I know there was a thread on here before comparing water pump types, cast impeller, stamped impeller, etc., but surely I can't find it again.

 

Anywho, just thought I'd post this pic of the old water pump (right) I removed from my '00 OBW, and the new one I just installed (left). Don't know if the water pump was replaced previously.

 

Just wondering if anyone had any comments? Thanks Louis

i'm not seeing a difference!! did i miss something?

 

I know there was a thread on here before comparing water pump types, cast impeller, stamped impeller, etc., but surely I can't find it again.

 

Anywho, just thought I'd post this pic of the old water pump (right) I removed from my '00 OBW, and the new one I just installed (left). Don't know if the water pump was replaced previously.

 

Just wondering if anyone had any comments? Thanks Louis

Well I don't think there is much difference in this case. Maybe water pump was replaced before. Other thread had a cast impeller or something that definitely looked much different. Some water pump was some 'high velocity' version for the DOHC. Maybe someone knows where that thread is....I need to cleanup my bookmarks.

Here's the thread you're looking for:

 

http://www.ultimatesubaru.org/forum/showthread.php?t=52560&highlight=water+cavitation

 

I installed a GMB pump with a stamped impeller when I did the t-belt at 105K miles and have not had any problems in 2K miles of service -- mostly highway.

 

All the Hondas and Toyotas I've owned have also used stamped impellers on the OEM pumps. Pep Boys has new Bosch pumps with the cast impellers for your car if you decide this is necessary.

you guys think too hard. and too much

 

you're overthinking this.

 

the new waterpumps are just fine

 

OR SUBARU WOULD NOT HAVE SUPERCEDED EVERY OLD WATER PUMP PART NUMBER TO THEM.... now would they...

 

Jamie

Interesting threads, thanks. The Paraut pump I bought cheap for my pending timing belt job on the '96 2.2 has the cast impeller.

In early June I bought a water pump, among other things, from subarugenuineparts (thanks again Jamie) and it had a cast-iron impeller, same as the pump removed from a 1995 engine. And Paraut is an (exclusive) aftermarket division of the OE supplier in Japan: http://www.central-auto.co.jp/international/paraut.html

Add: Endwrench does show different part numbers between 2.2 and 2.5, although that list might not be up to date: http://endwrench.com/oepropdf/enginecomponents.pdf?PHPSESSID=d481aeb7c626db6e5b02e8ce432b96af

Okay, this is a not the most gifted of questions: WHich way does the pump rotate?

 

 

Does it suck from the engine block or the radiator?

All the pulleys touching the smooth side of the timing belt rotate against the crank, that is counterclockwise if you look from the front. If you look at the pump from the inside, as on the photos, the impeller rotates clockwise. It sucks cooant from the radiator and creates high pressure in the round chamber from where the fluid flows into the block (separately top and bottom halves of it).

All the pulleys touching the smooth side of the timing belt rotate against the crank, that is counterclockwise if you look from the front. If you look at the pump from the inside, as on the photos, the impeller rotates clockwise. It sucks cooant from the radiator and creates high pressure in the round chamber from where the fluid flows into the block (separately top and bottom halves of it).

 

well it doesnt suck, it pushes. Impeller type pumps do not have an suction, its only flow (and high flow) and some pressure. The perceived pressure is created by the flow of the mass of water. If there was real pressure, you would be blowing things up all over the place. Impeller pumps need to be submurges in order to move liquids (ie a block full of coolant).

 

nipper

I dont really want to get hung up on this one and just want to say that it's all relative. What's important is that the pump creates a difference in pressure between inlet and outlet.