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on my 1997 jetta 2.0 i am having trouble getting the coolant to circulate. the top hoses are getting warm however the bottom one is not and there is no heat in the car. i am sure that there is a problem with the thermostat holding an air bubble but not sure it there is way for me to bleed it or not.
 

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Dont think a form of bleed is possible and the only way i can think of is if you grab the lower rad hose leading into the thermostat housing and squeeze it to try and force the water through the t/stat housing to try and remove the possible air bubble you speak of. Did you replace the t/stat recently or just put new coolant in? If you have replaced it, your t/stat could be broken in the closed position therefore not letting any water through the housing resulting in the cold water in the lower rad hose.
 

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May also want to consider your water pump malfunctioning. Easiest way I've gotten rid of air bubbles though, is to drive the car hard and take sharp corners. Not the best season of the year to be doing that with ice and snow on the road, but if you run out of options......
 

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This may seem obvious but did you let the car run with the cap off your coolant bubble to allow for any bubbles to escape?
Shouldnt need to, your reservoir should have a overflow pipe which will double as a "pressure release" pipe for bubbles. Remember that your car heater dial inside the car must be turned to the max so your heater core is wide open when starting the car when trying to bring it up to temp.

Good tip on the waterpump as well, check to see if that is operating when your car is on or take it to your local mech to test and get a 2nd opinion if you can...
 

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An overheating issue & also a hard to refill system after you have drained cooling system may be the small hose that comes off the back of the head and goes to the coolant bottle ( where coolant cap is located ) is clogged up. The hose may be restricted or plugged, the engine will have air in it and cause an overheating problem, the tube that comes out of the head is where it normally gets plugged up but also ck the hose. I use a 3/16 drill bit to clean the tube on the head, when clean with engine running you should be able to see a flow of coolant from the small hose into the bottle. If coolant flows out of the hose into the bottle, it should burp all the air out of the cooling system. Run it for a short time and keep adding coolant, but if it's still overheating then there is something else causing the problem.
 

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An overheating issue & also a hard to refill system after you have drained cooling system may be the small hose that comes off the back of the head and goes to the coolant bottle ( where coolant cap is located ) is clogged up. The hose may be restricted or plugged, the engine will have air in it and cause an overheating problem, the tube that comes out of the head is where it normally gets plugged up but also ck the hose. I use a 3/16 drill bit to clean the tube on the head, when clean with engine running you should be able to see a flow of coolant from the small hose into the bottle. If coolant flows out of the hose into the bottle, it should burp all the air out of the cooling system. Run it for a short time and keep adding coolant, but if it's still overheating then there is something else causing the problem.
Big help for me right here tonight....had to put a new neck on the head tonight and couldn't bleed the air out tonight....the small hose from the head to the top of the coolant bubble was cold, everything else was hot and the engine was over heating....cleaned out the tube this hose goes to and all was good...didn't have a problem before I changed the neck though...just a small leak, the reason for the change...all is good now...I'd probably still be scratching my head if it wasn't for this tip....Thanks!
 

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...your reservoir should have a overflow pipe which will double as a "pressure release" pipe for bubbles. Remember that your car heater dial inside the car must be turned to the max so your heater core is wide open when starting the car when trying to bring it up to temp.

A little bit of misinformation here bud... Just to clear things up, no air will escape the coolant system if you have the cap on. The system is designed to hold pressure, to around 15 psi. This increase in pressure allows the coolant to go over the boiling temp of water and not boil away.

Also, opening the heater dial all the way to HOT will do nothing. Our cars DO NOT have a valve to control the flow of coolant to the heater core. They have a "blend door" that just allows more or less cold outside air.

According to the Bentley, rev the car to around 2000 RPMs, and with the CAP OFF the overflow bottle, start squeezing all the hoses you see. Top up as necessary.
 

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A little bit of misinformation here bud... Just to clear things up, no air will escape the coolant system if you have the cap on. The system is designed to hold pressure, to around 15 psi. This increase in pressure allows the coolant to go over the boiling temp of water and not boil away.

Also, opening the heater dial all the way to HOT will do nothing. Our cars DO NOT have a valve to control the flow of coolant to the heater core. They have a "blend door" that just allows more or less cold outside air.

According to the Bentley, rev the car to around 2000 RPMs, and with the CAP OFF the overflow bottle, start squeezing all the hoses you see. Top up as necessary.
I am right is saying the euro version the heater dial must be wide open, that's what i read on vortex? Cheers, for the correction on the release pipe&cap, i will double check and post pictures of my reservoir and overflow pipe, the way i saw it regardless if the cap was on or off, the bubbles would've still got out thru the overflow pipe. I'll check tonight, i might be mistaken.
 

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Can't always trust the Tex man, some guys know their ****, even more dont know wtf they're talking about.
 

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Let it run with the cap off, add some coolant and hit the gas a few times, squeeze all of the hoses until air bubbles come out, had to do it with mine works everytime :]
 

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I think the principal issue is being missed here and Boost pretty much nailed it on the head earlier.

The upper hose is hot and the lower is cold.

This wouldn't be the end of the world since the lower hose is supposed to be 'cooler' than the top hose since it's the return hose BUT, he has no heat.

Having no heat in the car might indicate an air pocket but highly unlikely.

My vote is a failed water pump.

