Broken Distributor Bracket Leading to Possible Oil Pump Failure and Engine Damage

This is for a '93 XJ Sport with the 4.0L engine at 270K miles or so.

I had the distributor out the other day to replace the pickup coil (AKA camshaft position sensor) due to a crank but no start situation. I had it all put back together and took it for a 15 minute test drive, working it hard to check for any missing or other ignition problems. Everything wwas working and sounding good, so I parked it for a couple of days. My wife hopped in it to drive it to work one morning and got a few blocks away before the engine began making ghastly sounds and quit on her. I asked her what the oil gauge said before it quit and she had no idea, but I'm sure it was at zero. We got it towed home and I started it up for about 30 seconds to see what I was dealing with and the oil gauge read zero and the engine was making terrifying sounds. It was more of a grinding sound than just a tapping.

So, I checked the oil level with the dipstick and it read full to the line. Next I removed the distributor cap and distributor hold down bolt. I didn't notice it while I was removing the bolt, but when I went to pull out the distributor, I saw that the bracket had snapped off the distributor body. An inspection of the broken piece reveals that there had been a crack for some time that must have propagated the rest of the way through sometime after I torqued it and did my test drive. So, first problem is I obviously need a replacement distributor body.

I think that perhaps the distributor/oil pump drive shaft may have dis-engaged from the oil pump drive due to the broken bracket. Interestingly, the gear does not appear to be worn (on either the camshaft of the distributor shaft), and the engine seems to have kept the correct timing, because it does start up and run without missing or backfiring.

I wanted to check the condition of the oil pump, so I used a long slotted screw driver to manually turn the pump drive through the shaft opening and found it very stiff and difficult to rotate. I don't know how that compares to before I changed the pickup coil, so it might have been that way for a while. Does anybody know how easily that should turn by hand? Perhaps it's time to replace the oil pump. I've had the jeep for 10 years, since it was at 169K miles, so maybe it's just due for a new oil pump.

My biggest concern at the moment, however, is what might have been damaged by letting the engine run dry of oil? I was so hoping to squeak 300K from this Jeep and if I can salvage a few more miles from it, I'll be pretty happy. What should I suspect is damaged, and how can I check to know for sure? I'm pretty handy at most mechanical things, but I've never undertaken anything so major as an engine rebuild. Please chime in and help me figure out what to check and look at to get this thing running again.

Thanks!

The distributor shaft sits in the oil pump shaft 3/8" to 1/2". For the oil pump to stop turning the distributor would need to raise up that much, disengaging the oil pump or possible shearing the ears on the pump shaft.

OK, then perhaps the oil pump is just not performing as it should, or maybe when the distributor bracket broke, the shaft raised up enough to disengage the pump AND the cam gear. If the latter is true, then I'll want to find TDC and reinstall the new distributor to correct the timing. I should probably also get an oil pressure gauge and check the operation of the pump manually. Any thoughts on the hopefulness of the engine being usable?

Thanks!

so when you inspected it after the break down the bracket was broken, right? was there any evidence that dist had jumped up? or did it seem like it was still seated?
it's not likely that the dist would have popped up, made noises and stalled the engine and dropped back down in the correct timing location. and with the wires on the cap it would not have spun around either.
at this point it's hard to say if the oil pump is bad and the dist is unrelated, or if its the other way around. the oil pump should have some resistance to it because it is moving oil, but shouldnt be too tight to turn.
if the old dist is bad, pull it apart and use the shaft in a cordless drill and manually pressurize the system with the key on to see if gives pressure.

sidriptide said:

so when you inspected it after the break down the bracket was broken, right? was there any evidence that dist had jumped up? or did it seem like it was still seated?

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Yes, I found out the bracket was broken after the breakdown and removal of the hold down bolt. The distributor seemed like it was still sitting in the hole correctly, at least it didn't appear to me as being in an unusual orientation, etc. However, it didn't even cross my mind that the mount might have broken, so I wasn't looking specifically at how it was seated. It stayed in one place well enough that it didn't move around as I removed the cap, FWIW.

sidriptide said:

it's not likely that the dist would have popped up, made noises and stalled the engine and dropped back down in the correct timing location. and with the wires on the cap it would not have spun around either.

