# 1.8L - thermostat change , now over heating



## reebo (May 15, 2007)

Well , I changed the thermostat, ( and aside from the leak - very annoying because I sure as hell took my time and cleaned everything sanded everything and even lubed the new o-ring and its not my first time ) the car is now overheating. The fans never went on , and IT passed the notch after mid way. 
I did a little searching - and I know I need to purge the coolant system - I used to use a vacuum thing that sucks all the air out of the system, then fills it with coolant , but my car is no where near an air compressor.
What bleeder system should I get for this VW ? 
by the way its a 1.8L 97 Golf CL 
Aside : I have heard of claims or theories of an air pocket that develops in the thermostat housing and some people drill a tiny hole in the thermostat , some get the thermostat to open up before installing.


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## jorge r (Apr 27, 2006)

*Re: 1.8L - thermostat change , now over heating (reebo)*

I think it sometimes takes 3 cycles of refiling the coolant jug before coolant is topped. warm it up, let it cool, refill, by the 3rd time, it should be o.k.


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## reebo (May 15, 2007)

*Re: 1.8L - thermostat change , now over heating (jorge r)*

well. I have put this new thermostat in and filled it up. 
Started up the car - it reached operating temp. rad fan never came on, lower rad hose is still cold.
Let it sit a while , topped up the coolant , started it up again , reached opp temp - went a tiny bit hotter then mid range . shut it down , same thing - lower rad hose is cold. Do I have a bad thermostat ? - Did it 3rd time for good measure , no change.
It is of course a new thermostat , the coolant has been a good color and the rad is only 4 years old. so I was not thinking blocked rad . I'm not sure it the water pump pushes or pulls - does the rad get fluid in from the bottom and out the top ? or vise versa? - I guess I will test the thermostat ... IF I just used a hose to spray water in the top of the rad , It would normally just shoot out the bottom , correct ? 
- Thanks for anyone's input


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## dogyouare (Aug 10, 2009)

hot top---- cold bottom-----
water gets forced from pump 2 block and a hose running for head(on the side) when u bleed do you leave the cap off and let it burp? or put the cap on and start?


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## 1988Audi80NA (Nov 27, 2009)

Dont want to insult you or anything but I had a similar issue with a DSM I had as it turns out I installed it backwards and it did leak too. I kept tightening it until the housing broke. If it is installed correctly I would take it back and get another one it could be defective.


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## rjev (May 29, 2009)

defective out of the box is always a possibility. the bentley recommends you always test a new one in a pot of boiling water before installing it.


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## reebo (May 15, 2007)

*Re: (rjev)*

thanks guys , I got a vw motorsport technical bulletin:
In short it says to idle at 2500 rpm with cap off until thermostat opens. a water temp of 110 may occur.
At this point I don't believe I let it get hot enough. So I will give that a shot.


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## reebo (May 15, 2007)

well its been a while , but more developments. I started up the car, and sat there revving the engine after it warmed up a bit (Hot coolant geyser) . got it to suck up a lot more coolant leading me to believe that the thermostat opened and the rad filled up finally. After a while , adding more coolant and all that good stuff. It got hot enough to trigger the rad fan. I looked at the fan and it looked like it wanted to turn on. I knew because of the greenish and black smoke that started pouring out of the Rad fan, at this point I took a stick and started the fan off by giving it a little push and sure enough it started spinning. - and everything seemed good , the temp was not going past half way. This was about a week or two ago. Yesterday I finished up with the p/s pump and rear brakes and bearings, and decided to start it up again. just started overheating. no rad fan , no heat in the cabin.

- Will test the fan now I guess. Which two wires do I have to jump ? there are 3 I think - I'm assuming something to do with the fact that the fan may stay on after the car is turned off. ( haven't looked at the manual yet) . Shouldn't I have felt the heat in the car regardless of iff the fan came on or not ?


