Melling Water pumps!

[454cid]

Melling is now making water pumps for the 4.3L and small blocks! They goofed up their Vortec PDF, Though. They called them "Duramax" and don't start the year until 2000. I assume this is not correct, unless someone knows of a pump change that really only effected the vans that were still using the Gen1 engines.

The tbi info looks fine, as far as I can tell.

More Information for MELLING MWP505

https://www.melling.com/wp-content/uploads/2021/11/MWP-505-Melling-Water-Pump-web.pdf

More Information for MELLING MWP520

https://www.melling.com/wp-content/uploads/2021/11/MWP-520-Melling-Water-Pump-web.pdf

Too bad they don't have big block pumps. They're supposed to be assembled here in MI.

 

[xXxPARAGONxXx]

They goofed up their Vortec PDF, Though. They called them "Duramax" and don't start the year until 2000.

Must have outsourced their marketing team. LOL

 

[L31MaxExpress]

Melling is now making water pumps for the 4.3L and small blocks! They goofed up their Vortec PDF, Though. They called them "Duramax" and don't start the year until 2000. I assume this is not correct, unless someone knows of a pump change that really only effected the vans that were still using the Gen1 engines.

The tbi info looks fine, as far as I can tell.

More Information for MELLING MWP505

https://www.melling.com/wp-content/uploads/2021/11/MWP-505-Melling-Water-Pump-web.pdf

More Information for MELLING MWP520

https://www.melling.com/wp-content/uploads/2021/11/MWP-520-Melling-Water-Pump-web.pdf

Too bad they don't have big block pumps. They're supposed to be assembled here in MI.

Mexican L31 pumps have a different part number. I do not know what changed on them, but keep in mind the L31 was used until 2007 in the GMT800s and through 2003 in some US stuff like the Isuzu NPR and P30 box trucks and some Workhorse chassis. The 4.3L was around through the end of the GMT900 trucks and through 2013 or 2014 in the Express/Savanna. The newest 4.3L had a different aluminum timing cover with a cam sensor built into it. I suspect the latest model pumps may have more clearence for the later model 4.3L 58x timing cover but that should not change its fitment on a L31. I have a pump off a 2019 6.3L marine engine, but have never directly compared it against an older casting. I have seen a few aluminum "L31" pump castings but I have no idea the source of them. Wish I could figure that out though because the couple I have seen look very clean.

 

[L31MaxExpress]

One other thing to add, since I have been researching pumps for the Budget L31 anyway to replace the seeper it has on it that is nearly 20 years old. I discovered 4 pumps on RockAuto that list to be higher performance and all show modified impellers and streamlined castings. From memory GMB is the casting supplier for Flowkooler. Makes me wonder if GMB themself are building the Flowkoolers now. If so the GMB may have the flowkooler billet aluminum straight vane impeller. Plan to buy one soon and yank the back cover off it and have a look inside. The flowkooler pump cools my 383 in the Express well. The GMB pump may potentially be the same thing for less than 1/2 the price.

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