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jbhurley92
Samba Member
Joined: October 02, 2019
Posts: 121
Location: NC
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 Posted: Wed Jun 07, 2023 1:09 pm Post subject: Re: 85 Vanagon pressure in pressure tank while cold |
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| Wildthings wrote: |
| DuncanS wrote: |
Take an old pressure cap and destroy the spring seal. Refill the system and see what happens.
Duncan |
Keep a drilled cap in the glove box as a limp home device. |
Could you take a picture of the piece of need to break? |
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fxr
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Joined: December 07, 2014
Posts: 2325
Location: Bay area CA
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| Posted: Wed Jun 07, 2023 1:34 pm Post subject: Re: 85 Vanagon pressure in pressure tank while cold |
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| jbhurley92 wrote: |
| djkeev wrote: |
If coolant is coming out, it can't be holding pressure.
The very act of pushing out coolant is releasing system pressure.
What am I misunderstanding here?
Unless your tank behind the license plate has a crack it it. This is the only location that could leak coolant and you don't experience a loss of coolant. |
What I am saying is currently with the new cap it isn't pushing to the overflow but when I park the van and let it sit then open the pressure cap it hisses and coolant comes pushing out. |
Which shouldn't be happening. As the coolant cools and contracts, it should suck coolant back from the reservoir to the main tank, and remain at or slightly below ambient pressure.
NOT above ambient. 
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1984 1.9l EJ22 Westy Wolfsburg Edition
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djkeev
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DuncanS
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Joined: October 17, 2013
Posts: 4583
Location: New Hampshire
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| Posted: Thu Jun 08, 2023 7:38 am Post subject: Re: 85 Vanagon pressure in pressure tank while cold |
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The center part has been totally removed with a Dremel or whatever you have at hand.
When you can blow and suck equally by sticking the outlet tub in your mouth, you will have accomplished what you need.
Fill the pressure tank full and put the correct amount in the overflow tank, but do not put the overflow tank cap back on. Drive around until the engine is up to temp and see what the overflow tank look like. It should be almost overflowing. Then let the car sit overnight and inspect the overflow tank in the morning. If there is more coolant in there than you initially put in, then you have an exhaust leak pressurizing the system. If all is OK, then just put the regular caps back on and drive. Everything should be OK.
Duncan |
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Wildthings
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Joined: March 13, 2005
Posts: 50350
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| Posted: Thu Jun 08, 2023 9:58 am Post subject: Re: 85 Vanagon pressure in pressure tank while cold |
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A 1/4" diameter hole drilled through the bottom side of the cap is all that is needed. You just want to make it so the cap can not hold pressure, yet still dumps into the overflow tank. If you can blow both ways through the cap when done, you have accomplished what you want to do.
I will try to find an old cap to photograph, but since I moved to an aluminum pressure tank I no longer keep a modified blue (or black) cap in the glove box. |
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DuncanS
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Joined: October 17, 2013
Posts: 4583
Location: New Hampshire
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| Posted: Thu Jun 08, 2023 11:54 am Post subject: Re: 85 Vanagon pressure in pressure tank while cold |
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| Wildthings wrote: |
| A 1/4" diameter hole drilled through the bottom side of the cap is all that is needed. |
That's what I thought too, but not that easy. It turns out that the spring loaded seal started spinning around and the drill couldn't make it through. So I had to drill all around the metal spring loaded seal and then rip it out and get rid of the spring. Thought it was a 15 second job, but turned out to be ten minutes.
Duncan |
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jbhurley92
Samba Member
Joined: October 02, 2019
Posts: 121
Location: NC
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| Posted: Fri Jun 09, 2023 2:38 am Post subject: Re: 85 Vanagon pressure in pressure tank while cold |
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| djkeev wrote: |
Sit for how long?
Stone cold over night?
Or just a few hours? |
Stone cold.
Yesterday I took it on a 3 hour highway drive. Drove great never overheated coolant overflow went up maybe a 1/4 inch let it sit over night and I cracked the top and my coolant comes pushing out
And it's not a little bit it's a lot.
I spent 2 hours at my friend's house the day before bleeding it since his driveway has a nice hill.
This just doesn't make sense. |
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jbhurley92
Samba Member
Joined: October 02, 2019
Posts: 121
Location: NC
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| Posted: Fri Jun 09, 2023 3:00 am Post subject: Re: 85 Vanagon pressure in pressure tank while cold |
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| DuncanS wrote: |
The center part has been totally removed with a Dremel or whatever you have at hand.
