Advice: Purchasing WH Jeep GC

[mercury68]

I'm going to try and purchase a 2005-07 WH Jeep GC 5.7 Hemi next month when I head home to Brisbane for Xmas from Cairns

I have read everything I could find (useful links and faults & issues) and planned out a setup for the GC when I get her but the problem I have is when going to a dealer is what to look for since they have steam cleaned the engine, etc. so it's all sparkling and new like so I would like to know what to look for and where when buying a used WH GC.

If you can guide me in what to look out for it would be greatly appreciated

[JamesLaugesen]

Originally Posted by mercury68

I'm going to try and purchase a 2005-07 WH Jeep GC 5.7 Hemi next month when I head home to Brisbane for Xmas from Cairns

I have read everything I could find (useful links and faults & issues) and planned out a setup for the GC when I get her but the problem I have is when going to a dealer is what to look for since they have steam cleaned the engine, etc. so it's all sparkling and new like so I would like to know what to look for and where when buying a used WH GC.

If you can guide me in what to look out for it would be greatly appreciated

Common things you can spot pretty easily;
- Front diff bushes; the front diff is supported at 3 points, one directly in front of it which you can see easily laying on your back under the engine bay, and one on either side behind/above it, which you'll see if you sort-of look behind the inner CV joints/output shaft.
When failed you'll get a clunk when shifting between Reverse and Drive.

- Rear diff pinion seal. Doesn't matter how well the clean it, if it's leaking enough to worry about you'll be able to see/feel oil around it.

- Front sway-bar bushes. If they look perished or loose, they probably are.
An audible knock when one of the front wheels hits a bump is usually caused by these. Easy to do yourself about ~$100 max.

Fairly common but harder to spot;
- Clogged PCV valve (costs bugger-all and not a big issue anyway, and easy-as to replace yourself.).
- Dead EGR valve. Hard to tell until it throws a code (really just increases fuel consumption.).
- Front control arm bushes and tierods. You'd have a hard to spotting anything though.

There's not much you can look for around the engine itself, the hemi is a very solid unit (just look how many vehicles it's used in.).
So just the usual signs of maintenance; air filter, look for oil stains, etc.
It's normal for all hemis to tick a little when idling (google "hemi tick".), in-fact no ticking can sometimes mean the engine oil is too thick - Which is a common mistake.

But here's the big one(!)...
There has been a a lot of misinformation about maintenance, particularly oils.
When you combine that with lazy/ignorant mechanics there's some risk there.

So I recon your main job will be to suss out the dealer or seller if you're looking private too.
Probably with some leading questions, like "has it always been serviced here?".
Ask/look for any service receipts and look for any descriptions of oils used, and hit them with some leading questions about the various oils, components, etc.
Such as "They got rid of the chain-driven transfer case in this model ay?". Just to get a gauge of how knowledgable they are and get a feel for things.

You've probably found out already, but here's a run-down of what the oils should be;
- Full synthetic in the diffs with an appropriate friction modifier pack.
- Mobil 424 or genuine mopar in the transfer-case. We're finding a couple of others that look safe, but the jury is out.
Any "ATF" is NOT correct, and has a good chance of giving you a lot of trouble (see Doc's thread on here.), anything labelled as "gear oil" is also incorrect.
-- I'd strongly suggest that you ask them to prove that it has the correct oil right there on the spot, by cracking the drain plug open and checking it. When fresh it should be a very light yellowly oil clear in the right light. If it's red (ATF.) or at-all dark just walk away.
- ATF+4 in the transmission. Dunno how you'd check this easily, but the hemi has a dipstick so you can check the level (after a test-drive while the engine is idling obviously.).
- A 20wt in the engine; 0W-20 or 5W-20. A 25W (which is pretty unlikely.) is acceptable, and Penrite's 0W-30 is reasonable (I used it for a while without any trouble.). 5W-30 is very common and incorrect, it will at-least reduce the effectiveness of the MDS.

All oil manufactures in Aus. has listed all of the oils incorrectly at some point.
So even a "good" mechanic following the recommendations could use the wrong stuff.

The trans ATF+4 has been well known for a long time, so it's unlikely that's been done wrong (maybe ATF+3 if anything.).

The diffs have a fair-bit of leeway, so not too much to worry about there (as-long as it's a high quality full synthetic at the correct weight.), the QDI diffs (previous model.) were more picky.

Engine oil listings have gotten pretty good over the last ~3 years, but I still hear about heaps of mechanics using the 5W-30, and even some people doing their own servicing choosing to ignore the spec (it says "5W-20" right on the filler cap, so there's no excuse.).

Transfer-case is the big one, many manufacturers are still listing it as ATF or gear oil.
Thanks to efforts of guys here (bjm mostly.), Penrite have just recently fixed their info, so it should be flowing through to the rest.

