What You're Getting and What It Fits
This is the gasket that seats between the valve cover and the cylinder head on Cummins ISX and ISX15 engines - big displacement, common in Freightliner, Kenworth, Peterbilt and International trucks running Cummins power. It's a rubber/composite seal, not metal, so it's a one-time-use part once you crack the cover loose.
4026507 covers the ISX and ISX15 family, but Cummins made running changes over the years on cover bolt count and rail shape. Before you order, pull the old gasket or check the cast number on your valve cover - don't just go by engine family alone.
This isn't a kit with the breather or PCV parts included. It's the cover-to-head seal only. If you're already in there, check your breather element and injector harness grommets while the cover's off - cheap insurance on labor you're already paying for.
How the Cross Numbers Line Up
4026507 cross-references to 131668, CUP131668, and CUM4026507 across the aftermarket - these are all the same gasket dimensionally, just different suppliers stamping their own part number on Cummins' design. Baldwin lists it as PAI-131668, and Highway & Heavy Parts runs it as P023186. Same footprint, same bolt pattern, same seal profile.
Where guys get burned is assuming every ISX cover gasket is identical across model years. It's not just a rubber ring - the groove depth and bolt hole spacing have to match your cover casting exactly, or you'll get a slow weep that looks like a bad gasket when it's really the wrong one installed.
Confirm by matching the number stamped on your old gasket packaging, or pull the casting number off the valve cover itself. If you bought the truck used and don't have paperwork, give us the engine serial number and we'll run it against the VIN to be sure.
Ordering From PartStop
We stock this in the Tacoma warehouse, so if you're local and need it same day, call ahead and we'll have it at the counter. Otherwise it ships same-day nationwide - no sense letting a truck sit on a gasket.
This is aftermarket, not a Cummins-branded part, and we're upfront about that. It's built to the same spec and comes with our standard 6+ month warranty against material defects. We don't claim guaranteed fit sight-unseen - that's on the VIN check, not on hope.
Buy two if you're doing valve adjustment on schedule anyway. Cheaper to have a spare on the shelf than to park a truck waiting on a $99 gasket to show up.
4026507 Cross-Reference & Interchange Numbers
These manufacturer and aftermarket numbers commonly cross-reference to 4026507. 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 |
|---|---|
| Cross-Reference | 131668, FP-4026507, CUP131668, CUM4026507 |
| Baldwin | PAI-131668 |
| Highway & Heavy Parts | P023186 |
Frequently asked questions
Does 4026507 fit my 2013 ISX15 in a Kenworth T680?
Likely, but confirm before you order. Cummins changed cover configurations across ISX15 build years. Give us the engine serial number off the tag or the number on your old gasket and we'll verify against your VIN.
Is this the same as the Baldwin PAI-131668 gasket?
Same gasket, different label. PAI-131668 and our 4026507 cross to the same Cummins 131668 dimensions. Baldwin just packages the identical part under their own PAI number.
Why is my valve cover still leaking after I put in a new gasket?
Usually it's torque sequence or a warped cover, not the gasket itself. Check the cover for flatness on a straightedge, and re-torque in the pattern spec, not just corner to corner. If it's still weeping, double-check you got the right gasket for your specific cover casting.
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.