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gday guys,

my golf was underheating so i replaced the thermostat and everything went to plan...was heating well and temp was good. however now it wont heat up again. just sits on 70 degree. Any ideas?????this is only 2 drives after replacing the thermostat.

ta alex
 

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Well now, where to begin...

I bought my car (Golf Mk3 1997 with 120 000km on the clock) last June (first car).

Everything went perfect for perhaps 3 months, then I encountered the first problem... The car wasn't heating up properly and every time petrol was put in, it would struggle to start - the thermostat was replaced along with something else that regulated the fuel.

Then it went fine again for a month or two, when the temperature light started to flash on the dashboard, took it in again - apparently there was a leak with 2 of the Welsh Plugs, which they replaced.

Things went already for 3 or so weeks after that, when the same problem occurred where the 'low coolant' light came on. Took it to another place who said the thermostat had gone (after just replacing it). So they fitted a new thermostat and things seemed alright again for a while.

Then while on a trip probably 2 months later in an area known for a high crime rate the light came back on and I really was unable to stop, and had to drive the blatantly coolant lacking car 30km, though at no point did I see smoke - but when I got home the coolant was empty and there was a large leak in the one pipe, a metal pipe which had split.

I took the car in yet again where they replaced the pipe and said this thermostat too was shot, apparently from the car overheating and screwing up the wax in the thermostat.

A month or so later, same issue - but this time another visible leak - I took it in once again and finally they decided to check the head gasket, the mechanic originally looked with a lazer thermometer on the engine and said that it looked like my head gasket may be gone, but after they took the car in, they told me that the head gasket was fine and that they just flushed the radiator, replaced a welsh plug and replaced a pipe.

Things seemed fine once more, but after about 2 months, it started requiring coolant refills every 150km, which I could live with but now it is using up about 1l of water from the resevoir every 20km-30km it seems. I haven't had the money to do a coolant mix each time it runs out since it's almost daily, so I've been refilling about 3l a week of normal water into the resevoir.


Quite frankly, I do not have the money to keep trying to fix these cooling issues and it seems no mechanic is able to pinpoint what is causing it. Surely there is one central issue that is causing a chain reaction, such as pressure build up etc?

From the posts I've read here, many of the forum users seem far more versed than the mechanics I've taken my car to, so any help would be greatly appreciated.

The last time I checked there was no sign of white on my oil, and while my coolant is brown, I don't see or feel any hints of oil in it, and no excessive white smoke.

I do see evidence on the block where the radiator hose connects of coolant so I suspect there may be a light leak there, but that wasn't there throughout these issues and I can't imagine it's really something new causing this each time.

Thanks a lot.
 

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losing coolant.

It could be the plastic fitting the sensor is in. It bolts to the head and has an O ring seal on the backside. If it has become cracked or warped so the O ring cannot seal, you got to change the plastic fitting and O ring. Failure of this fitting is common.

Ainokea
 

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My "coolant/check temp" will blink sometimes during rides. I'll be going to the store and it doesn't come on then on the way home it blinks (it's random). My car does not overheat and the temperature only fluctuates if its cold outside. It will be at 195F warmed up and drop to 160F on the highway. Could it be that my T-Stat is stuck open?
 

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I made a video for how to change the thermostat on the 2.0 aba. I dont see a DIY sticky thread.. ill post it here and make a thread so we got one!

 

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There was no video and for some the video is more helpful is all. The pic DIY was a pain for me while I was doing this that's why I made a video to make it easier that is all.
 

