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mike switzer
mike switzer,
Category: Jeep
Satisfied Customers: 759
Experience:  lead diagnostic tech at Aamco
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I have a Jeep commander 3.7. About a year ago after an oil

Customer Question

I have a Jeep commander 3.7. About a year ago after an oil change my wife said I was leaking oil. Checked it and sure enough I hadn’t tightened the filter enough. Leaked out al but 1 quart full synthetic. It did have fine metal shavings in the oil but ran fine for a year. Then the oil pressure light started coming on but engine stil sounded fine. I changed the oil sending unit and changed oil. Worked fine for a month then the light started coming on again. Took the shavings I had saved to a machine shop. He said it probably was soft metal from timing components. I bought a timing chain kit and took it to a local mechanic for install. He tried several times to get the timing right but could not get it figured out. He agreeed to pay for a rebuild on the engine. He pulled the motor and I took it to machine shop. They pulled the timing cover and set it up properly. The owner reported that the engine looked pristine otherwise and did not recommmend a full rebuild. Took it back to mechanic for reinstslll. Motor started right up but was rattling a little. After 15 mins engine died and froze up. Pulled valve cover on suspicion the timing had come loose. Sure enough cranked the motor and the passenger side cam had no movement on the chain when cranking. Drug it over to machine shop for inspection. They said they were a little confused because the crank had a spot for a snap ring to retain the main timing gear but there was no part listed so they just slid it on and installed. The timing chain had walked off the main crank. They pulled the head and found it had dropped an exhaust seat and bent a rod. They claimed that the timing came off because the seat dropped. Mind you the engine ran perfectly when I brought it in for the original timing chain job. They claimed the bent rod was not their fault. I pulled the engine myself an brought it back to them for full rebuild at full price. 3 months after this all started got the rebuilt engine back. I reinstalled it. Started up fine but had a ticking noise. I have a video. Sounded like it was coming from the timing chain cover. Sound went away when rpms were slightly raised. After 10 mins of running engine suddenly died. I am afraid the timing came off again. I need an expert opinion on this hopefully from someone who knows the 3.7 Jeep. I am probably going to take it back to the machine shop. Questions. Was his assessment of the valve seat causing the timing to come off likely ? Also is there any trick on the 3.7 timing that perhaps he or his tech does not understand that could be causing this timing issue. Any additional comments. I would be willing to pay for up to three experts to comment on this.
JA: When we are ready I'll take you to the appropriate web page.
Customer: Ok
JA: Have you checked the oil? How old is your oil pump?
Customer: New oil new oil pump
JA: What year is your Commander?
Customer: 09
JA: Are you fixing your Commander yourself? What have you tried so far?
Customer: That’s all in my question above
JA: Anything else you want the mechanic to know before I connect you?
Customer: No
Submitted: 8 months ago.
Category: Jeep
Expert:  roybelding replied 8 months ago.

hello, my name is ***** ***** I will be glad to assist you. please allow me a couple of minutes to gather some basic info.

Roy

Expert:  roybelding replied 8 months ago.

ok,

when the engine locked up, thats when the damage happened.

when the exhaust valve or chain failed and the valves were open, there was a collision with the valve and the rod bent.

this all resulted from the cam locking up. it most likely locked up from damage over time from the low oil from before. metal shavings are usually the result of bearing material from the mains, rods and from the cams in the heads.

The machine shop holds some liability to the assembly of the motor but the root cause of failure goes way back to the beginning.

Sorry, tough case to prove either way.

Roy

Customer: replied 8 months ago.
The timing chain kit was brand new and the chain did not break it walked off the sprocket. He inspected the bearings, main shaft and said everything looked pristine on the first install. The second install he did a full rebuild and it appears to have walked off again.
Expert:  roybelding replied 8 months ago.

ok, but my concern is the cam lock up. it was starved for oil and thats why it locked up.

the chain walking off is another issue, I agree and it was not right.

when they did the rebuild, did they replace the head where the cam locked up?? that could have been the source of the metal.

Roy

Customer: replied 8 months ago.
I don't think I am being clear. When the engine was originally starved for oil about a year ago, i changed the oil and it came back fine. Subsequent oil changes did not have metal in the oil. The first time when I had the timing chain done the engine was running perfectly, all systems good except the oil light had been coming on. we think it was just a bad sending unit. The only thing the machine shop did on the first run was replace the timing chain and that failed after about 10-15 mins of running. The engine had good oil in it at that time, new oil pump, timing chain kit etc. The question is which came first. Did the exhaust seat dropping cause the timing chain to walk off the sprocket or did the timing chain walking off the sprocket cause the exhaust seat to drop and bend the rod? The only work done to the vehicle was on the timing chain and it failed 10 mins after its first run. Do you see what I mean? I'm not trying to lead you in my direction, I just want to make sure you understand the circumstances.
Expert:  mike switzer replied 8 months ago.

hi my name is ***** ***** have actually seen these engines valve seats drop. this is rare but does happen and if it dropped the way it did on you enough to lock the engine then it can cause the timing to come off because everthing is still wanting to move it will skip teeth. a slipped timing chain will not cause a valve seat to drop though. the ones i have seen drop have been from excessive overheating. doesnt sound like that happened in your case. the seats are just pressed into the head as they are on all aluminum heads.