Bobcat

The facts:

Bought truck new in May 1995, has 620k miles on it now, went to replace the timing cover oil seal and tab the kdp that I'd always "intended" to tab but never did.

When I took the timing cover off the kdp fell out on the garage floor. I do not know when it came out or where it was hiding but it missed the timing gears and did no damage, and settled somewhere out-of-the way.

Replaced the seal in the front cover, cleaned up the dowel pin, put green Loctite (sleeve and bearing mount) on it and drove it back in, put the tab over it (with red Loctite on the bolt) and put it all back together, runs fine but I still have an oil drip.

The story:

I'd read about the KDP from ~2002 when I first joined here and always "intended" to get to it. There was always some reason that it was too much trouble - and I thought, if the truck has been fine from 1995 until 2002, the pin is probably not one of the ones that is going to come loose, if it were it already would have. So - I was a fool (make that Fool with a capital letter) and I admit it. But a very, very lucky Fool.

The front seal did not seem wet or "bad", there was a buildup of dust around the spigot on the timing cover that was shielded by the harmonic balancer, no oil or wetness, but I figured it had to be leaking because I could not find any other place that was leaking, and since it was apart, and I had the new seal, I put it in (with the funny sheet-steel depth-setting tool that came with it) and put the timing cover back on again, using the plastic seal-protector that came with it to get the seal over the crankshaft.

I'd read about making sure the crankshaft was clean and dry, no oil film to interfere with the Teflon seal mating to the steel shaft; used brake-cleaner to make it clean and dry.

As the instructions with the kdp kit, I used Permatex silicon gasket-maker instead of re-using or replacing the timing cover gasket, which was not damaged anyway.

Anyway I think the moral of the story is, if you have a 12-valve, tab the kdp and don't be a Fool like me. Not everyone rolls 7s all the time.

And - if anyone has a guess about where else my oil drip could be coming from - about a quart in 3,000 miles (6 weeks), dripping on the front stabilizer bar - a gentle (or even harsh!) word about what you think would be totally welcome.

Thanks!

Lary Ellis (Top)

Wow....with luck like that you need to play the Lottery!

Bobcat

You are absolutely right. I couldn't even see a clear path from where the pin fell out of, to anywhere it might have been sitting, that missed the gear train. It is beyond me how the timing gears/case/engine did not get destroyed.

I'm grateful beyond words and needed to come out of lurkdom to warn people not to take this kind of thing for granted - open it up, tab it, and sleep better!

Required_Field

When I was reading up before tabbing mine, I read somewhere that it was possible for the pin to fall "harmlessly" into the oil pan. It's hard to see where it could lay for any length of time -- glad you got it taken care of! As to the oil leak, I believe I read somewhere about possible leaks on the back side of the timing case. Otherwise, you've got the filler tube, front crank seal, and your Permatex work to check. I'd clean everything off real well and then inspect frequently.

Bobcat

Interesting! It didn't even make it into the oil pan (probably would have found it during an oil change), it found some kind of "safe space" to hang out, inside the timing cover but not interfering with the gears.

I'm afraid you are right about where the leak is; the back side of the timing case.

Tomorrow (Saturday) I'm going to Gunk it down real well again, and get everything clean and dry. Then drive it a few miles (not all the way to work and back) and look again. Too long a drive and it will probably be all wet and I don't learn anything.

Robert Rausch

I wonder how many more trucks are out there like yours, with the dowel pin safely sitting somewhere inside waiting to be discovered.

Bobcat

No idea. Know anyone who tabbed their dowel pin and found it had moved at all, needed to re-seat it to tab it? Versus those who saw it had not even started to move and tabbed it anyway.

Are there any 'statistics' on how many 12-valve engines have been damaged or destroyed by dowel pins coming loose?

I have to admit, I read about the possible problem about 6-7 years after I got the truck and decided I needed to go after it "one of these days" - but it seemed unlikely to actually come loose. Like, maybe 1 in 1,000 came loose, and 999 in 1,000 never moved. That was wrong, in my case, and I'm totally grateful no damage was done.

This is like the guy with the bloody knuckles telling everyone else to pull, not push, when trying to get a stubborn bolt loose. Learned something - not really "the hard way" but I hesitate to describe my emotional state when I picked that pin up off the garage floor and realized what it was.

Robert Rausch

Mine wasn't tabbed. The guy who did mine added a small bolt through the cover that keeps the dowel pin from coming loose. I had that done in 1999. At that time it hadn't moved. So far so good, but I do admit I'd like to tab it just to be sure.

Bobcat

Just to update this, I did clean everything real well and found that the leak is higher up than the timing cover oil seal on the crank, it looks like it is coming from the timing case right under the water pump. May be the timing case to block gasket, or the KDP may have actually cracked the timing case but I can't see it. Ashamed if it is cracked and I did not see it when it was open!

Anyway this weekend I think I will drain coolant, pull serpentine belt, tensioner, and water pump to look for the gasket leak or timing cover crack.

I've considered the oil leak may be from higher up, like the head gasket, but would expect coolant not oil. Could be I just don't know enough about it.

Thanks.

Required_Field

Just a thought, if it's timing case to block or a crack in the case at that location, maybe it can be fixed with externally applied Permatex, after cleanup, of course. I wouldn't think there'd be much oil pressure in those locations, just splashing.
Looking at this picture of the timing case, I would expect the KDP to drop onto the cam gear, which would be rotating ccw and would tend to launch the KDP into the case wall at about the 11:00 position. Perhaps folks who have seen it happen can say for sure. It amazes all the more that yours just found a safe place to hang out -- unless maybe it was just about to come out and you bumped it the rest of the way out when you removed the timing cover ... wow. Million-Mile Cummins Rebuild Photo & Image Gallery

zachdkingnh

I bought my truck recently (Feb 2017) and went to do the KDP and found a giant wad of some sort of epoxy on the very top of the timing cover and my heart sank, luckily all the gears looked good and I stuck a new pin in, tabbed it, and JB welded the snot out of the old epoxy patch...they seem to really like busting a hole through the case at 10-11 o'clock which seems like it would be a hard patch, my JB weld is working for now, but eventually I'd like to replace the timing case...probably going to wait until I have a 2nd vehicle or a nice shop..Have you checked your vacuum pump? My truck is also a 95 which uses a 3 piece vac pump, which I rebuilt about 3k ago and that stopped the drips, but its fully leaking again...worth checking for sure if you haven't. It gets oil all over my track bar/gear box and everything!