[frank.oz]

I have a 2004 TJ with the 2.4l 4cyl engine. What could cause cylinders 1,2,3 to have no compression but 4 is ok? This seems to be a gradual processes and I would stall more and more and more difficult starts.

Frank

 

[Old Dogger]

Welcome to the Forum!

 

[Rixthe1]

blown head gasket, burnt valves, bent rods, flat cam. Now add a tablespoon full of gear lube to one spark plug hole at a time, and retest. If pressure increases, it is worn or broken piston rings and worn cylinder, if not, most likely bad valves.

 

[Jeepster20054liter]

As noted above, lots of possible causes and no single answer without diving more deeply into diagnosis. As mileage increases and engines wear low compression becomes a somewhat natural consequence of use. Some are fairly simple and not to costly to repair; others come with a higher price tag. Many miles on your engine?

 

[Digger84]

Since the 2.4 has a timing belt and 2 overhead cams it is possible that the timing belt broke and only one cylinder has both valves closed so only one cylinder has compression

although the 2.4 is a non interference engine (valves won’t contact pistons) if a cam moves independent of the other cam you can get valve to valve contact and bent valves

however if this occurred gradually it is not just due to a broken timing belt

 

[steve_k]

Yikes. Hopefully nothing bad that a head rebuild can't cure. Would suck to have to pull the whole motor.

 

[frank.oz]

As noted above, lots of possible causes and no single answer without diving more deeply into diagnosis. As mileage increases and engines wear low compression becomes a somewhat natural consequence of use. Some are fairly simple and not to costly to repair; others come with a higher price tag. Many miles on your engine?

119,xxx

 

[frank.oz]

Since the 2.4 has a timing belt and 2 overhead cams it is possible that the timing belt broke and only one cylinder has both valves closed so only one cylinder has compression

although the 2.4 is a non interference engine (valves won’t contact pistons) if a cam moves independent of the other cam you can get valve to valve contact and bent valves

however if this occurred gradually it is not just due to a broken timing belt

The timing chain has been replaced once when it broke. The engine light turned on and registered a camshaft position sensor warning but it stayed off after a computer warning. I changed the spark plugs and noticed there was a little oil in the plug holes.

Frank

 

[Digger84]

Unlike all other TJ engines it is a belt not a chain
Just see if the cams are turning as not turning would produce compression just in the cylinder with closed valves and not the other 3

 

[frank.oz]

The place that I brought it to checked that and the cam cover was off when I picked it up. Plus I've had it running with only one cylinder apparently.

Frank

 

[Jeepster20054liter]

Since the 2.4 has a timing belt and 2 overhead cams it is possible that the timing belt broke and only one cylinder has both valves closed so only one cylinder has compression

although the 2.4 is a non interference engine (valves won’t contact pistons) if a cam moves independent of the other cam you can get valve to valve contact and bent valves

however if this occurred gradually it is not just due to a broken timing belt

 

[Jeepster20054liter]

So it is driveable? I don't think that would be possible if it is only running on one cylinder.

 

[TJ4Jim]

The 2.4L is an non-interference engine as Digger said but if the timing belt broke while running I have heard (no personal exp) the valves can hit each other if the 2 cams are spun independently of each other.

 

[frank.oz]

So it is driveable? I don't think that would be possible if it is only running on one cylinder.

So it is driveable? I don't think that would be possible if it is only running on one cylinder.

It was, as long as i can get it started, just keep cranking it and give some gas. Then keep it reved up to prevent it from stalling. I had a bluetooth ODB2 scanner on there and it had said misfires on cylinders 1,2,3 but after i changed the plugs, wires, and ignition coil those never came back. I ran it for maybe half and hour before i stalled out. I got it started and drove to the shop and that's when they told me there's no compression on the 3 cylinders. I couldn't start it after that and had to tow it back.

Frank

 

[Digger84]

Check the compression on each cylinder yourself

 

[Jeepster20054liter]

Sounds like you had three cylinders struggling then finally gave up. Doesn't sound like an engine just getting tired and mileage isn't that bad. Would be interesting to see what the valves are doing now that it is not running.

 

[Rixthe1]

I have a 2004 TJ with the 2.4l 4cyl engine. What could cause cylinders 1,2,3 to have no compression but 4 is ok? This seems to be a gradual processes and I would stall more and more and more difficult starts.

Frank

I would remove the valve cover, and check for broken parts, valve springs, and rockers.
My dad's 76 ford 6 cyl van, had that problem. A shop said he needed a complete engine overhaul. I changed his oil, and used 3 quarts of rislone and 3 motor oil, within half an hour, it was running fine.