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Discussion Starter #1
my 2000 passat 1.8t keeps overheating started yesterday on the way to the gym. i got that overtheating icon came on my dash board and say stop. so i stop for couple of minutes and head home. i drove the car home even though it was flahing the overheating icon. soon as i got home i open up the hood and found the coolant reservior to low. some of the coolant escape from the overflow. so i fill her up with some g12 stuff and distilled water 50/50. i taught everything was o.k. until today driving on the freeway boom the meter started to jump from 190 to overheating temp. any idea what would cause this to happen. what should i check first. i did check for any leaks in the hoses that goes in to the resevoir and i did not see any leaks. i think it's the tank itself that is leaking fluid when it's hot enough it expand or something causing the fluid to leak throught the gap of the upper and bottom housing of the tank. so if anybody out there expriencing the same type of problem please let me know wassup. i'm going to the dealer for now to replace the tank assembly with cap, to see if this fix-it. i've notice that there is no rediator on this type of car just the coolant tank itself. any instruction on un-installing and installing back a new tank coolant for this car would be a great help. thanks....
 

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Yes, could be the pump assuming it is actually overheating.

The pumps have plastic impellers that just fall off after a while.

The dealer will probably be able to tell if the pump is doing its thing by measuring the amount of fluid that comes through to the reservoir via the small hose on top. In fact, you can yourself if you know how much it USED to run through there.
 

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It could also be that the thermostat has failed in the closed position.

I know on the AEB motors, the thermostat is located behind the water pump.

How many miles are on the car? If over 60k, then this would be a good time to replace all the belts because you will be taking them off if you replace the water pump anyway.
 

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It could also be a bad coolant temperature sensor/sender. I agree with 1ReclusiveOrc, if over 60K I would suspect the thermostat as well. Both parts are not that expensive, or overly difficult to replace. If you have not had a 2 year coolant flush, I would do all three at the same time (especially since it has been overheating anyway).

If you have not performed your tensioner replacement, have that done as well if they have to replace the water pump (the mechanics are in there anyway and it will save you double the labor rate).
 

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Discussion Starter #6
i've installed a new expansion tank and test droved it. after 10 min. or so of driving there it goes again the overheating icon comes on. so the tank was not the problem. i just assumed it was the tank cuz it look old. open up the hood and there was alot of coolant coming out from the small hose into the tank. so what now, you guys are saying it could be a bad water pump. damn i did have all the timing belt and accessory belt replaced at 60,000 mi. but did not replaced the water pump. cuz the mechanic wanted another $150 to have it replaced un top of the labor cuz of $425 for just replacing the belts. yeah i bought the kit from ecs-tuning i think... and came with the water pump. damn men, so now what, it could the the thermostat or the sensors, which one should i try to replaced first or should i say the easiest to install. any instruction on how to's for this 3 item would be a great help.... more info on my car it is the ATW engine code and at 66,000 something miles. could you guys tell me where the thermostat, the sensors, and water pump located at. so i can see for myself if i can do this job or not.
 

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Let’s regroup. We are trying to help but have hit you with a lot of information. The following is a list of the probable culprits, in order of likelihood based on your B5's age and mileage:

1. Thermostat, most likely and the easiest. (Bottom of the engine, under the belly pan)

2. Temperature sensor. My manual's picture is terrible. It looks like it is at the back of the engine compartment, forward of the battery, just behind the valve cover.

#1 and #2 are the cheapest to fix and will require you to refill the coolant system.

3. The main fan clutch or the electric auxiliary fan. Check these by idling the car with the hood up (emergency brake applied fully!). Watch both fans. If the main fan does not spin nearly equal to the engine RPM, or match the change in RPM, the fan clutch is most likely bad. If the electric fan does not kick on and you receive a high temperature light, the electric fan may be bad (I am assuming your temperature sensor is good). This test will not cost you any dollars, only time.

4. $$$Water pump. The water pump is behind your timing belt and tensioner. This is why many people do both whenever they go into perform either job, it saves labor charges. This replacement requires extending the entire front end of your car (the car is designed to do this). There is a very good write up with pictures on this site. If you are not a decent home mechanic, I would recommend you take it to a trusted shop. Members here can point you in the right direction for your location. Have the shop diagnois a waterpump problem before your shell out the cash for a mechanic to do this job. There are tests to confirm a water pump is not working. My response is alreay too long...

