switch from LDT to LDS

[b money]

this has probly already been covered at one point, but i couldnt find anything, so... does anyone know a timeframe wen the gov. started putting the LDS in deuces instead of the LDT? for example would a truck that was built in the mid to late 80's(without a rebuild) have a better chance of haveing a LDS then say a early to mid 70's(rebuilt) truck?

 

[Ferroequinologist]

They never really started replacing the LDT with LDS. The LDS wound up in deuces because some mechanics wanted a faster ride, or someone wasn't paying attention when they ordered a new engine for a deuce, or it was what was laying around at the time. The LDS is a multi designed for the M39 series 5 ton trucks.

 

[b money]

Oh, I knew it was ment for the 5 ton, but I also thought they started replacing the ldt with the lds. So basically it's pure luck if you get a truck with an lds?

 

[Ferroequinologist]

Yep. pure luck. Pretty rare as things go to get one off GL with an LDS already.

 

[Flyingvan911]

Mine has an LDS. I do feel lucky. There are threads on the forum that cover it. Try "LDS swap" and similar phrases. I did a bunch of research before I decided I could reasonably own a deuce.

 

[ken]

Usally these engines went to some place like toole for rebuild. Since the engines use the exact same block the tag went with the engine. If you have a LDS in a 2 1/2 ton truck that doesen't mean you have a LDS. You have a block that was originally in a 5TON. Unless you installed it. And swapped the oil pan around. Then used the smaller bellhousing. Your first give away will be if your turbo has a wastegate on it or not. Really there are very few differences between the two. Like the turbo, fuel injectors, bell housing, piston cooling nozzles and what way the oil pan is installed. There will be different oil pick up tubes. Both engines will produce the same amout of power. The fuel rate setting determines this. The desirible engine is one that is stamped TD on the passengerside block above the alt.

 

[doghead]

so... does anyone know a timeframe wen the gov. started putting the LDS in deuces instead of the LDT?

Febuary 29th 1981

 

[Ferroequinologist]

at 2401 hours

 

[Flyingvan911]

Usally these engines went to some place like toole for rebuild. Since the engines use the exact same block the tag went with the engine. If you have a LDS in a 2 1/2 ton truck that doesen't mean you have a LDS. You have a block that was originally in a 5TON. Unless you installed it. And swapped the oil pan around. Then used the smaller bellhousing. Your first give away will be if your turbo has a wastegate on it or not. Really there are very few differences between the two. Like the turbo, fuel injectors, bell housing, piston cooling nozzles and what way the oil pan is installed. There will be different oil pick up tubes. Both engines will produce the same amout of power. The fuel rate setting determines this. The desirible engine is one that is stamped TD on the passengerside block above the alt.

I hadn't concidered that. My truck has a C turbo. I will look for the TD.

 

[gringeltaube]

.......... If you have a LDS in a 2 1/2 ton truck that doesen't mean you have a LDS. You have a block that was originally in a 5TON........

Can you please clarify this? What else could it be? Are you saying that they did rebuild/assemble 5ton engines to 2.5ton specs and accessories, if it was to replace LDTs?
Do you really think they took a LDS465-1A block, left the dataplate untouched but used all internals plus BH/FW/clutch/IP/turbo/oil pump from an LDT, for final assembly? While it is possible (technically speaking) it just doesn't make sense to me...

I say that there is a 99.9% probability that one really has what the dataplate shows, regarding the so called long-block, and that if it reads LDS465-1 or -1A you can expect that motor to be equipped and able to run all day long producing 175HP!

G.

 

[jasonjc]

They stoped useing the LDS long ago. But Still used the LDT. Why would they take a useable core and throw it away. The EPA made them stop making the LDT,so if they needed a new/rebuilt LDT why would they not use the LDS block. Look at the parts book most all the parts are the same. I have a LDT with a LDS pump and it anit no 175hp eng! The Army will remove/replace an eng for a bad water pump I've seen it done. As for the tag I have a M35A2 with a printed REO Motors manf. tag. Reo was long gone when the A2 came out so why a tag for them? And no its not a rebuilt. Thats just like a "D" may have a "C" turbo.

