my friend has one with the 3100 engine. it'* leaking coolant, and it looks like the water pump. are these engines infamous for cooking water pumps?

BTW, it had Dex in it, and i plan on flushing it out and replacing with prestone all-makes. the rad cap and part of the rad itself had the "mud" in it. is there a good way to get that out? a certain cleaner?

i just don't want him to take it to a local shop and have them possibly tell him "new rad, new water pump, all new hoses, $800" when i could do all that for him for just parts charges.

any advice?

Yes, they are notorious for eating water pumps. DON'T let it overheat, otherwise he will be stuck with warped/possibly cracked heads, and blown head gaskets.

LIM gaskets were also a problem on those engines IIRC. The 3100, 3300, 3400, 3800 and the 4.3 all had LIM gasket issues I do believe.

yeah, i know that about the LIM gaskets, but this leak is external. he was telling me that his temp gauge was running higher than usual, so i gave his cooling system some water (cuz it was pretty low) and told him i'd look again in a day or two (the location of the leak makes it hard to pinpoint between the heater hose or the water pump, i'm hoping for the hose, but not optimistic). i'd guess the water pump just cuz of the "muddy" look of the rad cap and the inside of the rad.

ok, where would be a good place to buy a water pump? i looked on GMPD, and they didn't have the one for this motor, it was weird. any advice here? just any parts store? should i go to a GM dealer?