Are turbo pumps OE on an 89 NA?

Tishabet · 02-23-2004, 01:32 PM

Hello all,
I replaced my water pump a little while ago, and raninto something that I thought was odd. When I bought the pump, I invested the extra few bucks to get a new turbo block off plate, the little plastic dookickey that is used to tap off the extra output from the pump when using a turbo pump in an NA car.

But when I dissected my car down to the pump, I discovered that I already HAD a block off plate. "that's funny" I said to myself, "I thought this was the original pump?" Then, because I'm a moron, I suddenly came to the realization that there was a HOSE attached to the "block off plate."
Well, as things would have it, I needed to re-use the old "block off plate" from my pump because, you guessed it, it wasn't a block off plate at all. It was an output from the pump, complete with it's own hose. So....uh.....I always thought that only turbos had a use for that extra output from the pump? Guess not, since my 2.7 looks like it uses it as well. What's the deal here?

TCMdocs944 · 02-23-2004, 01:54 PM

Huhhmmmmm....

That is very interesting.

My early confused me when I looked and saw the blockoff plate. Found out that it had an updated H20 pump though (common upgrade)

You say your N/A actually has a hose attached?! Where does it go? Sound like a replacement pump /mod.

FYI - my cars first owner had the H20 pump replaced when it was only a few years old to keep up with all factory "updates"

Tishabet · 02-23-2004, 02:04 PM

Yeah, I figured mine had just been upgraded to a turbo pump but soon realized that there wouldn't be a hose attached to a block off plate. The plate on the pump when I removed it was virtually identical to the block off plate I had purchased, except that the old one was black and the new one was sort of opaque/white and wheras the blockoff had a fitting for a hose but was blocked off internally, the one off the car was definitely open to the pump. It was a smaller line (maybe 1/3 to 1/4 the diameter of the top radiator hose) and seemed to head over toward the resorvoir, it was side by side with the radiator hose but then kept on going after the rad hose connected to the radiotor. I'd have to go out and look at the car to give you a definitive answer as to where it leads, just somewhere over near the expansion tank. Bizarre, huh? It sure didn't look like a mod, seemed factory. Also the PO said they weren't aware of the pump being replaced, and they had owned the car since it was in the 20,000 mile area.

TCMdocs944 · 02-23-2004, 06:25 PM

Yeh

think mine was replace at about 15k with the origional owner.

I want to know where the hose goes!

I have always thought that the blocked off part was a great cooling mod just waiting to happen.

Britwrench · 02-24-2004, 04:39 PM

It's called parts commonality. Porsche only had to produce two pumps with the introduction of the 3.0S2; the 2.5L and the 2.7L/3.0L pump.
So all the '89-92 (968 uses a different pump) model years use one or the other. This was then rationalised on the older models so the whole 2.5 range (can)use one pump. Rebuilt versions of nearly all the pumps are available.
Note that the 2.7L 89 N/A uses the 3.0S2 pump.

Tishabet · 02-24-2004, 05:01 PM

Quote:

Originally posted by Britwrench

Note that the 2.7L 89 N/A uses the 3.0S2 pump.

Interesting! I never realized this.
So...uh....the pump I installed was the turbo pump, and the casting itself was stamped with 2.5
Is that a problem? I've put about 300 miles on the car since I did the pump, everything seems hunky dory.
Thanks for the explanation Britwrench!

Britwrench · 08:20 PM

The only difference is the impeller size. With a rebuilt pump anything is possible as the castings are the same (I think!!!)

944 '89/S2 944 106 021 YX
944T 951 106 021 JX

If you try and install a S2 pump on a 2.5 the impeller will jam on the cylinder casting.

Tishabet · 02-29-2004, 05:54 PM

So had a chance to look at the pump and the mystery line today.
First, the pump I removed has "2.7l" stamped into it, whereas the turbo pump I installed has "2.5l" stamped into it. So that makes sense.
Also, the line that I was trying to figure out? Goes to the expansion tank.
Huh!
As far as I can tell, it's the only line that goes to the expansion tank. Where does the line from the tank normally go?

Britwrench · 02-29-2004, 07:56 PM

The line is used because the early radiators are different. On early cars the hose goes to the radiator. On the Turbo the hose goes to the turbo.

The 2.5 pump shouldn't be installed on a 2.7/3.0. the 2.7/3.0 won't go on the 2.5 because the inpellor will jam up against the cylinder.