Use Existing Heads or Buy New ones?

[weasel318]

Hey guys. So my explorer had a Lean condition for both banks. I changed out the upper intake gasket and with my data logger it was still running lean. So I drove it and then it started smoking badly a few months back after I pulled into my driveway.

So I finally have time to deal with it and here is what happens.

Compression test showed that all cylinders were good at around 150psi. The scanner said Cylinder 6 was misfiring so i focused on that cylinder. It had 150 psi. However coolant was getting into the cylinder since the compression tester filled with coolant after a few cranks. So definitely a blown headgasket or cracked head.

So when I crank the motor with the spark plug or compression tester installed in Cylinder 6, the coolant will gush out of the radiator. Without anything installed in Cylinder 6 spark plug hole no coolant would gush out, but coolant will spray out a bit from the spark plug hole.

So after the tear down, it looks like it was just the gasket that was bad. The Cylinder 6 gasket ring was compromised. With a visual inspection both cylinder heads look alright without any cracks in the usual places like between the valves.

I dont plan on selling it since I did a 4x4 swap on it and other work already. My question to you guys is should I still throw any money in magnafluxing the heads and checking if they are any good or just skip that and go straight to buying new casting heads from Kings or Clearwater? Thank you!

Forgot to list my vehicle. It is a 2000 Explorer Sport Manual 4.0 OHV. Was a 2WD now its 4WD. It currently has 151k

A little more info. The headgasket has been changed before by a semi shady shop. It was originally my godmothers car and she said it overheated once and she got the headgasket changed. They used felpro for everything. Im not sure if these are the original heads or if they are aftermarket new casting. if someone knows what numbers to look for on the heads please let me know that would be a big help. I tried the search but all it comes up with is for the 95 and 97tm heads. I had the 98tm heads for sure since its a heart shape and the ports are circular.

 

[Hacra]

If no cracks are visible and head gasket failure was the only cause of your problems, just buy new head gaskets. I'd have heads resurfaced by local machine shop.

 

[974X4BLACKSPORT]

I'd reuse the heads too if no cracks are found. Resurfacing is a good idea, but if they are still straight/flat withing specs, I would just clean them real good to get ready for reinstall. I say this because being that this is the second time off the block, the head/heads may have already been resurfaced, and if you are just doing one head at this time, you dont want one head shaved down more than the other side. I would still diligently check the head for flatness though, and if it does need resurfacing, the best thing to do is resurface both heads so they are similar as possible.

 

[koda2000]

Have your old heads magnifluxed for cracks. Visually checking for cracks is not good enough as some cracks are very hard to see. If no cracks are detected, have the heads resurfaced and reuse them with new head gaskets and new TTY head bolts. You might consider having the valves checked and new valve seals installed while the heads are at the shop. The 4.0L OHV engines tend to develop cracked heads, especically if overheated. New 4.0L OHV heads are not that expensive, so you might want to compare shop costs to replacements.

 

[weasel318]

Yea Hacra and 974x4. I was thinking the same thing but sbop prices here are ridiculous and its hard to find a shop thats reliable. What worries me is that my godmother said it almost overheated once which led her to change the headgasket before. Not sure how "overheated" it was before and not sure if there is a micro crack that developed already but just isnt visible yet.

I am leaning towards new heads as of right now because of the cost. Magnafluxing them and then rebuilding them will probably be at least 300 bucks. Just a guestimate from rebuilding a lima cylinder head. New heads thats ready to go is 600 bucks and they are better casting so they shouldnt ever crack again right?

There are 4 rockers that have pitting in them/nicks and in those 4 rocker arms, there are two that have a deeper wear in the socket where the push rod sits.Also another question I have are the push rods. Should I be changing them? They arent a sphere anymore, theres a little flat surface at the ends of each one of them. Thank you for the advice guys!

 

[Hacra]

Well, it all comes down to how much you are willing to spend, if you see parts that are badly worn out, i'd change 'em. set of new rods shouldn't be expensive ~50$? i think amazon has rocker and rod kit for 120$, might be cheaper somewhere.

