Help!! Coolant Boiling Over!!!

[tpende]

Sorry right off the bat if i posted this in the wrong spot or say anything stupid. So my buddy bought a 96 jetta TREK with a 2.0 in it. his coolant was boiling out so he calls me up. I notice that when hes idling for a bit or turns his AC on his fans dont come on. So i use a jumper on the connetor for the thremal radiator switch thingy and they come on, so i replace that....nothing still boils over after 5min of idle. so i replace his water pump and thermostat...fun job BTW......still boiling over. what the hell is going on? is it because im leaving the cap off the coolant res while waiting for it to burp the air pockets out? PLEASE HELP!!!

[CodeMan]

Probably. Coolant needs to be pressurized to function, as pressurization raises the boiling point.

[tpende]

although ive read on here about that im doubting that the res cap is blame. it was fine all winter and the first day it got warm poof. and ofcourse the cap was on when its was puking coolant allover the parking lot. im wondering if it could possibly have a stopage some where

[tpende]

i forgot to note that the temp gauge does not get hot at all. it goes to normal operating temps

[CodeMan]

So it pukes coolant at normal operating temp with the cap on? Sounds like a bad cap to me.

Where is the coolant coming from?

[tpende]

Yes. i was trying to refill the system. my buddy said it holds three gallons. im guessing some stayed in the block, but since i pulled the water pump i would think that atleast 2/3 of it would run out, but i had only dumped about a gallon in and the res tank was full already. i started squuezing hoses to massage the air out. i got some but not much. and after 5min of idling with the cap off the res tank coolant started boiling out of the tank. tried agian, but put the cap on and same thing

[tpende]

i should note though that we didnt put G12 back in it. just unversial stuff, i doubt that makes much of a difference in this case

[CodeMan]

It sounds like the initial overheating (due to the fan switch) caused the o-ring in the cap to fail just enough to not hold pressure.

[Rockerchick]

i should note though that we didnt put G12 back in it. just unversial stuff, i doubt that makes much of a difference in this case

Actually it could make a huge difference. If you still had G12 in the system and then used universal stuff, you could end up with some lovely sludge problems. G12 does not play nicely with other coolants, universal or not.

[tpende]

i think it had the green stuff in there when this all started. plus with the ammount of coolant puking and swaping the water pump it should be pretty much flushed out. i noticed the drivers side radiator support is rottted away. he just bought it a couple months ago. so now im debating between if the last guy dumped a bunch of stop leak in there and clogged the radiator up before he sold it or it having a blown head gasket. im thinking its got a blown head gasket and when the thermostat is opening the compression is blowing the coolant out the res tank. would this happen? or would it just be pushing it out right off the bat? also if the radiator was clogged up i think it would have been overheating even when it was cold out. theres also the fact that his fans still dont come on....even with the AC on.....even after i swapped the radiator switch...but they worked when i used a jumper........im starting not to like this car

[tpende]

well.....now im REALLY thiniking its a head gasket. i put a new radiator in and same deal. idles for 5min fans dont come on and it boils over. so yeeaaaaahhhh im guessing the thermostat opens up and the compression is blowing the coolant out the res tank. odd though no noticeable climb in oil level

[CodeMan]

You're overthinking it.

[Kjheidlebaugh]

check fuses, and thermostat if fans are not working properly.

[Kjheidlebaugh]

also when you filled it, you were running it correct?

i always run my car's while filling the coolant, reduces the chances of getting air into the coolant system

[tpende]

I checked the fuses on the fan relay and they were good, plus when i jump the thermo switch plug on the radiator they come on. So im thinking they are fine. Yeah i had it running when i filled it up with coolant. The temp gauge says its in the normal operating range of 160 when it starts to blow coolant out, and i know they're not the most accurite, but since this is WELL below the boiling point of the coolant i dont think the res cap has anything to do with it. im still thinking its got a blown head gasket and as soon as the thermostat opens its letting the compression by and blowing the coolant out.

[vr2jetta]

Did you ever figure this out? I'm having the same issue except mine is a g60 and I am running an inline coolant filler with a 20lb standard cap. It doesn't get hot until all the coolant pukes out of the blow off. But it pressurizes over 20 psi and over flows. Weird....

[emkaytree]

You guys have blockages. Probably in the rad or head. First, I must allow myself to take this opportunity to double face palm, hard.

The original poster has blockages when he added the green stuff to the remaining g12. The system needs to be flushed out completely, COMPLETELY. Every drop of it, much less 2/3's Or else you will, WILL, get a blockage, somewhere. When I switched to green stuff in my VR off of gold12, I replaced crack pipe, tstat, flange, and hoses really good while out of the bay. New gaskets everywhere. Then once all together ran 3 entire fills (almost 10 gal) of pure distilled water through it. Then it saw green stuff without a problem. If you didn't flush out your system 2-3 times with PURE DISTILLED jug water, you epically did it wrong.

If you even had a film lining of g12 or little pools, like what is left in most hoses and head after drain, you clogged it. Wouldn't be surprise if half his system is clogged. Your probably looking at having to rebuild the entire cooling system, including heater core, all gaskets, and head. Good luck.

[vr2jetta]

Mine is surely not a mixture blockage. I lived in Florida and ran pure water for at least a year, while it leaked, and just recently had to start using green stuff done to moving to Ohio. I am wondering if its my setup... Here is a pic.