cracked heads are off, can I save my bottom end?

[siggy-TX]

Hey y'all, newbie here who just got his first explorer, 98 explorer sport, 4.0L OHV, 2WD, 5MT, 105,000 original miles. Picked it up for scrap cost from a friend because it had overheated and would idle okay but was almost impossible to drive. I've been trolling the forums to learn about this engine cracked heads comes up a lot (foreshadowing). I've done a few tests, pulled the heads, and now I'm deciding what to do. As I'm a fastidious type of person (read: detail overload), I'll build up my case real detective-like and put forward a hypothesis, and I'm asking you for your interpretation and advice on the facts at hand. I'm new to engine work (only done suspension and maintenance work before) so I'm here to do some learnin!

THE FACTS:
Car ran and drove when I got it (idled okay, smelled rich), but was real low on power (improved a bit when I switched two of the ignition wires around that a mechanic goofed up, switched 5 and 6...you gotta be kidding me....). No coolant in oil, but the level was high and it smelled like gas.

Compression test results:
(1) 180 psi
(2) 180 psi
(3) 65 psi (unchanged when wet)
(4) 115 (120 wet)
(5) 155
(6) 135

Leakdown test results:
(1) 10% leakage, moderate air flow from oil breather tube and slight intake flow
(2) 10% leakage, moderate air flow from oil breather tube, when tube is covered the flow switches to intake
(3) holds almost no pressure, high air flow from oil breather tube, exhaust flow, slight burbling from intake
(4) holds almost no pressure, significant air flow from oil breather tube, exhaust flow, slight burbling from intake
(5) 10% leakage, my notes are illegible, but possibly similar to cylinder 1 or 2 (similar compression)
(6) 35% leakage, significant intake and oil breather tube flow, small exhaust flow

Condition of parts:
throttle body - oil on butterfly
lower intake manifold - lots of oil, EGR tube looks like it's been working overtime
intake ports on heads - tons of oil and carbon build up
head gaskets - intact and in fair condition, lots of coolant gunk built up where it surrounds coolant passages
block - looks good to my untrained eye except for the nasty rust-colored (maybe burnt orange coolant?) gunk in all the coolant passages. Similar colored stuff came out when I flushed the coolant system pre-disassembly.

Condition of block:
Heads are pulled, bores look pretty good with no noticeable scoring. Cylinders 3 and 4 have some patterns on them that looks like it's from fluid, which could be gas from running rich, or oil, orrrrr from the coolant I leaked in there when I pulled the first head before draining my entire cooling system [facepalm]. The rest of the bores look quite good. A couple of cylinders even show factory cross hatching, and the crank is very easy to turn with a ratchet

block

cylinder 3

cylinder 4

Condition of heads:
(1) looks fine
(2) looks fine
(3) lots of carbon build up, significant crack between valves, exhaust valve looks like it's seating poorly from all the gunk
(4) lots of carbon build up, huge crack between valves
(5) some build up (probably from running rich when ignition was switched) but similar to 1 and 2
(6) significant carbon build up, small crack between valves

heads

(passenger side left, 1 on top, driver side right, 4 on top)

Exhaust ports look decent, nothing that looks too wild to me except for lots of oily gunk on cylinders 3 and 4, which makes sense due to the cracks and gunk build up in on the cylinder heads. This burning of oil could have also led to the EGR (driver side, two cracks in head) sending a lot of oily exhaust back into the intake.

THE QUESTION:
The $500 dollar question is can the bottom end "simply" receive some fresh dressed heads from Odessa Cylinder head ($450 shipped on ebay) as well as fresh gaskets and a cleaning on the intake and EGR parts, plus a thorough coolant flush? Or is this engine hosed and I need an entire new engine?

My hypothesis is that the bottom end is not perfect, but should be okay with new heads. The 10% leakage on the good cylinders isn't terrible, especially for an engine that has overheated and cracked and maybe warped its heads. The overheating may have been caused by a cooked thermostat, but I'm open to hearing input on this. It was likely consuming oil, but that could also have been a result of the cracks. I am concerned about wear to the bearings and such, as there was gas in the oil, but besides the engine issues, I didn't hear a hint of rod knock and it idled pretty darn smooth after the ignition issue was addressed.