And what goes to never cracking, even the new ones might eventually, but if your truck will see under 50k miles in the future... i don't know if new heads are worth it. Compare the prices of it all and see what makes most sense, also note that cheap option might be the expensive one eventually, like the saying goes here, poor man can't afford to buy cheap.

 

[weasel318]

I decided to buy new heads. Has to be reliable. I think a tow bill in the middle of nowhere is more expensive than doing it right lol. Its my dedicated offroader so it has to be able to go out into the sticks and come back LOL

 

[koda2000]

I would also replace any worn push rods and rockers, if not all of them. Did you keep the push rods and rockers in order when you removed them? If not them you might as well replace all of them.

 

[weasel318]

Replacing 4 rockers and all the pushrods. The other 8 rockers looks decent. 2 of them had pitting where the valves rested on. 1 had a work spherical area the push rod rested on. and 1 was worn on both ends it seemed. I kept them labeled and separated. Its a no no in my book to mix and match. lol

 

[weasel318]

I do have a question about the rocker arms and assembly. Alot of carbon from the top end of the motor go on it. How do I clean that safely without damaging anything?

 

[siggy-TX]

With help from many members of this site, I just brought my 98 sport back to life with new heads (and many other new parts), $415 shipped from J&C enterprises, out of Virginia I believe. If magnafluxing etc is going to cost $300, I think you're right in just buying new heads. Also, they may look good but they could also be warped which would probably mean another head gasket failure. Also as others have said, when you throw em back on, use new TTY bolts!

As for my rocker arms, I replaced 4 of them as well, the ones on the ends because I wasn't feeling like twisting off the mounting posts because they are on there tighter than a banshee (and I don't have a vice or workbench). It was a little tricky to get the retaining pins out without damaging them, and this is a part you can't just buy on rockauto (or at least I couldn't find it anywhere online), you would need to snag some from a junkyard which would be a huge pain. I used a block of wood drilled out the size of the shaft, with a groove cut in it to go around the pin, and applied some light pressure to the spring clip behind the pin with a clamp while pounding it out (gently!) with a hammer and punch. At the recommendation of a couple of people on this site (@rasouth and @96eb96 I believe) I soaked the new arms (melling parts, $5 on rockauto) in oil then gave them a nice coat of oil+STP oil treatment (has ZDDP in it) before sliding back onto the shaft. Of course, before I did all of that, I cleaned the assembly as best I could. Used a pick to grab out the carbon build up in the bolt / oiling holes on the posts. Next, I went to town with the good stuff in the green can, brake clean, and shot out all of the gunk i could in the shaft. It is hollow, so you can angle the tip of the can in there. Spray out the shaft through the rocker arms, too, there are oiling holes on the cups for the push rods, and if you line up the oil hole through the rocker arm with the ones on the shaft, you can get in there with the high pressure spray of the good stuff. I imagine soaking in a bath of mineral spirits would work as well, but then what are you gonna do with all that liquid after? Anyway the pressure does a real good job of forcing stuff out. I kept going over it until the spray out looked clean, must have been half a can of brake clean for both shafts.

Good call to replace the push rods. They were just over $3 on rockauto for melling parts. They are solid, unlike many that have an oil hole in them, so there is no flow from the hydraulic lifters through to the cups on the rocker arms. They only get the drip of the good stuff from the rocker shaft, and those oil holes are pretty small and pretty far from the pump. May as well clean out the lifters while you're at it, too. I shot brake clean into them wherever I could (seeing a theme here?) then soaked em in a bath of ATF for an hour or so before dropping them back into the bores. Put assembly lube or the previously mentioned oil+STP onto the push rod surfaces, rocker arms, tops of the valves where they meet the arms, etc.

Has the truck ever overheated in the time you've owned it? If so, may as well replace the thermostat, hoses, and give the radiator a real nice flushing. This is all the cheap stuff. I picked my 98 up from a friend for nothing because of the cracked heads from overheating, and when I tore the engine open I was disheartened by how nasty all the old coolant and gunk was in the passages. After cleaning everything real good and replacing all the cooling system components besides the radiator and fan, the temperature stays between 190 and 205, even with this absurd Texas heat.

btw casting codes are on the top of the heads, once they are off you can't miss them. Heads are also distinguished by different exhaust ports, but I recommend saying your prayers and hail mary's before trying to get those suckers off.

