Another Rad Fan not kicking in, recent overheat/exploded coolant expansion tank

Hey all,
1983 Golf Mk1 GTI DX
so basically about a week ago after probably the hardest drive i have given the car on the motorway (was a bit silly really)
also just to top it off my coolant temp gauge hasn't been working for the past month so yeah it was stupid for me to give the car a good ragging, anyway before i got home i stopped of at maccies and sat in the car with the engine running (thinking the fan would continue to cool it down if it was to hot)

anyway about 5 minutes later i noticed a load of steam coming out of the engine bay, so quickly cut the engine and popped the hood and yeah the expansion tank was shooting steam out of it and all the coolant had leaked out everywhere, so had to wait for it too cool a bit before taking cap off, once it cooled i checked the expansion tank and there was about 3 cracks in it  in different areas, they had now closed back up cause it had cooled down, so filled it with water and ended up having to bump start it to get me home, luckily my mates were with me! but it drove home fine but was only a couple mins away.

since then i just hoped i hadn't blown the gasket!
so i bought a new expansion tank and i was looking at temp senders but there only seems to be one for my car on vw heritage, this one:
https://www.vwheritage.com/shop/golf-mk1/V323088/vdo-water-temp-sender-m10x1-250f-120c/?crumbStartPage=1&crumbStartRow=1
it seems steep at £38 and my initial thought was that this was for a separate vdo gauge instead of the one built into the clocks.

so i carried on looking through and saw that the oil temp sender looked exactly the same and was like £6, but it was only after i purchased it that i noticed that the temp reading on it was 0-180 degrees celsius and the expensive vdo one was rated as just 120 degrees celsius. so could this cause the reading to be different from the gauge?

anyway i thought i would try it anyway, i earthed the temp sender wire and the gauge fluctuated so i knew that the gauge is okay.

Right so i got a new expansion tank, new cap, new temp sender (not sure it its right tho), new thermostat, radiator flush

so first i flushed everything with clean water, got quite a bit of rusty looking stuff come out, had heater fully open and everything, flushed in and out every possible way, reconnected it all up with the new tank and ran the radiator flush through it just to be sure then flushed again and then fitted the new sender/thermostat then filled with coolant/water whilst burping the pipes, tuned the engine on, filled the rest up until it was at max!

then i let it just run up to temperature so i could check it was all getting round correctly, the gauge gradually mad its way up past the warning light and the top rad pipe was getting hot but not the bottom and by this point i thought the new thermostat should have opened and the fan should have kicked in? so then the gauge went right up to the end and the light started flashing so i whacked the heater on and killed the engine but left ignition on the let the warmth out of the heater matrix. checked the bottom pipe again and was still cold, so i just chose to take the thermostat out all together and thought ill do that at a later date once i know everything else is working okay including the fan.

so now with thermostat the engine was staying cooler but was still gradually climbing up to 3/4s on the gauge unless i put the heater on which did drop it back down to half, so fan not working, took the connectors off the fan switch bridged them and fan came on so i know thats okay, so obviously fan switch faulty, put new clean connectors on anyway and a new fan switch, the fan still doesn't kick in, even when i get the gauge to the end. the fan switch is definitely hot, so i know there is water there, and I'm sure my water pump is fine because water comes out the overflow into the expansion tank.

so I'm slightly stuck here people, (if you are still reading at this point) is it possible the temp sender i bought is giving a different reading to the gauge? in my opinion its a bit concerning if the temp sender i bought (which is rated to 180degrees celsius) is showing that reading on the gauge. and then the fan switch aswel?
when the gauge gets to the end and its flashing the pipes are hot but not to the point where i cant touch them, should i test with a thermometer or something?
sorry for the essay just pretty stuck here!
 

Get the right sensor first.

yeah i thought that might be the case. so is the vdo one that i posted the link of the one that i need to get do you reckon? 

Get the right sensor first.
http://www.ebay.co.uk/itm/VW-Golf-MK1-1-8-GTI-Febi-Coolant-Temperature-Sender-Sensor-Unit-OE-Quality-Part-/301966946739?fits=Model%3AGolf&hash=item464ea1f1b3:g:ck0AAOSw0fhXkM49

You can check the new thermostat by putting it in some boiling water in a sauce pan and it should open, remove it and it should slowly close.
The bottom hose usally gets hot when the gauge is about 1/4 and the fan only kicks in when at 3/4.
Are all the other hoses getting hot and the whole rad is hot?
What colour expansion cap do you have, blue or black?
Black ones can cause problems with not letting pressure out if to hot so blue ones are the ones to fit.

Don't let the car sit there running after a fast run as they need the air to help cool them down as you found out it's a bad idea.

I started writing the 1st post pressed the wrong button and did not think it was posted so ignore that one!