CONCERNS:
I am worried about the air leakage from the oil filler breather tube on the leakdown test. I think I goofed a little and should have been listening from the dipstick, but would it make a difference? If I hear any air from the oil does that indicate a terminal amount of blowby or is that normal as the air has to go somewhere? 10% leakage doesn't seem bad, again, especially with possibly warped heads. The engine was cold for the leakdown, if that makes any difference. If any blowby from the leakdown is bad, how difficult is replacing all the rings? If the rings are bad, does that mean the bore is compromised, too? Is it at all likely the block is cracked? Does gas in the oil mean my bearings are likely shot? Again, I would much rather clean everything and install new heads because that is well within my skill level, and would be about the same cost as buying a running higher mileage engine pulled from a junkyard (500ish). Short blocks around me from the pick a part are about 150+tax etc, and long blocks are about 180+tax etc. Knowing these facts, what should I do to revive this old beauty?

Apologies for such a long post, I just wanted to get everything I know about the engine condition out there so someone more knowledgeable than me can interpret the same complete set of facts I'm working with. I thank you so much for making it this far through my post, and thank you in advance for your advice! If you need more info, or photos, let me know.

EDIT: can't figure out embedding photos, hopefully the links work, though. Advice appreciated! Can I use google photos like you would use photobucket or another hosting website?

 

[rasouth]

If the car ran okay when you bought it, maybe a little rough, I would say that the bottom end is good. This is a common problem with these heads... overheating causes warping and cracking. Pretty much any repair manual should give you step-by-step instructions with torque values. I replaced my heads on my '96 in just a day. I took more time checking the push rods, rocker arms, cleaning parts.
I bought my heads, gaskets and NEW head bolts, off RockAuto. Not bad prices and shipped quick. And , yes, you will need NEW head bolts because the old ones have stretched.

 

[974X4BLACKSPORT]

For your photos, upload them to "google photos", then right click photo and select "copy image address", then paste into the box that appears after clicking in the little "Image" box in the above tool bar next to the "happy face" (see below image).

Its that easy, I did this in less than one min.

 

[fast_dave]

@siggy-TX

FREE Photo hosting website: Imgur

Recommended Cylinder Heads: NEW King Cylinder Heads
LINK: https://www.kingcylinderheads.com/product-page/ford-4-0l-v6-c-95tm-98tm-assembled

So-So Quality Video that shows effects of the Cracked Cylinder Heads:
Link:

 

[koda2000]

Hearing air from TB during leak-down test means air is leaking from the intake valves/valve seats/cracked heads. Hearing air leaking from the exhaust pipe indicates exhaust valve side leak. Hearing air from the oil filler tube indicates leaking piston rings (AKA blow-by).

Seeing bubbles in the radiator or overflow tank indicates a blown head gasket into the cooling system.

Older/high mileage engines often have oil in the intake and back of the throttle plate, but that doesn't mean they totally worn out. Oil in the intake could be valve seal or PCV valve related.

If you don't have a lot of blow-by replacing the cylinder heads will probably get you back on the road. Te bottom end if the 4.0L OHV (or the SOHC) engine is very durable.

BTW - Your engine should not have red/orange extended-life antifreeze in it. It's not designed for it and it will clog up your cooling system.

 

[96eb96]

A bottom end failure is very rare on these engines. There is a cash for clunkers video where it ran like 8 minutes, 3 with a rod thru the block and all the coolant coming out. The heads crack and likely that was the overheat cause.
Even a brand new engine will have SOME leakdown.

Leakdown numbers could vary between equipment, but 10% and under from what I understand is new engine territory. Solid 180PSI compression is a very good sign. The other cyls had issues with the upper end. How do you know the JY block is going to be better?

 

[siggy-TX]

A bottom end failure is very rare on these engines. There is a cash for clunkers video where it ran like 8 minutes, 3 with a rod thru the block and all the coolant coming out. The heads crack and likely that was the overheat cause.
Even a brand new engine will have SOME leakdown.

Leakdown numbers could vary between equipment, but 10% and under from what I understand is new engine territory. Solid 180PSI compression is a very good sign. The other cyls had issues with the upper end. How do you know the JY block is going to be better?

@96eb96

good to know, thank you! And thanks to all for reading through my detail heavy post. Yes, even though I was feeling air coming out through the breather tube the numbers were good on all of the non-cracked chambers. Maybe they will be even better once some new heads are put on that aren't warped. I should check the block deck for warping though too, right? As for the dirt and grime in the cylinders and the oily carbon deposits all around, what's the best way to clean them up? I would rather not use compressed air as that might blow them around and into the crankcase. And what should I clean the cylinder bores and piston heads with to get rid of the little carbon build up there is? Should I / how do I check the lifters to make sure they are okay? And, new pushrods, since I'll be ordering a whole new top end?

