4.0 is junk, but trying to make it not

[antondubbs]

My buddy owns a 4.0 2004 SLT explorer with 197,000 miles. I am trying to help him get it in better operating order but have come to be stumped. Here is what is going on in my point of view:

1) CEL flashes which indicates misfire. It has thrown this code before and cylinders 4 and 5 were the culprits. My buddy changed plugs and coil pack, to no avail. I would suggest to him also wires but don't want to flagrantly spend someone else monies. It does not appear to be grounding out anywhere (I checked in pitch black settings in the middle of the night.)
2) Very rarely when driving, from a cold start, the temperature gauge will spike at any speed. Will do it after about 5 minutes of driving, again, on very rare occasion. That being said, it has more recently done it the past two times it has been driven. Buddy said he replaced the thermostat on it. This has me confused so I have not suggested anything at all. Could it be the pump? Radiator? Switch?
3) Then there is this horrendous squeal. I have narrowed it down to either the tensioner or idler pulleys. The tensioner slaps around when under load, more so than usual.
4) Last, but not least, you can smell the antifreeze burning out the exhaust mixed with rich fuel. I suggested one of the heads may have a slight leak in it and I was told that there was stop leak put in it a while back by some mechanic in Florida. And by while I mean a couple of years.

Other things that have been done to it are fuel filter, wheel bearings, catalytic converters, and a few other things I am drawing a blank on.

If there are any answers out there that could assist in the recovery of this once nice running vehicle, they are appreciated. Thank you in advance.

 

[Tech By Trade]

If its pissing antifreeze into the cylinder that's probably your miss and where your water is going to cause the spike in temp. Chances are it was ran low due to one of the common water loss points of the engine, being the plastic tanks on the rad, or the plastic thermostat housing that leaks. The water has probably destroyed your cats too if you have been driving like that. If thats the case your probably better off going to a wrecker and getting another engine. The SOHC is much like a bic razor, disposable.

 

[96firephoenix]

If you're going to grab a used 4.0, get one from 06-10... they are generally regarded as more robust. If it's a 2WD, you can get away with one out of a mustang, too.

I can recommend the ~2000 remanufactured unit off RockAuto - this is your cheapest way to get a rebuilt engine if you don't already have all the tools, and it saves you the royal pain that is the rebuild process.

 

[rhartmaier]

3) - 197,000 is pretty good in my opinion! My tensioner started making the feared tapping sound around 140,000, but my mechanic said the tensioner was not the problem, although he could not find what it was. The chain failed at 149,000 miles, and the engine was junk.
2),4) - Stop Leak will not help a failed head gasket. Sounds as though your friend has a major overhaul in the future. If he really wants to keep the vehicle, I would agree with Badger that a reman short block is the cheapest way to go if you and he have the tools and expertise to do the swap. For myself, I bought a KIA Sorento, and am loving every minute I get behind the wheel. 2.0 turbo has 50 more hp and gets 23 mpg city and about 29 mpg highway....

 

[Number4]

Misfire on adjacent cylinders is indicative of a blown head gasket. Do a compression test on the vehicle.

Then look for a replacement engine as mentioned.

 

[Drewmcg]

These engines are not particularly known for head gasket failures, but 197k is a lot of miles, and if the owner/prior owner let it overheat, it surely can happen.

If you've confirmed head gasket failure (coolant in oil? exhaust gas test in cooling system?), then the choices are replace the head gaskets or the engine. If you can find a relatively low-mileage engine (100k or so?) with good compression for a modest price, that can be an attractive option. Ford sold far fewer of these trucks/engines after 2007 (when the Edge came out and Explorer was getting long in the tooth). I'm not aware that any version/year of this engine is more durable after 2002 model year when they put in revised timing chain guides. I pulled a 179k 4.0 SOHC that suffered timing chain failure, and the cylinders still looked perfect (cross hatching). Strong, German cast iron block!

You can do the head gaskets w/o pulling the engine. You might want to do the front (left) timing chain and/or primary (also on front) if you go this route, since that's another fail point (even with the redesigned guides/tensioners) and, again, 197k is a lot of miles. Fortunately, your buddy has not slipped the timing chain, and so you could get the heads machined/valves checked w/o replacing several of them. He'd have a high-compression motor good for another 150k or more w/o the hassle/expense of replacing the engine. This assumes water has not got into the oil for many miles and trashed the bearings.

If you do get a used engine, budget in replacing timing chains, which is more work than you think, and about $300 in parts (get Cloyes) plus special tool kit (check ebay or Craigs list for used). You can only do the rear (right) with the engine (or trans) out of the car, and it would be shortsighted, IMHO, to replace a 4.0 SOHC with more than 75k miles w/o doing the timing chains. Streetrod2000 has a wealth of info on the job on this site. I recently took a 4k mile trip (Mich-Texas-Georgia-Mich) on a 116k engine I swapped into my '02 XLS (replaced timing chains), and it's a champ! Instead of recyclers, you might keep a sharp eye on Craigslist for an Explorer with a 4.0 SOHC and a blown transmission or body damage that someone is trying to unload cheap (though then you have to pull two engines, not one....). Good luck.

 

[mbed]

If you're going to grab a used 4.0, get one from 06-10... they are generally regarded as more robust.

Nice idea! do you know how much add'l work is required for going from a 2002 to hopefully a 2010 if I need to do it again? thanks!

 

[mbed]

Instead of recyclers, you might keep a sharp eye on Craigslist for an Explorer with a 4.0 SOHC and a blown transmission or body damage that someone is trying to unload cheap (though then you have to pull two engines, not one....).

Practice removal makes it easier to do again...usually doesn't take twice as long too!

 

[96firephoenix]

Nice idea! do you know how much add'l work is required for going from a 2002 to hopefully a 2010 if I need to do it again? thanks!

I think the valve covers and intake need to be swapped, but other than that, most of it should be physically comparable.