Mk3 Golf Overheating - Thermostat Change?

[PaleAssassin]

Hi all, Having looked through a good few of these threads relating to mk3's overheating or running hot, none seem to come to a definitive answer or let me know how an if their problems were solved. Therefor sorry if this is a bit of a repeat thread..

Here goes! My '92 Mk3 Golf 1.8 Cl is running hot. It tends to rise quite quickly and sits at just over 100 until I encounter traffic, at which point it runs to about 110 before the fan cuts in.

So far I've bridged the fan connection to make sure it runs properly, it does on both high an low speed although it is a lil rattley, there appears to be a bit of excess movement from the fan but nothing too excessive i think.

I've changed the Fan Switch too as I've seen it mentioned several times but that hasn't made any difference.

The thermostat seems to be the obvious next step and this is where I've hit a wall. I'm pretty sure I can see the housing (connected to lower radiator hose). However getting to it is proving to be a major pain in my already numb backside! From what other threads I've read - its the power steering pump in the way preventing me getting near the thermostat housing. Any help on how to gain access would be hugely appreciated!



I presume the red box is the thermostat location.. and where the green box is I think its one of the bolts I need to undo however the black bar is preventing getting any tools to it! Any ideas and general help would be appreciated!

[SammoVWT]

How does your coolant look? are you running the pink G12?

If its dirty try giving it a flush, see how that goes. The holts stuff is pretty good, worked a treat on mine.

Check for pressurised and hard hoses.

If the flush didnt work, try the thermostat, if its still overheating then, id lean towards HG failure.

Its not good for engines to run hot, warping of the top end is not nice

[PaleAssassin]

The coolant seems to be ok, yeah I'm using the pink stuff! I will say though, the guy that had it before me was really one for cars and I know the coolant had got low and he'd probably not checked it at all. took me a good 20 mins to get the lid off the coolant tank when I topped it up! A flush is planned but if I'm draining the system and flushing it then I want to change the thermostat at the same time. Just need to get to the bloody thing! lol

[charbel89]

Hi Paul,

I have a 1.8 Gl and I am hoping it will be similar to yours. (Here is my thread earlier: https://www.vwaudiforum.co.uk/forum/s...d.php?t=100883)

You need to check a couple of things.

The bottom hose off the radiator will be cool until the engine thermostat opens.

the thermostat opens at 87 degrees and is fully open when it reached 95 I think. When it is full open the water should circulate and the fan should kick in when temp reaches about 97 (at least this is from me monitoring mine).

Before you change the engine thermostat open up the expansion tank and see if the small hose connected to the top is trickling coolant into the expansion tank. It it is not then your problem is with the water pump , it is not pumping the coolant around to circulate.

If there is trickle of coolant into the tank then it is most likely your engine thermostat.

It is connected to the bottom hose off the radiator.

To do this:

Jack the car safely, and loosen the power steering pump and drop it a bit without disconnecting the Ps hoses, the PS has 3 bolts and the tension one, Two are vertical and are right below where the thermostat is and one is horizontal you may need to get to it from the top. (To do the bolt you refer to I used a small spanner, it was a bit tricky and painful, similar to the horizontal one)

when you drop the PS you will see the gasket where the rad bototm hose is connected to, undo the two bolts there, and that is where your engine thermostat is.

I did mine last week.

Here is a link on how to perform this:

http://faculty.ccp.edu/faculty/dreed/Campingart/jettatech/coolingmaint/index.htm



Here is my belt layout which is slightly different from the one described in the above FAQ:



Where:
A = crankshaft , B = alternator, C = water pump, D = power steering pump


Here is where my thermostat is (The blue arrow):

[PaleAssassin]

Thanks for the info Charbel89 - will check out the circulation tomorrow.

Now thinking it'll be far more sensible to check out every other option before I get cracking on the Tstat.. does look to be a pig of a job!

I shall keep updating the thread as I go along!

All the best

[charbel89]

If you got the right tools should not be too bad.

It took me about 2-3 hours.

The main part that took me long was to get the PS back in place to get the screws in. Must have spent about 1 hour on this. I had to screw an uncrew the bolts several times before I got the correct alignment. for all 3 bolts to fit smoothly.