Is it worth it to get an oil analysis from blackstone for some added info and peace of mind? I think it's $28 but I'm cheeeeeeap

@koda2000
Good tip on the PCV, I'll have to check it once the engine is back together. Some oil could be from the lower intake bolts, too, as I've read they back out on this engine (mine were at less than 10 lb ft i am guessing). Reassembly will involve loctite. Re: coolant, one of the first things I did after getting it was flush all that nasty coolant out, ran some prestone cleaner, then put some fresh green coolant in. Once it is running again I need to do another flush. Any opinion on the many methods of cleaning cooling passages in the engine? Is vinegar safe? Has anyone tried the radiator flush kit that you hook a garden hose up to some fittings and push water through the radiator and coolant passages?

PO didn't know much about cars from what I can tell, and was jerked around by a couple of shops while trying to deal with the overheating issue which is probably why there's orange coolant in there (and the ignition was switched around!). He said one shop even replaced the fuel injectors and coil pack and when the reassembled it they forgot to put one of the injectors in! Ridiculous. It's a shame because all this BS put this Explorer off the road, though I guess that's the only way I was able to get my greasy hands on it, hehe.

@rasouth
I'll be sure to get all new bolts, gaskets, etc. rockauto is one of my favorite websites
I want new gaskets all aroound (head, valve cover, upper intake, lower intake, egr tube, exhaust), new thermostat + gaskets, and a new rad cap.

 

[siggy-TX]

@fast_dave consensus seems to be that King cylinder heads are high quality (though they say they are 95/98TM, which IIRC are not exactly the same? But is there any difference besides the larger exhaust ports on the 95?)

Have you heard anything about Odessa cylinder heads? $450 shipped on ebay here (compared to $640 shipped from King)
Reviews on this site and others are a mixed bag, but I see more negative ones than I would like. $200 is some cash, though.

When I replace my heads should I also replace my rocker arms and pushrods? They look decent and it wasn't ticking or anything before removal so I would rather not (and I have everything lined up and organized so I would be able to reassemble correctly).

 

[koda2000]

Check the push rods and rockers for wear and replace as necessary. Probably a good idea to replace the lifters, as the heads have to be removed to replace them and they tend to tick when worn.

105K is not a lot of miles for the OHV engine. Other than the heads cracking, they can see 400,000 miles.

 

[siggy-TX]

Check the push rods and rockers for wear and replace as necessary. Probably a good idea to replace the lifters, as the heads have to be removed to replace them and they tend to tick when worn.

105K is not a lot of miles for the OHV engine. Other than the heads cracking, they can see 400,000 miles.

eeeeek! just priced lifters on rockauto...almost $400 shipped for 12. I wasn't getting any lifter tick before and idle was smooth (after ignition was corrected). Just checked the rocker arms and pushrods, the rods look good, nice even wear, no burring or pitting, but three of the lifters have some pitting on the valve contact surface so I guess I'll replace 3 rocker arms.

 

[96eb96]

@96eb96

good to know, thank you! And thanks to all for reading through my detail heavy post. Yes, even though I was feeling air coming out through the breather tube the numbers were good on all of the non-cracked chambers. Maybe they will be even better once some new heads are put on that aren't warped. I should check the block deck for warping though too, right? As for the dirt and grime in the cylinders and the oily carbon deposits all around, what's the best way to clean them up? I would rather not use compressed air as that might blow them around and into the crankcase. And what should I clean the cylinder bores and piston heads with to get rid of the little carbon build up there is? Should I / how do I check the lifters to make sure they are okay? And, new pushrods, since I'll be ordering a whole new top end?

Is it worth it to get an oil analysis from blackstone for some added info and peace of mind? I think it's $28 but I'm cheeeeeeap

No problem...always like helping a fellow redneck :lol:

No engine is going to positively seal 100%, especially at rest. When it runs there is oil on the walls and things happen fast before air escapes. If it sealed perfectly there would be much more friction and wear.

I would look it over and replace what is worn. It is very high mileage capable engine that could probably handle much more HP. It isn't powerful and the tradeoff is longevity. Now, if you had an SOHC, then we would be telling you to push it off the nearest cliff.

There are lots of products you can use to clean the bores - carb cleaner, brake cleaner, top engine cleaner, seafoam, let it soak then change the oil before you start it up. Of course use a brush that wont scratch (maybe those dollar tree nylon dish brushes). Don't use any roloc or abrasives to clean surfaces.

The pushrods are a wearpoint on this engine - they don't get much lubrication, but it seems to last anyway. My engine idles as good as a new car. It is not really powerful though. I have 4.10 gears so it helps a bit but the mileage sucks. This engine has lots of bottom end torque. Maybe even a bit more than the SOHC. HP sucks so after a certain point there is no power left. That is why the SOHC fixes but it is has a ton of other problems.

