially at this time of the evening!) but, if you are sure the hoses were reversed, I would say you will now see a marked improvement............ There is however a little niggle that won't let go. On my (later model) cooling system the bottom hose is shown as connecting to the top of the thermostat.......... (Mine is the plastic one, and I have just bought a spare from JK)......... I know it sounds crazy, but the whole cooling system borders on the lunatic.......... I do hope you are right, someone with the earlier pump/thermostat will be able to advise in due course.......

You deserve top marks for effort, and for your feedback.
Success will come.

Mike

damn - just refreshed this , and nobody knowledgeable has yet replied.....need more input, stephaniee . jaylo

sorry , i meant "answer solver" , not "knowleageable" . jay

[img:430:304]http://www.club80-90.co.uk/techhelp/radpipes.jpg[/img]
[img:551:578]http://www.club80-90.co.uk/techhelp/radpipes2.jpg[/img]

methinks you may well have got to the seat of the problem, now when you put it back together, bleed it properly, revs up, front up, caps off, ignore the bleeder in the engine bay, and make sure the heater is switched on if you had it switched on when you emptyied the system.