Help With Cat 3406B Issues

Low oil pressure is usually the rods and mains. They were recommended changed every 250k. Blow by probably the rings, though they may seal up after you run it a bit. Smoking when cold is normal. Very cold weather, really smoke and run very rough, till it’s warm. If it were me, I’d change the turbo, roll in new bearings. To avoid a disaster. Run it and see what you got. I’m not a mechanic, but I had a 1992 425C, It required bearings at 500k, which I had done. They’re great engines. King of the hill, back then. You’re gonna like the power, and especially the torque.

 

Everyone swore by Shell Rotella on the Cats. When mine started using more oil, I tried Mobil for a couple changes. Some claimed it would slow oil consumption. It’s hard to say. Typically the oil pressures pretty high. I forget exactly, maybe 60. Higher on average than my Detroit’s. The other thing to watch is the Damper. They will go bad, and wobble. At an idle, it’s easily seen. Water pumps that seep from the weephole. Cat never really fixed that. Instead they put a piece of spongy plastic type plug in the hole. It just sits in there. You can pull it out with a pair of needle nose. After many claims of fixing the problem. Occasional minor seeping is considered normal.

 

I’m assuming it’s a mechanical engine. Not a peec engine. Mine was a peec. It was a hybrid mechanical pump,controlled by a fuel cooled ecm. Only made for a few years, before the E model came out, around 1996. It was a real flop. Power was limited. The mechanicals could be turned up, by tweaking the fuel pump. Had to find a good Cat Mechanic to rebuild the pump. Not sure what they did exactly. But it involved the springs, I believe. But the power was amazing, easily out pull a 500 Detroit.The only other problem I can remember is exhaust manifold studs breaking. I ran mine for a few years, with 1 broken stud.

 

oil change no telling how long thats been in there

 

Get a new gauge on it to confirm oil pressure. My 1988 3406B puts out 65psu at 65mph and idles at 40psi with 100K on a complete inframe. It also grey/white smokes at idle when started. It's done it since before the inframe, and before. Once warmed up it idles nice and clean.

 

What about oil temp? If the coolers plugged up, might be the cause. I think it should be about 20 degrees higher than coolant.

 

Rod and main bearings have a tell tale sign.......really good pressure cold that falls off drastically with heat.


I have seen the timing advance on a B cause low oil pressure.....as well as most everything else mentioned.


Blow by could be coolant in the oil easy as not and honestly is my first guess. I realize the oil isnt milky but coolant will steam out the blowby way before you can see it in the oil. Pull the back valve cover off....its easy enough to do. I would almost bet your gonna find rust from it sitting or sludge from it running.


You can guess here and spend good money after bad......or take it a competent B model man and fix it. Notice I didn't say mechanic......even most CAT dealers #### these things up in this day and age