New owners often find themselves mystified by the cooling system of the Vanagon. Which is understandable, considering that it’s kind of an oddball setup.
A little historical context and a quick tour should help ‘splain things.
Most water-cooled cars, including the one you probably use as a grocery-getter, has the engine up front, right behind the radiator. So, the entire drivetrain is in one compact package.
Like all previous Volkswagen vans, the Vanagon/Transporter’s engine is located in the rear of the vehicle. But, unlike all previous Volkswagen vans, the 1983-and-later Vanagons are water-cooled.
A water-cooled engine relies on a radiator to dissipate heat, and the best location for a radiator is out front in the stream of fresh, cool air. To connect this rear-mounted engine to this front-mounted radiator there is a pair of long steel or plastic pipes running the length of the Vanagon’s underside.
In this regard the Vanagon/Transporter is indeed an odd duck, but at least it’s in good company; other notable production vehicles to utilize this unusual arrangement are post-1998 Porsches and the DeLorean DMC-12.
This design also calls for a separate coolant expansion tank and a coolant reservoir located near the engine in the rear, and here is where much of the confusion commences …
Overview
Let’s take a quick lap through the Vanagon cooling system.
When you fire up that little waterboxer or diesel and hit the road, excess heat from the cylinder heads is immediately transferred to the liquid coolant, which the water pump circulates back through the cylinder jackets & heads again, in a short closed loop. This prevents over-cooling and helps the engine quickly warm up to proper operating temperature.
Once the coolant reaches about 190˚F (87˚C), the thermostat opens and begins routing coolant via the long coolant pipe way up to the radiator. Here, fresh air draws away the excess heat, and the now-relatively-cool coolant goes back to the water pump and engine via the return pipe, completing its circuit.
Expansion Tank
Like any liquid, engine coolant expands as it is heated. As the name implies, the Expansion Tank manages this expansion; a pressure-sensitive valve built into the tank cap allows excess coolant to vent via a small hose to the Refill Tank. In a well-functioning closed system, the Expansion Tank will always be completely full of coolant, with no air space.
The Expansion Tank also has a built-in coolant level sensor, which detects a low fluid level and triggers a flashing red warning light in the dashboard temperature gauge. This same warning light may also be triggered by separate coolant temperature sensors, located elsewhere.
Refill Tank
This excess coolant flows to the Refill Tank, located just inside the license-plate access door, and which serves as a coolant reservoir. When the engine is turned off and begins to cool, the coolant in the system now contracts, and an equal amount is drawn back into the Expansion Tank from the Refill Tank. The Refill Tank’s volume will rise and fall with coolant temperature, between the MAX and MIN marks.
NOTE: These tanks are often and variously referred to by owners and even by the vaunted Bentley Workshop Manual as the reservoir, pressure, overflow, or burp tanks, sometimes interchangeably, which certainly doesn’t help matters. Expansion and Refill tanks are the terms most consistently used in both the Owners Manuals and the Bentley.
Heater Circuit
In addition to these basic system components, there is also a heat exchanger located inside the dashboard, with standard controls on the front dash panel, as well as a secondary heating element beneath the rear bench seat.
When the dash temperature control is set to “Warm,” a valve is opened, directing hot coolant from the engine to the heat exchangers to provide warm air for the cabin. This coolant is then routed back to the Expansion Tank for re-distribution.
Self-Bleeding Basics
In a later article I’ll cover how to properly bleed the cooling system of all air bubbles after a coolant change or other work. But, it may be helpful here to understand the interaction of the Expansion and Refill Tanks in daily operation.
Though in theory a closed loop, the Vanagon’s cooling system can sometimes develop bubbles or pockets of air, caused by incomplete bleeding following a coolant replacement, a leaking hose or clamp, or by a failing cylinder head gasket allowing exhaust gases into the cooling system.
These air bubbles will tend to (but not always) make their way to the coolant Expansion Tank, where normal operating heat and pressure will usually expel them to the Refill Tank.
As any child with poor table manners knows, a drinking straw in a glass of chocolate milk allows bubbles to be blown into the glass, but only liquid can be drawn back up. This is exactly how the Vanagon Refill Tank functions; it accepts both coolant and errant air bubbles from the Expansion Tank when hot, but sends back only liquid coolant as the system cools. In this regard, the Refill Tank functions as a sort of one-way valve, serving to ‘self-bleed’ air bubbles out of the system to a great degree.
I hope this clears up some of the common questions about the Vanagon cooling system!
would like to se articles about how to get A/C to work. And does it really take power away when on. I have had mine looked at three times over the years. They put it in, its gone in two days. Leak somewhere that no one ever finds. 90 Westy.
