2002 Limited 3.7L Engine Repair/Replace Advice

jeffreyropp

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New to the community but I hope someone can offer me some guidance on my 2002 as I'm now without transportation.

Engine started running very rough, error codes P0304-Cylinder 4 misfire, P0300- Random Misfire and P0306-Cylinder 6 misfire.

Local repair shop confirmed combustion leakage and thinks it has a blown head gasket but is also concerned that it might have a cracked cylinder head or even a cracked engine block.

What's the best way to proceed if I need to get the vehicle running reliably?
Am I looking at engine replacement? Cost?
Is it worth repairing at this stage?
Any advice on a good shop in Los Angeles (Pasadena) for the work?

Many thanks for your thoughts. Hope everyone is enjoying their Sunday.
 

lfhoward

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A head gasket or head replacement is not as expensive as an engine replacement (cracked block) would be. How many miles on it?

Before condemning the engine I would want to know what is the actual diagnosis. Never hurts to get a second opinion from another shop before embarking on something as expensive as this.
 

turblediesel

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Bummer!

How many miles on your Jeep? And how much rust? Did it overheat?

If it's just a headgasket it's probably worth fixing. The head can be checked for cracks while it's off. If it's a tired high mileage engine a Jasper rebuild might be the way to go. You could gamble on a junkyard engine but there are some compatibility differences over the years relating to tone rings(?).
 

jeffreyropp

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Thanks @lfhoward - really appreciate your response.

@turblediesel - thank you too!

130K miles, just put $2K into it for transmission work. Zero rust (I'm in Southern California). As to overheating, I've seen the temp gauge almost get to the red warning area a couple times before shutting things down. Passed a pressure test for the cooling system, but the coolant gets lost (presumably through the head gasket?). Wish I could be more descriptive - but I'm clearly not a mechanic!

Local mechanic told me what I posted so I don't know/understand much more. He performed the test that checks for combustion gasses in the coolant. Beyond that I got the impression that I had to to commit to quite a bit of labor to fully understand the extent of the damage and necessary work. I had hoped this was a $1500 head gasket job but he seems to be concerned there could be further problems (e.g., cracked cylinder or block) and couldn't tell for sure without committing to the labor to figure it out.

Hope that makes sense. Are there specific questions I need to ask? How can you tell if you ONLY have a blown head gasket vs other issues?

Thanks again,
Jeff
 
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turblediesel

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Your engine block is cast iron so I doubt it has a crack. Aluminum heads can warp or develop small cracks when they overheat or don't get a fair warmup. The headgasket has to keep oil, coolant, and combustion pressures apart. Any leakage between them or the atmosphere is a failed headgasket.

Usually you can tell where a headgasket leak happened by looking closely at the old gasket. The head can be pressure tested for cracks/leaks once it's off the engine.

I'm not very familiar with the 3.7. Are cylinders 4 and 6 on the same side of the engine?
 

DHBirren2

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I'm finishing up an engine replacement in my wife's '03 with tons of rust (she loves the thing, otherwise we would've junked it). The old engine had a head gasket leak that turned into bent valves and a hot mess of internal noise.

I found a 3.7 at the yard from a Durango for about $1300 (I think). I replaced its oil pan and every gasket. Had a little problem mating it to the transmission. The problem turned out to be a steel adapter ring in the back of the crankshaft. Once that was removed, everything fit like it came from the dealer that way. This project should be complete by this weekend (I hope!). All told, I think we've spent about $2K, but I now have an engine hoist and some other neat tools I never had before.

I hope that helps you consider your options. You mentioned that you have some recent investment in your vehicle. What you spend on the engine is a matter of how much you like, or love, that gas guzzler.

Good luck and have fun!
 

Michiman

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New to the community but I hope someone can offer me some guidance on my 2002 as I'm now without transportation.

Engine started running very rough, error codes P0304-Cylinder 4 misfire, P0300- Random Misfire and P0306-Cylinder 6 misfire.

Local repair shop confirmed combustion leakage and thinks it has a blown head gasket but is also concerned that it might have a cracked cylinder head or even a cracked engine block.

What's the best way to proceed if I need to get the vehicle running reliably?
Am I looking at engine replacement? Cost?
Is it worth repairing at this stage?
Any advice on a good shop in Los Angeles (Pasadena) for the work?

Many thanks for your thoughts. Hope everyone is enjoying their Sunday.
I had the same issue with our 03 back in 2016 with 140,000 miles on it . Replaced both Cyl Heads with a matched set ; though issue at the time was only one warped head . Cost working with a good shop here in Michigan was a bit over $3 K . Smooth as silk ever since . I agree.... shouldn't be anything with the cast iron block . 180,000 K on it now We have had the 03 since day one ..... 20 years later ; use as local car now but it never fails us ; and it is a tank in the Michigan snow.
 

Maxdestruction04

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Honestly it sounds like that garage is trying to take you for a ride, Ive been thrashing these 3.7l in jeeps and trucks for the better part of 20 years, and I have definitely blown a few of them up in some pretty interesting ways and I have not seen a cracked block yet. I would definitely get a second opinion, chances are better than not you have a warped head and both cylinder heads need to be brought to a machine shop and milled flat again. Head cracking and block cracking is not something that usually happens to these motors. These blocks just dont crack often and if your talking head issues its usually warped heads or losing a valve seat and bending valves, lets just say I would be very suprised if you have cracks in your motor. Sounds more like they are trying put cracks in you wallet to empty all your money out. I have a blown head gasket myself at moment and Im 100% sure its a warped head, however in my case I opted to switch motors myself rather than fix the head gasket because I had another good motor ready to go. But that turned out to be its own headache lol, there is a thread on here about it and oh what fun its been so far:)
 
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ehartz

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These 3.7L engine's are notorious for dropping valves seats when overheating. Was a compression test performed? That would identify as to a dead hole and get you closer to a diagnosis.
Just finished this repair on '06 KJ with 108K milage.
 

