Alex89

Here's a dumb question. I'm replacing the water pump and thermostats on my 951, including the tiny turbocharger thermostat. The old one was installed with the spring on the water pump side, same orientation as the normal full-size thermostat, but it was jammed open so I'm replacing it. The tutorial on Pelican Parts shows it installed the same way. However I was just flipping through the Porsche PET and the diagram 105-03 clearly shows it installed with the spring facing out of the pump, into the plastic cover. Someone else pointed this out on the Pelican tutorial and their staff assured him the spring side should go into the pump. So which way is correct?

Per the Pelican tutorial and how my old one was installed:


According to the Porsche parts manual that's backwards (item 5):

Thanks in advance!

ealoken

thats the correct way yes.

Dave951

To be clear, install it as Pelican shows/old one was.

Alex89

So the Porsche parts manual is wrong?

I was looking at the Clark's Garage diagram of the direction of coolant flow. It shows the coolant returning from the turbo and flowing through the mini thermostat, into the main water pump. So the hot side is the line coming to the pump through the "block off plate." That tells me that to get the thermostat to open the spring should be facing out of the pump, as per the Porsche diagram. I don't intend to be argumentative but can someone tell me why you would put it the other way (as per Pelican)?

Edit: Link to the Clark's page with the diagram: http://www.clarks-garage.com/shop-manual/cool-10.htm

Alex89

Follow up: Bruce at ArnnWorx has a page showing how he tracked down leaks in his turbo cooling system. Here is how he shows "the general position of the two thermostats". Link to source



The plot thickens!

931guru

If you are sure that you are right, install it the other way and let us know how it works out.

Alex89

I'm not sure of anything, that's why I'm posting here! I do know that my old one had the spring facing into the pump and it got jammed open. I posted my question on the Porsche 944 Turbo facebook group and multiple people there agreed that the spring should face out, so it's not just me. At this point I'm thinking I'll stick with the PET diagram (spring facing out of the pump) since that makes the most sense to me according to the coolant flow. I probably won't get around to installing this for a few days so if anyone else wants to chime in please do.

Alex89

Despite the lack of discussion here I have an update:
It is impossible to properly install the turbo thermostat the way that Pelican Parts shows. It isn't immediately obvious but the mini thermostat bottoms out against the internal body of the water pump, so tightening it down will damage it. I can see this not being noticed if the thermostat was installed with the pump already in the car, but here is a picture of my new Wahler thermostat in a new Zims pump on my bench. I couldn't get it to seat properly.



Installing with the spring out is consistently what I heard from Porsche mechanics, the Porsche manuals, other discussion groups, and my own logic and since it's the only way that the thermostat physically fits I think we can call this discussion closed. I'm planning to inform Pelican about their error but since someone already did that and was ignored I'm not expecting much. Hopefully this will help others who have the same question in the future.

Dave951

My turbo thermostat (Behr Thompson branded unit) sits fully flush in either orientation.

And just for the record that was me who originally commented on Pelican about the orientation.

Alex89

Mine is installed now but I haven't refilled the coolant so I could try the new thermostat in the original water pump to see if it's different. I still think the spring should face out though per the PET drawing, I guess you agree?

Dave951

It seems like both ways will work, but when I looked at mine again I opted for the way the PET/WSM picture it.