I know this is a old engine but I was wondering how reliable they are I recently bought a 81 western star dump with a 3406 that has 341,000 miles and it seems to run just as good as a new one.

dont know the difference between the A and B but ifits anything like he "B" motor then it should last a while. got a million 5 on our KW and still running strong with no sighs of giving up any time soon.

The 3406A/B those were the best of the breed when it came to the 3406 series of motors. I know that I have seen 3406B in the range of 6 million miles on them and the drivers refuse to get rid of them. My father had one that was set up with a 9 over 4.11 rears and the electronic fuel pump set for 400 and hardly ever dropped a gear on climbing west up Snowshoe in PA.

As & Bs did not have electronic pumps, they were PLN mechanical injection pumps. the C engine was the first to get peec controls, it still used a fuel injection pump, and it was known as a hybrid. the E engines were eui - mechanically actuated, electronically controlled (fuel timing, metering).

i agree they were strong engines.

Some of the A's were known for head gaskets going they seemed to be around the #6 cylinder. If I remember correctly there was a upgrade that involve drill a hole in the deck or head to relieve a steam pocket that could form in the head. This is really old info so I might be off a little I think the back piston was more prone to scuff than the rest too. Bob I know 2 guys that have C's with no electronic's on them so maybe they had an early C and a late one? their's are a 93 and a 94 Both of them say the C is the best of that style of CAT motor.

I would have thought a '94 for sure would be a peec engine... peec engines still have an inline fuel injection pump, same as the full mechanical. I'm not real familiar with them myself, but I know the "E" engines were born in '95, and that engine has no fuel injection pump, and peec preceded the "E" engines.

when engines overheat, they often damage the most rearward cylinder first, due to the fact that it is furthest from the radiator. the problem you speak of does sound familiar.

Yes there was an early non-PEEC C model and the later PEEC one. From what I understand the non-PEEC was somewhat rarer, but highly desirable because of all the other internal mechanical upgrades over the A and B engines. And get this, they were available until 96 or 97 on special order! If I had known then what I know now I would have bought a dozen trucks with those engines to run until 2015 or whenever they get the rest of this garbage sorted out!

Birken

This engine smokes a little when first started but clears up within a couple of minutes there's very little blow by and it use's no oil or water could it just be running rich or could there be other problems? I know the fuel has been turned up also what is a pyrometer and what temp should it run at.
Sorry about all the ?'s Im trying to learn as much as possible about this engine.

A pyrometer is your EGT's Exhaust gas temperature.

Dont know what temp it should run at.