Ken, generally speaking, the air conditioner on any vehicle is powered by the engine, so anytime the A/C is turned on it will indeed place an extra burden on the engine and reduce power to the wheels. Most modern engines are somewhat larger and more powerful than that of the Vanagon, and most passenger cars are also lighter in weight, so this loss of power may not be as noticeable in other cars. It may help to temporarily turn the A/C down or off when climbing steep mountain grades to increase engine power.
As for your recurring leaks, I assume you’re referring to the R-134A refrigerant. While most shops are probably happy to continue charging you to refill your A/C system, you need to find a shop with the appropriate tools to test the system to find the leak(s), then make recommendations on repair. Likely culprits are the condenser, compressor, or hoses. If it leaks down in only a couple of days, it’s probably a significant leak and should be easier for a good A/C tech to find.
Hope this helps!
Jeff
Would any good a/c place be able to work on it or do I need only a Vw guy? Not many in th.e Lehigh valley
In general, I always prefer to go to a VW specialist whenever possible. If you haven’t already, I suggest checking out the VW van mechanics recommended by members of VanAlert. I found at least 2 VW shops in your area, and there may be more.
Once you login or open a new account, you can search mechanics by city/state, and the mobile app automatically helps you find shops, campsites, and helpful members while you travel.
If you can’t find a suitable VW shop in your area, a good A/C specialist may be able to help. The only big difference between a Vanagon and most other cars is that the A/C system is split up because of the rear-engine configuration, so the tech will need to follow the refrigerant lines to keep himself straight. Maybe leave your Bentley manual with the tech while he’s working on your van, to help him figure stuff out.
Good luck!
I have a 1983.5 Vanagon with pop top. It’s the first water cooled engine. The dealer put on a Behr AC system. The AC is in-dash (not up above like other later models). Im replacing the whole system with a new condenser, TXV, filter, etc. The system was missing an AC compressor when I bought it, so Im buying a new enhanced compressor. My question is, does anyone know how much oil in the AC system I should start out with? Since it’s an in-dash system, there are long hoses to and from the dash.
As we all know with the 1986 Vanagon, the radiator in the front creates a lot of heat and especially in the summer heat heats-up the driving compartment significantly.
I thought about diverting the water away from the driver compartment to minimize the heat experienced in the summer time.
I sure would like your help in how to do that?
Sam
Sam, the problem you describe is true of all the water-cooled Vanagons/Transporters, and can indeed allow a lot of heat into the cab.
There are three main causes:
1. Heat being drawn away from the radiator body in turn heats up the ‘tunnel’ in the bodywork immediately behind the radiator, and this heat seeps into the cab; it’s often referred to as “Vanagon Hot Foot Syndrome.” Pages 19.20 – 22 of the Bentley manual show some solutions for this, and GoWesty offers a nice kit for some of the components. You may also want to cover the bodywork behind the radiator with foil bubble-wrap insulation, as discussed here: https://www.thesamba.com/vw/forum/viewtopic.php?t=237271
2. Some hot air leaks into the cab through the floor opening for the accelerator cable; make sure this area is well insulated and sealed.
3. An old and faulty control valve for the front heater may allow hot coolant through the heater even when turned off. Replace the valve with a newer, better valve which more definitely stops the flow:
https://www.thesamba.com/vw/forum/viewtopic.php?p=8633172&highlight=ford+valve#8633172
Hope this helps!
Jeff
Jeff, once again a great article for all of us. I do want to say that owners of older, less maintained Vanagon should replace those original VW plastic pipes coming from the radiator to the engine with stainless steel pipes. And try to replace, instead of just flushing, an old original radiator. These two things made a huge difference in my cooling system of my ’86.
Thanks, Larry!
Yes, because of the very small chambers inside the radiator, this is where hard-water deposits and other contaminants tend to collect, and where they unfortunately can have the worst impact on the functioning of your cooling system, causing overheating.
Owners who are unsure of the maintenance history of their Vanagons should inspect all the components (hoses, pipes, pump, etc.) for visible corrosion or leaks, and replacing the old inefficient radiator would be a great place to start.
Watch for more tech articles on these topics and more!
