99 Sohc 4.0 to 00 OHV 4.0

[99XLT-Explorer]

Hey yal i have 208k miles on my 4.0 sohc i did the primary chain,guides and tensioner about 500 miles ago, i just got done with the driver side cam chain and tensioner and guides. not even 5 miles after that the rear chain tensioner broke i believe the truck started to stall and slip timing in about 2 mins i had to get home. when i parked it it would stumble but not start. i dont believe i had interference.

anyway i found someone who wants to trade a ohv for my ohc once i fix the rear chain. my questions are these.

Are there any harness differences between the 00 ohv to my 99 ohc?

I know trans will bolt up however will the flex plate?

i did read something about a cam sensor signal being different but i believe in 99 or 98 they went to the same signal.

I know im going to get the question why not a 5.0 and bc i dont wanna deal with a new trans tcase and driveshafts aswell as any other differences and i dont want a 5.0 stuffed in there.

Tried searching up but couldnt find a thread where someone actually completed the swap.

 

[Carguy3J]

This is a foolish idea. Yes, it can be done. But why?

If you are going to fix the SOHC motor anyway, just put it back in. The timing chains/guides are the only problems with these motors, and you have/will be fixing that.

Of course, with the mileage, you may want to do a full rebuild, while it is out. But that would apply to the OHV you take in trade as well; especially since you don't really know the history of that motor.

You will be very disappointed after doing that swap. The OHV has about 40-50 less horsepower then the SOHC.

Also, since your truck is a '99, and the OHV was no longer offered in the '99 Explorer, from the factory, then it would technically not be a legal swap, as you would "downgrading" to an older, higher emmisions configuration.

 

[99XLT-Explorer]

i want to do it for these reasons

i dont want to do a full rebuild because to do it right it requires alot of specials tools that i dont want to buy.

the design of this motor is idiotic and problem prone i dont want to deal with the problems it can create

i like the ohv its very durable and simple. i plan to slightly build it as well.

i got the heads off the sohc yesterday and i have interference of the exhaust valves on every piston of the driver side bank.
im going to pull the block asap and i have found a few ohvs just need to call about them.

ive heard about running these motors on the sohc computer but i would rather not because i want the cam position sensor to operate correctly and id like to keep it as bolt on as possible.

lets just say if i was to get a ohv computer and the vehicle i pull it from still has the key in it will i be able to use that key and lock cylinder and everything work appropriately?

 

[99XLT-Explorer]

i found a ohv with 116k on it going to run a comp test on it and make sure it checks out good.

whats the compression supposed to be on a ohv?

it have been sitting but i will pull injectors and valve covers and clean everything out make sure everything is good.

any tips?

im going to get the whole engine harness for it aswell.

 

[Dono]

I can't remember the compression on mine before rebuild. It was low though. I think if you see all cylinders within 10% of each other and about 140 lbs your doing good.

Did you get the computer, and figure something out for the pats (passive anti theft) system?

My 2000 XLS came with the 4.0 ohv from the factory. I will say that this is an easy motor to work on, but definitely not a stellar example of the latest and greatest of technology. I'm looking forward to your results.

 

[99XLT-Explorer]

got the computer the other day from a ohv catchword PPG1

i realize im basically going back in time but id rather have reliability than power.

if i have picked up info correctly the pats code is in the steering column transponder rather than the computer.

 

[Dono]

I havn't lived the pats thing myself, so I really can't comment.
Don't get me wrong, I like my 4.0 ohv due to it not being complex. Im not sure how well I'd deal with having to work on the sohc heads and getting those cam's timed.

 

[2000StreetRod]

keys are unique

The microchip on the key makes each key unique. The PCM must recognize the unique identifier or it will disable the fuel pump and the injectors. Since you will install the OHV PCM it will not recognize your existing keys. If you get the keys that were for the OHV PCM they will not fit your door or ignition locks. You could tape one of the OHV keys near the PATS receiver and use your existing keys. Otherwise you will have to tow your vehicle to the dealer or a qualified PATS locksmith to program the OHV PCM to "learn" your SOHC keys. It may even be more involved than that if you don't have all of the PATS related components from the OHV doner to match the OHV PCM. Call first before towing your vehicle. Many dealers and PATS qualified locksmiths will refuse to attempt what you need done.

