Coolant Level issues 88 Vanagon

[58Special]

Question about coolant levels between expansion tank and overflow tank, which seems to operate opposite to how we thought it is supposed to work. When our '88 Vanagon is driven with both tanks full, the coolant from the expansion tank fills the overflow higher than the filler cap, and the expansion tank level drops down enough so that the sensor comes on, causing the light to blink. Anybody out there that may have some ideas about what we are experiencing? We are new to The Samba, and really appreciate any ideas! thx

[bobhill8]

Hi - welcome.
First, when you say the overflow tank is "full", do you mean up to the line, or completely full?
Second, when the expansion tank fills with gas, you need to figure out if it is air or combustion gases. Do you know how/have you tried to bleed air out of the system?
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1986 Westy
1971 Squareback

[Wildthings]

Certainly try to bleed the system, as it is about the cheapest and easiest thing you can do. Unfortunately as other have already mentioned you may well have a combustion leak into the coolant which will take more than a little effort and $$$'s to fix.

[djkeev]

The tank in the engine compartment should always be full.
Usually to the top but some mention theirs is a half inch or so low.

If the engine compartment tank is pushing out its coolant into the license plate tank, that is normal to an extent.
But it should never push the license plate tank to over flowing. This tank has a max and min mark.

If your engine compartment tank is pushing out excess coolant .....

The cap is bad and not holding the 15 lbs or so of pressure it should hold.

You are running excessively hot

Or

You are pushing combustion gases past the fire ring at the top of the cylinders. This over pressurizes the cooling system.

Dave
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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

[lcolon]

Is the expansion tank (next to the engine) bubbling? (if so would indicate a combustion leak if all of the air has been bled out) If you rule out the cap being the issue (a cheap fix) then you can get a combustion gas tester from your local auto parts store.

It has some blue fluid in it that will change color if you are getting gases leaked into your cooling system.

If the bottle in the engine compartment is filled to the top, it will push some fluid into the overflow bottle behind the license plate when hot. It should, however, suck that fluid back into the expansion bottle as the vehicle cools. The overflow should always have fluid in it and not be dry.
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1984 Vanagon Westfalia - Vanna
1971 VW Beetle

[?Waldo?]

[4Gears4Tires]

Or a coolant leak that is sucking air into the system. Mine was the rear heater.
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'87 Syncro
Ferric Oxyhydroxide Superleggera Edition

[58Special]

Thank you all for responding, really appreciate the info. This is our first water cooled unit!! We have had many air cooled of all descriptions but are struggling with the learning curve on this beast. There aren't any reliable VW mechanics in our area so we are going at it on our own. We have bled the system, even used the pressure pump from GoWesty to help with the process and have noticed some bubbling in the expansion tank when the engine has been run for a while. The over flow tank is full to just below the filler hole and the expansion tank full to the top. Took off for a trip, everything seemed to be working fine. The dash light blinked for a couple of seconds and then went out, the temp dial, when warmed up was right in the middle of where the blinking light is located and off we go. Checked the coolant in the overflow tank when we stopped and it was away above the filler hole and the expansion tank was down enough that the dreaded blinking light started. Settled in for a night of camping, the overflow level came down a bit, seems like just enough for the blinking light to stop. The motor does not seem to be overheating at all. Some one has suggested that they noticed that we were emitting out of the exhaust. We are definitely not using oil, so I have been a bit puzzled about this observation. Could this be an indication of what you have indicated as a possible combustion leak?

[?Waldo?]

[MarkWard]

Test the main expansion tank cap. Next would be to put the pressure tester on the tank to see what pressure is building in the tank with the engine running. It doesn’t sound good. When and if coolant is forced out the tank cap, when the cooling system cools, coolant should be drawn back in. It’s normally not something that requires attention. That the main tank puked enough coolant to trip the light is not normal.
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[58Special]

The cap has been replaced, i have not checked the pressure in the expansion tank with the engine running.

My reference to oil is related to emitting out of the exhaust. If i have combustion leak would this push out through the exhaust?

[Wildthings]

All your combustion gases are supposed to go out your exhaust, what you don't want is for a bit of them to leak into the coolant. When the engine and exhaust are cold the hot water vapors in the exhaust may condense out as they cool and produce a visible vapor stream.

When the engine is cold, having the coolant level at the bottom of the cap in the refill tank is too high, and you will probably puke the excess coolant over time. All the Vanagons I have owned would puke the coolant down to where it would be at the lower mark once the engine cooled.

If you have a compression leak, you will probably be puking coolant either continuously or at least from time to time and have to add coolant frequently to keep the system full. It may also be frustrating to try to bleed the system if there is a steady source of gases entering the system.

[4Gears4Tires]

If you disconnect the line to the blue cap and put a catch can down in the engine bay, you can use that line to fill the catch can and drain the overflow tank.

Then, remove the blue cap and start the van. Have a buddy/S.O. hold the RPM at 3000 (you'll see the coolant level really drop) while you pour that drained off coolant back into the van. Replace the cap and then they can let off the throttle.

Really important note to whoever is holding the throttle: They can always go in for more throttle, but never can they let up on the throttle. If they let up, coolant shoots up into your face. They need to keep a steady foot. And you need to work fast because their foot won't be as steady as they think. Lol.

I had to do this every day when I tried to go on a multi state camping trip last year and my rear heater was sucking in air. Same exact symptoms as you describe.
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'87 Syncro
Ferric Oxyhydroxide Superleggera Edition

[58Special]

Thank you, i will try the fluid levels as described. I have had conflicting opinions about the levels, most have suggested to have both tanks full to the max. The unit runs very well otherwise, lots of power, quiet and dependable. The coolant issue seems to be the only problem we are having. I have removed the plugs to check for condition, they are burning clean. We have had to add coolant a few times over a two year period. Only found one leak at the short pipe on the front of the right side head(plastic), we replaced. You could smell coolant at times at the rear of the vehicle but could not find any leaks. This seems to have stopped. Not ever a drop of coolant under the vehicle. Have wondered where the coolant is going!

[58Special]

4gears4tires...interesting procedure, have not had this one suggested. I gather that you would need to fill the overflow tank back up after this revoramma exercise?

[4Gears4Tires]

No, you just let it drain until it's between the min/max marks.

[bobhill8]

Do your best to determine if it is air or exhaust gases. I was able to watch inside the tank and saw smoke. If it is air, it will just be bubbles. At some point you might want to do the test for peace of mind.

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1986 Westy
1971 Squareback

[4Gears4Tires]

^ Doing an exhaust gas leak test is great information.

I snapped some pics to show you how I did the daily coolant transfer. The benefit of doing this is that on long trips you are never losing any coolant. Just constantly transferring it back as it gets displaced. So you won't have to keep buying coolant. Obviously, you want to find the root cause of the issue.

1 gallon coolant bottle sits nicely below the reservoir. Coolant line to expansion tank in the bottle and draining.

Once the level is appropriate, reattach the line. Note the raised min/max markers near the cap.

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'87 Syncro
Ferric Oxyhydroxide Superleggera Edition

[58Special]

Wow, pic's are great. Top notch photography! I have our unit ready to try things out. One more latte and then get to her.

[MarkWard]

Working properly the main tank should be a net zero gain or loss. Any fluid that ends up in the reservoir should get drawn back into the main tank as it cools. If that's not happening, something is not sealing properly.
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