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Yes, that makes sense. So, probably, the distributor assembly lifted up out of the hole, disengaged from the oil pump and also lost the timing, then dropped back in the hole. I should be able to remedy those two problems with a new distributor and finding TDC, etc. I guess I'll work towards that point (after checking the pump operation with a drill) and see how things look as far as further engine damage. Any tips on what might have been damaged due to lack of oil would still be appreciated.

sidriptide said:

at this point it's hard to say if the oil pump is bad and the dist is unrelated, or if its the other way around. the oil pump should have some resistance to it because it is moving oil, but shouldnt be too tight to turn. if the old dist is bad, pull it apart and use the shaft in a cordless drill and manually pressurize the system with the key on to see if gives pressure.

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That's a good idea, and something I can do before or instead of rounding up a manual gauge.

Thanks!

internal bearing damage is always possible when oil pressure is lost. it's just a matter of how long it was out before it was shut down. if it was just a matter of a few moments then you will probably be lucky enough not to have bearing damage. again, it depends how much time it took.
my gut says the distributor might not even be the problem. if it jumped up, it would not have seated itself again. pull the valve cover off when you spin the pump. look for damage there and the oil should be reaching the top of the rockers.
take a step back and think about oil pressure basics... pull off the oil filter and swap it with a new one.

Before you do anything, drain the oil, look for sparkles.

When the oil pump is primed, there will be a lot of resistance. I break out the heavy drill to prime the oil system.

I can't really picture the crack in your distributor housing, but side loading is a possibility. Look around for witness marks in less obvious places.

If you are really in need of getting more miles out of it, drop the pan and pull a couple of bearing caps. I have been known to slap a set of new stock bearings back I an engine if the journals aren't galled. My wife ran here Pacifica dry and it had terrible knocking. I swapped the rod and main bearings and she has put another 100k on it so far. The key is to not proceed until you know what the bearings look like. If you keep going on crappy bearings, you will take out the crank and more.

^^I have done this as well. As long as the crank journals are not damaged, this is an acceptable, if out of common usage, practice.

It can help engines that are suffering from low oil pressure as well. If you think about it, it makes sense. As the bearing wears, the clearance to the crank opens and the oil bleeds off easier.

These are all some great suggestions. I'll definitely take a look around at things to better assess the situation. It sounds like a good idea to change out the oil and inspect for metal shavings, etc. I think I'll start by putting the distributor back in place with the same timing as when I removed it last, then rotate the engine to TDC manually. I'm curious to see if the distributor timing was off; maybe that explains the rough running as much or more than the oil pump being malfunctioning. I also still want to run the pump with a drill and see that that does on the gauge. Depending on how things look at that point, I'll weigh option of dropping the pan. I'm going to be out of town for a couple of weeks, so I'll have to dig back into this then. (I'll try to post some photos showing the broken distributor housing then.) Thanks for all your great suggestions and comments!

Just wanted to post an update. I was able to get the Jeep running again and it seems to be doing well. Changed the oil, looking for metal in the old oil. I didn't see any evidence of metal. Next I manually rotated the oil pump with the distributor shaft to verify that pressure would build and show on the dash gauge. It did. Then I went through the process of finding TDC on the compression stroke and installed a new (junkyard) distributor with a new CPS already installed. After adding a couple bottles of fuel dryer/conditioner and priming the throttle body with starter fluid, I got it started. It blows white smoke, I guess from the old fuel and additives, but I think it will clean up once I get some fresh fuel in the tank. It's a great relief to have this thing running again! Thanks for everyone's input!

Oh, one other thing, I don't believe that my jeep had an OEM distributor hold down bracket, only the fork on the distributor body. I didn't even realize something was missing until at the junkyard I saw that all the jeeps had the separate piece that cantilevered to apply force directly to the distributor body. I guess at some point in the distant past the bracket was either lost or never used by the factory. Strange?

I don't anticipate any engine damage. If the distributor gear fails not only the oil pump stops but the distributor does as well. No spark, no run.