When you can blow and suck equally by sticking the outlet tub in your mouth, you will have accomplished what you need.
Fill the pressure tank full and put the correct amount in the overflow tank, but do not put the overflow tank cap back on. Drive around until the engine is up to temp and see what the overflow tank look like. It should be almost overflowing. Then let the car sit overnight and inspect the overflow tank in the morning. If there is more coolant in there than you initially put in, then you have an exhaust leak pressurizing the system. If all is OK, then just put the regular caps back on and drive. Everything should be OK.
Duncan |
Exhaust leak or combustion leak? |
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jbhurley92
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Posts: 121
Location: NC
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| Posted: Fri Jun 09, 2023 3:43 am Post subject: Re: 85 Vanagon pressure in pressure tank while cold |
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Here is a picture after opening the cap after the van sat for 10 hours.
Like I said it drove great for a 3 hour highway ride to pick something up well besides getting about 16 mpg.
Overflow had maybe went up a little less than a 1/4 inch but when I open my pressure cap here comes my coolant.
I'm starting to lean towards this new cap being garbage because I took it off and blew through and then sucked and it felt like I could suck some through.
Or could my thermostat be stuck open and cause a down push from the radiator and do this? |
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dabaron
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| Posted: Fri Jun 09, 2023 4:38 am Post subject: Re: 85 Vanagon pressure in pressure tank while cold |
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the pressure is a gas in the system. is it air or combustion products, i'm not sure, but you have something holding pressure that is not an expanded liquid.
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jbhurley92
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Posts: 121
Location: NC
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| Posted: Fri Jun 09, 2023 4:51 am Post subject: Re: 85 Vanagon pressure in pressure tank while cold |
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| dabaron wrote: |
| the pressure is a gas in the system. is it air or combustion products, i'm not sure, but you have something holding pressure that is not an expanded liquid. |
Could It just be lots of air in the system from not bleeding enough? |
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fxr
Samba Member
Joined: December 07, 2014
Posts: 2325
Location: Bay area CA
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| Posted: Fri Jun 09, 2023 5:32 am Post subject: Re: 85 Vanagon pressure in pressure tank while cold |
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| jbhurley92 wrote: |
| dabaron wrote: |
| the pressure is a gas in the system. is it air or combustion products, i'm not sure, but you have something holding pressure that is not an expanded liquid. |
Could It just be lots of air in the system from not bleeding enough? |
But how could that air remain pressurized when the van was cold, as it doesn't enter it under pressure? Exhaust gases however go in under pressure when a gasket is compromised, and the cap will only vent into the overflow above a certain pressure. When the engine is cold, there will be some remaining pressure that isn't enough to vent, but will push out the coolant until the pressure equalizes again to ambient.
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1984 1.9l EJ22 Westy Wolfsburg Edition
Vespa GTS 300 |
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jbhurley92
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Joined: October 02, 2019
Posts: 121
Location: NC
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| Posted: Fri Jun 09, 2023 5:39 am Post subject: Re: 85 Vanagon pressure in pressure tank while cold |
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| fxr wrote: |
| jbhurley92 wrote: |
| dabaron wrote: |
| the pressure is a gas in the system. is it air or combustion products, i'm not sure, but you have something holding pressure that is not an expanded liquid. |
Could It just be lots of air in the system from not bleeding enough? |
But how could that air remain pressurized when the van was cold, as it doesn't enter it under pressure? Exhaust gases however go in under pressure when a gasket is compromised, and the cap will only vent into the overflow above a certain pressure. When the engine is cold, there will be some remaining pressure that isn't enough to vent, but will push out the coolant until the pressure equalizes again to ambient. |
I see what you are saying but I just drove it on the highway for 3 hours at 65-70 mph wouldn't that push most of my coolant into the overflow?
My levels didn't look like they changed at all. |
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dabaron
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Joined: June 21, 2018
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Location: Philly, mang
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| Posted: Fri Jun 09, 2023 5:55 am Post subject: Re: 85 Vanagon pressure in pressure tank while cold |
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| jbhurley92 wrote: |
I see what you are saying but I just drove it on the highway for 3 hours at 65-70 mph wouldn't that push most of my coolant into the overflow?
My levels didn't look like they changed at all. |
try this... get the engine up to operating temp by driving around for 15 minutes and then let it sit for 1 hour. after that hour has passed, open the bleeder on the radiator, does coolant or "air" hiss out?
if "air" comes out repeat this cycle a few times. if "air" keeps coming out of the radiator bleeder you most likely have combustion gases in the coolant.
