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How to: 4.0 OHV Refresh

97Sandbox

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Thanks Dave.

You're 100% correct anyone considering an engine swap should check into legal ramifications before buying anything.

I currently have my Explorer registered here in Wisconsin as a "hobbyist" vehicle which is a nifty lifetime registration status for modified vehicles that meet the following (according to our DMV):
  • Street modified vehicles
    • Must be at least 20 model years old.
    • Can still be recognized as the original vehicle year and make.
    • Are altered from the original vehicle.
    • Are typically known as "hot rods" or "street rods".
The lifetime registration status means it never goes through an annual renewal process and thus never gets tested for emissions (or inspected at all) after it passes at the time of the initial registration (which my truck did last year). My wife and I are also planning to move to Nebraska next spring and they're even more laid back on the subject of vehicle inspections.

To be clear, I don't condone skirting past emissions controls, deleting cats, etc. I just want to run a standalone ECU which is unfortunately enough to "fail emissions" in most places regardless of what's coming out your tailpipe.

Thanks for the tip on the head bolts, I have them in my RockAuto cart along with the gaskets and some other odds and ends. I'll have to double check the torque/angle spec in my service manual too -- I didn't realize it was such a bear.
 



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fast_dave

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Mahle OHV Torque To Yield Bolts

P9120155.JPG


To Stretch the TTY Head Bolts, I used a Craftsman 1/2" Breaker Bar combined with a Floor Jack Handle as a "cheater" bar.
Take note that I am tightening the passenger side head bolts, and the cheater handle extends all the way to the driver side fender...

P9130159.JPG


P9130161.JPG
 






410Fortune

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there is no emissions requirements that can stop a 5.0 conversion into this truck, a v8 conversion can be done and made legal even in California as long as the conversion is done properly and the correct emissions equipment is retained.
I went through this same thing many times many moons ago.
I love my 4.0 OHV! It was the perfect engine for a Bronco II!!
However the auto transmission not so perfect! I had a built and bulletproof A4LD in my rig (transwerx in So cal built it)
The 4.0 served me well for many years in my truck
I wanted more power and a better transmission (blew up two a4ld before the transwerx unit)
Instead of supercharging the ohv (back then we could still get the BBK supercharger setup) and putting more strain on the a4ld and more heat under the hood I decided to go v8. Mostly because my buddy Brett had a 68K mile 5.0 drivetrain he wanted to sell me...hahahaha
SO I took the plunge, converted the BII to v8 and OBD2........ it was not an easy conversion, but they never are.
Best choice I ever made.
Conversion was done in 06
we are almost to 2023 truck starts runs drives same as it did in 06.........flawless v8 smooth idle, tons of power, 4r70w laughs at the little BII, no strain on the 1/2-3/4 ton transmission, no boost needed, v8 power in a little Bronco II, gets about the same MPG as the v6 did with the "taxed" auto trans

My swap is legal in Colorado and even in California.......because I kept all of the 5.0 emissions equipment (except for the secondary converters) and my truck is an 88 so putting a 97 5.0 is legal.
Now in 2022 the information is out there to make these conversion way more possible
Much easier and more possible to do the 5.0 with a 5 speed now that our PCM's have been "hacked" and there are so many out there with the ability to do a tune
You can always rebuild the m5od and sell it for top dollar or just sell the trans and rebuild kit to one of us :)

The OHV heads can be inspected pretty well at home, you wont be able to find any minute cracks, but the obvious stuff will jump out at you, it is worth a shot. If you find a problem then you will know how to solve it (new heads) or start planning and go v8 byou will not regret it!
I knew I was going to keep this BII forever so to me the V8 was money well spent, 16+ years later 5.0 starts with bump of the key and will continue to do so for another 20+ years I am sure
 






fast_dave

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Just sayin' -

All this sounds great to those of us that know our way around an engine bay.

Too bad it's the person on the other side of the counter at DMV who doesn't change their own motor oil that calls the shots ;)

Coming from a Contracts & Procurement background, I would suggest the following to anyone in the PRK (or any other state that follows PRK smog rules and regs) that pays a garage/contractor for a smog legal V8 swap.

Include your own "boiler plate" Terms and Conditions to the Sales Contract that requires the garage/contractor to not only certify that the conversion will pass your state smog inspection & approval process, but also cover, if needed, the cost of any legal representation and/or required mechanical/software changes as per DMV/CARB Review & Appeal to get it to pass.

Also, there is the question as what to do ($$$) if ultimately, the V8 conversion that you just paid for is not approved after the final DMV appeal.

Last, make sure you include a boiler plate passage that any court proceeding/disputes are conducted in your county in your home state.

