LDS vs LDT

[Tototex]

Alright, I threw a rod in my M51a2. New motor time!

I live in Newport, WA. So any local help is greatly appreciated. I am no mechanic. I will be be swapping the engines myself based on information here and what I can find on youtube. I decided to stick with the LDS or LDT to keep the truck more original as well as to keep it simple. Converting to a better motor like a Cummins sounds more complex than I want to get into.

I have found a local LDT motor for $500, it comes with no attachments.

I have found a local LDS with attachments (turbo, etc) for $900.

So here are my questions.

1.) Does the make of the engine matter? I know mine was a Jeep-Kaiser and the new LDS is Continental.

2.) Would the LDT have compariable power to the LDS? I was told that using the fuel injector from the original LDS motor would restore most of the power since it is a dual injector and the LDT normally uses a single. I do want to use the truck for some gravel loads and I do live on a steep hill.

All advice and useful information is greatly appreciated.

 

[porkysplace]

Go with the LDS.

 

[theeDIZ]

The manufactures all built the same motor parts are interchangeable , I'd stick with the lds if it where me

 

[red]

Lds

 

[Flyingvan911]

I misread it at first. I thought you said M151A2. He, he.

 

[gimpyrobb]

Id use whichever motor has the TD casting on the block above where the alt goes. You should have all the parts you need from your old motor to make a good runner. If they both have the TD cast in the block, save yourself time and get the more complete motor.

PM headed your way.

 

[jonesal]

What would really be useful is adding some information as to WHY an LDS. I'm don't think saying so without reasons is helpful to the OP.

Al Jones

(I thought it originally said M151 too - heh heh)

 

[gimpyrobb]

LDT=130hp

LDS=170hp

 

[simp5782]

DT466 or 6.9/7.3L International IDI (fits right in and there is an SAE 2 bellhousing adapter available) Just my

 

[tommys2patrick]

I thought those 5 ton trucks in the 800 series came with an LDS rather than the LDT. That was throwing me a bit. I know the LDS makes a bit more HP than LDT and a few other differences. Can you provide any background as to the motor that was in it originally and perhaps how it came to have a rod thrown. Under heavy load? climbing a hill at high rpm? oil loss? Sounds like you may want to work the dump as it was originally intended. Hats off, its a nice truck by the way. Not sure the manufacturer of the engine is as important as to its condition. Several companies made these engines under contract to Uncle Sam. I know some folks have a preference of one manufacturer over another but it seems more subjective than objective to me.

 

[clinto]

I thought those 5 ton trucks in the 800 series came with an LDS rather than the LDT.

M39 series 5 ton = LDS
M809 series 5 ton = NHC250 Cummins

 

[Tototex]

DT466 or 6.9/7.3L International IDI (fits right in and there is an SAE 2 bellhousing adapter available) Just my

A lot of people are recommending different engines as the multifuels dont appear to be to reliable.

To be honest, I like both the idea of keeping her original, and giving her a nice upgrade.

As I said, I am no mechanic. I do think I can take out an engine, and put the exact same engine back in. But when it comes to fitting a different engine back in, I imagine you need some knowledge of mechanics that I do not possess. This isn't something I would do without help, which I currently do not have

Maybe when the next engine goes, I'll slap in a Cummins or International.

 

[Tototex]

I thought those 5 ton trucks in the 800 series came with an LDS rather than the LDT. That was throwing me a bit. I know the LDS makes a bit more HP than LDT and a few other differences. Can you provide any background as to the motor that was in it originally and perhaps how it came to have a rod thrown. Under heavy load? climbing a hill at high rpm? oil loss? Sounds like you may want to work the dump as it was originally intended. Hats off, its a nice truck by the way. Not sure the manufacturer of the engine is as important as to its condition. Several companies made these engines under contract to Uncle Sam. I know some folks have a preference of one manufacturer over another but it seems more subjective than objective to me.

This truck did come with the LDS.

I bought this truck from a used car dealership that picked it up in auction. One of the oil filters was spewing out oil and they were driving it around anyway. When I changed the oil on the lot, only 2 gallons came out along with some fingernail sized chunks of metal. I test drove it around the lot and the engine was obviously lacking power. I jumped on the hwy and got up to 45mph in 5th gear before the rod threw out. It took a solid 2-3 miles to get up to that speed.

Maybe that was pushing it for such an old truck but I think the something in the engine was damaged when I got it.

 

[tommys2patrick]

Thanks Clinto. That helps. So its clear from the photo in the OP's avatar that its an M51 model of the M39 series truck. So it would have come with the LDS engine. However, as it was fairly closely related to the venerable deuce is it possible some had the LDT? Seems like they would have been under-powered for a 5 ton truck chassis. I suppose they might have been even with the LDS? any thoughts?

 

[Tototex]

Thanks Clinto. That helps. So its clear from the photo in the OP's avatar that its an M51 model of the M39 series truck. So it would have come with the LDS engine. However, as it was fairly closely related to the venerable deuce is it possible some had the LDT? Seems like they would have been under-powered for a 5 ton truck chassis. I suppose they might have been even with the LDS? any thoughts?

I haven't been around long, but I have put a ton of research into these trucks. I have not yet heard of a 5 ton truck that came with an LDT. There are plenty of people that have added LDTs later though when an engine replacement came about.

 

[Tototex]

Welp, the local LDS just sold out from under me. It was a thick deck as well.

The next LDS I found is in Western Washington and the guy wants $1200 for it plus my old engine. Not to mention that is 10 hours, round trip for me.

Price is climbing!

I have heard several people say now that the LDT will put out the same HP as the LDS as long as I use the attachments from the LDS. At least two guys mentioned that the LDT used a single oil inlet(Can't remember the exact name) where the LDS uses a double. This double part can be used on the LDT and puts the engines on more equal ground. Any input on this guys?

 

[tommys2patrick]

I seem to recall reading something about in the time of war etc etc, that the mechanics would do what they had to do to get the fleet rolling. even if that meant replacing a bad LDS with a LDT in the field. Probably not very common though. At least the engines are close enough to each other that they would work in the same engine space. Anywho, I think your idea of keeping it the same as what it came with would be good. While upgrading the engine to something else bigger or more powerful has some merit, it will also mean a lot of other mods will be required. those are the ones that become time consuming and expensive in my opinion. The price of $1200, while a lot, it would probably be a lot more if you can find one from a vendor and add shipping. Best of luck and want to hear more of your project.

 

[gungearz]

LTD and the LDS is the same motor... swap out the injection pump and time the ip correctly.... vwala.. got yourself a cheap hi-po trick... eagle4g63 did the swap... the multi in that deuce ran like a rapped ape.... the TD on the right side of the motor means tall deck which excepts the newer style head gaskets...
Hope this helps...

 

[tommys2patrick]

Just from outward appearances, it would seem more is different than just the IP. For instance, the air intake. It likely pumped more air and needed a larger filter so that may be why it was moved out to the fender. Not an expert, by any means, but as a nuts and bolts matter, a few other things must be different.

I know opinions vary, but to me, for an engine from the late sixties early seventies, to be able to walk out to it after it has been setting for months or years, put some power to it and hit the starter, then see her fire up without the slightest complaint says a lot. I think the multifuel is an amazing engine.

 

[tommys2patrick]

I also seem to recall someone mentioning that the piston lubrication is different in the LDT versus the LDS. With the higher HP in the LDT, keeping things lubed and cooled is likely a high priority. Sounds like you are doing some fairly thorough research on these options. Kudos