Former VWDieselParts.com Forum

I have a diesel vanagon with a brand new 1.9 TD engine. I'm having a problem with the van overheating at highway speeds. It runs just a needle width above normal around town, but on the highway it runs about 3/4 of the guage (210 deg to 230 deg). I've installed a new radiator and thermostat. What could be causing this?

Air in the system or a bad waterpump are a couple of scenarios.

Andrew

I have the same thing... I wonder if it isn't oil temp? Take a look at Bullisurfers... helps if you speak german.. my google link auto translates most of it.

http://www.bullisurfers.com/

look for their oil cooler thread. I dont know how important this would be compared to the expense of it... but if you figure it out please let me know.

What are highway speeds for you?..... 120kmph/70 erso mph?

You have checked for the things Andrew mentioned? How about a minute head gasket leak?

stv

I removed the water pump this week. It looks ok, no leaks and the impeller seems fine. As far as air in the system, I don't see any bubbles in the coolant when I bleed it, so I'm assuming that's okay.

As far as oil temp goes, I have read things about the oil cooler actually making the coolant hotter. I've always suspected that it's the oil temp raising my coolant temp, but don't know how to cure that. Would running full synthetic help?

What method of bleeding are you using? You need to get all of the air out of the radiator which is ABOVE the coolant filling tank.

Andrew

Yes the air in the rad reduces your van's cooling capacity by 1/3 to 1/2 if it has air in it.

Andrew how about your secret weapon! I am surprised you haven't post a picture of here......

Andrew Libby invented a great tool that costs $15 and works flawlessly for filling the van's cooling system. I made one and it work perfectly.

http://www.thesamba.com/vw/forum/viewto ... ing+stress
I hope you don't mind I make the link......

By all means post the link anywhere you like. I was just lazy enough to not go searching.

Not only does the air a pocket of air in the radiator reduce the cooling capacity of the radiator, it also MASSIVELY reduces the function of the waterpump by making it do only PUSH rather than the cooperative PUSH-PULL of a properly bled system.

Andrew

I just did 6300 miles from the west coast to the florida back up into Kansas west thru Highway 40 back to Monterey in my Vanagon diesel---12 days

averaged 500 miles a day. The swampland in LA was nasty. I miss AC.

I run 160 thermostat in mine. With 180/185 thermo switch in the radiator

Also |I have manual over ride, the pull up into Flagstaff and back towing a small trailer works the hell out of the engine

Needle NEVER went beyond the middle...even with my foot into it, and towing

I am a fan of cooler running motors....maybe at 160,000 on the engine with only one headgasket at 22,000 the cooler running engine seems to be working for us

I see 210 at the head outlet on a hard pull, and usually 190 normally at highway speeds.

Was that a 1.9td your driving? These AAZ's can make a lot of heat eh?

Do you figure it out? Was it bleeding or water pump or oil temp or timing?

So you shoot a potato into it????

I keep it under the rear seat for a conversation piece in case my vehicle ever gets searched.

Andrew

an update would be appreciated; I just ordered a new old stock longblock AAZ from nevada for potential van installation come springtime!

Nevermind, that shady reputed group dis-allowed the purchase because they didn't like the auction's ending amount. Their response? "it was an error".

So they accidentally listed several dozen engines individually, with different ending times; yeah, right. Never buy from these peeps. BEWARE!

Several years ago replaced the 1.9aaz with a brand new aaz with the modified crank. Everything new and the motor ran about 15 degrees warmer than the old motor. People said the motor was tight, and that was the problem. Sensors changed, voltage stablizer in the dash, thermostat, even though these parts were all new. No solution found.

4 years later water pump leaks and is replaced. The new waterpump had a flimsly pressed tin blade as opposed the the heavy molded fins on the old one. Tried to exchange but this was the only water pumps they now sold.

Result, motor runs 15 degrees cooler. Friend noticed the same with his aaz as well. Make sure you have the newer style pump on the aaz.

I have an aaz in a 82 vanagon that was new old stock as a vw industrial power unit and the thermostat that came in it is the 160F so I left it. Talking with one of the reputable importers out in Cali said that all the vanagons in Germany run their rad fan switches at 160F as well so I put that one in. It's now summer and the fan is kicking on all the time and the needle sits right at a quarter. If I hop on the highway it will rest on he left side of the led. My question is for since we do mostly city driving, should I put back the 180-185 rad fan switch?