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I'm doing a top overhaul on a 79 Westphalia, because it was really overheated. I suspect the overheating may have been caused by a combination of a very hot day and ignition timing being off plus a driver with a heavy foot. I'll find out more after I get it running.
The bellows thermostat doesn't work and I can't find a replacement. The thermostat operates a flap arangement to control cooling air. On my engine it seems to open the passenger side flap and at the same time close the drivers side flap closing off air to the oil cooler.
To me it would make more sense if it opened both sides allowing air to flow through the cooler and over all of the engine fins.
Does anyone know, if I would be better off to leave both flaps open. Or maybe even remove them since the thermostat doesn't work anyway.This bus won't be driven during winter so I'm more concerned with getting enough cooling during summer.

Best to leave in place, even with the broken thermostat in the full open position. It is not hard even on an installed engine to R&R that part when you find one.

If you do decide to remove the thermostat assy, remove only the right flap for the left flap must remain, in the open position it diverts a lot of air over the oil cooler, with out it your oil will cook down. Also the tapped hole where the swivel for the cable attaches to the case needs to be plugged (bolt installed) or you will leak oil, not all cases were tapped trough, yours may or may not be.

Thanks for the input, I have put the engine back together and reinstalled it in the bus.
The biggest problem I now have is that it won't run. This bus has a long history and I'll ask for some input on the fuel injection in another post.

Al

germansupply.com has an article on how to modify a T1 thermostat for use on a T4 motor.

As for the flaps, they are held open by spring and closed by the thermostat. So if you thermo is shot it only means it takes longer for you motor to warm up. There is no need to remove the flaps, just make sure the spring is holding them open. THe left side with the oil cooler is a more complicated flap and you should check to make sure it is working properly. Unlike the right side which is connected directly to the shaft, the left flap pivots from the bottom and moves by means of a lever. I have had problems in the past where the mount of the lever assembly was't permitting the flap to full seat ontop of the oil cooler which is needed to direct air through the cooler. The left flap when open splits the air stream with some going over the flap to the cylinders and some going under the flap and forced into the oil cooler.

I have split my cooling housing open in the past just to check on the operation of the flaps. It can be done while the engine is still in the bus. I had excessive oil temps during a trip and found the rivet which holds the mounting braket had failed not allowing the flap to properly fit over the oil cooler.

not sure if " Z " can be modified to work

http://www.performancechoice.com/pc.html?frame=5.6520

greggholmes wrote:not sure if " Z " can be modified to work

http://www.performancechoice.com/pc.html?frame=5.6520

The bellows themselves are very close to the same. Haven't had the need to modify a set myself, but I am sure it could be done without too much effort.

Proper warm up occurs when the termostat is in place and working. I recently got one for a 2.0 I am working on. I believe it was from the Bus Depot. http://www.busdepot.com/. It was pricy if I remember right. Good luck

Bart1958 wrote:Proper warm up occurs when the termostat is in place and working. I recently got one for a 2.0 I am working on. I believe it was from the Bus Depot. http://www.busdepot.com/. It was pricy if I remember right. Good luck

Bus Depot says that theirs is a Type 1 unit. I assume it comes with instructions for fitting it to a T4 engine. These things are available out there, just picked up one off of eBay along with several other items of some worth for 7 bucks plus shipping.