944_S_TYPE

I recently changed my waterpump and Tstat. I bought a rebuilt pump from 944 online. I noticed that I could not use the "O" ring that came with the new Tstat. Long story short. The new T- stat Has failed already (hot water check) I Went to clarks garage and read that the new vs. old H20 pumps had the machined snap ring groove in a different place. the updated one requires a backing plate and round "o" ring. the old/ non modified one requires the type of o-ring that mounts th the thermostat.... Is this correct?

Charlotte944

Well, sort of.

I just got a rebuilt pump yesterday. It is an "early" version for an '86 951. These pumps use a metal shim ring or spacer, but NO O-Ring or other seal.

I was a bit perplexed until I realized that later pumps with the 7mm snap ring gorove placement use a thermostat with a seal AND an O-Ring.

I tried to install a new T-Stat with the split seal. The T-Stat fit the pump inlet, but I could not get the snap ring to lock into the groove because with the seal installed the T-Stat was about 1mm too thick.

I finally installed the T-Stat with the metal shim, and the snap ring locked into the gorrve. The T-Stat is just a tad loose, but I don't see this as being a real problem.

944_S_TYPE

I BELIEVE YOU HAVE INSTALLED THE T-STAT INCORRECTLY. There is no shim required in the early pumps. Without an o-ring there is nothing to keep water from bypassing around the thermostat.

TAKEN FROM CLARKS GARAGE:There are two different styles of water pumps used on the 924S and 944 (including Turbos). The new style coolant pump has a guard rail for the timing belt an a larger idler roller (46.2 mm vs. 32.0 mm). The new style was installed on all cars produced after July 1986. I recommend installing the new style pump when replacing the water pump. For cars which previously did not have the new style pump installed, this requires modifying the rear timing cover and purchasing a belt guard and larger idler roller. Some of the new style pumps will come with the belt guard already installed so ask your parts supplier when ordering. The groove for the thermostat snap ring has also been moved. Previously, it was 4.5 mm from the sealing surface and is now at 7 mm. This requires the use of a new thermostat and spacer.

On Turbocharged cars, there is a nozzle on the water pump which supplies cooling water to the turbocharger bearing housing. On Normally Aspirated cars the nozzle is a block-off plate. The block-off plate / nozzle is sealed to the water pump by an o-ring which should be replaced when the new pump is installed. On some pumps, the block-off plate / nozzle is mounted using a 6 mm stud and nut and a 6 mm x 20 mm bolt. However, most of the new pumps come with two bolt holes. This requires transferring the 6 mm stud from the old pump to the new one or purchasing another 6 mm x 20 mm bolt.

New Style Pump Part Number
Water Pump Gasket 1 944 106 132 04
Guard Rail 944 105 213 01
Guard Rail Lock Nuts (2) 999 084 092 02
46.2 mm Roller 944 105 241 03
Block-off Plate / Nozzle Part Number
Block-off plate (NA cars only) 944 106 313 00
Nozzle (Turbo Only) 951 106 313 00
Thermostat for Turbocharger 951 106 311 00
O-Ring (NA or Turbo) 900 174 049 40 or 999 707 283 40
Washer (2) N 011 524 7
Bolts 6 mm x 20 mm (2) N 014 704 1
Thermostat Part Number
Thermostat (New) 944 106 019 00
Thermostat (Old) 944 106 129 05
Spacer (New Style Pump) 900 234 160 00
O-Ring (New Thermostat) 944 106 929 08
O-Ring (Old Thermostat) 944 106 929 05
Thermostat Snap Ring 900 042 025 01

Charlotte944

I don't really want to pop your bubble, but the early water pumps DID NOT use an O-Ring or any seal around the T-Stat, but they did use a spacer ring. When T-Stats with integral seals are introduced, the spacer ring was not necessary. However, it appears that newer aftermarket T-Stats have an integral seal that is too thick.

My old '84 was this way, and my '86 951 is this way. My '87 NA uses the O-Ring AND the integral seal because the snap ring groove is 7mm from the T-Stat seat, where in earlier pumps the groove is at 4.5 mm from the T-Stat seat.

If I install a new style T-Stat with an integral seal, the snap ring will not lock into the snap ring groove. If I install the T-Stat without the seal, the T-Stat is loose and has about 0.5 mm of play. When I install the ring shim, the T-stat is tight.

BTW: Check out Tech Bulletin #1 in the Parts and Reference manual as well as the picture of the water pump and associated parts on page 19-4 "Removing and Installing Parts of Cooling System" in the Work Shop Manual section on the engine.

944_S_TYPE

The old style o-ring is part of the thermostat, not a seperate ring that is placed behing the t-stat. I have one, It takes up the slop. I just need a place to buy a new one.. I'll post a pic when I get it back out.


Check the PET. There is no part number for a spacer on the early style pumps. Plus the Orings and thermostats are a different P/N.
Thermostat Part Number
Thermostat (New) 944 106 019 00
Thermostat (Old) 944 106 129 05
Spacer (New Style Pump) 900 234 160 00
O-Ring (New Thermostat) 944 106 929 08
O-Ring (Old Thermostat) 944 106 929 05
Thermostat Snap Ring 900 042 025 01