Detroit Deisel Rear Main Seal?

From what I see, the StepUp 1 kit contains main bearing shells which tells me the crank was out... and therefore the rear main seal. I'd tell 'em they are smoking crack... get it fixed.

 

I found the info about the kit contents on Detroit Diesel's own site. Having formerly been a truck mechanic, I can tell you that it is possible to slide the mains into place without dropping the whole crank... but not recommended.

It is also possible to replace a rope style or two piece rear main seal without dropping the crank. And again, I wouldn't do it this way now.

Are you positive that it's coming from the rear main? The mechanics in our shop have been having to replace the timing case on all of our trucks that have Detroits in them—they are cracking around the oil galley due to the cover flexing. Not enough support on the alternator/accessory bracket I guess. They will then start leaking like the Exxon Valdez.

 

LOL sorry barcode, but i have never ever seen anybody drop a crank to do rod and main job! That goes for the rear main seal as well, YOU DONT DROP THE CRANK TO DO THIS!

sgreer, it could also be the transmission seal around the input shaft, but its unlikely if the engine is just idling and it still leaks. A rear main seal is easy to replace, BUT the pain in the arse comes from dropping the trans, clutch, flywheel to get to it. I think its a $400-450 job.

 

Here is my take on this, i dont know how detroit does the main bearings, but in order for them to get the main bearing around the crank they have to drop the crank a little bit once the main caps are loose, again not much but just 1/8th of an inch enough to be able to slide the main bearing up into the main bore without scratching anything. Once they did this it COULD put stress on the rear main seal and caused some damage. Its unlikely that they did cause the damage but id still blame them for it and have them replace it, fact is it didnt leak when you took in but it does after you got it back from them so id sure as hell raise a stink and make em do it.

 

I look at it like this:

If I'm going to spend the money on an overhaul, I'm gonna tear the thing down to every last nut and bolt—remanufactured, if you will. That means pulling it out of the frame and setting it in a stand. I want it to run another million like it was brand new.

I've done plenty of rear mains with the crank in place (both trucks and cars). Believe me, nothing is more frustrating than to do it, have it leak and then have to redo it because there was a nick in the seal surface, or something else you didn't see because it was still up in the motor.

 

yeah but to pull a crank for a seal? come on man, seriously. ive rebuilt plenty of CATs in frame without ever touching the crank, some are over 1 million now.

 

If that's all you're gonna do is the seal... to buy some time before a rebuild, then yep... slide a new one in there.

And I've been sitting here thinking about this for a while now:

Realistically, would I bother rebuilding a million-miler? Probably not anymore. If the motor has a million on it, so does the rest of the truck.

This truck I'm driving right now is 8 years old and has almost a million on it. Even if the engine were to be replaced, what else on the truck would need replaced also? Would it be worth it?

I saw a truck on I-40 the other day—one of those Fairbanks scale trucks—that the rear axle had come loose from the rest of the truck and tore that truck up. Judging from the skid marks on the road, it was a pretty wild ride to get it stopped. What caused that to happen? Cracked frame? Broken bolts? Who knows?

Most trucks are not scrutinized for fatigue defects like aircraft are. How many times will those front springs take a beating before one snaps and off you go over the side of the mountain? I don't think I wanna find out in person.