Need help identifying a Cat 3406

I'll give that a shot, thanks!

 

33mm ended up being a good fit but snapped the socket so went up to a 3/4" drive 1 5/16" and that did the trick just fine on the end of a long breaker. Got the crank, pistons, connecting rods and sleeves out. In frame kit is due in tomorrow so hopefully we'll be able to keep making progress at a good pace. Thanks again for all the help!

 

Still not 100% sure on exactly what I've got, more like 99.9% sure. Never did find the serial number on the block but I did find some "group casting numbers" on the block as well as the front cover that come back to a Cat 3406C. Kenworth tells me that the truck originally left the factory with a 4CK 3406C PEEC motor. Fuel pump is a 7W3906 for a 3406B.

My best guess is that somebody got fed up with the PEEC system and converted it over to mechanical.

 

The plot thickens a little bit more. The 4CK pistons that came with the in frame kit did not match the pistons that came out of the engine and would not connect to the connecting rods, the pistons that came out came back to an industrial motor such as a firepump or genset. Ordered the correct pistons and the engine is back together and just about ready to go back in the truck.

Anybody have any good tips for installing the rear main seal? We were able to install the front one no problem but we're having some issues getting the rear one to go in, it's almost like the flange on the crank is larger than the inner seal that rides on the crank. Any ideas? The part number I have is 1425868 which appears to be the correct part.

 

You're welcome, the real thanks goes to all the folks who've helped out via this site during the build.

Is your motor leaking at the air compressor itself or at the front cover? If it's leaking at the compressor that's an easier fix than if it's leaking from the front cover. If you're leaking from the front cover a bunch of stuff has to come off: harmonic balancer, all the pullies, alternator, AC compressor, engine fan along with possibly the shroud, water pump, PS pump and maybe the air compressor. You don't always have to go to CAT for the parts but sometimes they actually are the fastest, cheapest and best quality available. When we did our engine we used RTV for the front cover. I wasn't crazy about the idea but that's what the manual called for and since the truck has been back in service(July 2012) it's yet to leak.

Good luck and let us know how you make out.

 

Almost forgot, on the 3406 the front motor mounts are bolted in THRU the front cover which is probably the biggest PITA but with a 3 ton jack and stands you'll be fine.