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Discussion Starter #1
Hey guys I have question about overheating with my 98 cabrio 2.0. I looked through the Engine Temperature + thermostat issues thread and couldn't find a good answer specific to my needs. I have had a slow coolant leak for a while and went through 2 different bottles of coolant one being dexcool and adding them to the stock coolant. The leak is from the plastic flange located on the driver side of the engine. My car has never overheated but recently it seems to only overheat when I'm at a stop light or in freeway traffic. Both the incoming and outgoing coolant hoses on the radiator get hot, and my heater works, and my fans work.
-Could this be a tstat stuck in the closed position?
-Or could it be due to the fact that I've mixed 3 different coolants? Or possibly the water pump? I recently burped the coolant reservoir by idling it and taking the cap off..I noticed the coolant is still cycling through so does that rule out the water pump?
-Also I noticed that my car heats up to the middle of the temp gauge REALLY fast (20 sec or so) from a cold start...only overheats at a stop or slow traffic.Any input would be appreciated
 

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You should replace the coolant flange and the thermostat - if your coolant is cycling the water pump is probably fine but you still want to get a visual inspection on the pump to see if any coolant is leaking from it. If you are still driving the vehicle regularly without a massive failure yet the water pump is likely okay. The coolant flange is very cheap at german auto parts (i think 10 or 20 bucks) and its not a very difficult job, the thermostat is also cheap and a little less accessible than the flange.

As far as mixing coolant is concerned its not the best idea. Get the coolant flange repaired and give the whole system a flush and fill it with fresh, one type of coolant. People might call me crazy but I run regular ass prestone green coolant in my daily golf and it gets 30mpg average and has 245k miles, the temp needle hasn't moved a tick in years.
 

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Discussion Starter #3
Yeah I'm just going to start with replacing the flange to fix the leak and flushing the cooling system and using 1 type of coolant. I mixed all the colors of the rainbow in there :) I know the water pump isn't leaking though there is no coolant stains or crusty stuff around it and my car doesn't leak huge amounts of fluid..just drips from the flange and dries and crusts up on the engine right under it..or if that's the trans not sure ;P....I'll reply back and post my results so other people can see what I've done maybe it will help them.
 

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My guess would be water pump. Sure it may be circulating coolant, but how well? The low pulley speed at idle would circulate barely any coolant if there is a impeller or bearing problem.
 

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Discussion Starter #5
Hmm it doesn't create any whining noises..is there a way to check the pump? Can I take the coolant cap off and rev the engine in idle and check to see if the coolant circulates faster? Should it spray out of the top? I did this to try to get any air out of the coolant lines..but I don't think anything sprayed out the reservoir when I rev'd the engine..maybe bringing it up to 4000+ rpms?
 

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Discussion Starter #6
Well today I let my coolant completely drain and found that the fluid was dark orange..not thick though, but was pretty dirty almost like black sand was in it...I didn't fix the leak yet, but I put clean coolant in it, and fired it up for a little just to cycle it through and burp the cooling system...then had to do some other stuff...Later on, I drove about 12 miles on the freeway and back to my house..let it idle and the gauge did not budge over halfway mark. Although it is significantly cooler here in LA at night, it has been warm the past few days when it did overheat, but I do feel a little better. I'll try to keep this updated as I try it out with warmer weather and after I fix the leak just in case there's anyone else out there that has overheating problems whilst mixing over 3+ coolants in their system...they might want to try just draining all the old stuff out first before doing annoying work such as the t-stat replacement or worse the water pump.
 

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help

Im new here so forgive me. I also have overheating prob. even without engine running. pour water in and it come out the back of the engine? Is there freeze plugs on back of engine? OR? Any thoughts please. 2002 beetle 2.0
 

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Discussion Starter #8
Hmm so I was driving my little cabrio pretty fast around 100+mph on the freeway and when I got off the freeway and stopped at a few stop lights the temp gauge started to go up again :(...I noticed that my fans ONLY come on when the gauge reaches around 230 degrees mark. My A/C doesn't get cold (needs recharging) but the fans don't even come on when I switch the A/C on..should the fans always be running or only when the car gets around the 230 degrees mark on the gauge? Is there a coolant temp switch or something that might have gone bad for the fans?
 

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Discussion Starter #9
Well if anyone still cares..it was a mixture of bad coolant, air in the lines, and filling up my coolant level too much. Been pushing my lil cabrio hard and can't get it to overheat...oh and the leak is fixed. So anyone else out there that feels they have a working fan/waterpump/thermostat might want to start with a complete coolant flush first before they start changing other parts.
 
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