5. Hole in your radiator or minuscule leak in a hose. Possible, but most unlikely based on your description.

I would invest in a Chilton repair manual for your B5 (#70700). While it is not a great repair manual by any means, for $16.00 it does cover enough to make a decent decision and compare what a mechanic is telling you. The manual will help you through #1-3 above. I would use the write up on the site for #4 if you insist on doing the job yourself.

Good luck.
 

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Discussion Starter #8
alright someone told me that to check your thermostat if it's all good is to run the heater.

o.k. so woke up this morning let the car warm-up for about 10 min. or so.

drove the car around the block to get it to normal temp. ran the heater and it's blowing hot air after a good 15 to 20 min. of driving around the block. so i'm guessing my thermostat is good then..

o.k. now i'm trying to overheat my car at this point by accelarating hard around the block.

after another 10 min. the temp start to climb to 260 so i head back to my house real quick and stop, let the engine ran..

i looked at the temp after idling for about couple minutes it went back to 190. so now i know that it only overheats during driving mode and not on idle.

it's gotta be the water pump then guys right. any test that i can do for the water pump. also what is that small fan for is that for the ac cuz it wasn't spinning during this test.
 

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If your heater is working then that proves the water pump is ok. bad pump=no water circulation=no heat from heater. It is looking like the thermostat is staying in the closed position and only allowing the water to circulate in the engine & heater.
 

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I am having the same problem you are having, mine started today 2/1/04...the light came on blah blah went up to 260 and I opened the hood and it started to smoke and my expansion tank was bubbling coolant...you can see where mine starts to drain, and it is right about at the radiator spot...I dunno what to think? I have a 2000 also, it is a 2.8 V6 not a 1.8 though...let me know if anything happened?
 

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Discussion Starter #12
o.k. here is a pic under the hood... can you guys tell me if this is where the thermostat is at where the red arrow is pointing.



if so please give some instruction from beginning to end on how to replaced it. i do have the chilton manual book but the picture that is shown in there is the v6 model which is inside the engine block...

from looking at it, look like i can do this job with a little tip or intruction. as long as i don't have to remove the whole front end or any belts i think i can handle it...

i did not see any drain plug for the radiator though, cuz the manual says before doing this job, you must drain the coolant from the radiator and place the radiator support panel in the service position (whatever this means)

common guys i know i've read a couple of post here that they flush there whole radiator coolant, just can't find it on the search option.

i would want to replaced the thermostat first cuz i think it's the easiest one to fix, now the for the water pump i think i'm gonna have to go to shop on that one. i'm not comfortable enough on removing the whole front assembly and then removing the accessory belt or what not..
 

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Discussion Starter #13
so o.k. i got a hold of this guy, supposedly he works as a mechanic at camelback volkswagen here in phoenix,az.

now he told me that the water pump is covered under the 100,000 miles powertrain is this true.

the only thing though is that if it is the water pump i have to make sure that it is the the water pump. cuz you know how stlealership are 90 bucks for diagnose the problem.

so say it is covered under the 100,000 powertrain, how would i go about calling the dealer and have them do a job under warranty. i hoping it is though men.....
 

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Ok, just to make sure...
is your car ACTUALLY overheat? Or it's just gauge acting up?
Replacing thermostat most likely get you nowhere if hoses to/from radiator hot to toch then thermostat doing it's part good enouf. Ooinn99 provided you with good info there. Concentrate on #2 and #3 first. Actually, changing the temp sensor is way easyer than changing thermostat. And you only need a liitle coolant to top off afterwards.
Edit: on the picture, yep this is thermostat and big bolt on the left is the drain plug another drain plag located on the driver' corner of radiator.
If youcan get warranty cover the repairs - do it. Waterpump is PITA.
 

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Okay here is what happened, it is the water pump that went wrong in your car...the same exact thing happened to mine. Luckily I had just bought the car two days prior and they paid for EVERYTHING... they even changed the timing belt for me which saved me a ton of money. I know how you feel, it pissed me off but made me so happy when they said they would pay for it. Good luck with everything.
 
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