| Author |
Message |
Wildthings
Samba Member
Joined: March 13, 2005
Posts: 50352
|
 Posted: Mon Oct 04, 2021 10:18 am Post subject: Re: Is this a sign of a bad coolant pressure cap? |
 |
|
| AtlasShrugged wrote: |
Try running an air gap in the top of your coolant tank long term and save yourself a lot of expensive coolant system problems. |
Since with a stock WBXer system if you leave the pressure tank half full and keep the overflow tank at least at the low mark then the pressure tank will be full excepting for maybe a smallish bubble after a few heat cycles, I don't see where what you write makes any sense. I sounds to me like you have a clog in the line between your pressure cap and your overflow tank. Or at least an air leak in the system somewhere.
The system is designed to purge the air from the expansion tank as the engine heats up and to suck coolant in as the system cools down, and I have found it quite efficient at doing this. The temperature doesn't even need to cycle through its full range, climb a long hill and the pressure cap will purge air and then on a long downhill it will suck coolant back into the system. After an hour or so of driving there should be no more than a small bubble left in your coolant tank. |
|
| Back to top |
|
 |
djkeev
Samba Moderator
Joined: September 30, 2007
Posts: 32632
Location: Reading Pennsylvania
|
|
| Back to top |
|
|
pdm777
Samba Member
Joined: August 06, 2012
Posts: 348
Location: Clovis, CA
|
| Posted: Mon Oct 04, 2021 1:43 pm Post subject: Re: Is this a sign of a bad coolant pressure cap? |
|
|
A few prior comments are misinformation / confusion.
Waldo's last post is accurate.
OP's first post, the level is down at least 1/3, (not a bubble).
There are two coolant tanks:
REFILL TANK - behind license plate door. non-pressure cap. MAX/MIN marks.
EXPANSION TANK- the one with the pressure cap. (no max/min marks).
OP- did you tighten the loose clamp(s), fill the expansion tank,
fill the Refill tank between MIN and MAX marks, and test drive?
TEST DRIVE:
Note the level of the Refill tank, then go for a drive and get it HOT.
When Hot, stop, look at the Refill tank level- it should be near MAX.
When Cool, (hours later) the Refill tank contents will be sucked back
into the Expansion tank,and the Refiill coolant level will fall back to MIN.
There should be no air in the Expansion tank, hot or cold.
Small bubbles are not a concern
Please report back!
_________________
1990 Westy Full Camper |
|
| Back to top |
|
|
SyncroHead 
Samba Member
Joined: May 23, 2005
Posts: 1145
Location: Northern Nevada
|
| Posted: Mon Oct 04, 2021 2:25 pm Post subject: Re: Is this a sign of a bad coolant pressure cap? |
|
|
I'd love to encourage the Vanagon community to adopt better language and nomenclature clarity. As pdm777 writes and djkeev shows in a pic from the manual, these are the REFILL TANK and the EXPANSION TANK .
| pdm777 wrote: |
There are two coolant tanks:
REFILL TANK - behind license plate door. non-pressure cap. MAX/MIN marks.
EXPANSION TANK- the one with the pressure cap. (no max/min marks). |
Over the years I've heard these two tanks called everything including calling the EXPANSION TANK the "pressure tank" and the REFILL TANK called the "overflow" tank or even called the "expansion" tank.
We might not like the terms VW used, but since they are the ones printed in the owner's manuals (and Bentley 19.8-19.17), I'd suggest we stick with these as best we can to help avoid future confusion. Imagine nbeing
Our vendors could do a better job too, keeping to standardized language. GoWesty calls the expansion tank an expansion tank, but calls the refill tank an "overflow reservoir". Van Cafe calls the expansion tank a "pressurized reservoir", and also calls the refill tank an "overflow reservoir". Meanwhile Bus Depot calls the expansion tank a "recovery tank". Confusion makes finding the right parts tougher than it should be.
Imagine being new to Vanagons and people using "expansion", "refill", "pressure", "overflow", and "recovery", all while you're trying to figure out what's what. 
Maybe put this in the Sticky FAQ along with other terminology & nomenclature?
Jim Davis
_________________
"A Vanagon? It's not a car or a van. It's a hobby!"
Check out:
www.VANAVATION.com
www.SyncroSafari.org and
www.Vanagons.org
| sphet wrote: |
| I have *no* idea what the previous owner carried in his Westy... angry donkeys? |
|
|
| Back to top |
|
|
?Waldo?
