What You're Actually Buying
This is the gasket that seals between the water pump housing and the engine block on Cummins ISX engines. Thin, flat, cut to the exact bolt pattern and coolant passage openings of that pump mount - no room for error on the shape since it's sandwiched under bolt torque and full coolant pressure.
Four to a pack because shops doing ISX work go through these. Pull a pump for a leak, a bearing, a seal - you need a fresh gasket every single time you break that joint. Reusing an old one is how you end up back under the truck in two weeks with a weep at the mating surface.
Fits ISX engines in Kenworth and Peterbilt trucks - the two chassis makers running Cummins ISX most commonly. It's a Cummins-spec gasket, not a truck-brand-specific one, but the engine has to be the right ISX variant for the pump housing this gasket matches.
Why These Numbers Cross
591597C2 lines up with Cummins part numbers 3004242 and 4988280 - these are Cummins service and supersession numbers for the same gasket, same engine family. Cummins renumbers gaskets across running production changes and parts catalog updates, so you'll see more than one Cummins number pointing at the same physical part.
On the aftermarket side, 54916 and 154916 are gasket manufacturer numbers that cut to the same pattern and material spec. Gaskets are simpler to cross than a pump assembly - there's no arm length, spline count, or pulley diameter to worry about like you'd check on a wet-arm pump or a steering box. What matters here is bolt hole pattern, coolant port cutouts, and overall thickness/material matching your water pump housing.
Still - pull the old gasket off the truck and match the shape and bolt pattern before you order, or better yet get the number off the water pump housing casting or your parts invoice. ISX had running changes over the years and a gasket that's a hair off on a coolant passage will leak or restrict flow even if the bolt holes line up.
Ordering From PartStop
We're out of Tacoma. Order before cutoff and it goes out same day if we've got stock on hand, which we usually do on a common item like this. Ship nationwide, so it doesn't matter if you're running Kenworths out of Fontana or Petes out of the Midwest.
6+ month warranty on the part. If it's a bad gasket out of the pack or wrong pattern for your application, we'll sort it - just don't wait six months to find out it's wrong, check it against your old one before you button the pump back up.
Confirm by VIN or by the number stamped or cast into your old water pump housing before ordering. Cheap part, but a wrong gasket means pulling the pump apart again, and nobody's got time for a second trip under the hood over a $15 pack of gaskets.
591597C2 Cross-Reference & Interchange Numbers
These manufacturer and aftermarket numbers commonly cross-reference to 591597C2. Use them to identify the part — then confirm the exact fit by VIN or the number stamped on your old unit before you order. An interchange is a starting point, not a fitment guarantee.
| Brand / Line | Cross-Reference Numbers |
|---|---|
| Cummins | 3004242, 4988280 |
| Aftermarket | 54916, 154916 |
Frequently asked questions
Does 591597C2 fit my Kenworth T680 with an ISX15?
Depends which ISX variant and water pump housing your T680 is running - Cummins changed pump castings across ISX production years. Pull the old gasket or check the pump housing casting number, or give us your VIN and we'll confirm before you order.
Is this the same as Cummins 4988280?
Yes, 4988280 is one of the Cummins numbers that crosses to this same gasket - it's a supersession/service number Cummins uses for the same part. Doesn't hurt to match the physical shape against your old gasket anyway.
Why does it come in a 4-pack instead of just one?
Because a gasket only gets used once - every time you pull the water pump for service you need a fresh one. Ordering four at once saves you from reordering a $4 gasket every month if you're doing fleet maintenance on multiple ISX trucks.
Not sure it fits? We check before you pay.
Run your VIN and we’ll match parts to your exact truck, or call the counter — a person who knows trucks verifies fitment by OEM number before the order ships. No wrong-box returns.
More cross-reference guides
Need the part, not just the reading?
Every part below is a Premium Quality aftermarket Direct Replacement with published OEM cross-reference numbers, a 6+ month warranty and same-business-day shipping from Tacoma, WA. Not sure it fits? Run your VIN — or call and a person who knows trucks will verify fitment before you pay.