Jeff
I Brian gode had a 1988 vanagon that was the worst antifreeze leaker I ever knew of after now just seeing on this I pad what I was told I learned more on this I use to clean car shops learned plenty from all automakers any where in the world they all make good bad whatever autos parts some of the worst seen was with drivers owner stupidity no one could not doing proper maintain everything on time only things when they can not use the vehicle or use it but it is very worn on brakes or otherwise some problems are they way it is made or the most unsafe is how the nut behind operates the vehicle if one wants a safe one park it anywhere wreck the motor so it could not be driven I was once a freelance news camera man newspaper reporter I have seen it all with auto crashes who would only believe them seeing the real scene or proper photos worst is drunks drugs alcohol or what who knows one guy had more needle marks in his whole body cops there told me not that many drugs at four locos drug stores or needles in a pin cushion see street uses at dry cleaners sewing have a nice day if
Thanks Jeff, for all these helpful articles. Super informative. As a newbie to Westfalias and auto repair in general, I really appreciate them. Thanks!
Joe,
Thanks, glad you found it helpful! Planning to add more tech and travel articles, but feel free to send any ideas for future topics.
Keep on vannin’!
Thanks for the article- follow up / basic question-
Do I check the coolant levels based off of what’s in the refill tank when the engine is cold? And if it’s low, do I open up the expansion tank and add coolant in there?
The coolant level in the Refill Tank can be checked either hot or cold, though of course the results will be different:
When cold, the coolant level should be be somewhere between the MIN and MAX marks.
When hot, the coolant level should be slightly above the MAX mark.
Generally speaking, additional coolant should be added to the Refill Tank in order to bring it up to the proper level. But if there is a large air bubble in the Expansion Tank, coolant should be added there, but ONLY when the engine is cold and the pressure cap can be safely removed. Ideally, there should be NO air in the Expansion Tank.
Watch for an upcoming article on draining, refilling, and bleeding the Vanagon cooling system!
Does this help?
Very helpful, thank you!
Man! Thanks so much for the cooling system clarification. I’m on vanagon number 3. It’s an 87. A plastic T just behind the rear heater just broke today on a trip. Yeah – fun. We fixed it in some parking lot. And it only took the entire day!😁 Anyway, all these years, and three vanagons later, I read that I’ve had the purposes of the two tanks reversed. I’ve always kept the expansion tank a little over 3/4 full ( yep 1/4 full of air) and the refill tank pretty much empty. I can’t believe it. So – thanks for the clarification!!!!
Great, glad to help!
It’s a pretty unique system, with a few quirks, so I’m glad you got it working.
Keep on vannin’!
I think I bled all of the air following the repair of the plastic T behind the rear heater. As i was replacing the broken one, I noticed that there are actually 2 Ts. Is it possible to remove my back heater and replace the two Ts with straight metal couplers of some sort before the other T blows out. I never use the heater back there and I never will. I’d rather have the storage space… thanks!
Yup, and GoWesty makes a slick little kit for exactly that. Make sure you follow their installation instructions to avoid impacting the function of your front heater.
https://www.gowesty.com/product/bundles-and-kits/23996/rear-heater-delete-kit-?v=
Good luck!
Great! Thanks so much for your time!
Thanks for this article. I have an ’82 Diesel Westy and I’m currently trying to troubleshoot my cooling system. I run hot normally, since I’ve purchased the van. According to the gauge – about 1 needle or so beyond midline, basically all the time. It might go up slightly on a long grade but always comes back down going downhill to my ‘normal’. I bled the radiator today, and under the screw it was clogged, so I’m thinking it’s likely that the radiator might also be clogged up. Coolant levels are all good/stable. I’ve only driven it in cooler temps (purchased in late October in PA). It looks like I’m going to be attempting to replace the radiator with the newer 83+ option, which will require some modifications. Any tips/input would be greatly appreciated!
Hi, Nicole!
Actually, your temp gauge behavior sounds normal for a diesel Vanagon; most run at about 60% on the gauge, rising and falling with hills, slow traffic, or heat. Still, a 38-year-old radiator is likely becoming clogged with sediment and minerals, so should be preemptively replaced to avoid overheating your engine.
To replace the 1982 diesel radiator with the newer radiators available now, you’ll need the ’83 lower radiator mounting brackets, the later fan shroud, and a temp sensor for the later type radiator. It may also require a bit of rewiring of the temp sensor harness. You’ll also need to fabricate the upper radiator brackets, but these are very simple aluminum bars and don’t carry any weight.
The 1986+ radiators have larger hose connections, and now is a good time to replace both 38-year-old hoses too. You’ll need a pair of these adapters to fit the new 1.5″-diameter hoses to your old 1.25″ pipes:
https://www.vancafe.com/VCHOSEADAPTER-p/vchoseadapter.htm
Aside from that, swapping is fairly straightforward; here are a couple of write-ups:
https://www.vanagain.com/article/how-to-remove-and-replace-your-radiator-in-an-87-91-vanagon
https://shufti.blog/2011/11/page/2/
Final coolant bleeding is covered near the end of this article:
https://www.vanagononline.com/articles/water-pump-replacement-for-1-9l-waterboxer-vanagon/
Hope this helps!
