94 4.0 Heads

HER2702 said:

Hi Guys, been gone a while but still around. I've got a couple of questions I need some help with. First question I'm really looking for advice from some of our professional techs you know, the certified guys that do this every day for a living. No disrespect meant to anyone who 'Shade Trees' or 'DIY'. That's where most of the pros got started. I'll take advice from anyone who's had experience with this I just really need some concrete pro help.

OK, 94 Ranger, 2wd, original 4.0 OHV X engine, M5R1 trans, 246K miles. This is my daily driver, 85 to 90 miles a day, 5 & 6 days a week. Since I've owned it, over 15 years, the oil has been changed every 5000 miles religiously with Valvoline 10w30 Hi Mileage and Wix filters. Over the last few months she's had the 'disappearing coolant' issue. Over the last 3-4 weeks she's picked up a light miss, barely noticeable at idle or at speed but really noticeable below 1500 rpm under load (cruising down the street, 40ish in 5th and accelerating). The last several days it's gotten worse. No CEL set but it is running very rich. If I struck a match behind the tailpipe I could probably have a afterburner lol. It has been hot a time or two but not what I would consider to be 'overheated'. In the past 6 months it's had a set of new injectors, a full tune up, Autolite XP105 Iridium plugs, new wires, new coil pack. The MAF, IAC, TPI have all been cleaned and tested, all good. The old coil & wires tested OK but the wires had been on the engine for 5 or 6 years and I found corrosion in the bottom of the #5 tower on the coil pack so I went ahead and replaced them. Trying to narrow down the problem I've pulled plug wires one at a time and unplugged injectors one at a time to see which one of either made the least difference in the way it ran. Everything points to #5 cylinder (center cylinder, passenger side). Pulling the wire made almost no difference in how it ran, unplugging the injector did make a noticeable difference. I've checked and replaced vacuum lines, disconnected the cruise modulator vacuum, checked the intake manifold gaskets with starting fluid and with water (no difference with either). The only checks I haven't done are the glove test and a compression test which I will be doing this weekend.

IMO everything is pointing at the head gasket or head at #5. Following the compression test I'll be pulling at least the passenger side head, probably both to see what the Gremlins have been doing in there. Now for the question; What is the probability that the head is cracked, as they are known to do, and should I go ahead and lay hands on 1 or a set of heads beforehand? I can't afford to have her down for too long, it is my daily driver, but I'm also on a tight budget. I don't intend to skimp or cut corners, it will get what it needs in good quality parts (shameless plug for ROCK AUTO) lol. I plan to steer clear of used heads of unknown origin, I'm leery of reman OE heads due to the cracking issues but I'm not sure about some of the "new" aftermarket heads I see online.

Comments, Recommendations?? Any and all help greatly appreciated.

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Angie said:

When was the last time you changed your fuel filter?


"Over the last 3-4 weeks she's picked up a light miss, barely noticeable at idle or at speed but really noticeable below 1500 rpm under load (cruising down the street, 40ish in 5th and accelerating)."


this is why i asked

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holyford86 said:

Not entirely sure why you'd pull the passenger side head for a cylinder 5 issue, as that cylinder is the middle cylinder on the driver side, it seems that 160 to 200k is the sweet spot for head gasket failures but they usually just start leaking down the outside of the block at that point.
You should just be able to swap the oil pump drive from your engine to the explorer engine and be fine, as there are no differences there. I believe that the passenger side exhaust manifold is the same, Assuming the truck you're swapping is a federal emissions truck, it will not have egr as the explorer engine does, you will need to swap your driver side exhaust manifold over. crankshaft position sensor is the same, so you don't need to mess with that. Engine wiring harnesses are not even close to similar, and swap your upper intake manifold and vacuum lines, as many of the sensor connections and locations will be different

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adsm08 said:

I know I am a little late to the party here, and I didn't read everything, but as to how to drive the oil pump, I do have something.

Take the drive slug out of your old engine and put it in the new one.

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