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## Kimdome (Apr 13, 2005)

*wher in the bentley does it say this?*

thanks


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## Kimdome (Apr 13, 2005)

*whoops I meant to respond to below*



rjev said:


> defective out of the box is always a possibility. the bentley recommends you always test a new one in a pot of boiling water before installing it.


wher in bentley does it say this?


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## reebo (May 15, 2007)

OK - here is an update. ( I'm now very interested in getting my hands on a coolant vacuum fill tool) Snap ON has a great one for 156$ or around there. IS there a cheap one at Princess ?

By the time I finished there were many beers involved so I took notes.

I went over to the car (coolant cap on) I started the car , and went for a short drive, basically until I hit the brakes ( stiff slider on the front - so that jammed up) came back and revved it to around 2000RPM the temp suddenly quickly moves from 0 to 90 deg and holds there for a short time , then starts over heating. bottom rad hose is cold and no heat in the cabin.

let it cool a bit.

Take off the cap, start car, rev engine to 2000rpm - car heats up to operating temp and stays there (90 deg) lower rad hose is hot, and there is heat in the cabin, wait the heat in the cabin goes away rad fan doesn't turn on. I shut car off.

let it cool a bit.

Coolant cap off, start the car , rev the engine to 2000+ rpm (2300) spraying coolant all over the place. temp up to 105 - hot lower hose - oil pressure warning light flashing and buzzing - shut off car.

.5 or an hour later ( 2 beers) I add about 2L coolant

I replace rad cap and start the car rev to 2200 rpm - cabin air is cool. temp reaches 90 deg rev to 2500rpm hit 100 deg and still no rad fan. now hit 110 deg cold air in cabin , cold lower hose.
then I remove rad cap and coolant sprays out.

Let engine cool slightly. no more boiling over of coolant , I add more , and the thing is still chugging on the coolant , wait 15 min , coolant is down , I add more coolant, wait 10 or 15 min , coolant level remains the same.

now I'm not sure how many beers down, but I thing the coolant cap is on.

restart the car and I'm right to 89 deg and car is just idling. cool air in cabin lower rad hose is cool
- now I rev the car to 2100rpm now I get hot air in cabin and Im still at 90 deg - I check the lower rad hose - its easy to touch. still hot air in cabin at 90 deg. now I am sweating I turn the fan down to 2. 92 deg 95 deg 100 deg still no rad fan.
- lower rad hose burnt my hand ( just very hot)

So next - I'm like - " you stupid rad fan" - so I jump it with some straight battery power.

left to right the colours are R/Blk R/W Brw
of course there are only two pins in there so - I hook that up and sure enough it spins. - so the fan works

Now I am many beers in. And I decided to record a minute per minute account of.......this same crap ( i will sum it up here its a little sloppy)
- in short , I burn my face off with the cabin heat - and the engine goes over 90 deg

that is it. Sorry for the length of this fail.

Is this still sounding like air pocket ? -
- rad fan switch ?


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## 1988Audi80NA (Nov 27, 2009)

I would get that thermostat out and test it in some boiling water if it opens and looks good then reinstall and start checking the rest of the cooling system step by step.

There should be a cooling fan relay to take up and have a local auto parts store test then test the temp sensor in the rad.

Here's a link to test most 8v cooling systems

http://www.oneilcastro.com/A2Bentley/GE02/ch3.2.1.html


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## CLARKSTER75 (May 25, 2010)

*I have the same problem*

As long as your lower radiator hose is getting warm, I would be pretty sure that your thermostat is working, my 01 2.0 jetta has the exact issues that you have.
I am now leaning toward replacing the water pump. If the pump impellor is loose/broken it wont be cooling the car/pumping to the heater/or getting the air out the system. 
I kept filling mine as you have and I am no better off. I don't know what else it could be, but I do know replacing the h2o pump is a killer.
If i take it to the shop this week I will let you know. Hes closed today and I have to call in morn for an appt.


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## Dozier (Jun 18, 2007)

did you ever get it figured out?


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