- Hello. I have a 2005 Jeep Wrangler Sport, 4.0L manual, with 190k miles. My issue started shortly after a bad cases of death wobble. Within a few miles of the wobble, the jeep threw a code for cylinder 1 misfire. It had been a while since plugs were changed, so I replaced all plugs. This didn't resolve the issue, and the misfiring became worse, then I replaced the coil assembly. This didn't resolve it either.
- I took the jeep to a mechanic who didn't do much diagnosis, but they mentioned that the cylinder 1 plug was fowled and simply recommended a motor swap. When I replaced the plugs initially, I inspected each and saw no signs of fowling, so I was a little concerned. I asked them to check compression. This resulted in 0 compression on cylinder 1, with normal readings on cylinder 2-6. Again they went with motor swap, only because their shop doesn't have staffing to do internal work anymore. I asked them to borescope and perform a blow down test. Per them, the borescope showed no signs of internal damage to the cylinder and 2 blow down tests at different crank positions both resulted in escape from the exhaust. I had the jeep towed back home hoping for something asveasy as a bent lifter rod... Here's where we are today.
- Turning the crank by hand through all cylinders' strokes is as expected, until I get to the exhaust stroke of cylinder 1, where it is extremely difficult to rotate. I have removed the rocker assembly for cylinder 1 and the lifter rods are not bent. This leads me to believe I may have a bent valve or stuck lifter. I'd rather not remove the head myself, as I have a hard time taking off work and am about to move out of state in a couple months. I fear I won't have time to get this done myself, if the head comes off.
- Looking for any ideas of other things to look at before I put her back together and try a different mechanic.
- I appreciate everyone's time and look forward to your response!
- Eric
Sounds like you may have have a burned or cracked exhaust valve. If that's the case there's really no choice but to remove the cylinder head. (You really need to do that anyway to see what's going on, hard to see a way around it if nothing showed on the borescope. Was a scope used that could look back up at the valves?)
If it is a bad valve you could do a minimal repair and just replace that if the seat is OK, or you could rebuild the head, or even install something like an aftermarket Clearwater cylinder head for the 4.0. Maybe someone else can come up with an alternative but I'm thinking that head has to come off.
Chuck,
Thanks for the reply. I don't know if they were able to look up. The most detail I got from them was that there was no excessive scoring considering the miles on the motor, no damage to the piston, and no signs of metal debris from a shattered valve.
I appreciate the lead on the aftermarket head assembly. I'll consider it as an option since it's most likely coming apart anyway.
no signs of metal debris from a shattered valve.
I had a similar problem on a car years ago, the engine lost all compression in one cylinder. When I pulled the cylinder head there was an exhaust valve that had cracked from metal fatigue. Fortunately the piece had not completely separated so there was no debris. At that time the car had about 200,000 miles on it. I installed a rebuilt head and drove it another 200,000 miles. So that's one possibility.