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2000 cherokee cranks won't start

M

martness

NAXJA Forum User
Location
Poland, OH
I have a 2000 xj 4.0 115k I've recently replaced the oil pump and the head gasket, problem is it won't start. I have spark, I've grounded the coil pack and checked each cylinder, spark is good. It gets better, after the initial cranking session I changed the plugs they were wet. I've checked the timing by rotating to compression TDC and checking the cam positioning sensor all good. After repeated cranking I checked the oil, it smelled of gas I drained about 8 qts of gas and oil mix out of the crankcase. when I had it apart I cleaned the injectors with carb cleaner I didn't touch the fuel pressure regulator, pressure at the rail is 45-50 lbs. It did run although extremely rough before I did this. I don't want to just replace parts but would like to narrow it down a bit. Thanks for any help.
 
Thanks for the reply, I checked compression with a pushin guage it was low, 75, but that was right before I found the 2 qts of oil in the gas. I thought that would account for it. I can't understand how that much gas got in there what could cause that kind of flooding.
 
I guess the repeated cranking sprayed gas into the cylinders and it got by the rings. Did you crank it over some with the plugs out to clear the cylinders? I guess you could unplug the injectors to do that too. 75PSI is kind of low, but at least one good running XJ reported that 75 compression also.
 
I gave it a more thorough compression check with a screw in gauge. I get 100 on most cylinders after spraying a little oil in the cylinder. #3 though only gets 60#s. This is an 0331 head and when I removed it i assumed it was cracked from all I had read about that head. The local parts store that handled the rebuild assured me that it wasn't cracked, he told me they would pressure test it, now I find out that wasn't done. He said if it was cracked we would have seen it. could it be cracked and not be visible, to an off the engine inspection.
 
A couple of other things, tonight I had the valve cover off everything looks ok I cranked it a couple time with the cover off, the valves seem to cycle alright but I thought I noticed some exhaust gas escaping. When I had the oil pan down I could just see a little bit of the timing chain there seemed to be a lot of sag. Like I said earlier I've checked the timing at TDC and it looks good but could a stretched timing chain throw off the timing enough to cause a no start. Thanks again for any help.
 
Before you took it apart, did you have any symptoms of the dreaded 0331 head crack. Coolant level going down. Milky residue on bottom of oil filler cap. If you have only 60PSI on #3 cyl, you have a problem. It is not a stretched timing chain. 75# is the lowest reported working engine and it should be relatively even on all cylinders.
 
Before I took it apart I had all the symptoms of the cracked head, when I took it into the shop to have them look at it they told me it wasn't cracked but they would pressure test it, I fully expected to have to replace the head. I was looking at an Alabama Cylinder Head for 500.00. Today I found this, http://www.naxja.org/forum/showthread.php?t=987078&highlight=0331 and loosened my rocker bolts and got over 90 psi. The parts store told me they had to take .015 off the head but I think they must have taken more. He thinks they make a head shim for .020 or over stock removal (head). He's checking on it for me. I would like to find a washer type shim to go under the saddle, I feel like I seen something like this at Summit.
 
did you check the crank position sensor?
 
yea I had just replaced the Crank sensor and then the cam sensor I have good spark, I've grounded and checked the coil pack. Does any one know what the head height should be. Winterbeater that thread is what tipped me off to loosen the rockers. My parts guy says he can get me a head shim .020 another 50.00 and a new gasket 50.00 that 500.00 head looks better and better in hindsight. One of the reasons I stayed with this head, I thought if I had one that didn't crack I should stay with it. I don't know if I like a double layer in the gasket area, i think I'd rather have the washer under the saddle.
 
I put .020 copper shims under the rockers, good compression 90 to 100 but no start. Whats the best way to check preload. TDC and check #1 ? I'll probably bump it up to .030 and try it. But I would like to get it set right.
 
When I had the head off I removed the lifters with a magnet I was able to move the top insert on the lifter up and down slightly maybe .050 in. is this acceptable? I was thinking that a hydraulic lifter without oil would have this much play but now I'm questioning everything.
 
It sure seems like the lifter should collapse a lot more than that. They should be loose until they pump up. The FSM doesn't cover that. I would guess that they should go down at least 1/8". I'll see what else I can find.
 
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