2012 Kenworth T800 ISX15 - Heavy Oil Leak at Front of Engine

Question

Woke up to a huge puddle of oil under the front of my T800. It seems to be coming from behind the crankshaft dampener, but it's spraying everywhere so it's hard to tell. I'm losing about a gallon every 500 miles now.

I thought it was the front main seal, so I swapped that out last weekend, but the leak is still there and maybe even worse now. Is there something else in that area that can let go? The timing cover looks dry around the edges.

DieselDan_77 · Accepted Answer

✅ Confirmed fix: You likely didn't check the wear groove on the crank. On these high mileage ISX engines, the front seal wears a groove into the crankshaft snout.

A standard seal won't seat right. You need to install a 'Speedi-Sleeve' or the Cummins oversized seal kit that comes with the wear sleeve. I put the sleeve on with the installer tool and used the 4965569 seal kit. Zero leaks for 10k miles now.

WeldShopWanda · Answer

Check your air compressor. On the ISX15, the compressor is gear driven right behind the front gear housing. If the gasket where it mounts to the housing fails, it looks exactly like a front main leak. Also check the accessory drive seal.

2012 Kenworth T800 ISX15 - Heavy Oil Leak at Front of Engine

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