With the 4wd low and the 4.10s it could probably pull a house off its foundation.

 

[974X4BLACKSPORT]

I watched the above posted video (4.0 OHV Teardown) and got disgusted when some very seriously bad advice was given. I want to tell you that if you dont have the willingness, diligence, or intelligence to keep internal engine parts in order and in their respective location upon reassembly, you have NO business working on automobiles, automobile engines, or any other mechanical device for that matter. The reasons for this statement are not debatable, and the explanation would fill complete textbooks, which I have no need to, or am willing to write for the sake of proving myself correct on an automotive forum.
I also want to point out that any and all gasket material that remains to be cleaned off the engine block must ONLY be removed with razor blades, manual scrappers and a vacuum cleaner to remove the debris at the same time, taking great care not to get dirt and debris inside the engine block and cylinders. Preparation is the key to keeping the engine clean when "cleaning". DO NOT USE high speed rotating power tool with abrasive pads or wire wheels, as these methods ejects debris when in use, and this debris then gets inside the cylinders between the piston and piston rings and cylinder walls, and also engine block.

 

[96eb96]

I watched the above posted video (4.0 OHV Teardown) and got disgusted when some very seriously bad advice was given. I want to tell you that if you dont have the willingness, diligence, or intelligence to keep internal engine parts in order and in their respective location upon reassembly, you have NO business working on automobiles, automobile engines, or any other mechanical device for that matter. The reasons for this statement are not debatable, and the explanation would fill complete textbooks, which I have no need to, or am willing to write for the sake of proving myself correct on an automotive forum.
I also want to point out that any and all gasket material that remains to be cleaned off the engine block must ONLY be removed with razor blades, manual scrappers and a vacuum cleaner to remove the debris at the same time, taking great care not to get dirt and debris inside the engine block and cylinders. Preparation is the key to keeping the engine clean when "cleaning". DO NOT USE high speed rotating power tool with abrasive pads or wire wheels, as these methods ejects debris when in use, and this debris then gets inside the cylinders between the piston and piston rings and cylinder walls, and also engine block.

That guy(I actually emailed him) is a professional diesel engine rebuilder. He rebuilds bigrig engines(which aren't that much different, they are large OHV engines). Not saying good or bad but I think he knows what he is doing?

Yeah, I mentioned above not to use any roloc to clean surfaces. GM had some issue years back with head gaskets and a recall and the techs were cleaning with air wheels and they would get major engine damage a few months later and a big comeback. Some engines can take it though, from what I understand.

 

[siggy-TX]

@96eb96 Thank you for all the advice! I'm looking forward to feeling the torque of this engine. I have a 4 cyl Ranger with the duratec in it, great engine and good on gas, likes to rev, but not that torquey. The explorer has a 3.27 non LS rear end though, so maybe I won't feel the torque, lol. At least the highway mileage should be good, right?

From all the information in this thread and other research, I'm going to buy new heads from King, a full enginetech gasket set from rockauto (anyone know how to find out exactly what gaskets come in it besides emailing the company?), new pushrods, 3 new rocker arms to replace the ones with pitting, (gonna cheap on the lifters and clean them / soak in motor oil before installing again), new water pump, new head bolts and exhaust studs, and give everything a thorough cleaning including the fuel injectors and fuel rail (shoot w/ carb cleaner for the injectors and soak the rail in mineral spirits then blow out with comp. air).

Some questions i still have:
- the EGR port on my plastic upper intake manifold looks a little scuffed up on the outside, is it fine to reuse? I'm gonna inspect the sealing surface again, but can't guarantee it won't get scuffed when I reinstall the manifold. What a PITA to get it over that bent EGR tube end. I was thinking about using a little bit of RTV on the port in addition to the o-ring on the tube, especially if my gasket set doesn't come with a new o-ring (it's a little deformed but still intact).
- oil passages might be a little gunked up, I was thinking about running sea foam in the crank case for a few miles before the first oil change after rebuilding the top end (of course I will give it fresh oil before starting for the first time, too). Is this a good idea?
- should I put assembly lube on the ends of the pushrods? Is there anything else that assembly lube should be used on, like the rocker arms where the meet the rail? On the valves of the new head? Any other types of lubrication I should do before assembling? I'm a little worried about a dry start for the top end since it will be a brand new head.
- The coolant passages are gross. Any insight into doing a manual flush (heater core, too) with one of those garden hose adapter kits from prestone you can pick up from walmart for a few bucks? The search bar indicates that it's a good idea for routine maintenance, but since this truck was overheated the particulate build up is significant (cooling passages between block and heads have a lot of crusty bits).