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1991 Vanagon GL Camper
i had no idea i wanted to be a mechanic
"burnin oil and cookin coils" -- Destructo
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jbhurley92
Samba Member
Joined: October 02, 2019
Posts: 121
Location: NC
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| Posted: Fri Jun 09, 2023 6:00 am Post subject: Re: 85 Vanagon pressure in pressure tank while cold |
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| dabaron wrote: |
| jbhurley92 wrote: |
I see what you are saying but I just drove it on the highway for 3 hours at 65-70 mph wouldn't that push most of my coolant into the overflow?
My levels didn't look like they changed at all. |
try this... get the engine up to operating temp by driving around for 15 minutes and then let it sit for 1 hour. after that hour has passed, open the bleeder on the radiator, does coolant or "air" hiss out?
if "air" comes out repeat this cycle a few times. if "air" keeps coming out of the radiator bleeder you most likely have combustion gases in the coolant. |
It definitely does. I mean I spent +1 hour bleeding it the other day. Just sucks I'm leaving Tuesday for a 7 hour drive to Bonnaroo. |
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jbhurley92
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Posts: 121
Location: NC
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| Posted: Fri Jun 09, 2023 6:03 am Post subject: Re: 85 Vanagon pressure in pressure tank while cold |
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| dabaron wrote: |
| jbhurley92 wrote: |
I see what you are saying but I just drove it on the highway for 3 hours at 65-70 mph wouldn't that push most of my coolant into the overflow?
My levels didn't look like they changed at all. |
try this... get the engine up to operating temp by driving around for 15 minutes and then let it sit for 1 hour. after that hour has passed, open the bleeder on the radiator, does coolant or "air" hiss out?
if "air" comes out repeat this cycle a few times. if "air" keeps coming out of the radiator bleeder you most likely have combustion gases in the coolant. |
It's just strange though because with my other coolant caps if I drive around for awhile all of my coolant will be in my overflow but with this one
That doesn't happen that's what I'm not understanding |
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djkeev
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jbhurley92
Samba Member
Joined: October 02, 2019
Posts: 121
Location: NC
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| Posted: Fri Jun 09, 2023 6:13 am Post subject: Re: 85 Vanagon pressure in pressure tank while cold |
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| djkeev wrote: |
New parts....... especially the plastic "radiator" caps are often crap.
It has been said about the caps to buy three or four so you MIGHT find one good one in the lot!
These caps and the crap plastic tank is why I upgrade to a welded metal tank with a "real" radiator cap on it.
Dave |
I'm seriously thinking this cap is just holding pressure and sucking it in also maybe it's got a crack on it.
Because of I had a leak driving wide open for 3 hours my coolant levels should move..
Also when it first came I could blow throw it and not suck but now I can suck some air through and it's a month old. |
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Wildthings
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| Posted: Fri Jun 09, 2023 9:42 am Post subject: Re: 85 Vanagon pressure in pressure tank while cold |
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If you have enough coolant in the system it should self bleed the rest of the air pretty quickly. Like most I was a bit panicky when I firsts got a watercooled Vanagon 30+ years ago, and went through all the hoops in the books to bleed the engine. Pretty quickly I figured out one didn't need to raise one end, but after draining or serious loss of coolant to just crank the vent on the radiator and pour in whatever coolant one could before starting the engine, then dump in more coolant with the engine running until the pressure tank is full, and then block the throttle open until the level sucks down in the tank and dump in even more coolant, put on the cap and close the bleeder and let the system purge any remaining air as you drive.
While your cap may be bad, even with a bad cap the system should not have pressure once the system cools. |
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djkeev
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| Posted: Fri Jun 09, 2023 10:03 am Post subject: Re: 85 Vanagon pressure in pressure tank while cold |
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| Wildthings wrote: |
If you have enough coolant in the system it should self bleed the rest of the air pretty quickly. Like most I was a bit panicky when I firsts got a watercooled Vanagon 30+ years ago, and went through all the hoops in the books to bleed the engine. Pretty quickly I figured out one didn't need to raise one end, but after draining or serious loss of coolant to just crank the vent on the radiator and pour in whatever coolant one could before starting the engine, then dump in more coolant with the engine running until the pressure tank is full, and then block the throttle open until the level sucks down in the tank and dump in even more coolant, put on the cap and close the bleeder and let the system purge any remaining air as you drive.
While your cap may be bad, even with a bad cap the system should not have pressure once the system cools. |
While my experience is only about 10 years, I've come to the exact same conclusion.
I will add, if your system doesn't self bleed?
You've got a compromised system which needs repairs.
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