TheSamba.com :: View topic - Boiling Coolant/leak from exp. tank/Not overheating?[RESOLVED]

Mon Aug 22, 2016 12:21 pm

Hey all. Posting here to not hijack other posts.

Here's the problem I'm having.

Lately my expansion tank is letting fluid out of the threading between the Temp Level Sensor, and the washer (!!!). It only seems to happen when I park, after I've shut the motor off after driving a good distance. Sometimes the coolant is boiling.

I'm going to get the sensor switched, or the tank swapped depending on where the problem is. But here's what I'm having a hard time understanding:

1) I don't seem to be overheating, The coolant is getting hot, but the engine temp is staying okay. It never gets past the first white line after the light, and that's only when I've been stuck at a signal, or at a stop for A WHILE. The Radiator was replaced very recently, so that might have *something* to do with it. . . but I'm not sure.

2) My radiator fan has not been kicking in when even when the temp needle rises further above the idiot light. I know my radiator fan works with the AC on, but since I've had this problem, the radiator fan does not engage, even as the temperature starts to creep above the light. *Stage 1, Stage 2 resistor was also replaced not too long ago* Thermostat?

3) There are almost no signs of leaking when I'm in motion, or prior to stopping. It's only coming out of the sensor "hole" after I've stopped. . . . could be a slow leak out of the top when in motion. Last night when I heard boiling when I stopped, I grabbed several rags, and carefully unscrewed the Expansion tank Cap. It was definitely under *some* pressure, as I heard a HSSSSS before letting the cap blow off and the system and spit for a while.

I'm just totally confused. It's gonna go to the shop to get some other work done, and this will be looked at too. but I'm really annoyed that I don't understand what's happening. :?

Mon Aug 22, 2016 2:32 pm

Abelabelabel wrote: ...I don't seem to be overheating, The coolant is getting hot, but the engine temp is staying okay. ...Last night when I heard boiling when I stopped, I grabbed several rags, and carefully unscrewed the Expansion tank Cap. It was definitely under *some* pressure, as I heard a HSSSSS before letting the cap blow off and the system and spit for a while...

Was it 'boiling' (i.e. above 212°) or was it bubbling violently (looked like boiling water)? An IR thermometer would quickly answer that.

I'm suspicious because I would expect cap removal to be a much more dramatic & dangerous event if the coolant was truly boiling.

Removing the cap (and releasing pressure) would actually increase the boiling (lower the boiling point) with ensuing drama.

Isn't this a variation on last month's coolant issue:

http://www.thesamba.com/vw/forum/viewtopic.php?t=632409&highlight=

Mon Aug 22, 2016 2:47 pm

on mine the pressure cap stopped working, no longer pressurized the system, upon stopping the tank would boil over. pressure increases the boiling point, lack of pressure decreases it. so test the pressure cap, if you can blow through it with mouth pressure both ways, it has failed.

on mine, when I replaced the cap, I finally had a pressurized system and in short order the old plastic pressure tank burst, the only reason it did not burst sooner was that it was not under pressure cuase of the failed pressure cap!!! a new metal tank fixed it for ever. word is the replacement plastic tanks now sold as new have a defect and hence they have a high failure rate, hence my choice of the metal tank. at least that is what van cafe told me.

Mon Aug 22, 2016 3:43 pm

Ahwahnee wrote: Abelabelabel wrote: ...I don't seem to be overheating, The coolant is getting hot, but the engine temp is staying okay. ...Last night when I heard boiling when I stopped, I grabbed several rags, and carefully unscrewed the Expansion tank Cap. It was definitely under *some* pressure, as I heard a HSSSSS before letting the cap blow off and the system and spit for a while...

Was it 'boiling' (i.e. above 212°) or was it bubbling violently (looked like boiling water)? An IR thermometer would quickly answer that.

I'm suspicious because I would expect cap removal to be a much more dramatic & dangerous event if the coolant was truly boiling.

Removing the cap (and releasing pressure) would actually increase the boiling (lower the boiling point) with ensuing drama.

Isn't this a variation on last month's coolant issue:

http://www.thesamba.com/vw/forum/viewtopic.php?t=632409&highlight=

Thanks for the reply. That was last years issue ;). A lot has been replaced, repaired, addressed since then.

