302 Rebuild Kit (1998 Explorer 5.0) | Ford Explorer Forums - Serious Explorations

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302 Rebuild Kit (1998 Explorer 5.0)


Well-Known Member
May 19, 2006
Reaction score
City, State
Oceanside, CA
Year, Model & Trim Level
1998 Eddie Bauer 5.0

I have a 1998 Explorer Eddie Bauer w/ the 5.0 V8. I've replaced the entire cooling system, and the entire A/C system (literally lol).

The truck has 170,000 miles on it. It runs strong, but the MPG is very poor, and the engine is getting tired (although it is reliable!)

So, is there a specific type of rebuild kit I should look for? The ones Ive found replace pistons and everything, and they around $400-600.

Also, given an average mechanic skill, how many days should I allocate for such a project? Does the block have to be yanked?

If I was to pay a mechanic for this job, how much could I expect to pay?

Lastly, how big of performance / MPG can I expect after this is done? (I plan on replacing all the spark plugs as well)


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Subscribing, as I would like to know some of this info as well. Mines got simaler mileage, but still runs and pushes like a champ. I would mind trying to tackle a rebuild once I get a new vehicle.

If you do a compression test on all the cylinders and they all check out fine, Then i would just pull the heads and have then freshened up with a good valve job and have the intake hot tanked and cleaned up, i did this on my thunder bird years ago and gas milage went way up.

King$nake, what kind of mileage you are experiencing? I am driving 98 EB 5L v8 and I get aout 15.8mpg on street and abotu 18mpg on highway. it has roughly 11.2k miles.

I get about 13-14 in city driving, and 18-19 on the highway.

The 5.0 has been good to me, I figure she deserves a refresh w/ a rebuild kit.

Couple weeks ago, I cleaned the MAF sensor and that brought the mileage up from 14.5mpg to 15.8mpg in city driving.

What do you mean by tired ? Is it burning oil ? Dead cylinder ?
To be honest if its running pretty decent rebuilding the motor will probably do little to improve mileage and power. Maybe you could gain 10% on both if its running badly.

Yes the motor must come out, probably 6-8 hours out, 6-8 to go disassemble and re-assemble the motor. possibly a week if the crank needs grinding and heads need surfacing & valve jobs, rods reworked, block bored and honed. 6-8 to put back in.
To pay a mechanic to do it is going to be alot. I charge $500 to change a motor like
that, but retail mechanics are going to be around $1500 to swap an engine, to rebuild it ? Moneywise ? Fuhgedaboutit.

That mileage is about as good as the V8s get. That mileage isn’t bad if the oils been kept up. You’d probably get better results from a set of injectors and coils.


If the engine is sound and doesn't use much oil, your choice should be to do minor items and nothing else. Changing the timing chain set is a priority item at this mileage, the water pump and timing cover has bolts that are hell at this age to remove(and are obsolete). Going through the major support items like the injectors and O2 sensors etc, those are a given for any full servicing at high mileage.

If it uses oil, prior owners have neglected the oil and filter at some points before. Expect that to require rebuilding the heads to help with that.

When the engine gets truly tired and worn out, that's a full rebuild project. The block with crank and rods go tot a machine shop for renovating, the head too of course. Pistons can rarely be reused, and shouldn't be unless the cylinders have cross hatching and the pistons clean up like new etc.

If you want anything beyond the stock performance and fuel efficiency, you better get ready to spend more time than a rebuild, which that alone can take months given machine shop turn around times. The only good way to improve the engine is to change significant parts, and include new computer programming. That adds hundreds to the project just for the tuning, which is not typically easy to get done everywhere. Then you can plan for useful gains like more compression, better heads if you can afford it, custom camshaft, port the intake or another, improve the entire exhaust etc.

A lot can be done, but the costs are not cheap like decades ago, and these 2nd gens with the terrible exhaust manifolds, the gains will be less per dollar than other vehicles.

So plan as little as you can, because the costs sky rocket when you talk about actual power gains.