SOLVED: Jeep died, throwing P0340 code, distributor assembly seems broken

CAD1 said:

If you need any pages of the service manual concerning changing out the distributor let me. I'll send them to you. It is an easy process but few step you need to take.

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Thanks, I've previously downloaded it from this site. I'm going to look it over today to get a good overall idea of what I'm getting myself into here.

OK, so looking through the FSM, this is what I'm seeing regarding the process for timing chain replacement. I don't see in the steps that the radiator needs to be removed. Is removing the radiator optional and just makes it easier to access the front of the motor? I also don't see that the alternator needs to be removed. Is this also optional?

I'd be curious from anyone whose replaced a timing chain before while the motor was in the vehicle, how long did the job take? Bonus points of you have a particularly good video or other resource you found helpful.

I think I'm going to give this a shot.

JKP said:

I don't remember how long, I did pull the radiator because the puller I had was too long to work with it in.

It's also a good time to replace the crank pulley if the rubber on it is cracked as they can eventually separate and cause problems with the belt.

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I'll look at that as well.

It seems from a process standpoint, it may not make sense to buy any parts until I actually open up the timing chain cover and get eyes on how everything looks?

Then I can determine what I need to replace like the crank pulley, water pump, serpentine belt, harmonic balancer, etc.

Anything else I should probably inspect for possible replacement while I have it opened up?

Ok, so here's a bit of an update, since you guys gave me the motivation to tackle this job on my own!

Over the last 2 weekends I've been tackling this job in steps. Last Sunday I removed the radiator, fan clutch and serpentine belt, giving me good access to the front of the motor. That took me a couple hours, and I called it a day feeling good that I'd made good progress without hitting any major issues (this is all new to me).

Today, in between the rain we're getting here in socal, I pulled the harmonic balancer off, so all that's left is to remove the timing cover which I plan to do tomorrow. I've purchased the following parts and tools to do this job:

40-200 inch lb torque wrench

Gasket scraper

Harmonic balancer puller (loaner)

Harmonic balancer installer (loaner)

Seal driver set (loaner)

Fel pro timing cover gasket kit

Melling timing chain kit

Here are some photos of the radiator and fan as well as the harmonic balancer.

Is there anything you guys recommend I do with the radiator while I have it out? What about the fan? I haven't had any cooling issues with this Jeep (yet), is there anything obvious to look for with the fan clutch to tell if it should be replaced?

macleanflood said:

Rubber looks pretty cracked on the harmonic balancer... I'd replace it. I replaced mine and it looked worse.

Flush the radiator out with a hose and give it a good shake or two. Mind the fins and don't break anything. I pressure washed mine with a 40 degree nozzle...might be able to take it to a car wash if you don't have a pressure washer. I wish there was a good source for radiators cause if it was any other vehicle I'd just replace it.

From what I see on the thermostat housing...the red...looks like you need a good flush or two.

I'll let others speak about testing the fan clutch...if I remember right it should lock up under a certain temperature. So I'd test with a heat gun or propane torch and my laser thermometer. Probably an easier way.

Gonna have fun cleaning up that timing chain cover! Nice work, great progress and keep up the good work!

-Mac

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Yeah the balancer looked pretty rough even to my untrained eye as well, so I'll order one of those as well.

I do have a pressure washer so I'll clean up and flush out the radiator as well before reinstalling it. Thanks for the advice!

One other question that occurred to me is whether it would be a good idea to reinstall the distributor while the timing cover is off and I'm having to reset the timing anyway?I know the distributor has to go in at a specific angle with the engine at TDC, I'm wondering whether setting the distributor correctly is any easier with the timing cover off and the gears visible?

My fear is that I don't get the timing set quite right when I replace the gears and chain, put everything back in and then can't get the distributor set correctly and have to pull everything back out again?

JKP said:

Yes, you can put the distributor in with the timing cover off. However, when you have the timing dots on the gears aligned, the distributor rotor will need to be pointing at the number 6 cyl terminal, not number 1 as most would assume. I found this out the hard way when I replaced the timing set on my 92 4.0. Lined up the dots, put the distributor in with the rotor pointing a cyl 1, nothing.

The FSM doesn't mention this, and I only found a few mentions on the web.

Or, you can rotate the timing dots to where they are opposite each other and install the rotor pointing to cyl 1. In both cases, the crank key will be at 12 oclock.

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Ok so I spent the better part of the day today removing the timing case cover, took way longer than expected, but for good reason. I didn't realize it but I needed to remove the AC compressor assembly to have better access to the bolts. I also removed the pulley pictured because it was obstructing access to the cover. In order to move the AC compressor I had to remove a hose which was under pressure and what I'm assuming was the freon all escaped. Not sure what ramifications will be for that yet.

Removing the timing cover itself wasn't difficult, in fact most of the bolts were surprisingly very easy too remove, almost loose on some if them.

I've attached photos and video showing the amount of play in the chain, which definitely seems loose to my untrained eye. I spent at least an hour trying to clean the timing cover and scrape away the gasket. The cover was absolutely caked in grease! Photos attached are of the condition of the case after I cleaned it as best I could and removed the crankshaft seal.

When I removed the timing cover, the chain tensioner I noticed was broken at one end. Not sure if this is related to my original problem or not? After inspecting the gears, I did not see any signs of damage to the teeth or other obvious indications that it has jumped any teeth. I was able to align the timing marks on the gears while confirming TDC on cylinder 1, so I don't think the chain skipped? Maybe my mechanic misdiagnosed it as a skipped timing chain and it's something else?

hear said:

The easiest way to set the diz if you've already found TDC is to pull the diz and put a small pin through the alignment holes, making sure you use the hole for 6cyl vs 4cyl depending on which motor you have. This pin will lock the rotor in place for TDC. It can only be dropped back in with one orientation due to the hold down bracket, so you get it lined up for drop in, pull the pin and push it into the hole. It will rotate a smidge due to the helical cut of the gears.

If you get the diz aligned wrong you won't need to pull everything apart, just lift it up, re-align it, and push it back down. But this way is pretty foolproof.

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I think my situation is a little unique in that the distributor is not currently installed with the rotor aligned at TDC. Just to recap my issue since this post is 3 pages deep at this point:

3 weeks ago motor died on me and threw p0340 code, which upon inspection I discovered that the distributor had broken off at the hold down collar.

I took the Jeep to my mechanic thinking it just needed the distributor replaced, which he had originally installed for me 6 months ago. My mechanic tried installing 2 different distributors but wasn't able to get the timing correct on either distributor which led him to believe that the timing chain had skipped teeth which is why he couldn't get the timing correct with either of the 2 new distributors.

So now my concern is that the distributor is not currently installed in the correct position, and that I will need to set this myself without the benefit of simply using the alignment holes like you mention above?

Does this make sense?

I'm trying to understand how to remove and reinstall the distributor with the rotor in the correct position without the benefit of those alignment holes? My understanding is the rotor should be pointing in the 5:30 direction of cylinder 1 terminal on the distributor while I'm at TDC on cylinder 1?