-Techs/Owners whom have installed the "single-lip" front crank seal, please pipe-in with real-world reports of reliability-
During major maintenance I'm currently performing on my '05 CRD (140k), I replaced the front crank seal. The old seal was a 'standard' double-lip seal and seemed very well made (and it didn't leak). While I am certain that the tbelt was replaced twice previously, I have no idea if they included replacing the crank seal or if this was the original factory seal. It is 40x55x exactly 8mm wide (ignore oil-painting in background):
However, the replacement seal supplied by IDPARTS is a single-lip seal and seems very poorly made. It arrived in an OEM mopar box tagged Part #0517 9633AA-001, with an IDParts in-house sticker #3588. Searching online pics, it appears that this single-lip p.o.s. oil seal may actually be the current OEM part, listed as Part #5179633AA. It is 55x40x6mm wide:
It's infuriating to be stuck installing such an apparently inferior oil seal rather than a standard double-lip seal. Consequently, I've been hunting for a superior-quality double-lip substitute before continuing with reassembly.
Some oil seal manufacturers use the oil seals three dimensions to assign it's part #. In this case, "40558" or maybe "40X55X8".
Apparently, seal-manufacturers size them differently than you'd expect because their "40mm" seal is quite snug on the 38.5mm crank (the O.D. of the crankshaft at the front seal location is 38.5mm, tapering to 38mm at the end where the woodruff slot is located).
SAE equivalent oil seal size = 1.575" x 2.165" x 0.315" (width).
Materials used for oil seals range from Nitrile at the low-end to Viton at the high-end (DuPont-patented material). Both are rated for oil and fuel applications, but differ greatly in thermal rating:
Nitrile= -40 to 225 F.
Viton= -40 to 400 F. (most basic of four grades of Viton).
I locally-sourced a Nitrile seal that's 40x55x8.75mm; brand is ABI (made in socal), part #223831. Here in MX I paid a whopping 50 pesos=$2.50. Worth mentioning: the gentleman at the "pulleys and seals" store here in Ensenada, B C., MEXICO, was great. He emphasized that their on-hand nitrile seals might be inferior to the (unknown-material) double-lip seal I had removed, and then kindly educated me with thermal-rating documentation. In other words, he was competent, courteous and HONEST, at the likely expense of a sale.
The seal looks kinda' gross in the pic because I always pre-lube oil seals' I.D. using vaseline, and coat the O.D. with ultra-black sealant (can't hurt):
A serious consideration is the distance to the crank's internal bolt-caps from the outer-lip of the block; = 9mm:
The ABI seal I installed is 8.75mm wide. Fortunately, there's about 2mm of room between the block-lip and the inside-edge of the crank sprocket. Pic is side-view of crank pulley (with dangling chain-wrench and chunk of old tbelt for pulley removal&installation):
Solution: leave 1mm +/- of prevail when installing the 8.75mm ABI seal. Actually, I set it slightly further-in after this pic:
One confirmed alternative to either the lame OEM or the borderline-width ABI Nitrile: there's a company called "Colonial Seals" in the US (NJ) that sells a 40x55x8mm Viton seal for $28, Part #A1048 (confirm size pre-ordering). Multiple European Viton suppliers sell the same size seal at $15 ("Kramp" seals look Deutsche-grade badass, Part#40558CBVP001).
While I'd much prefer a Viton seal, I've already lost too much time waiting on parts to justify the upgrade. Regardless of its material composition, I have to believe that flappy single-lip seal is worse than the solid, double-lipped Nitrile in-hand.
Any experienced opinions on the long-term reliability of Nitrile for a front crank seal application? Obviously, crankshaft seals are subject to twice the rpm's, and subsequent rotational friction, as cam seals (as well as a larger surface area).
As for cross-referencing identical-sized seals by vehicle, apparently some tractors use a 40x55x8 seal.
If anybody disputes listed dimensions, please share.
Keywords: front crankshaft oil seal, front crank oil leak, leaking oil, crappy oil seal, junk front seal,
I LOATHE oil leaks
, I want my mommy, etc.
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