OHV to SOHC swap?

[csnider14]

Ok so my 99 OHV is toast, so im considering swapping in a SOHC 4.0, What are you guy's thoughts on this? What all would need to be changed? and also will it work with the transmission i have? Thanks in advance!

 

[koda2000]

Ok so my 99 OHV is toast, so im considering swapping in a SOHC 4.0, What are you guy's thoughts on this? What all would need to be changed? and also will it work with the transmission i have? Thanks in advance!

imo, this is too much work. all the engine related electrical wiring would have to be changed and the pcm. i think the trans would be fine. besides the SOHC engine is a POS. if it were me i'd just put in another OHV. the only benefit to the SOHC is more HP, but the timing chain problems aren't worth it.

 

[delexploder]

imo, this is too much work. all the engine related electrical wiring would have to be changed and the pcm. i think the trans would be fine. besides the SOHC engine is a POS. if it were me i'd just put in another OHV. the only benefit to the SOHC is more HP, but the timing chain problems aren't worth it.

Lol koda hates the sohc, if you get the same year with its motor harness it should work fine, there are a few on here running like this, if you do it just be sure to replace all the timing parts, and it should be fine for a long time, I was happy with mine and they make great power and get better MPG than an ohv in the same truck,

 

[csnider14]

yeah i plan on replacing the chain and all timing parts, as well as all the sensors. i just could use the extra power and the MPGs never hurt anyone. I just wanted to make sure i could do it with a long block cause i dont have the dough for a new tranny as well. From what i can see the crowd is 50/50 between the OHV and the SOHC

 

[lobo411]

yeah i plan on replacing the chain and all timing parts, as well as all the sensors. i just could use the extra power and the MPGs never hurt anyone. I just wanted to make sure i could do it with a long block cause i dont have the dough for a new tranny as well. From what i can see the crowd is 50/50 between the OHV and the SOHC

The OHV is bulletproof. The SOHC is a time bomb.

 

[delexploder]

Mine had over 260,000 and still ran strong when i pulled it for my v8 swap, now it was noisy but when we pulled it apart it was all still within spec so my buddy who needed a sohc replaced all the timing parts and swaped the externals and it is now in a 02 explorer and running better than ever,

 

[csnider14]

so im sure i would need the SOHC wiring harness and computer right?

 

[koda2000]

so im sure i would need the SOHC wiring harness and computer right?

yes. and i would definitely do the timing chains kit (aka M0012), water pump, and front/rear crank seals, oil pan and u/l intake manifold gaskets and thermostat before installing it. at least that way you stand a good chance of ending up with a reliable engine.

one thing i don't know about is the connection from the exhaust manifolds to the head pipes. is it the same for the OHV and SOHC?

 

[delexploder]

yes. and i would definitely do the timing chains kit (aka M0012), water pump, and front/rear crank seals, oil pan and u/l intake manifold gaskets and thermostat before installing it. at least that way you stand a good chance of ending up with a reliable engine.

one thing i don't know about is the connection from the exhaust manifolds to the head pipes. is it the same for the OHV and SOHC?

No, grab the manifolds and the y pipe / cats , just in case cause they had a few different setups for the sohc

 

[csnider14]

yeah good point. I may just grab a full exhaust from the junkyard off of an E VIN

 

[2000StreetRod]

what year engine?

What year SOHC engine are you planning to install? As I recall there were differences in the type of sensor used for the camshaft position. Some of the synchronizers used reluctors and some used hall effect. Do you plan to use the stock OHV PCM or the PCM for the SOHC? Transmission shift points, ignition timing and WOT air/fuel ratios may be different. If you swap PCMs then there's PATS issues to deal with.

 

[csnider14]

What year SOHC engine are you planning to install? As I recall there were differences in the type of sensor used for the camshaft position. Some of the synchronizers used reluctors and some used hall effect. Do you plan to use the stock OHV PCM or the PCM for the SOHC? Transmission shift points, ignition timing and WOT air/fuel ratios may be different. If you swap PCMs then there's PATS issues to deal with.

well im hoping to find a 99 SOHC and swap out the Harness and pcm since my truck is also a 99. Do you think i will still run into problems here?

 

[2000StreetRod]

issues

If you install the 1999 engine, engine harness and PCM then your sensors, wiring and PCM will all be compatible with each other. However, your new PCM will not be compatible with the other stock PATS components (keys, anti-theft transceiver module and possibly remote anti-theft personality module). I'm not very familiar with PATS so you should determine what modules are required from the donor. Getting the ignition keys and cylinder lock may save you a tow to the dealer for reprogramming.

I think most of the swaps that have been done are either prior to PATS or the stock PCM was retained with a minor sacrifice of optimum performance.

The exhaust configuration may also be different (series cats vs parallel cats). I suggest that you determine all of the work and costs before starting the project. It may not be worth a gain of 50 hp. Do you have another vehicle to drive while the swap is in progress?

 

[csnider14]

If you install the 1999 engine, engine harness and PCM then your sensors, wiring and PCM will all be compatible with each other. However, your new PCM will not be compatible with the other stock PATS components (keys, anti-theft transceiver module and possibly remote anti-theft personality module). I'm not very familiar with PATS so you should determine what modules are required from the donor. Getting the ignition keys and cylinder lock may save you a tow to the dealer for reprogramming.

I think most of the swaps that have been done are either prior to PATS or the stock PCM was retained with a minor sacrifice of optimum performance.

The exhaust configuration may also be different (series cats vs parallel cats). I suggest that you determine all of the work and costs before starting the project. It may not be worth a gain of 50 hp. Do you have another vehicle to drive while the swap is in progress?

Yeah i have another car to drive in the meantime. I put 31s on the truck a while back and it was just really sluggish. just makes me think the SOHC would be better but it does sound like a job. looks like i have some thinking to do lol :roll:

 

[koda2000]

Yeah i have another car to drive in the meantime. I put 31s on the truck a while back and it was just really sluggish. just makes me think the SOHC would be better but it does sound like a job. looks like i have some thinking to do lol :roll:

what gear ratios are your diffs? 4:10's would give you quicker acceleration than say 3:73's.

 

[csnider14]

Everything is still stock so i think 3:73's im not worried about acceleration and power as much as fuel mileage.

 

[BubbaFL]

The OHV is bulletproof. The SOHC is a time bomb.

I used to think the 4.0 SOHC was a piece of ****... then I had to rebuild the 3.8L OHV engine in my wife's Windstar... makes a SOHC timing job look like a breeze.

To the OP - it's probably not worth the hassle of doing that swap on a 14 year old truck. If everything else on it is stock, I'd fix it, sell it, and buy a SOHC or V8 (or maybe just scrap it).

 

[2000StreetRod]

engine swap justification

. . .To the OP - it's probably not worth the hassle of doing that swap on a 14 year old truck. If everything else on it is stock, I'd fix it, sell it, and buy a SOHC or V8 (or maybe just scrap it).

I agree. To me, unless there has been a significant investment already made in an Explorer, an engine upgrade swap is not justified if the upgrade configuration was a manufactured option. Examples of justified upgrades: 5.0L V8 in a 2 door Sport, 5.8L or 347 V8 in any 2 or 4 door model.