My car was staying cool. Obviously it was stuck open. Then when I replaced the coolant sensor I noticed the fan was playing up so I changed the fan switch. The parts I bought were not VW and appeared to be faulty. I had to get the VW original parts for these sensors.

At the end of all this I replaced the Tstat. Thinking about it now , probably the Tstat the only thing that required changing.. but doing the others is a necessary evil to keep things ticking as they should.

After I replaced the TStat I used my old coolant sensor and fan switch and all was working fine.


Charbel

[PaleAssassin]

Right, I've just been our messing about with the motor for a bit, realised that my coolant level has dropped way below the minimum. Obviously got a leak!

Having had a good look at all the hoses for traces of leakage etc, All I can see an I'm now pretty sure is the problem is where the hoses meet the bulkhead.....



This is directly below where the hoses are connected to the bulkhead



Can see signs of corrosion and liquid having run down the bulkhead. Now I presume this is going to involve the heater matrix... and that Im now looking at a pretty big pain in the @$$ job......

Right now someone telling me that this'll be easy would be much appreciated!! Any thoughts?

[PaleAssassin]

So does anyone have any ideas whether this is likely to be solvable from the engine side of things? Not looking forward to potentially removing the dash!

At the moment the heater works fine, heats up etc.. the blower is a little off. Works the same on 1+2 doesn't seem to work on 3 very well and is fine on 4, air blasts out nicely!

Hoping it might be as easy as changing the clips on the coolant hoses.........?!

[DropKickMurphy]

hi there,

my HM failed on my Mk3 golf and rather than remove the entire dash i opted for the easy route and bypassed the whole thing.

if you look for a 90 degree barbed plastic elbow joint you will be able to join the two ends of the hose which enter the bulkhead on the engine side.

somthing like this:

http://cgi.ebay.co.uk/90-DEGREE-ELBO...item255b36945f

you can then whip the pipes off the connectors on the bulkhead (you will lose some coolant) then fit the elbow and clamp it with the green clips on the ends of the pipes.

this will mean the coolant will go in a big loop out of the back of the cylinder head rount the black pipes and then back into the cylinder head. i would recommend using a cable tie to attach the black pipe to something to stop it from flapping about.

now the disclaimer - this is not a guaranteed fix, and it could pop off at any time, although the damage it can do is limited as long as you make the join on the engine side of the bulkhead. if you see clouds of steam erupt and the warning lights go off telling you the coolant is low then you can expect that one of the pipes has popped off. mine never did this, but thats not to say yours wont.

also, be aware that you will have no heater. it will blow out ambient temperature air provided the blowers still work, but trust me on this one - it is no fun at all in cold weather, or if its raining. I spent many hours driving along wiping the inside of the windscreen becuase it fogs up really quickly on the inside if you have the windows closed, and its raining.

if you can live with the above, it should fix the issue. it worked for 9 months for my golf before i sold it.

DKM

[PaleAssassin]

Hey All,

Just wanted to keep this updated just in case it proves to be any help to anyone else out there!

Following DKM's advice above I have discovered that it was definantly a leak from around the heater matrix or where the hoses enter the bulkhead leading to the heater matrix (which has presumably blown at some point in the past). Had steam coming through the vents when the car was overheating and found a puddle in the passenger side footwells..

I have basically bypassed the heater matrix on the engine compartment side as advised. This seems to have done the trick! During normal running the temp settles at nearer 90 than it ever has done, I'm not losing coolant and I no longer have the luxury of a paddling pool in my footwells!



Although I did buy and use the elbow from ebay in the link provided by DKM it turned out it was a bit small (16mm) for my hoses so I replaced it with a 19mm piece which was much more snug. It seems my hoses are a bit bigger than normal. Unfortunately I could only find a straight piece rather than an elbow in the larger size so I've had to kink the hoses a little more but all seems to be ok at the moment.



You can see above where the pipes that come out of the bulkhead have actually disintergrated when I pulled the hoses off!

First step on the road to recovery for the MK3! Hopefully in the near future I shall come up with the time / money to sort it properly but this will do in the meantime.