 

[gringeltaube]

...... I have a LDT with a LDS pump and it anit no 175hp eng!

Agreed and I even have a LD motor with the 5ton IP and head, although it was installed in a M109, not a fresh depot rebuilt.
But the other way around, has anyone ever had a "fake" LDS465-1A?

And there still is the root question: if internals are all the same, what makes a "true" 5ton LDS cappable of delivering 50 more horses, continuous?

G.

 

[ken]

When they switched to the 800's for the 5tons they then had LDS engines with no home. So they rebuilt and re used them in 2 1/2 tons. I have also opened a egnine can and found a tag on a sopposed LDS that read. "this engine has 2 1/2 pistons installed. " And as far as the 50 More horse power. It's a simple fuel rate setting.

 

[jarhead1086]

I remember reading another post I could not find again on this topic that had more details and discussion. All the different parts between the two were identified and most were ruled out as being the culprit of the 50 extra horses. I am hopeful that Ken is right and it is simply fuel adjustment. Has anyone measured and tuned their injector flow on an LDT to match LDS requirements to see the effects? Knowing nothing about diesels and a little about military maintenance I could see being bound by the maintenance manuals and not turning up the fuel past the requirement. I always had somebody telling me not to do something without giving reason and I usually listened because to do otherwise was painful.

 

[tm america]

I think they just threw whatever parts they had in front of them at the time and threw it in the truck that was there.......My truck had a td block tagged at a ldt-1c but has a lds427 turbo and injection pump and the motor i have sitting on the ground has a ldt-1d td block with a c turbo .both trucks were rebuilt by the gov in '92..Some say lds and have c turbos and ldt heads..unless your truck has a waste gate turbo and lds injection pump i wouldnt get your hopes up about power ratings . i believe they used the parts and spec'd them to the ldt that was in there so count on lowered fuel rates .cuz the air filter wouldnt keep up and motor would be junk by now

 

[ranchhopper]

LDS has a much bigger turbo its a dead give away unless it has a deuce turbo D or C you can bet that bigger turbo is pushing out more HP than a standard LDT.

 

[jollyroger]

To answer the question originally posted I don't think there is a start and end date when you could expect to see a certain engine in a certain year truck. If you are able to find a truck with an LDS good for you.

I know that some National Guard units got tired of the 2.5's not keeping pace with the 800 series 5 tons and replaced the LDT's with the LDS. I am sure this happened in the Army as well. So The LDS replacement would be random and no easy way to know without checking every truck you come across.

What I do know are the differences between the two engines. LDS has 5 piston rings instead of 4 for the LDT. There are "improved" oil nozzles for the LDS. The turbo is bigger producing more boost and has a wastegate. Fuel rates are different. LDS has a gear driven pump for power steering.

Hope this helps.

 

[wsucougarx]

Hmm, wonder if Doyle would be able to answer this one

 

[Flyingvan911]

I just got my deuce from Fort Riley. A friend (and deuce guru) helped with the recovery. My deuce has a LDS-465-1A with a C turbo. He said it is the real deal because mine is a rocket and wants to jump up to past 60 MPH. He says it's louder than the LDT and accelerates alot better. I have to watch it so I don't let it wander over 55 and 2,450-2,500 rpm. It is nice to have the extra power when I get into a tight situation. The turbo does scream like a Banshee. It likes to run about 160 degrees.

 

[jwaller]

I just got my deuce from Fort Riley. A friend (and deuce guru) helped with the recovery. My deuce has a LDS-465-1A with a C turbo. He said it is the real deal because mine is a rocket and wants to jump up to past 60 MPH. He says it's louder than the LDT and accelerates alot better. I have to watch it so I don't let it wander over 55 and 2,450-2,500 rpm. It is nice to have the extra power when I get into a tight situation. The turbo does scream like a Banshee. It likes to run about 160 degrees.

MPH has nothing to due with what engine you have.

If you are going 60+mph in your deuce then you are turning too many rpm's.

Loud turbo means you prob have a C turbo and it's very very loud even at idle.

160deg is too cold. You should put a cover on the rad to get it up to proper temperature. low temps can cause the pistons not to seal properly in the cyl causing very fast wear of the cyl walls.