 

[Carguy3J]

got the computer the other day from a ohv catchword PPG1

i realize im basically going back in time but id rather have reliability than power.

if i have picked up info correctly the pats code is in the steering column transponder rather than the computer.

The PATS code is not "in" the steering column. The only thing in the column is the transceiver which polls/receives information from the chip in the key. It relays this info to the GEM, which then decides if it will allow the edcm to permit the vehicle to start. The ecm and the GEM have to match (be from the same vehicle), or you have to take the whole vehicle (which won't run at that point, so it will have to be towed there) to a Ford dealer to reprogram. You also need a matching key, or you will have to have them program the GEM to your current keys.

I'm pretty sure the exhaust (manifolds, y-pipe, and cats) are different between the SOHC and OHV. You're really subjecting yourself to whole lot more work then you realize, only to gain absolutely nothing.

The SOHC is not an "idiotic" design. Its actually a very good design, with one minor problem. That problem is more of a materials issue, then a design flaw. The best thing to do is find a low mileage late model Mustang SOHC, swap your intake, etc... onto it, and put it in. Or, find a decent used Explorer SOHC motor, and while it is out, do both the front AND rear timing components, with the updated parts. It should be fairly easy to do, with the motor out. Once this is done, you shouldn't have any more timing problems for a long time; probably longer then you will have the vehicle.

On the other hand, the OHV has a weakness of its own; also in the valvetrain. It has poor top end oiling, and prematurely wears pushrods tips and rockers,leading to lots of slop. You're just trading one problem for another, with a huge loss of power/fuel economy as a "bonus".

 

[99XLT-Explorer]

got the computer the other day from a ohv catchword PPG1

i realize im basically going back in time but id rather have reliability than power.

if i have picked up info correctly the pats code is in the steering column transponder rather than the computer.

 

[Dono]

Truthfully, I'm going to agree with Carguy. He is right on all counts.
If you could find yourself a newer sohc motor at a wrecker, you would have reliability, and an easy swap.

I really thing that the pats transponder in the steering column is just a reader. You will need another module from the donor truck, and the keys from the donor. While your at it, you should take the door locks and steering column tumbler.

 

[masospaghetti]

2000 was the last year the OHV was offered in the Explorer, with the 5-speed manual only (edit: and apparently still with the automatic - thanks Dono!).

You're really subjecting yourself to whole lot more work then you realize, only to gain absolutely nothing.

The SOHC is not an "idiotic" design. Its actually a very good design, with one minor problem. That problem is more of a materials issue, then a design flaw.

I have to disagree, the SOHC engine is not a good design, it has way too many moving components for the benefits it provides. Most SOHC engines use a single belt or chain. This one uses 3 or 4 chains, one that is essentially unserviceable. Not to mention that the guides on the traction side of the chain are curved which means they are guaranteed to wear out.

Not that I disagree with your conclusion though since low-mileage SOHC engines are easy to find with better timing components, and it would surely be less work.

On the other hand, the OHV has a weakness of its own; also in the valvetrain. It has poor top end oiling, and prematurely wears pushrods tips and rockers,leading to lots of slop. You're just trading one problem for another, with a huge loss of power/fuel economy as a "bonus".

I've had 2 OHV motors, one with 172,000 miles and another with 235,000, neither has any noticable valvetrain noise. I don't think the oiling issue is much of an issue if you use good oil.

Also the fuel economy ratings from the EPA for the OHV engine were actually better than the SOHC.

 

[Dono]

hahaha...This is funny.

My 2000 XLS has a 4.0 OHV auto from factory. It was clearly the very last of the run.

I'd say everyone is right here. The SOHC is clearly a higher tech motor, but has its engineering issues with those chains.

The ohv does run for a very, very long time without having any valve train noise at all, and the repair is really very inexpensive to do (New rockers and push rods). Labour is no biggie either, just pop the valve covers.

In the end, the op has made the decision that he wants to install a ohv. Lets try to help him.