Greetings. Just picked up a 98 XLT 5.4, few ?s.

[hooraah]

Hey all,

Picked up (or agreed to pick up) a 98 Exp XLT with a 5.4L, 2wd, 197k miles from a family member for next to nothing. Its a bit rough (by a bit, I mean a lot) but this is going to be used for towing our racecar (Chumpcar Porsche 944 if you're interested) and more or less camping out of the back of in the pits.

I read through the sticky on 'what to look for' and I have a pretty good handle on most things. The Exp doesn't have much in the way of maintenance history. The PO had issues fixed when they came up but didn't keep good records and wasn't great on maintenance.

It runs decent, but will need a new battery off the bat. Its been sitting for around 6 months, but was daily driven before that. No misfires that I can tell. CEL is on with codes P0135 and P0155 for the O2 sensors, but no misfire codes. PO changed coils/plugs on a here and there basis as they became issues with little papertrail to follow. The 90 deg vac elbow was replaced by me a few years ago when I was helping the owner out with a stalling issue (which cured it). I also know that most of the coolant was replaced about 2 years ago when the heater core leaked it out all over the place. The heater core has been bypassed and wasn't fixed. We're in FL, I'm not worried about it.

The downshifts are a bit rough, as in it seems to slam into gear, but it still shifts at the appropriate points and doesn't slip. Not sure if this is a real issue, as I'm used to driving a 3000lb car with a 2.5L engine and a manual gearbox, so totally different size engine and transmission.

I plan on hitting all of the basics first - trans fluid, diff fluid, coolant, oil, and brake fluid, and will inspect the balljoints and brakes ASAP.

Now, questions -

I hear much about coolant leaking on coil #4. Where does this coolant leak from? Is the 5.4 one of the engines that needs a manifold gasket change when the coolant leaks, like on my friends 4.6 F150?

Are the intake manifolds Al or plastic on the 5.4? If plastic, are they the ones notorious for cracking on the crossover coolant pipe?

Anything else you'd recommend (besides the usual stuff) I check or replace off the bat just based on age?

I imagine that at 197k the shocks are probably not great. Considering thowing a cheapo set of Monroes on from AAP. Some people say they're a bit rough for driving around town but that should be fine as, like I said, the truck is only going to be used to tow on race day. They've probably better than whats on there now.

 

[jbanks]

Do you have any thoughts on the PO135 and PO155? With both of them on, it sounds like a wiring problem. Is there a fuse for this?

As for other things to do. I recommend this:
Meguiar's Ultimate Compound : Amazon.com : Automotive
If I were in Florida, I would come do it. I would be so satisfying to see that paint shine again. At least, where it's not completely gone.

 

[hooraah]

On the P0135 and 0155, no I think its just two bad sensors. The code is for a bad heater circuit, the part of the o2 sensor that preheats it so it can get readings faster. In my experience, this is the first part to break. If the wiring harness were bad, you would probably see codes for no o2 sensor signal.

I have a OBDII scanner that does live data with my phone over bluetooth, however, it did not work on a friends 97 F150 so I'm not sure if it will work with the expedition. If it does, I can look at hte o2 voltage and make sure its at least working somewhat before replacing the sensors.

Either way, 2 sensors from the auto parts store should clear it up, I hope.

As for the polish, yes, I may get aroudn to that. I have an entire shelf of polishes and waxes I've used from time to time so will probably throw something on it. Considering either painting the whole truck matte black or painting it to match the race cars colors.

 

[FordandPolaris]

]5.4's are an aluminum intake. I would agree that both codes probably just indicate two bad upstream O2 sensors. More than likely they are factory original and need replacing. Mine are the same way, but thanks to living in the rust belt, I cannot get them to bust loose.

At that age (assuming they are factory original and have not been replaced already), I would make sure that wheel hubs, upper/lower ball joints, inner/outer tie rod ends, rear axle seals, PCV valve, rear lower trailing arms, and the windshield seal are all good. Those are all issues I have had with my truck and that are common with these vehicles.

I did a set of cheap Monroe's on all 4 corners and the front wore out in a week. Not even joking. Only thing I could figure out is that the front shocks are stressed a lot more since the suspension (torsion bars) are horizontal by design and not vertical. I had a lot of up and down motion with regular driving and bad front shocks. The rear (vertical coils) is much better at controlling the motion on bad shocks, which is where I am at now. My Monroe's in back lasted about a year. One thing to consider though is that my tires are also much heavier than stock, and so they naturally wear out shocks faster anyways. Right now I have Rancho in the front and have a set of heavier duty Monroe's for the back that will go in when it gets warmer.

 

[hooraah]

]5.4's are an aluminum intake. I would agree that both codes probably just indicate two bad upstream O2 sensors. More than likely they are factory original and need replacing. Mine are the same way, but thanks to living in the rust belt, I cannot get them to bust loose.

I don't know the love of the rust belt, but in my experience the best way to get O2 sensors off is with an impact gun. It sounds like the wrong tool for the job, but if you get the wiring disconnected first, and you can get clearance to the sensor with that special o2 sensor socket, put a little PB blaster on the threads and WHAM WHAM WHAM with the impact gun, even the most nasty stuck o2 sensors pop right out.

On two occasions, I've seen people trying to get o2 sensors out and either couldn't get it to budge or were just starting to strip the threads and didn't know what to do. Impact gun worked both times. I think the shock of the impact does particularly well for the rusted parts.

At that age (assuming they are factory original and have not been replaced already), I would make sure that wheel hubs, upper/lower ball joints, inner/outer tie rod ends, rear axle seals, PCV valve, rear lower trailing arms, and the windshield seal are all good. Those are all issues I have had with my truck and that are common with these vehicles.

Rear axle bearings/seals were supposedly done around 130k (like I said, PO didn't keep great records and am just going by what he told me from memory). Will obviously check to make sure theyre safe. PCV valve and elbow I did myself when I was helping him a few years back. Rear control arms I will have to check as well as trailing arms.

For front upper/lower ball joints I am thinking we are just going to replace them with the shocks if they need it or not. Will look into the windshield seal. I'm in FL, which gives us free windshields if they're damaged at all. Wonder if that would qualify?

I did a set of cheap Monroe's on all 4 corners and the front wore out in a week.

Hmm. Well, thats no good. If this were a car that required a spring compressor to get the shocks out, I'd say its not worth it. But since its 2 bolts and a quick replacement I think I might give the cheapos a try and just keep good receipts (I always do).

Thanks for the help!