Sorry if these are newbie questions. This is by far the most serious work I've done on a vehicle and I want to be sure I get it done right!

 

[rasouth]

When I replaced my heads and reinstalled my rockers and push rods I soaked the rockers in oil for a couple hours just to get oil into the nooks and crannies and oiled the push rods before installing them. I did not use any assembly lube.
Personally I would not use RTV on the EGR tube. It is a PITA but can be done. I had to tap mine with a piece of wood to get it settled.
It sounds as if you have a good idea on what you need to do. Replace what looks bad, re-use what looks good.
I got the top side gasket set from Rockauto and it came with everything from head gasket to oil seals. The usually have a description of what comes in the set.

 

[974X4BLACKSPORT]

When you reassemble your valve train, you can use some home made assembly lube by mixing 50/50 , STP/regular motor oil, put it on all contact points like valve stems, push rod to rocker arm, and lifter to push rod areas. After you clean and inspect your lifters, refill them with just fresh oil by using and oil squirt can and squirt oil into the hole in the side of the lifter until it comes out the top hole where the pushrod sits.

 

[siggy-TX]

@rasouth did the gasket set come with fuel injector o-rings or do I need to buy them separately? And did it come with the thick gasket that goes between the fuel rail and lower intake manifold?

@974X4BLACKSPORT Thanks for the advice, I'll do that. I got some squirt bottles especially for pre-lubing parts. What is STP, though? All I know is that they make motor oil but are you referring to a particular high-viscosity oil product they sell?

 

[lobo411]

I have a 4.0 also and my head gaskets had a minor leak right around your mileage (115k for me). Mine had never overheated so I was fairly confident that it was just a gasket issue. I took the heads to a machine shop and got them magnafluxed, pressure tested, cleaned and repainted, valve job including grinding and new seals etc... for something like $150.

Why not just ask the shop to test the old heads? I think the cost just to have them tested is not that much. If they're not cracked or warped then just have them refurbished.

Of course, if you *don't* establish that the heads are the problem, then you run the risk of replacing good heads with newer good heads and suffering the horrible fate of spending a crap ton of time and money without fixing the real problem.

 

[rasouth]

I think you will have to buy the o-rings separately. As of the gasket for the fuel rail, Rockauto has pictures of all the gasket sets. My gasket set came with everything for the upper rebuild, i.e. head gaskets, intake gaskets, plenum gaskets, valve cover gaskets, exhaust gaskets, oil seals, EGR gasket. They have one listed that includes everything for upper rebuild including water pump and timing chain cover.

 

[siggy-TX]

I have a 4.0 also and my head gaskets had a minor leak right around your mileage (115k for me). Mine had never overheated so I was fairly confident that it was just a gasket issue. I took the heads to a machine shop and got them magnafluxed, pressure tested, cleaned and repainted, valve job including grinding and new seals etc... for something like $150.

Why not just ask the shop to test the old heads? I think the cost just to have them tested is not that much. If they're not cracked or warped then just have them refurbished.

Of course, if you *don't* establish that the heads are the problem, then you run the risk of replacing good heads with newer good heads and suffering the horrible fate of spending a crap ton of time and money without fixing the real problem.

@lobo411 This truck overheated a couple of times before it ended up in my hands for scrap cost, and a few mechanics goofed up some really basic stuff and made the problems worse. Honestly I think I could have got it for even less than scrap cost, the guy was just so happy to see me drive it off his lawn and onto a trailer. I pulled the heads last week and discovered 3 cracks: 1 minor, 1 significant, and one HUGE, all between the valves. they are toast, unfortunately. Leakdown test didn't even register a readable percentage of air they could hold on to, though the other 3 cylinders had great compression. I wish it was just a gasket but I was getting no coolant loss due to combustion. Now, the water pump and thermostat cover on the other hand...I see a few drip marks. Both will be replaced. Luckily both are inexpensive on rockauto and the brand seems to be trustworthy (Gates).

@rasouth there's a timing chain cover on the OHV engine? Where is it? Or is it just buried somewhere else that I haven't discovered? They aren't a problem area on the OHV are they, like they are on the SOHC? I really don't want to mess with that if I can avoid it, ditto for the oil pan. I see the gasket set you are talking about I think on rockauto. It's an engine tech kit, somewhere just north of $100, lots of little rings and gaskets. I figured about the injector o-rings but now I'm wondering what all those little o-rings are in the photo. It's no biggie though, the fuel injector o-rings are very cheap. Could the small rings be gaskets for the valve cover between the bolt and cover? Mine had some RTV seeping out around the bolts before I pulled em