Jeffrey,
My ’82 is constantly overheating, but I must confess it has a Chevy 350 V8. The sealed VW system seems to function but rapidly exceeds 200 degrees F and boils into the expansion tank or blows off a hose due to excess pressure. I have read at least one hundred articles on the thermostat and how important it is to regulate both engine and coolant temps. I have tried a 170 F and 180 F and 187 F version for the GM 350 thermostat. Still overheating. Recently I risked running without the thermostat, and the engine temp settled quickly around 180 degrees F. The constantly flowing coolant is also from 180 F near the output of the engine to 140 near the front radiator and return lines. Is it possible my setup might the rarest of occasions where a thermostat is useless? I am getting moderate but consistent blowoff to the expansion tank this way, but not overheating, underheating, or seemingly causing any other problems. Engine performance seems good.
Scott,
The Vanagon cooling system is somewhat overbuilt and typically offers more than sufficient cooling capacity for the stock engines. But a small block Chevy V8 is nearly three times as large as the largest stock Vanagon engine, and may simply be too much for the cooling system.
Though I am reluctant to guess whether there is any chance the stock cooling system has even a chance of providing sufficient cooling for that engine, here are a few things to look into:
1. The routing of the stock cooling system is quite complex; be sure it is connected to the engine correctly.
2. Insufficient coolant flow; a small or weak pump (or one that is rotating backwards!) will not move enough coolant through the cylinder heads fast enough to absorb sufficient heat and draw it away.
3. Even a strong, stock Chevy 350 pump may not be well suited to push 4.5 gallons of coolant through the sheer length of the Vanagon system. And certainly not a system constricted by incorrect routing or old mineral deposits, etc..
You may find more helpful answers from Vanagon owners with more engine-conversion experience on the Samba Vanagon discussion forum:
https://www.thesamba.com/vw/forum/viewforum.php?f=20
Hi Jeffrey,
Thanks for putting out all this info on vw cooling. I have a1989 vanagon camper and the light is flashing in the temp indicator area on the dash. It can take 20 min driving from engine start to flash or it can flash when the engine has only run a minute or so from cold start. There is more:
When this first started the expansion (blue cap) tank coolant level was MIN and the refill tank was empty, and the engine was cold. I filled the refill tank to MAX and let the engine idle for about 5 min. The light flashed continuously.
Checking the tanks again, both were empty. I had to remove the exp tank cap to verify the coolant level. 15 min later they both were still empty. During this time the engine was off.
I filled the refill tank again to MAX and decided to drive the car for 20 min both on the freeway and on city streets. The light Flashed on and stayed flashing about 18 min later as I was decelerating on the freeway offramp. At home with the engine off i waited 10 min to check levels. Both tanks were empty and the exp tank was barely warm. Another check 10 min later showed the same status.
From the beginning i’ve been checking the road and under the van for leaks after each trial. I also checked the heater compartment area under the bench seat. Nothing. I have added coolant only to the refill tank. Could I have upset the pressure balance of the closed system by opening the exp tank? But the light was flashing before i opened the exp tank.
Do you have any suggestions for other things to check. OR do you know whats wrong? Thanks.
1. Stop driving the van until you or a helper are able to completely refill the coolant system and bleed all air bubbles from it. Continuing to drive it without coolant in the Expansion tank, especially with the warning light flashing, runs serious risk of overheating and possibly permanently damaging the engine.
2. Both tanks should always be nearly full: the Expansion tank full, and the Refill tank filled to the MAX mark. From your account, it seems that at no time have you refilled the Expansion tank before driving it, meaning the engine has been running without benefit of its vital coolant.
Keep in mind that the ONLY time the Refill tank is able to ‘refill’ the system is AFTER the vehicle has been driven, and is cooling down. Refilling the Refill tank but neglecting to refill the Expansion tank, and then driving the vehicle, risks permanent damage.
3. It’s possible that that coolant loss has been caused by a small undetectable leak, and completely refilling and bleeding the system will restore things to normal. You’ll still need to find the leak, but at least the engine will have been saved.
Here’s some info on general troubleshooting the Vanagon cooling system:
https://www.thesamba.com/vw/forum/viewtopic.php?t=629012
And some info on bleeding the system after refilling:
https://www.thesamba.com/vw/forum/viewtopic.php?t=694264&highlight=bleeding
Good luck!