# mk1 gti 1.8 coolant temp readings and diagnosing



## Dropped325i (Feb 10, 2007)

is it normal for 1.8 to reach 3/4 on my gauge? 2-3 lines before the red on the dash at idle at like 50 degrees F outside ? 
i changed the thermostat, twice lately, all hoses and the radiator are all getting hot, the fan turns on for like 10 seconds when its up there (2-3 lines before red on the dash) and shuts off and the temp gauge doesn't really move.. 
it seems its coming and going, sometimes goes down to a line below half on the gauge sometimes up to 3/4 a couple lines before the red on the dash. 
i'm thinking maybe my fan switch is not working fully, and its intermitting? 
i just left my cap off for the night.., i was reading and some said maybe air in the system.. 

anyone?











_Modified by Dropped325i at 4:43 PM 3-29-2010_


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## dogyouare (Aug 10, 2009)

mine sits at 1/2....


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## Dropped325i (Feb 10, 2007)

*Re: (dogyouare)*


_Quote, originally posted by *dogyouare* »_mine sits at 1/2....

dash? whats the floor one at idle/highway 70ish?


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## Travanion (Sep 4, 2007)

*Re: (Dropped325i)*

Floor one? Do you mean the oil temp gauge?


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## Dropped325i (Feb 10, 2007)

*Re: (Travanion)*

aint that a bit** thats oil temp lol..





















good to know that http://****************.com/smile/emthup.gif 

and btw, i removed the cap last night to see if it would drop, it did a little over night, topped off the coolant this morning, was low like a glass full, and drove to work which isn't far and didn't go above 1/2.. before it was intermitting.. 
i called GAP, there sending me the correct fan temp switch (they sent me a 2 prong but far apart from each other)
anyone know where to source a low temp fan switch?



_Modified by Dropped325i at 4:47 PM 3-29-2010_


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## Low Life (Apr 1, 2008)

*Re: mk1 gti 1.8 coolant temp readings and diagnosing (Dropped325i)*


_Quote, originally posted by *Dropped325i* »_is it normal for 1.8 to reach 3/4 on my gauge? 2-3 lines before the red on the dash at idle at like 50 degrees F outside ? 
i changed the thermostat, twice lately, all hoses and the radiator are all getting hot, the fan turns on for like 10 seconds when its up there (2-3 lines before red on the dash) and shuts off and the temp gauge doesn't really move.. 
it seems its coming and going, sometimes goes down to a line below half on the gauge sometimes up to 3/4 a couple lines before the red on the dash. 
i'm thinking maybe my fan switch is not working fully, and its intermitting? 
i just left my cap off for the night.., i was reading and some said maybe air in the system.. 

anyone?









_Modified by Dropped325i at 4:43 PM 3-29-2010_


my cabrio does the same excat thing,,,i checked my coolant and its full i reflushed the system and new radiator and fans kick on.I would also like to know if this is common or what?


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## Dropped325i (Feb 10, 2007)

cars still good since.. i think let'n it air out overnight and topping it off did the trick.. still awaiting rabbitparts low temp rad. fan switch, since i put in a 180 thermostat..


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## edub122 (Mar 17, 2010)

*Re: (Dropped325i)*

This is common for older vw's my gti does the same thing. No worries


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## Dropped325i (Feb 10, 2007)

i spoke to soon, happened yesterday again. still awaiting from rabbitparts the 180 fan switch.


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## Dropped325i (Feb 10, 2007)

update... i put in the new 180 fan switch and new coolant temp sensor, now at idle it will go all the way up, i shut it off 1 line before red. i noticed upon letting it cool down, the radiator was hot on the passengers side, and the drivers was cooler. which the temp switch is on the drivers side. so i figured then after all this time its my radiator. i also tried to jumper the fan switch so it would constantly run, and it was still getting hot. i noticed the lower rad. hose was not as hot as the top. i brought my radiator today to a local garage, he had a pressure water thing and sprayed it both ways and water came out and he said it was fine. i assemble it back in and same thing. so i go to napa and buy a 180 t-stat from them. install it and same thing, the lower radiator hose is cooler than the upper. 
now i'm thinking it has to be my water pump right?
all the other hoses are hot.


