Looks like I need to replace my HO/6spd motor or have teh bottom end overhauled. I've found a low mile used unit but its hooked to an auto so I'm guessing its an SO motor.

If I swap it in and use my injectors/electronics will that make it an "HO" or is there something different internally? Thanks!

 

The biggest difference between the HO and SO (other than programming) is the HO has piston coolers. This is for the 3rd gen, not sure on the 2nd.

MikeyB

 

More info needed. You're posting in the 3rd gen section and your sig is the only indication of what vehicle you're talking about. Manual or Auto doesn't have effect whether it's SO or HO. Find out the H.P. rating on the ID tag on the engine. Depending on what it says or what year the truck is, will determine what setup it is.

 

piston bowls are different also from SO to HO.

 

I have an '03/6spd with a bottom end knock and can pick up a low mile '03/auto engine. I thought all 6spd in the 3rdgens got the HO and most of the autos got the SO with the HO as an option.....

I'll ask the guy to check the tag but if it is an SO I'll be losing the piston coolers... hmm kinda would like those.....

 

I don't know that the lack of piston coolers has ever caused a failure or more excessive piston wear on the SO engines (in theory yes, but in practice??). Just throw a mild chip on it and it'll be every bit as good as the HO.

Of course, you may lose a little re-sale value on the SO, but on the other hand- you can use that to beat the guy you're buying the engine from down on price.

 

I ordered an early 03, and at that time if you wanted an auto you would have gotten the 47RE and SO.

A few months later, though, the 48RE was released, so you could have an 03 with HO and 48RE...

 

Check the build date on the engine before worrying too much. After December 02 all the autos were 48RE and the motor was the same as the HO except for minor differences in the piston bowls.

ALL Cummins engines have piston coolers. The only difference is the implementation of the coolers. Some of the very early MY03 still had the same coolers as the previous years but that was changed to the gallery cooled pistons in late 02.

I foyu ar enot looking for big power and full emissions compliancy don't sweat the piston cooler differences.

 

Ok so I picked up that engine and will be installing it in the next couple of days.

What should I keep from my engine? I figure I'll swap over the computer on the side of the block, looks pretty simple. What about the CP3? Any point in swapping that? Turbo, are they same from an SO automatic to an HO 6spd? How about injectors? My HO injectors have a set of Jammer nozzles on them, I've been told I cann't use HO injectors in an SO engine because the combustion chambers are different and it will cause problems. Can I swap the Jammer nozzles from my HO injectors to the SO injector bodies?

Also whats with the cam o-ring at the back of the engine? The guy gave me an o-ring for it when I picked up the engine. Guess I better look it up in my manual.


This is on an '03 BTW.

 

Turbos have the same numbers on them so it looks like they are the same....

 

Ok its installed and running! Ended up reusing my HO turbo and ECM. The turbo that came with the SO was leaking oil and the truck would not run with the SO ECM. The ECM on the truck is programmed to the ECM on the motor. Using the SO ECM caused the security system to shut the truck down 2 seconds after starting.

I also had to use the original HO wifing harness. My truck is a late '03 build and the donor SO truck was a late '02 build. Still CR though but the APPS was mounted above the injection pump just like on my '01 wheres the APPS on my '03 truck was under the driver's side battery. This required using the orginal HO wiring harness.

As well since the donor SO motor was from an auotmatic and my truck is a 6spd the original cooling tubes from the HP motor had to be used and fitting from the driver's side of the block had to be removed and plugged. I imagine the extra ports were for the block mounted tranny cooler.

Everthing else bolted right up. Didn't open it up except the pan but I forgot to check to see what it had for cooling nozzles. Power is definatly down for before. Was surprised at that as I'm using the HO computer. Could be cause I havn't swapped in the jammer nozzles from the HO head yet.

 

Thanks for the update, good info!

(hope I never need it though )

 

Do the 3rd gen HOs and SOs have different compression ratios like the 2nd gens?

 

From looking at the service manual, I don't think so.