The boiling was boiling, it was a little spit and sputter of fury after I removed the cap, once enough pressure was released, the cab did "blow" off. The engine bay was hot, but not unusually hot, the only "tell" was the gurgling sound from the expansion tank. Maybe I totally screwed up the bleeding, or maybe there's just a partial failure somewhere. The tank was holding some pressure, and the boiling did get more "violent" once the cap was off, at least for about 20 seconds or so.

It's bothering me that it's inconsistent.

Thanks for your replies fellas. Let's see what the mechanic says. Let me know if there's anything else I should ask.

Sun Aug 28, 2016 11:11 am

Expansion tank isn't holding pressure, and the plastic threading looks like it's failed. It was an aftermarket one from Gowesty.

I'll be switching to the aluminum TANK from RMW, and purchasing an additional thermostat to test. Fingers crossed that I didn't have a headgasket failure less than 10,000K from a rebuild.

Sun Aug 28, 2016 11:30 am

Change the tank & the cap.
You're losing pressure at the tank.

Be like leaving the radiator cap off of any standard vehicle.

As soon as you shut it down, it'd boil over.

Simple stuff.

Sun Aug 28, 2016 11:31 am

Terry Kay wrote: ...

As soon as you shut it down, it'd boil over.

...

Yes, once the gerbils in the engine see the light they will all try to escape

Sun Aug 28, 2016 11:50 am

Abelabelabel wrote: 1) I don't seem to be overheating, The coolant is getting hot, but the engine temp is staying okay. It never gets past the first white line after the light, and that's only when I've been stuck at a signal, or at a stop for A WHILE.

I don't know WBX engines all that well and the usual disclaimers apply... My understanding is that if you have the 2.1 plastic thermostat housing and the sensor is in an air pocket, then it will read the temperature of the plastic which does not conduct heat very well. Because of this, you can have have an engine that is severely overheating with a gauge that reads a relatively normal temperature.

Sun Aug 28, 2016 8:50 pm

The expansion tank is failing. Not at the cap but through the threading where the level sensor plugs in to. It's been slowly failing for months now that I think about it. Now it's at a point where the expansion tank no longer holds pressure at all. Anyway pretty sure the mystery is solved. A year ago I would have called a tow truck as soon as I saw things spill out. Now I've got the tools and knowledge to understand and fix myself. Not too shabby.

Mon Aug 29, 2016 4:25 am

it may just as likely be the sensor falling apart - a much cheaper and more commonly available part. i had a sensor fail. it blew into a million pieces due to extreme pressure. it was just like the safety valve on a pressure cooker.

but i think this is perhaps wishful thinking. you said the system was under pressure when you turned the cap.

the parts may be failing because there is too much pressure. once you put that metal tank in there, watch the rest of the plastic parts, radiators, heater cores, start to leak. i spent $2k on a similar chase before rebuilding my engine. http://www.thesamba.com/vw//forum/viewtopic.php?p=6144999

but maybe the plastic parts are failing just because they are old. that happens. but if you haven't measured the temperature of your boiling cauldron you are missing the cheapest stop on the cooling system replacement train.

if you do have a head gasket/compression leak (not a waterjacket leak), you can drive the van for a good while before it becomes so frequent that you have to stop and refill the pressurised coolant tank on each trip. but be warned, if your blue cap isn't working to release pressure at 10-15psi *or* if your engine produces pressure faster than the cap can release, then pop. or make one of these caps as wildthings suggested: http://www.thesamba.com/vw/forum/viewtopic.php?p=7749339#7749339

Mon Aug 29, 2016 8:32 am

It is time to bite the bullet and order not only RMW's tank but consider replacing the thermostat housing and coolant tower too.

This old plastic Eventually simply gives up and leaks.

I did mine with new plastic but as time ticks by I'll
Upgrade to metal replacements.
Already did the RMW tank after my aftermarket non "Blau"'cap failed me.

Dave

Mon Aug 29, 2016 9:12 am

Both the expansion tank and sender can and will crack and leak. Replacing one without replacing the other is just asking for a quick repeat of your problems. Due to quality problems with everything associated with the stock style expansion tank, going with a RMW tank is a better option.