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## Dropped325i (Feb 10, 2007)

also i read on the gti club uk webiste last night, that the black reservoir cap is prone to fail and the blue one is the new redesigned one.
about to call GAP on monday and order the blue cap & water pump..wish i would of known this earlier today i would of ordered it today for fedex tomorrow delivery..


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## dirtywabbit84 (Mar 17, 2004)

*Re: (Dropped325i)*

my old rabbit was allways a bit above the half, mk2's that i have owned that were CIS lambdas just like rabbits where allways at 3/4 . I wouldnt worry that much about it.

BTW: if you change low temp one thing then change them all....in other words if you get lowe temp fan switch get low temp themostat to match.
and oG vw mechanic told me that you dont even need any of that, vw;s run hot regardless. Just make sure all the sensors are where they need to be and that the fans are kicking on and you should be good.







http://****************.com/smile/emthup.gif


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## Dropped325i (Feb 10, 2007)

i added the 180 temp switch yesterday.. 
the temp is hot, its coming through the over flow little hose showing some steam. 
but the bottom corner where the fan temp switch is isnt as hot as the side the hoses are on? reasoning for the fan not to run correctly..
but even with the fan on, jumpered, its still up there.. and thats running all the time..
i was driving my car before and it would go around middle sometimes, i assume my water pump impeller was failing and now failed?
also with what i mentioned above, reading on the black/blue cap issue, i will get a new blue cap..


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## dirtywabbit84 (Mar 17, 2004)

*Re: (Dropped325i)*

even if your black cap is bad and your impalers are failing unless the WP isnt spinning at all...
I'd say just make sure ocne again that the temp for the t stat and the fan switch are the same and that your coolant temp sensor is good.
and if its still that hot something must be wrong with your radiator and just so you know radiator can go bad and actually NOT leak( happened to me once).


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## Dropped325i (Feb 10, 2007)

*Re: (dirtywabbit84)*


_Quote, originally posted by *dirtywabbit84* »_even if your black cap is bad and your impalers are failing unless the WP isnt spinning at all...

i believe it maybe waa failing causing the once in a while 3/4 and normal 1/2 temp.. and now its failed/shot?

_Quote, originally posted by *dirtywabbit84* »_
I'd say just make sure ocne again that the temp for the t stat and the fan switch are the same and that your coolant temp sensor is good.


i bought the 180 like 5 weeks ago, from german autoparts, and did it again with one from autozone like 2 weeks ago, and then today with a another from napa. and i read the coolant temp switch and for sure it is the low temp one, that was from rabbitparts also the coolant temp sensor.
i assume the coolant coming back from the over flow showing some steam confirms the high temp gauge is correct.


_Quote, originally posted by *dirtywabbit84* »_
and if its still that hot something must be wrong with your radiator and just so you know radiator can go bad and actually NOT leak( happened to me once).

i mentioned, i had it checked out in front of me today at a radiator/mechanic place, the guy flushed water in it and it came out both ways, my dad seen me mess with it and he thinks the same thing that the radiator is bad, since the left side is getting hot but the drivers side isn't as hot for some reason, but i'm unsure. i'm assuming now the water pump isn't pushing the fluid?


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## Dropped325i (Feb 10, 2007)

i checked the pump, stuck a screw driver in the impeller and tried to turn the pulley, wasn't any play. i noticed the pulley was wearing on the lower timing cover and the pulley was lose, i screwed it in and it rubbed harder, so i removed the lower timing cover. tried it again, still would go up to like 1 or 2 lines before red. i didnt change the pump, although i bought a new german one and drove 1.5 hrs one way for it thinking it was it, also bought another german 180 thermo stat while i was there, fcp groton had a grand re-opening at there new location and i got 20% off. i ended up removing the thermostat. now all is golden. and i have heat in the car too, which i would of thought i would of lost. temp gauge was fluctuating, from as high as one line above half (then the fan kicks on now at that point all the time when reached), then as low as 1/3, kinda odd, but its working great now. Ive spent enough time on this, wish i would of thought about this a while back.



_Modified by Dropped325i at 4:45 AM 4-11-2010_


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## Dropped325i (Feb 10, 2007)

well, my bro came over, i was running the car, the thermostat housing started to leak, i checked it, it seems a little warped. so now i'm gona be down a couple days do to a damn housing


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