What You're Looking At
This is the O-ring seal that sits on the camshaft, sealing off the bore where the cam rides in the block. It's a small rubber piece but it takes constant heat cycling and oil pressure, so it hardens and cracks over time — usually you'll spot it from an oil seep at the front of the engine or oil showing up somewhere it shouldn't.
Fits DD13 and DD15 diesel applications. These engines share a lot of internal architecture across model years, which is why one seal number covers a wide range of trucks, but the block casting and cam bore machining can shift between production runs.
If you're doing a cam job, timing cover work, or chasing an oil leak at the front of the block, this is a cheap insurance part to replace while you're in there — don't reuse the old one.
Reading The Cross Reference
PAI 121423, FP Diesel FP-4299125, and Mahle/Clevite M-3679934 all cross to this same seal. Different brands, same fit — PAI and FP Diesel both build to the OEM print, and Mahle/Clevite makes the rubber goods side for a lot of diesel platforms, so their number lands in the same spot.
With an O-ring this size, the numbers matter more than they look like they should. Inner diameter, cross-section thickness, and the rubber compound (Viton vs standard nitrile) all have to match for it to seal under heat and oil pressure. A seal that's a hair off on cross-section will either not seat right in the groove or get chewed up in a few thousand miles.
Surest way to confirm: pull the old seal and check the number stamped on the packaging your last one came in, or match it against the OEM 4299125 casting number if you can still read it. VIN lookup works too if you're ordering blind — don't just eyeball the size.
Ordering From Us
We keep 4299125 in stock at the Tacoma counter — grab it same day if you're local and need to get the truck buttoned back up before end of shift. Nationwide shipping if you're not close by.
At $19.99 it's not worth agonizing over, but it's still worth confirming fitment before you order, especially if you're mixing engine years or running a rebuilt block with different tolerances.
Comes with our standard 6+ month warranty. If it doesn't seal right or something's off with the part itself, call the counter and we'll sort it out — just don't wait until the engine's back together to check the fit.
4299125 Cross-Reference & Interchange Numbers
These manufacturer and aftermarket numbers commonly cross-reference to 4299125. 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 |
|---|---|
| PAI Industries | 121423 |
| FP Diesel | FP-4299125 |
| Mahle/Clevite | M-3679934 |
Frequently asked questions
Does 4299125 fit my DD15?
Likely yes, but confirm by VIN or by matching the number off your old seal first — DD13 and DD15 share a lot of architecture but block casting changes have happened across model years.
Is this the same as the PAI 121423?
Same seal, different label. PAI builds to the same spec as 4299125 — cross-reference and physical dimensions match, it's just packaged under their part number.
Can I reuse the old O-ring if it looks okay?
Not recommended. These get heat-hardened even when they look fine on the outside, and a failed camshaft seal means pulling the timing cover again. At this price it's not worth the gamble.
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.