98 vw 1.8CLX said:
i will double check and post pictures of my reservoir and overflow pipe, the way i saw it regardless if the cap was on or off, the bubbles would've still got out thru the overflow pipe. I'll check tonight, i might be mistaken.
You are mistaken and not because your theory is stupid but because it's not possible on the VW coolant system. Unless there is a leak in the coolant system air cannot escape when the system is sealed and pressurized. The overflow tube does not run open like some vehicles do, it runs INto the back of the cylinder head. The only way to relieve air bubbles from the VW coolant system is have a way for the air to escape. Some cars actually have bleed valves but VWs do not (not on the ones I've worked on anyway). The way to bleed the coolant system is to remove the cap and rev to 2000 rpms until you see the bubbles pop in the reservoir.
 

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I disagree, if the top hose is hot, then it has circulation, yes it could be a pump, but trust me its a pocket, i had the exact same issue last week. Just keep filling it with coolant, you would be supprized how much it will need.
 

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The heat comes in from the top (the head is where the explosions happen), if the lower is cold, then the coolant isn't moving anywhere.

So, could be a bad pump, closed thermostat, air pocket, blocked lower rad, blocked lines.
 

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Big help for me right here tonight....had to put a new neck on the head tonight and couldn't bleed the air out tonight....the small hose from the head to the top of the coolant bubble was cold, everything else was hot and the engine was over heating....cleaned out the tube this hose goes to and all was good...didn't have a problem before I changed the neck though...just a small leak, the reason for the change...all is good now...I'd probably still be scratching my head if it wasn't for this tip....Thanks!
Your welcomed kickinkz It happened to me its a very important parts of the cooling system, if that little tube is plugged the engine will OVER HEAT.
 

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I wanted to post my recent journey regarding this problem so if someone comes here as I did they may find a solution. I did find out that the dealer uses a pressurized system to add coolant to the Jetta because of this very problem. I was able to get it on my own while it was a huge pain. I would probably take it to a shop with a pressurized system to save the headaches, time and possible overheating damage.

On the way to work one morning my 96 Jetta GL overheats on the freeway. I add water and get it to a place to look at it. No leaks. Confused I assume I may just have been low on coolant and go about driving it again. Overheats on freeway again :(. Coolant is low again. I add some and get it back to my garage. Still no leaks. No milkshake in the oil, oil level is staying the same. Exhaust doesn't smell sweet. I run it on idle on jack stand for 15 minutes looking for leaks. I end up pulling on the throttle and sure enough a drip from the water pump! So I replace the water pump, which anyone who has done it knows the hell it is to get to the dam tstat let alone getting the water pump off. I replace the tstat since I had it all apart. Side note, it the original Audi tstat still working before I replaced it just in case. The water pump was very wobbly so I knew it was bad but when I got it all back together and filled with coolant it was still overheating. it took 3 days of running it, jiggling hoses, shaking the car and adding more coolant to get all the AIR out and coolant completely through the system. The first time the fan kicked on again because there was water in the radiator was a grand celebration. It has been cooling great ever since. Air, air was the big problem!
 

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N_flames was dead on about the little hose that goes to the TOP of the coolant bottle. i just had my head gasket replaced this week because that hose wasnt flowing coolant back the the bottle, car overheated and burnt the head gasket in three spots. just got it back yesterday after 700 dollars shucked out.
With the engine OFF, take that little hose off the bottle. Start the car and see if you have coolant coming out of that hose. You HAVE to have coolant flowing out of that hose back to the coolant bottle. That is the part of the cooling system's return. If there is nothing coming out of that hose, turn the engine off and let the car cool down, then take that same hose off the head. Like N_flames said, drill a 3/16" hole into the spout where that hose connects to the head. The grooves in the drill bit should be full of junk when you pull the bit out. Mine looked like mud when my mechanic did mine this week. it was a combo of rust, calcium and i dont know what else. Make sure that hose is not clogged by blowing it out with air, looking thru it, or however you wanna make sure its not blocked. once you know that hose isnt blocked, hook it back to the spout on the head that you took it off of, do NOT hook the other end to the coolant bottle, (just aim the other end of the hose into a container) start the engine and wait. My engine ran for over 5 minutes before coolant started flowing out of it. for about 5 minutes the only thing that come out of the hose was steam. then chunks of junk started spitting out of the end of that hose, then finally coolant. This hose is the main hose responsible for letting the air bubbles of of your cooling system. It is possible to get all the air out even if this little hose isnt working but it takes FOREVER! Look at the plastic thing on the side of the head that has a big cooling hose hooked to it and 2 sensors stuck in it. just fyi, the back(One closest to firewall) sensor tells the a/c compressor NOT to come on and the front one is the one that tells your temp gauge on the dash how hot your coolant is. Make sure where the edge of that flange touches the head, there is no gap. when mine overheated, this plastic piece distorted from the heat, and if you have a gap where the plastic flange is supposed to be flush up against the head, it will leak coolant. please check all this on your car IMMEDIATELY! i dont want you to have to shell out big money to have your head gasket replaced and your head machined flat. hope this helps.
 

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Take a garden hose and pump water through every coolant hose you can get ahold of. I did this today after having weeks of coolant loss issues and no heat and it was fixed after the flush. No more coolant spraying out of the bubble and my heater blows hot =D


on my 1997 jetta 2.0 i am having trouble getting the coolant to circulate. the top hoses are getting warm however the bottom one is not and there is no heat in the car. i am sure that there is a problem with the thermostat holding an air bubble but not sure it there is way for me to bleed it or not.
 
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