Valve Issue? Misfire?

swtchk · **Joined:** Mon Mar 21, 2011 10:55 pm **Posts:** 6

Hello all I was a previous member a long time ago when this was a small community and I have another Jeep now (03 Renegade) so I turn to you for help. Im sure this topic has been beat to death but I was having trouble finding it so Ill bring it up again.

So i'm driving to visit a friend and i make a turn and hear a slight "pop". The engine starts to lose power and starts to misfire and then the CEL starts flashing at me. I am able to nurse it to my friends house and start to check it out.

I have a misfire in #6, code 306. Checked the usual suspects plugs, coils, ect. and all seemed to be fine. So i did the compression check and i have nothing. It popped up to about 20 but i think that was just the left over fuel evacuating. I have heard of a valve spring issue, could I be seeing this problem? The part that burns me is there is only 64k on my Jeep which I in no way expected mechanical failure this early. I maintain regularly and use Mobil1 synthetic oil. So im kinda at a loss here. Any thoughts or help is greatly appreciated.

Thanks in advance.

Liberty02sport · **Posted:** Tue Mar 22, 2011 12:14 am

You may want to have the valve springs checked. My '02 sport had a flashing CEL and as it turns out it had dropped a valve after the valve spring broke so I wound up having to get a new engine. :evil:

redsnake · **Joined:** Fri Nov 26, 2010 9:51 pm **Posts:** 41

Sounds like a similar issue on my wife's '03 KJ.... been chasing a P0306 miss-fire code for a while. I think the Valve or spring turned loose on us Friday. Getting her towed to a shop hopefully tomorrow for a full diagnosis and possible fix or engine swap. Not sure I want to drop $5K on an $8K vehicle... but we'll see what we see tomorrow.

@ 63K miles that's HORRIBLE for you!! Let us know what you find out. At least my wife's KJ has 129K miles on the clock (still way to early to drop a valve in my opinion)

kjon · **Posted:** Thu Apr 07, 2011 2:03 pm

I had the same issue shortly after I bought mine with 70,000 miles or so. The engine chugged real bad, but I made it to the dealer. It was indeed a broken valve spring, but luckily mine didn't drop and ruin the engine. It only cost me like $500 :roll:

I think it was the same cylinder too.

jeepskate · **Posted:** Thu Apr 07, 2011 2:48 pm

Welcome to the club. Sorry to hear your story. I had the broken valve spring at 100K (valves replaced on all 6 at that time) and the valve dropout at 196K, which destroyed the engine. I'm on engine No. 2 now and have about 235K on the odometer. Every time someone posts about this, people jump in to say you only read about the problems online and nobody posts about their great experience with the 3.7 and it happens with all engines, blah blah blah. All of which is true. But it's also safe to assume that not everybody who has this problem posts about it either. Personally I think the 3.7 is not a very reliable engine. I replaced mine because it made the most financial sense to me at the time and I got a 100,000 mile warranty on the replacement. But I think the evidence is mounting against the 3.7. I took great care of mine too.

redsnake · **Joined:** Fri Nov 26, 2010 9:51 pm **Posts:** 41

jeepskate wrote:

Welcome to the club. Sorry to hear your story. I had the broken valve spring at 100K (valves replaced on all 6 at that time) and the valve dropout at 196K, which destroyed the engine. I'm on engine No. 2 now and have about 235K on the odometer. Every time someone posts about this, people jump in to say you only read about the problems online and nobody posts about their great experience with the 3.7 and it happens with all engines, blah blah blah. All of which is true. But it's also safe to assume that not everybody who has this problem posts about it either. Personally I think the 3.7 is not a very reliable engine. I replaced mine because it made the most financial sense to me at the time and I got a 100,000 mile warranty on the replacement. But I think the evidence is mounting against the 3.7. I took great care of mine too.

Thanks for the info. I haven't heard back f/the mechanic yet, so soon I'll know just how much damage was done and what needs to be done then.

Since you replaced your engine and got another 100K mile warranty... can I assume this was a Jasper engine? Or can you tell me what you are currently running and your impressions and cost associated w/it? Much appreciation. Looks like it's financially the way we may be going too... replace the engine w/a Jasper (or another if feasible) Thx!

jeepskate · **Posted:** Thu Apr 07, 2011 10:27 pm

redsnake wrote:

Since you replaced your engine and got another 100K mile warranty... can I assume this was a Jasper engine? Or can you tell me what you are currently running and your impressions and cost associated w/it? Much appreciation. Looks like it's financially the way we may be going too... replace the engine w/a Jasper (or another if feasible) Thx!

The remanufactured engine I got was sold by Mopar through the local Chrysler dealer. It was $5,200 for the engine plus labor and tax. So slightly less than $7500 all told. It was a lot to pay, but I didn't want new car payments, so the choice came down to this: I could buy another used Jeep that would have 100,000 miles on an engine model that I no longer trusted to last much longer than that, or for the same price I could put a new engine into a Jeep I'd already sunk money, blood and sweat into for mods and was otherwise happy with.

I've put about 40,000 miles on the second engine and it runs like it's brand new. The warranty is 3 yrs or 100,000 miles. For me, that's about the same thing.

XJMA · **Posted:** Fri Apr 08, 2011 2:16 pm

We had that code on an 05 or 06 work KJ after one of the cats got clogged and was replaced under warranty....still had that code. Cat got ruined due to fuel coming out valve and burning up in cat, or so they say!!

mechanics replaced all valve springs and retainers and everything, had head checked and it was fine, code kept on coming up. Turned out to be a bad camshaft!! Had to pay dealership to replace all the stuff that had already been replaced!! Our mechanics were like "we've checked everything and the only thing left that could be wrong is if the camshaft is messed up...and we can't see how the camshaft would be able to get messed up while in the engine." Well, that was the case, dealership had to replace it not under warranty!! STupid cheap camshaft with pressed on lobes!!! Hope it's not that!!

Pote · **Posted:** Sat Apr 09, 2011 3:22 am

question...so on high mileage Libertys 140-150K+ that are still running fine, is the valve springs (all 6) something that would be a good thing to just out and out replace as preventative maintenance? what kind of cost would be associated with replacing those even if there are no symptoms yet?

redsnake · **Joined:** Fri Nov 26, 2010 9:51 pm **Posts:** 41

Hopeful to find out the damages today to get this '03 KJ fixed or if we decide to just sell outright for a rebuild or parts.

Apparently the Valves/Springs on the 3.7, 4.7 & 5.7 are a known problem area for the Chrysler motors. Not sure how to quantify percentages, but still a known weakness. Not ALL are weak, just more than what I think should be. Hopefully it'll be good news today...

UPDATE:

Not good news. Busted Valve guide on Cylinder #6. Busted spring and valve and also likely a bent rod. Looks like it's going to be Reman + Warranty of 100K miles... all for ~ $5560 out the door. Now to hit up my bank for a signature loan...

Valve Issue? Misfire?

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