 

[weasel318]

I bought most of my stuff from Ford. Im in California and theres tax now and shipping and some stuff came out to be cheaper from Ford. Pushrod was ~6 after tax. It seems like the rear cylinder rocker arms suffered the most wear, especially the exhaust one on both sides of the engine.


Im using new bolts from Home Depot for the head bolts. Im just making sure its grade 8.


And no the truck hasn't been overheated the time I had it. The day it died, I was almost home and I smelled something horrible. Didn't know it was my car since it wasnt smoking or anything, just the check engine like was on (was on before, and came back on that day after I did my upper intake gasket). Pulled into the driveway and shut it off. Came out later to run codes. After running the codes and getting a misfire in cylinder 6 the car started smoking like crazy and I knew it was probably a headgasket or cylinder head lol.


I am replacing everything just in case. DOnt want to have it back together and have to tear it apart again. I already had it apart for the upper intake gasket and that didnt fix my lean condition before and lead to the headgasket blowing now.


The inside of the engine looks clean except for all the pistons and heads with alot of carbon build up. Its either running rich from before due to exhaust manifold leak or its because I was running 91 in it for kicks LOL.


I saw a bunch of numbers, and they are for sure 98tm. Just not sure if they are recasted heads or OEM ford heads. Not sure if my godmother changed them before or not.



ALSO, im kidding about the Home Depot bolts LOL. i bought new ones from Ford. I never reuse headbolts even if they are not TTY. The only exception to that rule is for my SVO. The OEM head bolts are better than the aftermarket ones and buying new isnt an option since they are like 50 bucks for each one (so ~400 bucks for a new set).

 

[koda2000]

The head bolts need to be "torque to yield" (TTY) bolts). They cost around $22 per head for Felpro TTY bolts from places like Summit Racing. Don't use grade-8 Home Depot bolts or you'll be running a good chance of breaking bolts during torquing and quite possibly blowing more head gaskets.

 

[weasel318]

I know LOL, last part I said JK. i bought new ones from ford.

 

[siggy-TX]

LOL you almost got me with that one. weasel indeed!

As for the casting, my aftermarket casts didn't have 98TM on them. They had some cast numbers that I honestly didn't pay much attention to, so I bet yours are original. All the more reason to swap em out. My rocker arms on the ends of the rails were the most worn, too. The oil must not flow too well on the corners, which is convenient because they are the easiest ones to swap out! My suspicion is that this engine just doesn't have amazing oil pressure in the top end. One of the banks on mine was bone dry when I pulled the valve covers.

 

[weasel318]

Yeah mine didnt have 98tm anywhere I can see. But I do see a letter A casted onto one of the exhaust ports. Mine was pretty well when i pulled the covers off. It might be because my oil is super thin from the steam diluting it. Before I pulled the motor apart, when i pulled the dipstick out the oil was just dripping off the stick like water.

 

[fast_dave]

It might be because my oil is super thin from the steam diluting it. Before I pulled the motor apart, when i pulled the dipstick out the oil was just dripping off the stick like water.

@weasel318

At any point before you pulled your heads off, did you experience a Oxygen Sensor Check Engine Light/Code - specifically a P0133 Slow 02 Sensor Response code?

 

[weasel318]

No. Oxygen Sensor Code, just a lean code P0171 and p0174. Tried to fixed that with upper gaskets but didnt do anything. Right after changed the gaskets, i data logged it and the Ltfuel trim was around 21-24% which is still too high. I think i blew the headgasket from driving it too long with it running leaning. As for the air leak, im guessing it was the valve covers that might be letting unmetered air into the pcv? hopefully it doesnt run lean when i get it all back together

 

[koda2000]

Also clean your MAF sensor.

 

[weasel318]

Already did that when the lean codes came up. Didnt do anything.