Samba Member
Joined: February 22, 2006
Posts: 9752
Location: Where?
|
| Posted: Mon Oct 04, 2021 2:36 pm Post subject: Re: Is this a sign of a bad coolant pressure cap? |
|
|
I'd be fine with using the terms that the Bentley uses if they made any sense... The term 'expansion tank' being used to describe the tank in the engine compartment does not make any logical sense considering its function. It doesn't really have anything to do with the expansion of the coolant. I will continue to call the that tank the 'pressure tank' (thank you very much) because that term actually makes sense considering it is the tank that is under system pressure. I personally prefer 'burp tank' to describe the tank at the license plate as that most accurately describes its function (allowing air to burp out of the system). 'Refill tank' is sorta ok, but I don't ever use it for refilling the system and 99%+ of the coolant I add when refilling the system goes into the pressure tank.  |
|
| Back to top |
|
|
4Gears4Tires
Samba Member
Joined: October 08, 2018
Posts: 3054
Location: MD
|
| Posted: Tue Oct 05, 2021 7:11 am Post subject: Re: Is this a sign of a bad coolant pressure cap? |
|
|
^ Agreed. I think burp tank and pressure tank make a lot of sense as a name. I am adopting them.
_________________
'87 Syncro
Ferric Oxyhydroxide Superleggera Edition |
|
| Back to top |
|
|
SyncroHead
Samba Member
Joined: May 23, 2005
Posts: 1145
Location: Northern Nevada
|
| Posted: Tue Oct 05, 2021 9:00 am Post subject: Re: Is this a sign of a bad coolant pressure cap? |
|
|
I thought I'd get support on using common language to avoid confusion. I'd be happy to use "Tank 1" and "Tank 2" to avoid confusion if that's what the owner's manual and Bentley called them. Oh, well, let the confusion reign while we each pick our own names for the Ralph and Wanda tanks! 
Jim
_________________
"A Vanagon? It's not a car or a van. It's a hobby!"
Check out:
www.VANAVATION.com
www.SyncroSafari.org and
www.Vanagons.org
| sphet wrote: |
| I have *no* idea what the previous owner carried in his Westy... angry donkeys? |
|
|
| Back to top |
|
|
Wildthings
Samba Member
Joined: March 13, 2005
Posts: 50352
|
| Posted: Tue Oct 05, 2021 9:14 am Post subject: Re: Is this a sign of a bad coolant pressure cap? |
|
|
| SyncroHead wrote: |
I thought I'd get support on using common language to avoid confusion. I'd be happy to use "Tank 1" and "Tank 2" to avoid confusion if that's what the owner's manual and Bentley called them. Oh, well, let the confusion reign while we each pick our own names for the Ralph and Wanda tanks!
Jim |
The problem is that whatever you call them causes confusion, the Bentley names are misnomers and any other names used are not "factory". I have tried using Expansion (Pressure) Tank and some people still take issue. |
|
| Back to top |
|
|
Zeitgeist 13
Samba Member
Joined: March 05, 2009
Posts: 12115
Location: Port Manteau
|
| Posted: Tue Oct 05, 2021 9:56 am Post subject: Re: Is this a sign of a bad coolant pressure cap? |
|
|
Since they were mentioned earlier in the thread, I've now seen two GW aluminum tanks fail to backfill from the overflow tank. Since they seem to be designed to maintain an air gap at the top, I don't know if this is by design or not. I do know that my 124 MB has an overflow tank system with an air gap, and it does exchange fluid during normal operation. I'd be curious to pressure test all three cap types to see which open/close at lowest and highest pressures.
_________________
Casey--
'89 Bluestar ALH w/12mm Waldo pump, PP764 and GT2052
'01 Weekender --> full camper
y u rune klassik? |
|
| Back to top |
|
|
sphet
Samba Member
Joined: November 09, 2016
Posts: 345
Location: Vancouver, BC
|
| Posted: Tue Oct 05, 2021 10:25 am Post subject: Re: Is this a sign of a bad coolant pressure cap? |
|
|
This thread has got me curious too about the air gap. I have an aluminum tank which was custom fabricated years ago before any vendor offered an option since the diesel 82 pressure tank has been NLA for years. No matter how often I refill it, it always has an air bubble at the top. Any extra fluid seems to happily get pushed out to the burp tank, but never sucked back enough to fill that headroom. I’ve come to just accept it. I have asked two mechanics to do a combustion gas check and they’ve indicated no issue. Maybe my return line is clogged. Or maybe the burp tank (which has a flap on top) is letting the compressed air in the burp tank to escape, but that then creates a vacuum for the return fluid on cooldown, sucking air in from a crack or small leak in a pipe?
