t-kads

Ok so background, i have a 2000 XJ sport 4.0 I6- I recently replaced battery, terminals, alternator.. over 4 days I drove about 750 miles from nj to md and back and out to PA for the nascar race.. Jeep ran fantastic the whole trip, made sure my fluids were all in check and put some plus in, and the night before we left to come home i did a little mudding. got about 50 mi back towards home on the highway late the next day and while driving there was a bad clacking sound and i lost all power. had to get towed back home ($$) and since then this is what ive done:

Replaced starter (See below)
Checked flywheel for damage
Replaced battery ground
checked bloc ground to firewall

When I turn the ignition, i hear the starter relay and then just a single whack sound (which is why i thought it was the starter possibly not engaging the fly), I'm thinking it may be a dead short but im having trouble figuring out what it might be, all fuses and relays for the starter and ignition check out.. couldnt be the fuel sys cuz it doesnt get to that point.. any help is appreciated..

Lowrange2

The motor isn't spinning at all? The old starter and new starter did the same thing?

Will the engine spin by hand? See any oil that wasn't there before?

With limited info it sounds like something is keeping the engine from spinning over. Before I start assuming catastrophic failure I'll wait for more details.

First things first... spin the engine over by hand. Second, stay out of the mud.

t-kads

old starter and new starter nothing changed, there was a minor leak in the oil pan, nothing new w oil, im not sure how to go about turning it by hand.. my one friend just suggested that it could be the crank position sensor, but thats the only lead ive got and im working w/o a volt meter until later this afternoon

Lowrange2

Put a big wrench on the crank pulley and turn it clockwise.

If it spins by hand I'll move on to trouble shooting the starter circuit. A bad starter circuit isn't going to kill an engine while riding down the road and it's certainly not going to make a bunch of clanking.

CPS has nothing to do with spinning the engine over.

t-kads

how hard should it be to turn it? ive only got a short breaker bar and so far it doesnt want to budge (fyi i dont have that much upper body strength haha

Lowrange2

It shouldn't be that difficult. Pull the spark plugs out, and pull the belt off then try again. It should spin really easy that way.

My next step would be to drain the oil in a pan and look for pretty metal flakes and/or chunks of piston skirt.

DFlintstone

I second lowrange's advise. The reason not to go counter clockwise is because that might loosen the bolt. (me, I might try it a tad), then if it moved come forward and listen/feel for a "bonk".

Also I might make double sure I have shiny lead on the insides of the terminal clamps. A thin hard crust there could cause your starting symptom. (probably not the clanking and dieing though!).

photophelps

Check your distributor cap.. Mine went out while driving, killed the engine and wouldn't turn over. It's an easy fix and could be your solution.

t-kads

when i turn the ignition the pulley was turning very slightly with each try, So i tried to hand crank to no avail, she wouldnt even budge with full body weight, my buddy came by and I tested the voltage to the starter when I turned the ignition and it went from 12v to 7v and you could smell something burning, most likely the starter motor unable to turn the fly.. I believe she may be seized unless there might be another explanation.. only problem i have with the seizing theory is that its been running great, i recently replaced essentially the entire cooling system, cleaned out most of the crap (there was a decent amount) under the valve cover and had been running seafoam through the system for a few months (until the oil pan leak), it was running on good temp and oil pressure for the long trip i took so no real warning signs at all.. im baffled and think i may have to bring it to the pros..

freegdr

How did you clean the stuff under valve cover ?

DFlintstone

Lowrange2

Are you being serious? You're saying that a faulty distributor cap will prevent the starter from spinning the engine?

Sounds like yer motor imploded. Sorry bout that.

Have you drained and inspected the oil yet?

Will you please pull the oil pan and take a picture?

t-kads

there was a lot of gunk built up when i went to change the HC gasket so i took to it with some razors and an air compressor, as well as running it with just seafoam/tranny fluid to break it down a bit, then did oil changes w seafoam every 2 weeks until the oil was clear, that was about 9 mo. ago.. since then ive been runiing rotella and every few oil changes id throw some seafoam in until the oil pan leak started showing and i realized i comprimised the gasket.. since then ive been adding oil as needed keeping a very close eye on it especially the past few weeks with the trips.. At this point I dont have the resources to pull the pan to show you, but tomorrow ill drain the oil and check for any debris..

Lowrange2

I'm sure you've checked the oil level since the implosion?

t-kads

yep same as when i left before the last leg of my trip, ive kept a very very close eye on the fluids for this trip and there were no signs of anything wrong with temp, oil pressure, oil level, coolant level tranny fluid, everything was solid for 750 miles and then it just died.. at a very big loss for words haha