Your mileage may vary - hope that helps
 






410Fortune

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Anytime the emissions checkers would flag one of my trucks I setup an appointment with a referee to inspect the conversion. Each time my trucks have been signed off on given paperwork to run legal tags. This was in Colorado which has similar emissions to California
Never had an issue that could not be overcome
Of course I had researched similar conversions for year before I finally was able to do it, also had a few v6 conversions under
My belt. Learn by doing!! Research is your friend.
 






97Sandbox

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Before we conclude that the best way to refresh a 4.0 OHV is to replace it with a V8, I do plan to make one last effort. I'll get the Mahle gaskets and bolts on order and inspect my heads closely upon removal. Fingers crossed the V6 comes out of surgery stronger and healthier!
 






97Sandbox

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Another 2000 Ex with an OHV showed up at my local salvage yard this week -- same harvest gold like mine even, but 4 door and automatic.
PXL_20221113_175432731.jpg

Anyways, I'm debating pulling the heads off it and getting them magnafluxed and checked for warpage so that I could have a pair ready when I tear into mine and replace the gaskets. I'm kind of worried my heads might be cracked or warped from overheating.

This yard only charges $50 per head, so it seems like a decent gamble considering reman heads are a few hundred each. However, there's no telling what issues this Ex had that sent it to salvage. It has 230k on the dash, dipstick shows very low on oil and there's stop leak in the radiator -- any opinions if I should take or leave these heads?
 












fast_dave

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That bumper does pull the truck together :cool:
 






97Sandbox

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Nice looking bumper
That bumper does pull the truck together :cool:
Hahaha I'm out here trying to get my engine to stop burning coolant meanwhile you guys can't get enough of a base model bumper?

I personally prefer the look of the '95-'98 front bumper. Had I known folks liked the all-black '99+ bumper, I'd have saved mine!

As for the heads, I think I'll probably pass due to the questionable engine health. Hopefully I'll be able to hunt down a decent pair if mine do turn out to be cracked or warped.
 












97Sandbox

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$475 for a pair sounds like a solid option in the event my heads are unusable. Thanks @fast_dave!
 






97Sandbox

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After a few months of playing with suspension upgrades, interior reinstallation, and getting the Sport into my local body shop to dial in the swapped rear liftgate, I'm ready to dig back into my 4.0.

Task #1 will be to perform a cylinder leakdown test. You may remember it passed a (cold) compression test just fine, but I'm hoping the leakdown test might expose something the compression test didn't. If my theory of a tiny breech between the cylinder and a coolant passage is correct, I'd expect to see bubbles at the radiator when I pressurize some cylinder(s). What pressure do y'all recommend setting my compressor regulator to? I've heard 100psi, but that seems low given the cylinders pumped up to 160-170 when I did the compression test.

Task #2 will be narrowing down the source of a new oil leak. The engine now leaks more than it did before I "refreshed" it and the oil seems to be coming from somewhere high and towards the back of the block (it's running down the bellhousing and trans) -- I'm thinking my cam synchronizer may not be sealing well.

Pending the results of the above investigations, I'll get to pulling the intake back off and seeing what I uncover along the way. Any tips regarding what to look for are much appreciated!

It's probably also worth mentioning I've been driving the Sport around town periodically with my scan tool plugged in and plotting ECT and it has not experienced overheating -- the thermostat is opening/closing as expected. Overall, the truck runs well without misfiring, but often stumbles on a cold start (it's fine restarting after being parked for a few hours). The coolant in the reservoir has gotten dirtier/rustier looking, but there's no sign of oil in coolant or coolant in oil.
 






fast_dave

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Task #2 will be narrowing down the source of a new oil leak. The engine now leaks more than it did before I "refreshed" it and the oil seems to be coming from somewhere high and towards the back of the block (it's running down the bellhousing and trans) -- I'm thinking my cam synchronizer may not be sealing well.

Pending the results of the above investigations, I'll get to pulling the intake back off and seeing what I uncover along the way. Any tips regarding what to look for are much appreciated!

If I recall correctly, per my suggestion, you have swapped aftermarket cam synchronizer parts into your Factory / OEM Cam Synchronizer Body.

So when you manufactured your "Franken Synchronizer", did you remember to swap over the NEW aftermarket O-Ring that wraps around the Cam Synchro assembly?

I believe that the Cam Synchro Assembly is "splash" lubricated - but if the old rubber O-Ring was reused that might be your source.

The other area to watch in the rear is the RTV Seal between the aluminum lower intake manifold and the top/rear of the block.

CSA1_Front__ra_p.jpg


It's probably also worth mentioning I've been driving the Sport around town periodically with my scan tool plugged in and plotting ECT and it has not experienced overheating -- the thermostat is opening/closing as expected. Overall, the truck runs well without misfiring, but often stumbles on a cold start (it's fine restarting after being parked for a few hours). The coolant in the reservoir has gotten dirtier/rustier looking, but there's no sign of oil in coolant or coolant in oil.
Slight stumbling:

Do you smell any coolant on cold start-up??