S
_________________
1982 Diesel Westfalia 1.6 NA - The Shellakabuukiee |
|
| Back to top |
|
|
djkeev
Samba Moderator
Joined: September 30, 2007
Posts: 32632
Location: Reading Pennsylvania
|
|
| Back to top |
|
|
wesitarz
Samba Member
Joined: August 20, 2012
Posts: 1491
Location: Victoria,B.C.Canada
|
| Posted: Fri Oct 08, 2021 8:42 am Post subject: Re: Is this a sign of a bad coolant pressure cap? |
|
|
| Zeitgeist 13 wrote: |
| Since they were mentioned earlier in the thread, I've now seen two GW aluminum tanks fail to backfill from the overflow tank. Since they seem to be designed to maintain an air gap at the top, I don't know if this is by design or not. I do know that my 124 MB has an overflow tank system with an air gap, and it does exchange fluid during normal operation. I'd be curious to pressure test all three cap types to see which open/close at lowest and highest pressures. |
Put a Subaru in it. That will fix it. |
|
| Back to top |
|
|
DanHoug
Samba Member
Joined: December 05, 2016
Posts: 4800
Location: Bemidji, MN
|
| Posted: Fri Oct 08, 2021 9:01 am Post subject: Re: Is this a sign of a bad coolant pressure cap? |
|
|
| Zeitgeist 13 wrote: |
| Since they were mentioned earlier in the thread, I've now seen two GW aluminum tanks fail to backfill from the overflow tank. Since they seem to be designed to maintain an air gap at the top, I don't know if this is by design or not. I do know that my 124 MB has an overflow tank system with an air gap, and it does exchange fluid during normal operation. I'd be curious to pressure test all three cap types to see which open/close at lowest and highest pressures. |
this is more likely a failure of the hose between the nipple of the aluminum tank and the overflow. any crack/pinhole/loose fitting will allow air into the pressure tank upon cooling, instead of drawing coolant back from the overflow tank.
the Stant caps and pre-made necks they fasten to are darn reliable. what messes up refilling from the overflow is #1 airleaks to the overflow, and #2 coolant stop-leak smoodge gumming up the vacuum relief on the Stant cap.
_________________
-dan
60% of what you find on the internet is wrong, including this post.
'87 Westy & '89 Westy both 2.1 4spd
Past projects can be found at--
www.thefixitworkshop.com |
|
| Back to top |
|
|
djkeev
Samba Moderator
Joined: September 30, 2007
Posts: 32632
Location: Reading Pennsylvania
|
|
| Back to top |
|
|
?Waldo?
Samba Member
Joined: February 22, 2006
Posts: 9752
Location: Where?
|
| Posted: Fri Oct 08, 2021 2:40 pm Post subject: Re: Is this a sign of a bad coolant pressure cap? |
|
|
I don't see how this has anything to do with the OP's system which is stock.
If you are pushing coolant out of the pressure tank and drawing air into it, then you have an air leak between the pressurized system and the burp tank. Install a clear line. I have tygothane (versilon) for that line on mine. It will make it more obvious what is happening. |
|
| Back to top |
|
|
djkeev
Samba Moderator
Joined: September 30, 2007
Posts: 32632
Location: Reading Pennsylvania
|
| Posted: Fri Oct 08, 2021 4:26 pm Post subject: Re: Is this a sign of a bad coolant pressure cap? |
|
|
| ?Waldo? wrote: |
I don't see how this has anything to do with the OP's system which is stock.
If you are pushing coolant out of the pressure tank and drawing air into it, then you have an air leak between the pressurized system and the burp tank. Install a clear line. I have tygothane (versilon) for that line on mine. It will make it more obvious what is happening. |
I think it does apply.
The OP was concerned about coolant exiting the pressure tank into the expansion tank but not returning on cool down.
This has evolved to discussion about if an air pocket in the pressure tank as being normal or not.
Mine tends to favor a low level, I don’t care if the tank is plastic, steel or aluminum…… it’s a tank with a pressure cap.
Why is there a constant “happy” so called “low” coolant level in certain vehicles?
Some folk empirically say “No!” “It is Impossible!” Yet others are living with a “low” coolant level without any harm.
I’m monitoring my air bubble. If it remains constant …….. what’s the harm?
I’ve spent a lot of time topping off my pressure tank only to suck the accumulated coolant out of the expansion tank when the level rises to the fill cap or above.