VW heritage coolant sensor is silly money don't buy one from there.    

thanks for the info mate, i got the blue cap so thats all good and my old cap was the black one! i tested the old thermostat and it did open so i probably should of just listened to the old saying 'if its not broke don't fix it" haha!
but i will check the new one today anyway!
im also going to test the old fan switch in boiling water too and check it is working if you reckon thats a good idea?

i ordered that sensor that you linked me too, thanks for that!

as i say, i can drive it because when I'm driving it normally doesn't go above the halfway mark on the gauge its only when I'm sat there that it starts to rise so ill just pop my heaters on to cool it down a bit, its just annoying that the fan isn't coming on even though its a new switch and the fan works when its bridged!

yeah all the pipes get hot, the only one that doesn't get as hot is the main pipe from the expansion tank that splits into the water pump/heater matrix, but i presume thats because the water going back into the expansion tank is cooler? it still gets hot but not as hot as everything else! (if that makes sense)



 

as said twice, get the right sensor first

the oil temp and that random one you linked are the wrong resistance for the temp gauge so neither will read correct.

fit the right one, fit a thermostat that works and check the rad fan and thermoswitch to see if both are working ok:
http://www.vwgolfmk2.co.uk/forum/viewtopic.php?f=37&t=14913

Yeah i was hoping it was that it had something to do with the sensor, will have the correct sensor tomorrow hopefully and will report back.I also tested both thermostats today (new and old) and the old one opened quicker and had a much bigger gap than the new one, the new one didn't seem to open as much at all, even though its 'meant' to be the correct one.
it also doesn't have any holes on the inner plate like the old one does.




I imagine the holes are there to let at least a bit of water through, compared to the new one that i cant see much getting through even when its open.

 

Your new one is the same as fitted to both my cars and they work fine, you don't need loads and loads of water rushing through as I found when my old thermostat got stick open the car would take an age to warm up and on frosty mornings on my 25 mile commute to work, I could not get the oil temperature to go above 80 degrees (I have an water feed oil cooler) and the heater was not very hot, I don't really get stick in any traffic so the engine is getting blasted by cold air it was only when I stopped in traffic the temperature would rise so I guess the thermostat must open and close while the car is driving even when warm.

If the old one seems to work I would give it another go after you have the right sender, if no better fit the new one and hopefully one of them should work.

You might need to order a few of these.
30% off if the use the code "HOLLOWEEN30" and free delivery, I always carry a spare as that is how I drain the coolant when changing it every couple of years.

http://www.eurocarparts.com/ecp/c/Volkswagen_Golf_1.8_1983/p/car-parts/cooling/car-cooling-parts-and-car-heating/thermostat-housings-gasket/?369440050&1&b25506b383453d65ec5769742fde4367b45db871&000574

When I flush and Back flush my Engine/Radiator, I also separate my Heater hoses and flush and back flush that as well.

When I do this every couple of years I also replace my t-stat and Radiator fan switch.  I have had issues in the past with things being bad out of the box, so I tend to test them prior to install.

With the advent of the new t-stats being closed, and sitting on the bottom of the system, you have to take care in filling your system.

You can fill the Radiator from the top hose, then fill the block via the top hose to prevent the "air" bubble syndrome, but you have to fill it gradually.

You can drill a 1/16 or 1/8 inch hole in the lip of the new t-stat to prevent this, which is my preferred way.


For wondering if your head warped, you can do a quick glove test.  

Cold engine, remove the res cap.
Tie a latex glove over the open hole Tightly.
Start the engine, and from under the hood raise the RPM to 3000 or better, and wait 45 seconds, If the Glove inflates and gives you the finger, then you have a bad head gasket usually.  Any longer than 45, and the heating of the coolant will inflate the glove and negate the tests.

thanks for that mark1gls, i order 10 of them so that should keep me going (haha) along with some other bits whilst they had 30% off!
well the new correct temp sender arrived today so I'm going to fit that once i get home from work, then get it running and see how it cooperates and hopefully the fan will come on at around the 3/4's mark!

so if everything goes well i will put the old thermostat back in aswel and see what happens but i always have that new one there if i need it!

Briano1234 thanks for the info, i did back flush everything i could and separated all the hoses so i could check they weren't blocked or anything! I'm petty sure everything is nice and clean now cause I'm not getting any horrible colours coming back into the expansion tank!

with putting the thermostat in I'm going to have to re fill the coolant again anyway so ill make sure there is no air bubbles anywhere! i was pretty careful with filling it and I'm sure there are no air locks but you never know!

i did actually think about drilling a couple of holes in the new thermostat to replicate the design of the old one so i may do that!

I'm just itching to get home now to try this sender out! will let you all know how it goes!  

Got it sorted, the new (correct) temp sender works great and fan kicks in at about 2/3 on the temp gauge so all is good, thanks for everyones help!

Good to hear it's now sorted.     

Did you use the sensor that I had linked?

Yeah that one you linked was the one i fitted! thanks again, appreciate it!

although i have just bought a mk4 1.8t for the engine, so you will see me asking 35345984985 questions within the next few months haha!

start here
http://www.clubgti.com/showthread.php?267196