Looking at '98 5.9 ZJ

[pajeepman]

What should I check out on it....what tends to be problematic?
It is all stock and looks clean in the pictures.

 

[ryan13]

The stock t-case is most likely in need of replacement. If you turn tight on hard surface and it bucks, the VC is toast in the t-case.

Check for rot under the body covers (cladding, skirts).

Another problem they will all eventually have is the Plenum Plate gasket blowing out. It's not that bad of a fix but just be aware of it. This can cause some pinging and worse MPG's than it already gets as well as some oil consumption. You can check this by popping off the air hat and looking through the TB to see if there is any pooling oil in the intake plenum.

Last thing is make sure the owner was using premium fuel.

Besides that...check all the normal things you would with a 15+ year old jeep.

Good luck! If you get it, they are a ton of fun!

 

[squashman702]

All of what Ryan said.

They also tend to be tough on transmissions.

I've had 3, you can PM me if you have any specific questions.

 

[POLAR_JEEP_04]

plenum gasket is probably blown.
drivers (sometimes passenger side too) heating element stops working.
the VIC usually breaks solders and says that you have problems that you don't and can get annoying.
if either of the cooling fan temp switches dies, they are near impossible to find.

other than that they are fun and quick for an old jeep

 

[squashman702]

I'd add that the carrier bearings in the D44a tend to go bad.

 

[vetteboy]

My transmission is rock-solid at 200k.

I replaced the plenum gasket, made a big difference.

Also swapped in a 242 as the VC was shot.

Driver side heated seat hasn't worked in a few years.

I've rebuilt the D44a rear twice.

Replaced the radiator fan motor; some Ford motor bolts right in place of it so you don't have to replace the entire assembly, which is expensive. On mine the low-speed winding crapped out so if you had the A/C going in traffic, it wouldn't blow air over the condenser, and the system wouldn't work right.

Aside from that, it runs great, gets 14.5 MPG on premium, and is a comfy and fast cruiser. Pretty much what everyone else has said.

 

[pajeepman]

Do they need premium gas or is it just recommended?

 

[squashman702]

Do they need premium gas or is it just recommended?

Some had the "death flash" which means that a dealer reprogrammed it to run on 87 at a lower performance level.

Other than that, they need 93.

 

[killedbydeath]

every 5.9 we have gotta at work has had the rear lower control arms seperated from the body...I assume from the Northeast rust as well as people beating on it

 

[vetteboy]

I actually got the best fuel mileage ever on mine running on 87 octane, after the NJ gas pump jockey screwed up my simple request.

Basically because it'll detonate, ping, and generally run like shit unless it has premium, so I had to drive it like a grandma for the entire tank.

 

[pajeepman]

Looks like it sold before I could really check it out. Thanks for the info guys.