Timing belt driven water pump rumination

novaderrik wrote: i think that the DOHC 3.4 that was put in a handful of GM w-bodies in the 90's drove the water pump off the accessory belt because GM was smart, but stupid for not using the awesome engine in more cars

ftfy.

timing belt driven water pump = dumb

patgizz wrote:

novaderrik wrote: i think that the DOHC 3.4 that was put in a handful of GM w-bodies in the 90's drove the water pump off the accessory belt because GM was smart, but stupid for not using the awesome engine in more cars

ftfy. timing belt driven water pump = dumb

What's wrong with driving the pump off the timing belt? The pump has to nestle back there anyway, and you usually have to remove the belt to change the pump anyway. Why not make it so if the accessory belt fails, the engine will still run and not overheat?

As for the 3.4 DOHC. That engine just plain sucked all around to work on. Timing belt driven off of the dummy cam in the middle of the block, so it had a timing chain too. Bracketry that made it impossible to remove the valve covers without careful saw-clearancing or heavy dismantling.

And the kicker: You know the dummy shaft O-ring that leaks all the time on every DIS 60-degree V6 that Chevy ever made? (Also known as oil pump drive O-ring, distributor O-ring even though there's no distributor)

The Twin Dual Cam has it too. And it leaks, too. And to change it, you have to remove one of the cylinder heads, because the head overlaps.

3.4 DOHC: I don't miss it!

Between the 3.4 DOHC and the 3.6, it seems like proof that GM should just stay away from trying to make DOHC designs, at least with V engines.

Personally, a timing belt driven water pump doesn't bother me. It's usually pretty cheap, so you just replace it like another maintenance part during a timing belt service.

things like water pumps that are common wear items should be accessible without taking half the engine apart to get to them. but they like to package things in nice and tight to keep everything nice and compact, so we get water pumps that are driven by the cam drive..