Mon Aug 29, 2016 9:18 am

Abelabelabel wrote: Fingers crossed that I didn't have a headgasket failure less than 10,000K from a rebuild.

Hopefully its just the tank threads and or a need to bleed the system, but bubbles and "boiling sounds" are a bad sign.

There are hydrocarbon tests that determine if your coolant is contaminated with combustion gasses. You should get that done so you know for sure.

I agree that a bubble in the tank, keeps the temperature sender from reading accurately.

Mon Aug 29, 2016 11:06 am

Thanks again for all of the extra information. I've stopped driving the Vanagon Daily while I wait for the RMW tank to arrive. I'll be taking the van to a shop to get new stainless exhaust in a couple of days, so I'll have them check for exhaust gasses in the cooling system.

Mon Aug 29, 2016 11:15 am

Abelabelabel wrote: Thanks again for all of the extra information. I've stopped driving the Vanagon Daily while I wait for the RMW tank to arrive. I'll be taking the van to a shop to get new stainless exhaust in a couple of days, so I'll have them check for exhaust gasses in the cooling system.

get the engine test done prior to the exaust work. also consider a leak down test, and a cooling system pressure test, also check oil pressure. wear limits for test found in bentely manual. no sense spending money on new exhaust if the motor needs to be rebuilt immediatly.

hopefully all will be ok.

Mon Aug 29, 2016 5:46 pm

bluebus86 wrote: Abelabelabel wrote: Thanks again for all of the extra information. I've stopped driving the Vanagon Daily while I wait for the RMW tank to arrive. I'll be taking the van to a shop to get new stainless exhaust in a couple of days, so I'll have them check for exhaust gasses in the cooling system.

get the engine test done prior to the exaust work. also consider a leak down test, and a cooling system pressure test, also check oil pressure. wear limits for test found in bentely manual. no sense spending money on new exhaust if the motor needs to be rebuilt immediatly.

hopefully all will be ok.

That's the plan. I have a feeling that the problem lies with the pressure tank and maybe a bad thermostat. I'll be doing everything to make sure all problems are solved. I'm running out of things to repair and address, so I'm feeling cautiously optimistic. As for the exhaust it's for more than just bling - I recently failed smog and there was evidence that the exhaust was leaking before the cat so new cat and exhaust are actually needed!!

Tue Aug 30, 2016 6:28 am

a leaky exhaust may be repaired by welding, sometimes the headers crack. good luck.

Fri Sep 02, 2016 10:23 am

Whelp,

RMW Expansion Tank is installed. Gremlins are gone.

The culprits were:

Aftermarket fan switch in my new radiator was not working correctly. Swapped with an OEM.

failure or old expansion tank.

Dumb owner forgot to tighten bleeding screw in Radiator. (I filled and bled coolant in preperation for my short drive to the shop. . . . and may have skipped a step before putting my front grille back on. . . )

Shop took van for a ride to make sure the radiator fan was kicking in when expected (Radiator is new as of about 3 month ago).

All is good for now! I just need to yell at the shop for not correctly addressing my wiper issue, but that's for a different thread/post.

First impressions of the RMW tank:

It looks good, and installs in a much more tucked-out-of-the-way place than the original tank that I like. I'm really liking the way my engine bay looks now. I'll upload some pictures when I'm able to step away from my desk later today.

Sun Sep 04, 2016 10:09 pm

Mon Sep 05, 2016 5:12 am

I absolutely love my RMW tank!

Just did 5,000 + miles with it, had no worries at all about the tank, although my thermostat gasket decided to piss some coolant about 2,000 miles in.

My only complaint, and it is minor when compared to the benefits of having a solid tank with a real pressure cap, it that you cannot at a glance know the system is full.

You must remove the pressure cap to check the coolant level, not a joy to do on a hot engine.
I did check my system coolant level every morning when the unit was cold.
It was only low when the thermostat gasket leaked.....

Admittedly, Removing the engine lid every morning is a PITA, but there was a comfort to glancing at all systems before beginning a days drive.

I've also become obsessive at looking under the Van and into the license plate door at every stop! But, that's how I noticed my thermostat was leaking.

Dave