Dave
_________________
Stop Dead Photo Links how to post photos
Ghia
http://www.thesamba.com/vw/forum/viewtopic.php?t=392473
Vanagon
http://www.thesamba.com/vw/forum/viewtopic.php?p=6315537#6315537
Beetle
https://www.thesamba.com/vw/forum/viewtopic.php?t=482968&highlight=74+super+vert |
|
| Back to top |
|
|
?Waldo?
Samba Member
Joined: February 22, 2006
Posts: 9752
Location: Where?
|
| Posted: Fri Oct 08, 2021 4:29 pm Post subject: Re: Is this a sign of a bad coolant pressure cap? |
|
|
| djkeev wrote: |
I’m monitoring my air bubble. If it remains constant …….. what’s the harm?
I’ve spent a lot of time topping off my pressure tank only to suck the accumulated coolant out of the expansion tank when the level rises to the fill cap or above. |
Then you should identify and fix the leak that is between the pressure tank and the burp tank. I gave what I would use as step one in my last post.
One aspect of harm is that you already stated that your level sensor is not working. If you have a catastrophic coolant leak, you will not get any additional warning. An additional harm is that it is a solid indication that you have one or more causes of air infiltration into your cooling system and a change in the amount of leakage will be hard to tell whereas completely full is easy to tell. Another additional harm is that if the level drops low enough, it could result in your temperature gauge no longer giving any warning of overheating. In the 2.1 if the gauge temperature sensor is not submerged it reads the temperature of the plastic it is mounted in which is a big insulator of heat and makes the temperature gauge reading meaningless. |
|
| Back to top |
|
|
djkeev
Samba Moderator
Joined: September 30, 2007
Posts: 32632
Location: Reading Pennsylvania
|
| Posted: Sat Oct 09, 2021 5:46 am Post subject: Re: Is this a sign of a bad coolant pressure cap? |
|
|
Yes, I'm aware of my coolant level light....... I'm on top of it. There are folk way smarter than I running my very tank without any coolant level indicator at all.
Thanks for your concern.
There is indeed something going on....... and I'm obviously not alone which is why I'm pursuing this here for everyone to read, see...... and laugh if they must.
Today I'll double check my return vent hose to make sure it is good.
I do wonder if my coolant cap is functioning properly too. I'll take a look at that as well.
I think I have another cap lying about that I'll try to locate.
If Not I'll pick up a 16lb Stant 10230.
I agree it should be full but the harsh reality is that it isn't.
I do wonder if the level it consistently sinks to is the expansion quantity of coolant expelled when hot.
I wonder if my system is working much like an old Chevy storing the expansion bubble in the top of the radiator tank?
I haven't checked for air in the radiator bleed screw yet but there are zero running hot indications.
Heat is good and the cooling fan operates as it should.
Dave
_________________
Stop Dead Photo Links how to post photos
Ghia
http://www.thesamba.com/vw/forum/viewtopic.php?t=392473
Vanagon
http://www.thesamba.com/vw/forum/viewtopic.php?p=6315537#6315537
Beetle
https://www.thesamba.com/vw/forum/viewtopic.php?t=482968&highlight=74+super+vert |
|
| Back to top |
|
|
?Waldo?
Samba Member
Joined: February 22, 2006
Posts: 9752
Location: Where?
|
| Posted: Sat Oct 09, 2021 8:26 am Post subject: Re: Is this a sign of a bad coolant pressure cap? |
|
|
| djkeev wrote: |
| I do wonder if the level it consistently sinks to is the expansion quantity of coolant expelled when hot. |
From what you describe, yes, of course it is. Then instead of drawing coolant back in when it cools it pulls air in from somewhere, and it shouldn't.
| Quote: |
| I wonder if my system is working much like an old Chevy... |
Yup, probably, and it shouldn't. The system is not designed to pull air in, it is designed to pull coolant back in.
It could be that there is an issue with the pressure cap. The negative pressure required to properly open the stock vanagon cap and pull coolant in is very low. If your cap has a higher vacuum requirement for pulling coolant back in, it could be exacerbating a leak somewhere less noticeable (e.g. at the heater core) and the air is ending up in the pressure tank as it should but is not being purged as it should. That sort of situation may not cause any additional problems, until it does so in a dramatic way. |
|
| Back to top |
|
|
djkeev
Samba Moderator
Joined: September 30, 2007
Posts: 32632
Location: Reading Pennsylvania
|
|
| Back to top |
|
|
|