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My temp light comes on even though my coolant level is good(no leaks), expansion tank sensor is good, new thermostat in(works great), new fan motor, and my car does not overheat(stays at about 195F). I tried jumping the radiator fan via the radiator switch with a paper clip and only the low speed worked. I check all the fuses(all good), but I noticed that my fan control module on has one fuse. Am I missing one that goes there or is my module going bad? Please help asap. I have looked online everywhere and not getting an luck in finding an answer or even people with my problem. :(
 

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I have a 1998 VW Golf that was over heating slowly. First thing I replaced was the Thermastat. Than I replaced radiator coolant switch and Coolant sensor that is mounted on the coolant Flange. The car still over heated slowly I checked all fuses and relays they all seemed to be good. The Top Radiator hose got hot and I could feel water running threw it while it was getting super hot. The Bottom hose didnt get very hot and fans only worked when the A/c was on. Which lead me to believe my Radiator was plugged. I took off the top hose and blew in it it seemed to be working fine i could here the air come out on the other end.
Conclusion:
1. I found a wire that wasnt connected under the round Coolant expansion tank (where you put fluid). I hooked it up and immediately i heard the fans turn on.
2.) Started the car while letting it run for a few minutes unscrewed the radiator coolant switch to see if water was circulating nothing was circulating but when i started screwing it back in water stated to shoot out of it like its suppose to. Long story short a had a loose wire under the Fan control module and air bubble in the radiator that stopped the air from circulating.
 

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Discussion Starter #92
My temp light comes on even though my coolant level is good(no leaks), expansion tank sensor is good, new thermostat in(works great), new fan motor, and my car does not overheat(stays at about 195F). I tried jumping the radiator fan via the radiator switch with a paper clip and only the low speed worked. I check all the fuses(all good), but I noticed that my fan control module on has one fuse. Am I missing one that goes there or is my module going bad? Please help asap. I have looked online everywhere and not getting an luck in finding an answer or even people with my problem. :(
Fan module only has one fuse. Check your engine coolant temperature sensor and replace it.
 

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I changed out the coolant temperature sensor (looked kinda bad), but still fans are not working. I jumped them again but only the low fan speed works.
 

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New to this forum and hopefully I'm posting in the correct area. I have done a lot of work to this 97 jetta gls 2.0 aba that I picked up for hella cheap. I was able to clear all of the codes and the thing runs beautifully now with only a couple of issues left so here goes.

new water pump, thermostat, coolant fan, coolant fan switch, Fan control module, and ECT. Overheating still when driving. I have jumped the fan switch and both high and low speed work but the fan will not come on at all when plugged in. All new components and no corrosion on any of the contacts. I have cleaned all the grounds except for the negative battery ground to the trans which I have literally just read about so I will be doing that today. All the fuses and relays are good and in the correct places.
The heat in the cabin is luke warm from the vents so I am wondering if there may be some air trapped in the system. What may be a good way to burp this baby and make her cry? could I relieve pressure from the fan switch to see if it weeps water or air?
 

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Discussion Starter #95
Just sounds like air in the system. I always just let it burp itself by just driving it. After i drive it, i let it cool then crack the cap open and let the air vent.
 

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Thank you for the reply Mr. Mcrow.

I see you are the coolant master after reading through a lot of these threads. --smiles-- I have driven it a couple of times, only for short rides, to try that very suggestion. But with no avail, I get the same results each time. Just to be sure, the t-stat does go in spring end block side right? I just finished cleaning up the negative battery cable ground on the trans bell housing(and it definitely needed it). I may go try this burping ride again and this time take note of any hot and cold hoses.

once again thank you.
 

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ok so after the ride I have noticed a couple of things. This time I let the temp get up to 230 and then it quickly shot back down to around 170 and then back up to 230. It did this like a short in the system, not like the coolant had circulated. Pulled back into the driveway and checked the fluid bulb. No change in the fluid level and the lower rad hose is bone cold. All other hoses are hot. I do know the water pump is working because as I accelerate, the air coming from the vents gets warmer and then cooler as I decelerate.
After all this, I unscrewed the coolant bulb cap to relieve the pressure to see if any change in the level occurs. Remembering a few posts about an o-ring that should be around the threads of the cap...I have none. Could I be loosing valuable pressure causing this problem?
But even still, the lower rad hose is cold with a new t-stat and pump.
Not sure if they would be related, but would the A/C refrigerant pressure have anything to do with the fans not coming on at all? Just something I read in an older post from a guy that had almost the exact same issues.
I hope this is the correct place to be posting these questions. As a noob here I'm still trying to figure it all out.

Thank you again.
 
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