Oh, since you specifically said 2005-2007, I guess you're after the QDII?
Ask to prove that it's working correctly somehow (depends what sort of area the dealers is in I guess.); put in low range and get cross-axled somehow, driving a front wheel up a ramp or something.

[mercury68]

Thanks for info there JamesLaugesen it has help me understand some of the problems I have read about but not exactly what to look out for but just some questions from the above.

So if ATF is in the transfer case I presume it's a pull out of vehicle and a clean/replace parts job so therefore expensive? If it was just put in at the dealers and only driven say less that 50km (so still that bright clear red), could a few drains, refill with correct oil, drive for a few days and repeat a couple times, could that prevent the damage or it's just total stuffed once the ATF is in? I'm just thinking that the ATF is "sticky" and clogs everything up once heated up enough.

With the cross-axle, am I looking for the tyres off the ground to be rotating at a similar rate to the grounded ones?

[JamesLaugesen]

Originally Posted by mercury68

Thanks for info there JamesLaugesen it has help me understand some of the problems I have read about but not exactly what to look out for but just some questions from the above.

So if ATF is in the transfer case I presume it's a pull out of vehicle and a clean/replace parts job so therefore expensive? If it was just put in at the dealers and only driven say less that 50km (so still that bright clear red), could a few drains, refill with correct oil, drive for a few days and repeat a couple times, could that prevent the damage or it's just total stuffed once the ATF is in? I'm just thinking that the ATF is "sticky" and clogs everything up once heated up enough.

With the cross-axle, am I looking for the tyres off the ground to be rotating at a similar rate to the grounded ones?

No worries.

I haven't seen any reports of transfer-case problems after short-term use of ATF.
It's usually more that someone starts have confusing TC problems, goes through the usual troubleshooting process, and eventually finds out that it's had ATF for a long time.

So only ~50km (done at the dealer.) would almost certainly be fine to just drain a few times and change.
Probably even ~10kkm would still be ok... there's too many variables.

I haven't seen an explanation about why (exactly) ATF isn't good, so everyone's just going off the chrysler service spec and (strong) anecdotes.

The general symptoms seem to be excessive wear of the centre differential clutch pack (which is within the TC.) and excessive wear of the chain and a few other bits.
Where-as the guys with heavily modified WH's who drive them hard (like Valpacer on here.) don't have these problems.

ATF would have a higher concentration detergent pack than a hydraulic tractor fluid (like mobil 424.) which could have something to do with it, but any hydraulic tractor fluid is also just made from higher quality base stocks, so who knows.


Re; cross-axled.
The video is pretty lame but it shows shows what I meant;

You Tube

Put it in 4-Lo and somehow get crossed like that. The lifted wheels will spin a bit, then once enough pressure has built up in the diffs, they'll start to "lock" (clutch pack inside the diff engages.) and all wheels will start turning at the same speed.

If you spin the wheels reasonably fast (like ~2000rpm.) it should "lock" fast enough to give you a bit of a jolt as the car starts moving. It's smoother than a mechanical locker, but still not a gradual slip like a normal LSD.

If anything isn't working properly the wheels will just spin, maybe with a little bit of drive to the other wheels.
The system is basically an oil pump inside the diff, which pressurises a clutch pack regulated by a solenoid (controlled by one of the computers.). So a problem could be worn pump (never heard of that.), worn clutch plates, leaking seals, solenoid not activating / computer issue, or excessively slick oil (excess friction modifiers, someone dumping a moly additive in, etc.).

[roscoea26]

Originally Posted by mercury68

I'm going to try and purchase a 2005-07 WH Jeep GC 5.7 Hemi next month when I head home to Brisbane for Xmas from Cairns

I have read everything I could find (useful links and faults & issues) and planned out a setup for the GC when I get her but the problem I have is when going to a dealer is what to look for since they have steam cleaned the engine, etc. so it's all sparkling and new like so I would like to know what to look for and where when buying a used WH GC.

If you can guide me in what to look out for it would be greatly appreciated

Have you found one that you're currently considering ? I noticed one at Cricks Noosaville, it's a 2005 WH 65th Anniversary Model V8 only done 57,000ks' on their site it's advertised for $17990 but in yesterdays Noosa Today they have it for $16990. colour is Kaki. Just Google Our Stock- Cricks Auto Group and u you'll be able to find it.

Anyway just thought I'd let you know seems OK on paper.

[mercury68]

I'm going to be arriving in Brisbane next Tuesday and the only GC 5.7 Hemi I have seen this week is a private sale.

What do you think of a private sale since you haven't got a warranty, etc as with a car sold from a dealer as I never had bought from a private seller before?

[mercury68]

I bought the jeep I was looking at from the previous post

Just have a question, I can't get the seat position memory to stick with my settings since every time I press the "1" button on the drivers door it reverts back to the previous owners settings.

Edit: forgot to mention that it's a 2007 GC Limited 5.7L Hemi.