1984 3406b ???

what's wrong with the motor? that should dictate whether to do just rods and mains or the complete inframe.

 

On my 3406C,,which is the same basic engine,,I had a low oil pressure problem,,,asked around and no one could give me an answer,,,got lucky and a roller started eating a lobe on the camshaft,,,when we took the front cover off,,,the bearings on the bull gear where junk,,,replaced everything that needed replacing behind the front cover,,which wasn't too bad since it was caught in time,,oil pressure is right back up to where its supposed to be!!!
Mine usually ran at 58 lbs,,,when the oil pressure was dropping,,it would drop down to 48-50 lbs running down the road!!!

 

The 3406B and 3406C is the same basic engine design, but there is critical differences, and in this instance it's the narrow rod bearings of the B'..

 

Genuine parts is the only way to go and you can buy them from a Caterpillar shop or truck dealerships that offer Cat service..

Cat suggests doing bearings every 250,000 but I think most are lucky if they get done before 500,000..
I don't recall the exact price for a bearing kit, which includes the oil-pan gasket, or two if has the spacer, and oil pump o'rings.. The last two sets I bought were with inframe overhaul, but I'd say between $250 and $500 plus the oil-change depending on location and greedy dealer inflation.. :smt117

I wouldn't consider an overhaul unless there is excess blowby or using alot of oil or low on power etc..
It's never really a done deal regardless with any engine, because "sht happens".. :smt025

Simple stuff like a wore-out air compressor can effect oil psi among other things.. But just as well I have took the cheap way out before by just replacing a cracked cylinder head or a blown head gasket only before where the cylinder packs looked like new... Only to discover water in the oil 10,000 smiles later because of o'rings on the sleeves takin a leak..

This buisness can get real freaky at times.. Which is why I take the superstitious approach anymore.. I'd really prefer being more lucky most of the time rather than being good..

 

Any old timers that's worked on older 3406A Cat's have any clue here on a couple of things related to changing an air compressor on one? I removed the old one yesterday thinking I had a good, almost brand new spare off a B, but they're different in a couple of ways. (I should mention this is a 1978 A Model Caterpillar pre-cup motor.)
First major difference is the A compressor has a splined 1" shaft that slides directly into gear train, rather than the conical gear on most 3406B style compressors.
Second is the oil return line on my A is on the bottom, B's are up higher on the side...So I'm FUBAR'd with this.
Been sitting here surfing the interweb for an hour now, looking for another compressor but I think I'm going to work for this one...nothing some extra $$$ can't solve though from some supplier around here I'm sure.
Lastly, for the veteran wrenches here; How on God's green earth do you tighten the bottom 3/4" nut on these A model compressors, with the oil return line/fitting in the way? It's mathematically impossible to put an extension on, or swivel, or even a speed wrench like I wish. I removed the upper two in 2 minutes. The bottom one was a challenge. I turned it with a box end, flipping it over each flat I could catch...and probably gained 5 mm on each turn...man was that a son of a gun, but I got it.
The only solution I see for mine is to cut a 3/4" wrench down to about 4" long to miss the frame rail enough to get some more traction...?
Looking for some old crackerjack input here...old school if you will...

 

I just bought a 1986 freightliner flc64t with a 3406b motor. When i start it up harmonic balancer wobblers and pushes outta crankshaft 2".

What causes this?

 

My '89 3406B has 334k original miles. Oil pressure is real good and I've been debating whether I should do bearings or not. "Not" keeps winning the argument.