Should I get new heads?

[Jsmooth65]

Hey guys, been lurking on here for awhile, and learned all kinds of stuff. Just trying to get a good feeling before dropping the money.

Here's the story. Its my inlaw's jeep. 2004 Liberty 3.7L. Their kid overheated it, twice, most likely caused by a water pump failure. After fixing the water pump, it stopped overheating, but it was pumping out white smoke and eating coolant. I did a compression test and confirmed the passenger side head had massive head gasket leak. Lots of water in the oil, too.

So, I pulled the heads and had them cleaned up and decked at my local machine shop. Installed new gaskets, and sent them on their way.

6 months later, white smoke and coolant loss has returned, along with a cylinder 5 and cylinder 6 misfire, according to codes. I ran compression test on all the cyls, and got in cylinder order 1-6: 145,135,148,145,160,145.

Bad coils won't explain the coolant loss and white smoke, so I'm leaning towards another HG job or new heads. All the horror stories I've read on here indicate that an overheated head will warp it, making it irrepairable, and new heads (from dealer) will fix it. At $500+ per head, I'm trying to avoid this route, but will take it if I have to. Thoughts?

 

[lautinjr]

The machine shop should have been able to tell if there was a problem. They should have not just decked, but cleaned and checked if needed grinded vavles. Considering they did a decent job I would suspect possible installer error when head job was done.

 

[Jsmooth65]

They DID say something to the effect of "Had to take alot of material off, but its in spec now"

 

[Porkchop]

Were they tested for cracks?
Was it pressure tested after the head job?
Sorry but my after thought is what coolant did you use?

 

[tjkj2002]

They DID say something to the effect of "Had to take alot of material off, but its in spec now"

Can't "un-warp" a alloy head,decking it makes the sealing surface flat but the head is still warped and will continue to do so after some head cycles and why it's leaking again.

So yes it's time for new heads or good used heads.

 

[Jsmooth65]

There seems to be alot of 3.7L engines around, and it makes me nervous to yank heads off one not knowing its overheating history. Is this a common failure point in these motors?

 

[tjkj2002]

There seems to be alot of 3.7L engines around, and it makes me nervous to yank heads off one not knowing its overheating history. Is this a common failure point in these motors?

Poeple overheating them.

 

[04Liberty]

It's definitely a common problem with the 4.7's once they've been overheated. Sometimes it's bad enough to allow a valve seat to drop.

 

[Jsmooth65]

OK after listening to you guys and some other Jeep and aluminum heads guys, it sounds like the cast iron block/alum head combo really screws with the heads after an overheat or two. I think I am just going to get some brand new heads from the dealer and call it good. Hopefully I can change the flavor of this lemon.

 

[Paul M]

After a valve spring retainer failed (due to a really weak design), then paying the Dealership a huge amount to replace the entire head as an assembly (because they said the heads could not be rebuilt by them and only come as an assembly), plus everyhting else required for the job, I figured I needed MY head examined or replaced! :Insane:

 

[Jsmooth65]

After a valve spring retainer failed (due to a really weak design), then paying the Dealership a huge amount to replace the entire head as an assembly (because they said the heads could not be rebuilt by them and only come as an assembly), plus everyhting else required for the job, I figured I needed MY head examined or replaced! :Insane:

You have got to be insane to let a dealership do any labor.

 

[Paul M]

You have got to be insane to let a dealership do any labor.

Agreed, but had no choice at that time...at least I thought. Afterwards called Chrysler Care and managed to wrangle $1200 out of them because as far as I was concerned this was obviously premature failure and a poor design, they agreed...so wasn't all painful.

 

[Jsmooth65]

Agreed, but had no choice at that time...at least I thought. Afterwards called Chrysler Care and managed to wrangle $1200 out of them because as far as I was concerned this was obviously premature failure and a poor design, they agreed...so wasn't all painful.

Good call on that!

 

[Jsmooth65]

Paul M., do you know what all the new heads came with? valves and springs I assume?

 

[Paul M]

Paul M., do you know what all the new heads came with? valves and springs I assume?

Not sure...they told me it was an entire assembly as a single Part Number, so I assume it had everything installed. I'm an hour from town so never got the chance to see the old or new one beforehand.

 

[|V3nom|]

how about getting them ported and polished while youre at it?

 

[04Liberty]

Get them ported and polished, then get some custom cams ground, then custom tuning. Whole new Jeep!

 

[Jsmooth65]

So dealership says no dealership has new heads anymore and they are all remans. And they are $700+core each now. Now, this Jeep is a 2004 model, but I've found online that the 2005 heads can be had for much cheaper, but they are a different P/N. Anybody know why? Compression change?

 

[Marlon_JB2]

So dealership says no dealership has new heads anymore and they are all remans. And they are $700+core each now. Now, this Jeep is a 2004 model, but I've found online that the 2005 heads can be had for much cheaper, but they are a different P/N. Anybody know why? Compression change?

Exactly. The 3.7L was changed a tad bit for the 2005 model year. One of those changes was the compression ratio.

 

[tommudd]

So dealership says no dealership has new heads anymore and they are all remans. And they are $700+core each now. Now, this Jeep is a 2004 model, but I've found online that the 2005 heads can be had for much cheaper, but they are a different P/N. Anybody know why? Compression change?

No new heads??
Guess that makes my spare set of new heads even more valuable doesn't it ?? :shrug: