Water pump: versions and notes
Why the water pump belongs with the belt job, which versions exist and how to spot leaks.
In short: The water pump sits in the timing belt drive; to reach it the timing belt has to come off. That is why it is usually checked or replaced together with the belts.
Versions
There is an old and a new version. The new one has a guide rail for the timing belt and a larger idler roller, needs a different thermostat with sealing ring and support washer, and was fitted to cars built after July 1986. Converting an older car requires modifying the rear timing cover.
The Turbo pump has an extra nozzle that feeds coolant to the turbocharger bearing housing; on naturally aspirated cars a blanking plate sits there.
Spotting leaks
Water traces around the timing cover point to the pump. On Turbo-style pumps the O-ring at the blanked nozzle is a common leak point.
Turbo: electric after-run pump
The Turbo also has an electric pump for the charger. It should run for about 30 seconds after shutdown, regardless of coolant temperature.
Tightening values and procedure: workshop manual.
Technical values
Only work with the workshop manual and the correct tools. Do not use unverified values without checking them – wrong tension values can destroy the engine.
Sources
- Secondary source Water Pump Information and Replacement
Water pump versions (old/new, Turbo/NA).
- Secondary source Buyer's Guide: Porsche 944 / 944 Turbo
Enthusiast buyer's guide (1998), checks on the lift and on the test drive.
- Secondary source 944 Turbo (951) FAQ
Secondary source on the Turbo: charger, boost, wastegate, model years. Some figures quoted from the workshop manual, unverified here.