OR

Do you smell fuel which would indicate leaking fuel injector pintels due to 21 years of fuel by-product buildup.
 






97Sandbox

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If I recall correctly, per my suggestion, you have swapped aftermarket cam synchronizer parts into your Factory / OEM Cam Synchronizer Body.

So when you manufactured your "Franken Synchronizer", did you remember to swap over the NEW aftermarket O-Ring that wraps around the Cam Synchro assembly?

I believe that the Cam Synchro Assembly is "splash" lubricated - but if the old rubber O-Ring was reused that might be your source.

The other area to watch in the rear is the RTV Seal between the aluminum lower intake manifold and the top/rear of the block.
Great memory! I actually swapped the OEM synchronizer guts into the aftermarket body with the new o-rings. The assembly fit darn tight into the block, so I'd honestly be shocked if it's leaking, but that's the general region the oil is coming from. I'll have to take a closer look if it could actually be leaking from the intake seam -- I carefully applied the Mahle silver RTV there (and in the front too), but something could've shifted.

Slight stumbling:

Do you smell any coolant on cold start-up??

OR

Do you smell fuel which would indicate leaking fuel injector pintels due to 21 years of fuel by-product buildup.
Unfortunately I haven't smelled much of anything since I got Covid in 2020. I can usually notice the presence of a strong smell (like gas) but I can't smell the difference between gas, exhaust, acetone, even coffee smells like a vague unpleasant smell to me now. Anyhow, I wouldn't be able to smell coolant, but I haven't notice steam out the tailpipe. The injectors I currently have installed are ebay remanufactured OEM injectors and they looked good before I installed them, but who knows.

I didn't get around to the compression test this past weekend, hopefully I'll find the time next weekend. Then it'll likely be time to tear into things and start coming up with answers (I hope!).
 






Clutch5sp

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Hi...first post here BUTT I read a lot. I'm a few days ahead of you having the engine pulled and on a stand. Both heads were found cracked between valves on cylinders #3 & #4. I've been chasing LTFT issues for some time now having been through exactly all the same things you have. My 2000 truck only has 101k on it. Cylinder walls look good but have weird stains. Today, I'm just going to take it all the way apart for inspection and decide to refresh everything from there with a good honing and super-duper cleaning. Kings Heads has a special right now $325.00 each for fully asembled heads no core. The RockAuto has some options to choose from with kits etc... I'm not going to trust a reman longblock. Any way you look at it, it's still cheaper to repair than it is to buy a new truck.

This was priceless the other night as the engine was dangling on the hoist with wires fluids and all sorts of mess going on as I called my wife out to see her baby, "Well there's your problem". ha ha ha ha
 






Clutch5sp

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You have an oil leak rear and high up? The china rails (lower intake manifold to block) are tricky to get sealed and will leak oil. Also, how are your fuel trims looking? I could not get my LTFT numbers %down (lean condition) affecting both banks which screams...VAC LEAK VAC LEAK. Cracked heads fooled me the whole time as the extra un-metered air was coming from the crankcase also exhaust gas which explains the sludgy oil under the valve covers. There were signs of head gasket problems as the side of the block was rusty. Then the coolant went yucky colored similar to peeing out your poop the morning after lots of beer & tacobell. Then the white smoke gushing from tailpipe as the head gaskets finally gave out. Once you get the heads off for inspection, it will be the AH HA moment.
 






97Sandbox

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Finally got started prepping to run the leakdown test. Pulled the fan/shroud/belt, removed the plugs, and cranked my way to TDC on cylinder 1. Hoping to run the actual test tomorrow.

One interesting thing I noticed already, the cylinder five plug's ground electrode is pretty yellowish while all of the other plugs look normal.
sRAuKInRDmV0XPAJQdLw6eo2y=w1247-h938-no?authuser=0.jpg

02LRXL7k2GyV-VyGIOLU3Wsz6=w1247-h938-no?authuser=0.jpg


From what I understand, yellow electrodes are a sign of high speed glazing but I'm not sure how that would affect just one plug.

This ought to be an interesting investigation!
 






donalds

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Plug #6 and #5 looks different from the rest
The porcelain is sticking out less than the rest

They all look good except for #6 #5
 



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97Sandbox

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Plug #6 and #5 looks different from the rest
The porcelain is sticking out less than the rest

They all look good except for #6 #5
I wonder if that has something to do with when I had the 5 and 6 wires swapped when I first got the engine back together. Those were the two plugs with fuel on them when I pulled the plugs back then and at least one of them was doing the ignite-on-the-exhaust-stroke thing which gave me those weird pops.

Do you think I'm okay to keep running these, or should I pick up a couple new plugs?
 






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