Water pump replace

[DIESEL/VETTE]

It's time to replace the water pump on my 2003 lb7, starting to show coolant dripping 187,800 miles. What do most of you use for a replacement? Leaning to oem.

[DmaxMaverick]

OEM definitely preferred, but check with John Kennedy for the latest updates on that. There was a period of questionable reliability for all of them, even to a point that a modification was required. I haven't checked in a while, so it may be old news by now.

[Kennedy]

Anything LB7/LLY has a risk of the cast impeller slipping/spinning on the shaft especially in a race/high perf application. The OE pumps never really had an issue back in the day unless racing, but most anything used as replacement should be welded. I've only ever seen one non welded pump spin on a "stock" truck but that was enough.

Option 2 is a hybrid where you use a LBZ/LMM pump with the composite impeller and weld on a smaller hose neck to match the LB7/LLY size. One more relatively minor mod to a lobe for a bolt and it's done. I run a hybrid on my 2002 after destroying a welded cast version in 2012.

FWIW Any vendor selling a welded or pinned LBZ/LMM pump has no understanding of what is going on.