SWilliams

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If it were mine and a rust free one (never happen in NY unless I imported it) I would likely rebuild the current engine. Use all the newer updated parts and drive it until the wheels fall off. Or drop a reman in it that has a warranty. I would also find another shop for a second opinion and a list of repair options.
 

JibeHo22

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In an earlier reply, OP (Jeff) mentioned that a test was done to check for exhaust gas in the coolant.
Jeff: what was the result of that test??

All: If that test was negative, would that eliminate the possibility of a head gasket issue? If the test was negative and head gasket is not the issue, then is the problem most likely with the valves?
 

hvacmrm

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New to the community but I hope someone can offer me some guidance on my 2002 as I'm now without transportation.

Engine started running very rough, error codes P0304-Cylinder 4 misfire, P0300- Random Misfire and P0306-Cylinder 6 misfire.

Local repair shop confirmed combustion leakage and thinks it has a blown head gasket but is also concerned that it might have a cracked cylinder head or even a cracked engine block.

What's the best way to proceed if I need to get the vehicle running reliably?
Am I looking at engine replacement? Cost?
Is it worth repairing at this stage?
Any advice on a good shop in Los Angeles (Pasadena) for the work?

Many thanks for your thoughts. Hope everyone is enjoying their Sunday.
Nothing for nothing but,,, how bout crank and or cam sensor?
Could be not picking up properly ans sending mixed signals.
 

KeithKj02

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New to the community but I hope someone can offer me some guidance on my 2002 as I'm now without transportation.

Engine started running very rough, error codes P0304-Cylinder 4 misfire, P0300- Random Misfire and P0306-Cylinder 6 misfire.

Local repair shop confirmed combustion leakage and thinks it has a blown head gasket but is also concerned that it might have a cracked cylinder head or even a cracked engine block.

What's the best way to proceed if I need to get the vehicle running reliably?
Am I looking at engine replacement? Cost?
Is it worth repairing at this stage?
Any advice on a good shop in Los Angeles (Pasadena) for the work?

Many thanks for your thoughts. Hope everyone is enjoying their Sunday.
My best advice is too ask the local dealership on a cost for a new engine i know it’s a bit expensive but guaranteed because i had to change a 3 engines at local shops and it costed me the same cost the dealership offered me . Or u can buy a used one with a warranty and have someone trusted to install it .
Best of luck
 

Kelvis

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Seeing as you are loosing coolant it is fair to say you may have a bad head gasket. Saying that a bad head gasket will quite often result in the cooling system being pressured up and pushing coolant out the overflow. Check your oil, make sure it is not contaminated with coolant. Coolant in the oil is not good for the bottom end. Identifying where your coolant is going is critical. How fast are you loosing coolant? Double check for external leaks. A simple thing to try is to swap the engine coils. Swap #4 which is the suspect with #2 and see if the miss moves from cyl 4 to cyl 2, maybe a bad coil and a coolant leak.
 

Plasterman5000

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I recently was having many symptoms on my '07 liberty that at first, I thought was a blown head gasket as well. Being that my disposable income is at near zero, any major problems with my jeep would be devastating. So painstaking do all the pre-checks that you could possibly do. Harbor Freight has inexpensive tools so you could do pressure checks and what-not. Arm yourself with as much knowledge as possible. Mine turned out to be a bad coil pack on cylinder 4. And I had to replace all 4 oxygen sensors and I was rollin down the road again. Maybe as a band-aid, check those mechanic-in-a-bottle products. I've used them in past vehicles and they worked to buy me some time until I could get it fixed properly.
 

Siesta

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New to the community but I hope someone can offer me some guidance on my 2002 as I'm now without transportation.

Engine started running very rough, error codes P0304-Cylinder 4 misfire, P0300- Random Misfire and P0306-Cylinder 6 misfire.

Local repair shop confirmed combustion leakage and thinks it has a blown head gasket but is also concerned that it might have a cracked cylinder head or even a cracked engine block.

What's the best way to proceed if I need to get the vehicle running reliably?
Am I looking at engine replacement? Cost?
Is it worth repairing at this stage?
Any advice on a good shop in Los Angeles (Pasadena) for the work?

Many thanks for your thoughts. Hope everyone is enjoying their Sunday.
I agree with the other reply to get a reliable second opinion. I have had those SAME codes and misfiring with just a coil tower going out of spec. (a simple fix). The coil on plug set-up on these Liberties must be minimal engineering, as I'm now down to just two remaining original ones. When they hobble you 'far from base' it can be annoying. I think I'll even start carrying a spare. I drive an '03.
 

malibuz16

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Block should be fine...the head on the other hand maybe roasted. I had the same problem on my sister's '10. Currently replacing both heads and gaskets. Soon as I can I will post a pic of the head surface that eroded from the combustion chamber to a coolant passage.
 
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I just replaced the engine in my 2002 Liberty Limited 4WD. Lessons learned:

Dealers won’t be much help to you these days, as Chrysler no longer makes many of the parts, and the ones that are available are 20+ days lead time, so internet retailers will be the way to go.

Don’t buy any part made in China. It will fail or won’t fit right out of the box. If you buy something of unknown origin and later find out it’s made in China, then return it. I know non-China parts can be 5x the cost and harder to find, but they will save you many times the amount in avoided frustration

Double whatever your repair budget is. You will find all kinds of things needing repair, while your engine is out. Don’t be tempted to put off those repairs as having the engine out of the way gives easy access
 

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