First Jeep, just bought, '07 3.7, dealer says cam needs replaced, need advice/help - Jeep Garage - Jeep Forum

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Old 09-05-2014, 12:50 PM
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First Jeep, just bought, '07 3.7, dealer says cam needs replaced, need advice/help

To make a very long story short:

Was purchasing from an acquaintance, and it had a CEL on and a slight miss on idle/under 5 mph. He let me take it to get diagnosed before purchase. I had the code read at O'Reillys and it was a generic cylinder 3 misfire. So I called the dealer, I told them I had a cylinder #3 misfire, and they that it would be a $95 charge to find out what was causing it. I took it to them, and after two hours they came back and said "You have a cylinder #3 misfire, but I'm 99% sure it's nothing major, and I'll need to spend another 2 hours at $95 an hour to find out what it is" after getting into with the service manager (because thats not what I was initially told) they lowered what I owed to $45 and I decided to take it somewhere else.

Meanwhile, the seller could not wait any longer, so I decided to purchase it, because the service tech told me it was virtually certain it would not be anything major.

I took it to a Firestone who are always extremely nice to me. They spent over 2 days on it, replaced plugs, coil pack, and injector, and they said it helped a little bit, but they weren't comfortable charging me for that and just leaving it be. So they left the plugs in, and put the other original parts back on. They then wanted to do a compression test, which I allowed. They said that it had compression, but it was leaking out, so they suspected a burnt valve. $155 for everything they did and told me I'd probably have to take it to the dealer.

Took it to a second dealer near me, and after a compression test, they said the compression was fine. (Up to $380 in charges at the dealer at this point.) He said he'd have to go further into it to figure out what it would be, and that it would be another $135. I had no other option to ok it. He called me back today and they're saying it is the camshaft on the side of cylinder 3. It has excessive wear and pitting, so it's not allowing the valve to open/close all the way :-(

He recommended getting the timing chains replaced at the same time, since it has 119k miles and they have to come off to do the camshaft. From what I was reading though, they usually don't have to be replaced all that often seeing as their chains and not belts?

He said it's going to get pretty pricey, and he would get me a price soon. Any idea how much this is going to run me? Also, is the timing chain necessary/cost effective at this point?


Another concern I had, was if this cam is worn excessively, is the other one worn/going to go out soon? I asked and he said he wasn't getting a code from that side, but it sounded like he didn't even look at that side.

Im almost $700 in the hole just in a diagnosis so far, and I'm really hoping someone has some advice for me. In college and have 2k in tuition due next month, and this jeep is eating into all of my savings that I had for college, really don't have much left. :-/

As I was writing this he just called back. $1006 for the cam shaft, 600 for the timing chains, and 488 in the diagnostics they've done so far. He said he did have the tech look at the other cam shaft and said he saw no signs of wear on it and it looked good.

I asked what happens if I do all this and it's still messed up, and he wasn't sure what to tell me. Swapping the engine for one with ~90k miles would be 3291 + taxes.

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Old 09-06-2014, 06:38 PM
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Re: First Jeep, just bought, '07 3.7, dealer says cam needs replaced, need advice/hel

I PM'ed Strongjeff about your issue. Here's what he had to say:

"well without really getting my hands on it, it's difficult to really say at 100%....

but I think that the cam is not the issue. it could be a number of issues but nothing really major. id start with new plugs and since coils have apparently been swapped and the issue stayed at #3, it may be wise also to swap out the cam AND crank position sensors. that's my optimistic answer on this...

Worse case, since its 50/50 on compression and its still #3. it could be a valve seat potentially on its way out. that would require a new head. its actually a common thing on the 3.7/4.7's for them to drop valve seats when they are over heated.

id have him start with the spark plugs and cam/crank sensors and we'll go from there."

As I said on the other forum, pull, or have someone pull the valve cover again and take a look for yourself. If it is the cam, it'll be fairly obvious. Keep us posted on your progress. I would also recommend you not jump into anything too soon without having a very good idea what is wrong. Some stealers and independents will just keep replacing parts (at your expense) until they stumble on to the problem.

Also, what Jeff said about cam and crank sensors, (especially cam sensor) might be an inexpensive place to start, if the cam looks good when you pull the valve cover. Each sensor costs about $25 and are quite easy to replace.

If you can find out what the compression pressures were for each cylinder, that would help too. If you can't get them from the shop that did it, maybe it would be a good idea to have it done again, especially if the cam still looks good.

This is the order I would use to troubleshoot this.
1. Pull the valve cover and check the cam.
2. If it's bad, you know what needs to be done. If it's good, go to No. 3.
3. Do a compression check again, and report the compression pressures for each cylinder. If the No. 3 cylinder compression pressure is low, do a cylinder leak down test to isolate what is causing it.
4. If all is good this far, and the injectors, plugs and coils have been swapped without any change, install new cam and crank sensors.

This shouldn't really be too hard to figure out when the steps above have been followed. As I said earlier, cam lobes don't usually fail, unless there is an oiling problem. The only time I've seen one fail is on a new install, and it failed shortly after install, not after 120K. One other side note.......when the valve cover is off, look to see how gunked up the area is. If it has caked on oil and sludge, it has not been properly maintained. It should be very clean inside there. Again, keep us posted.
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Old 09-08-2014, 06:48 PM
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Re: First Jeep, just bought, '07 3.7, dealer says cam needs replaced, need advice/hel

Im glad that you made the long story short, because it already became quite a story.
I agree on all the above, but have also one more item to add: carbon buildup on the valve stem (normally the exhaust valve) can cause delayed closure of the valve and subsequent misfires. You could run some seafoam through the brake booster vacuum line without letting the engine completely stall and then switch it off an let it soak for an hour or so. Repeat this one more time and see if it helped. Eventhough a cam lobe can be pitted due to lack of lubrication, the lobe should be worn away quite a lot to cause a misfire.
If you would decide to pull the valve cover, check the hydraulic valve lifters for play and/or spongyness. A failing lifter will reduce the valve opening time a lot and can cause misfires as well.
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Old 09-14-2014, 05:19 AM
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Re: First Jeep, just bought, '07 3.7, dealer says cam needs replaced, need advice/hel

ANY update on this?
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