Hi all!

I'm Wreklus.
I joined the Mopar crowd last year when I bought a 2008 Grand Cherokee 5.7L 4x4.
Various reasons for wanting a WK, but mostly because my Dad had one and we used to beat the hell out of it off road and it never broke in any significant way.
I had project car / daily driver before this that I just couldn't afford to maintain (read: kept breaking with mods that put out more than the transmission could take). I intend to mod the jeep once the warranty runs out (about 5k miles from now), without torquing axles and chewing up clutch plates.

I'll be stalking the forums, looking for any wisdom / experience on the Gen 3 5.7. I'm not going to go too crazy with it because I've spent enough time in a rental Prius as my atonement for breaking the sacred laws of modding already.
But, it will soon be undeniably mine, good, bad or ugly.

Any Gen 3 5.7 tips, warnings, or wisdom welcome!

 

Welcome. No 5.7 wisdom here, my mechanic son probably knows the good and bad but internet searches will probably give you plenty of info through many of the truck forums.

 

Early gen 3 heads drop valve seats.

 

Iowan,
Would zinc oil additives help with the valve problem at all?
Would it be safest to go ahead and put on stronger valve springs and etc?

Coronet,
No worries, dude. I will definitely be taking a look at the ram pages.

 

Bob posted this last week and its worth posting again, a one stop shop for the gen 3.

https://redirect.viglink.com/?format...hophemi.com%2F


there is plenty to make ya druel.

 

Iowan,
Yup, Yup, Yup!
Enough to make a man consider taking a second job, just to support a parts addiction!

 

I'm with Iowan on the early 5.7... The problem was the seat margen in the head was too thin. Not enough meat to hold the seat in place. So after some miles, the seat would come loose in the head and if you where lucky enough to catch it early enough you could stop valve from snapping off at the thin part of the stem and doing the really good damage.
So you just need to be careful on the engine and heads you get. and make sure the machine shop checks and corrects the issue.

 

RacerHog,
I get ya.
I was hoping I could "cheap N easy" my way past the problem. But I looked up some videos that show the problem and the potential damage...
Funny you only find the truth after you buy. I always thought the 5.7 was reasonably stout!
Thanks for the advice. I'll have to figure out who's shop is worth their salt here in Charleston...

If anyone else wants to throw in their 2 cents, feel free.

 

The last one I saw dropped a valve and punched a hole in the cylinder, piston and head.

 

Man,,,, Your in the back door of Bouchillon Performance and Rick Hendricks Racing.... And no one can tell you a good Machine shop..... Oh crap I'm speechless !!!!!

 

Not sure if anyone else wants more info on the early 5.7 valve issue, but...

Looks like RacerHog is spot on with his assessment.
Valve seats aren't installed snug enough in the factory and wiggle themselves loose over time. Generally, this seems to happen right around the 100,000 mile landmark.
There are a few videos on YouTube regarding how a shop can machine the cylinder heads and fit new seats to eliminate the problem.
Here are current fix options:
Install OEM 6.1 heads and reuse old internals - $2000 ish for parts.
Install performance heads with performance internals, throttle body and cam from shophemi.com - $2950
Get seats machined and port & polish original heads - $700 ish

Be aware that replacing the heads with OEM parts incurs a core exchange charge if you don't send back your old parts.

The obvious winner for me is machining the original heads.
I just don't want to shell out my hard-earned cash for the internals right now. The hard core performance stuff could net me close to 100 extra hp with a solid 93 octane tune, which would be great. But, I just wouldn't feel good about dropping all that dough right now.
Maybe after I find me a new job with a bigger salary. For now, stashing away the money to buy a house, with a yard big enough to build a little shop of my own to tinker in, is the real goal.


Anyway,
Thanks all for the really valuable input! Couldn't have been beter timed, I was wondering why I never got better than 16mpg no matter how cautiously I drove! Maybe valve seats are screwing up my air flow.
If I do accidentally make performance changes, I'll be sure to make a thread and share pics / video.

 

For those who stumble upon this thread and want more info:
Hop over to the Member's ride section and find the 345ci Grand Cherokee thread here:
​​​​​https://moparforums.com/forums/f66/2...5ci-4x4-21759/
I did end up deciding to modify internals.
At the time I am writing this post, work is in progress.