84 Vanagon Coolant/Head Gasket question

[trforfun]

I recently purchased an 84 vanagon. Don't have any maintenance history. It appears that there is air trapped in the coolant system. A knowledgeable VW mechanic thinks it could be a sign of a head gasket problem. The van runs fantastically so I'm thinking that since the vehicle was purchased through the "Drive Away Hunger" program from the Portland Rescue Mission that someone may have inadvertently opened the coolant reservoir that shouldn't be opened and allowed air to be introduced into the system. Any comments? I was given a somewhat complex method to test, flush and top up the radiator and get rid of the air. Any suggestions would be helpfu. Thanks.

[Jeffrey Earl]

Opening the expansion or reservoir tanks will not introduce air into the system, but replacing a hose or water pump (or a leak in one of those places) certainly will. After replacing the lost coolant, the offending air must then be bled out of the system.

I find bleeding is best done with the front of the van jacked up 12-18". Open the bleeder valve on the top of the radiator and run the engine up to temperature. When you have a steady stream of coolant flowing out the bleeder screw, tighten it down. Drive up and down a couple of steep hills to slosh loose any remaining air bubbles, jack up and bleed one final time. That's it.

Once you've expelled all the air from the system, it should stay out. If you need to continually and repeatedly fill and bleed, that suggests you're somehow getting air into your system. One probable cause may be a leak in a hose, radiator, or gasket that allows air to be sucked into the system during cooldown. Or perhaps you've simply allowed the coolant reservoir hidden behind the license plate to run dry. Or perhaps a dreaded head-gasket leak(!) is pumping air and combustion gases into a coolant passage in the engine block. You need to determine where your coolant is going and how the air is getting in there.

Browse here for more info:

http://westfalia.org/eve/ubb.x/a/tpc/f/91860355/m/2656012411

[trforfun]

Thanks for the info. A knowledgeable tech (who owns the same Vanagon) told me to jack up the BACK end 18 degrees, loosen the top bolt on rad., then with the engine at a constant 3000 rpm's, open the inner reservoir, disconnect the hose from that to the overflow tank, keep fluid level topped off as car runs, let it run until water coming out of front bolt is VERY hot, turn on all fans/heater valves in car, let run until rad. fans come on, after they turn off and then come on again, tighten bolt, close tanks and turn off the engine. What do you think of this method? --Bruce

[Jeffrey Earl]

In general, that sounds like good advice. The important thing is that you incline the van to encourage air bubbles to migrate to either end, where they can be bled out. (My diesel is a slightly different configuration and tends to self-bleed more easily, so I generally bleed only from the front.)

Whatever method you employ, be sure you replace the pressure cap on the expansion tank BEFORE reducing RPMs, otherwise the coolant will geyser up out of the tank and you'll have to add more.

When done bleeding, keep the coolant topped-up in the overflow tank behind the license plate and drive the van for a few days, preferably up and down a few hills, then re-bleed any residual bubbles out. Keep an eye on your coolant consumption; if it requires frequent and/or never-ending refills, you are either losing coolant thru a leak somewhere, or a leaking head gasket is allowing combustion gasses to force coolant out.

Good luck!

Jeffrey Earl
1983 diesel Westfalia "Vanasazi"
http://www.vanthology.com/

[weinerwagen]

I've never had a problem with any of my waterleakers, and diesels, burping out the air in the system EXCEPT.....on 1.9 I bought that was complete dry.
Once the system was refiled, it ran hot a few times while the system purged itself...

Put the nose up, burp the air from the radiator, then put the tail up, see if you can purge out the air...

If the head gaskets are leaking, (this is an old diesel trick), wait til the engine is stone cold. Overnight is best. Open the rear water reseviour, make sure the water is at the top or near the top. Fire the motor...if you see bubbles
when the engine is cold, you have a leaking head gasket. If you don't see any bubbles, and the thermostat opens once the engine warms up to temp, chances are, the headgaskets are not leaking INTO the water jacket. Of course, you can always crawl up under the engine and take a peak at heads. Anti freeze has an odour of its own....if you have a leak, pretty good chance you can smell it from outside the van
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Retired attorney--Tort King.

[Captain Pike]

Occasonally the heads will leak internally,sometimes hot sometimes cold.A pressure guage will tell if this is happening,look for little pluses on the needle that go away when the offending cylinder is shut down(remove plug wire)If it is really bad it will pulse out of the cap_nasty mess.
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LEARN TO SELF RESCUE
59 Panel bus, 1966 Single cab. 73' 181. 73 Westy. 91' H6 Vanagon 3.3L.
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