good ways to tell whats going on with my coolant?

[RabbitJockey]

been having some issues with pressurized coolant, no oil in my coolant or coolant in my oil, just sometimes when i shut my car off i can hear a noise like a baby blowing bubbles and when i look my coolant reservior cap is making the noise and dripping out coolant, my car doesn't over heat or anything, and i run it up low 20's in boost currently, maybe like 22psi.  when i feel the radiator hose it's not that hard, i mean i can squeeze it.  there is a spot on the front of the motor like at the front passenger side corner where it looks like coolant leaks out cause of a white residue, but i've never real caught it while it was wet. motor runs fine and stuff though, i just don't really understand the problem, i assume it's the headgasket but i dunno...

[jtanguay]

just throwing this out there, but could it be a faulty rad cap?

[RabbitJockey]

it could be.  i don't really thinkt he rad caps on these do much?  just seal

[jtanguay]

they bleed the pressure off if it gets too high... i think they bleed excess air off too...  im not sure if they are more prone to stay stuck shut or stay open..?

[AdAm84]

sounds like the cap to me. my overflow tank is cracked and does the same thing. just sounds like tour cap is faulty. we can trade to find out.

[745 turbogreasel]

My frinds Jetta had failed cap so bad it would lose about a liter as soon as you turned the car off, accompanied by lots of gurgling noise.   It hardly dripped while running.

A new cap fixed it completely.

[GTD.]

Replace your black header tank cap with a nice new blue one!

[jtanguay]

Replace your black header tank cap with a nice new blue one!

No comment.  :?

[RabbitJockey]

i'll try switching the one from my bunny to my jetta

[GTD.]

Replace your black header tank cap with a nice new blue one!

No comment.  :?

They are not "just a cap" they are a pressure relief valve, they get old wear out and fail, considering the low cost of a new "blue" replacement reservoir cap its just not worth pissing around with crap second hand caps.

In Europe as part of routine service VW replace the old style obsolete black coolant reservoir cap with the improved "blue" coolant reservoir cap.

Usually a damaged sealing "o" ring or tired spring causes the pressure cap to fail, dumping water out of the system.

i'll try switching the one from my bunny to my jetta

Just buy a new (genuine) one, FFS!

[VWCaddy]

Have the cooling system (and cap) pressure tested.  Then you can also do a chemical test on the coolant to see if it is being pressurized with exhaust gas:
- http://www.arrowheadradiator.com/head_gasket_or_combustion_leak_test.htm

[GTD.]

Have the cooling system (and cap) pressure tested.  Then you can also do a chemical test on the coolant to see if it is being pressurized with exhaust gas:
- http://www.arrowheadradiator.com/head_gasket_or_combustion_leak_test.htm

Head Gasket or Combustion Leak Test Procedure (Gasoline Engines Only)

That doesn't always work, I had an 1.6 88 carbed auto mk2 which was tested by the AA (AAA to you guys) it registered as a head gasket leak, took it to the vw specialist and it turned out to be the thick rubber carb gasket was shot

[SMOKEYDUB]

brand new cap form vw is 14 bucks. I have the same problem as you but i have bought 6 different oem caps and it didnt do a thing. so i keep have a re occuring problem. Either headgasket for me or cracked head..... F@#K

[jtanguay]

Replace your black header tank cap with a nice new blue one!

No comment.  :?

They are not "just a cap" they are a pressure relief valve, they get old wear out and fail, considering the low cost of a new "blue" replacement reservoir cap its just not worth pissing around with crap second hand caps.

In Europe as part of routine service VW replace the old style obsolete black coolant reservoir cap with the improved "blue" coolant reservoir cap.

Usually a damaged sealing "o" ring or tired spring causes the pressure cap to fail, dumping water out of the system.

i'll try switching the one from my bunny to my jetta

Just buy a new (genuine) one, FFS!

Now I will consider buying one!!!  :wink:

[55mpg06]

Hi guys. I have been watching this site for about a year and have learned A LOT. It comes in handy since there are 5 Jetta diesels running around my house. Sorry in advance for my long post. But, I didn’t know if I should start a new tread :? . In any-case I have much the same problem sort of…

After blowing out about 3 or 4 head gaskets (I am not quite quick at changing them) I totally rebuilt my 1.6 N/A head at a VW shop (they were AWSOME) a year ago. Apparently mine was the most worn out head he had seen in working on them for over 22 years. Among other things the carbon deposits were the only thing keeping one of the valves from falling out. :shock:

Last fall I rebuilt the bottom end myself (a shop checked the block out first though) since the top was a little too tight for it to handle and I had my own mosquito control coming out the tail pipe. Also I rebuilt the injection pump with the help of your forum and found how one wrong size o-ring will make the car refuse to suck fuel, and how a wrong throttle adjustment will also make the car refuse to start (under ANY conditions) only cough along with driving me nuts for 3 days :x .

So all has been rebuilt yet this is what is happening. After doing the head about a month later I was leaking coolant out of the sensor on my reservoir so I replaced the sensor thinking it was the o-ring. Soon after the expansion tank cracked. Replaced expansion tank with a new aftermarket one and it lasted a week then cracked (apparently faulty plastic I was told, and it did look cheap). Replaced it with a used VW one along with a new Blue cap and it worked great. Problem solved so I thought.

After rebuilding my bottom end including new frost plugs, I started it up late that night for a test run. After getting up to temperature I heard a faint “pop” followed by the rush of anti-freeze on the shop floor. A frost plug let go and the others seemed loose. Since I needed it at noon the next day, a quick trip to the store the next morning, and my car now has 3 block heaters for those really cold nights… :wink:

Around the same time I have been having really weird things happening with my heating system. Sometimes it will heat up and other times it won’t. I went camping in the hills and climbing up backroads loaded with gear for over 40km yet I could not get heat even with the rad covered in cardboard. Coming back down a week later I got lots of heat even with the cardboard having fallen off. (Yep - Thermostat has been replaced 3 times since fall all different brands). Also if the coolant level is up to normal after about 2 weeks it has all sprayed out again until it is just below the min mark and stays there. I have no hard starts, zero white smoke, and no coolant in oil.

Had enough and gave in and took it to a good rad shop in town. They were nice but wanted to do a “block test” I said O.K. but it was a chemical test for exhaust gasses in the coolant. After taking the car for a long test run they did the test. After the car ran for “a while” and nothing showed up, they ran it for 40minutes with heater turned off. Only by doing this the test showed positive. I was told that I might have a slight leak in the head gasket or small crack in head. However in doing research I was found that this method apparently is not that accurate in diesels. However this situation would make sense, only I don’t think I am burning any antifreeze. I have been running like this since fall and it hasn’t got any worse. Any other way of testing? Any ideas what it could be?

Thanks