Multifuel engine life

ken said:

Bjorn, Can you take some close up pics of that turbo? And mabye of the tag too?

Click to expand...

A bit hard to get to, but I'll give it a better try another time. The turbine looks smaller than the "C" on a deuce, but is offset and the compressor is larger....

when you get the m998 back with the new engine ask them to do the same test.............

Thanks bjorn. The compresor looks the same as the one on my LDS. I haven't seen one on a multi with the exaust gas casing like that.
My m35 has 53K in the ticker now. I got it with 13K. I change the oil every 2K or 6 months weather it needs it or not. I rarely run it over 2200 RPM's. I know it's rated for contuis duty at 2600 and WOT. But i just can't seem to bring myself to run a engine that close to redline for very long. It spends alot of time running 1500 RPM's to run air tools in the woods. With regular and often oil changes these engines will run alot of hours. Mabye i should do a valve clearence adjustment soon? Anybody know how many engine hours between valve adjustments? Mabye this will help with it's life?

My multi has about 1,200 hours on it. I don't run it really hard and change the oil every year which is about 100 hours. What's the biggest killer to this engine and do you think I still have alot of life left in mine even though it's so old. I see no rebuild tag on it and it's a '68. I am pretty sure the engine has been replaced at some point but never rebuilt. I hear a hell of a knocking rattle at start until oil pressure builds sometimes. I feel like I'm losing bearing material each time I hear each knock. Also, do yall think it's worth sending in an oil sample to a lab like Blackstone on a year old oil change with 100 hours on it? I bet it's 25% fuel, it seems super thin. I idle my truck alot for the turbo and I get it wet sacks alot.

-Kelly

-Kelly

Got it back 15 years ago. It didn't even make it back across base befor parts started to fall off. The same guy also did a service on my platoons M35a2. We (2 of us)had to go help it seems most of the hard stuff was driver level Like rotating all 11 tires. And no air tools And we had to clean up there shop Boy I whish we could have made the pilots do some work. The motor pool guy went to start the M35 so as to sweep under it, But he had the fuel filters off. Big mess fuel evey ware. Lotts of floor dry. got most of it up when he did it a secound time to clean up the mess from the frist time He must be an officer by now

Ken, the attachement to the exhaust is the crankcase breather termination, part of the under water running feature.

Before I bought my Deuce I called an old Vietnam Vet friend that spent time in a motor pool with the 101st. I wanted his opinion before taking the leap.

He said they changed engines in M37s like changing sox but considering how the Dueces were treated they were bullet proof. He said the average operator slammed his hand in the door (got mad at it) before starting the engine and then drove the holy heck out of it with absolutely "no slack". He also said maintenance was almost non-existant.

Peventative maintenance takes a back seat with rockets start sizzling-in.

I personally think some long overdue common sence TLC driving habits along with improved oil filtration and a pre-lube system will go a long way towards making the multi imortal.

I'm not sold on a pre-lube yet...i think the spin-ons and an oil-bypass will suffice...but then again, when i get that work done...i can share a more informed opinion.

The quailty of motor oils we have today is lightyears from what they had in the 1960's. I would think wear would be greatly reduced.

the deuce motor is not rated for any use at 2650 except brief moments when you need max power and have your fingers crossed. 2300 rpm is really pushing it hard. this is why the data plate gives max speed. in the 5 ton they went way beyond reason and set high idle at 2800, it is no wonder many failed at low hours.

The data plate says 56MPH in 5th.. I assume that is 2650RPM or so, is it correct? I usually turn 2500 on the highway. I wish there were more detailed documentation on the RPM issue such as TM or factory docs or equivalent. Maybe I have not read enough. I certainly do not knwo enough about diesel engines to argue the point.

I've spent about 30 hours at 2500rpm by now....

m-35tom said:

the deuce motor is not rated for any use at 2650 except brief moments when you need max power and have your fingers crossed. 2300 rpm is really pushing it hard. this is why the data plate gives max speed. in the 5 ton they went way beyond reason and set high idle at 2800, it is no wonder many failed at low hours.

Click to expand...

Any references for this Tom?

According to my experiences, I have no reason to think that the TM maximums are for short time use only. Commercial engines may be rated much higher in output, but only for short intervals, the Multifuel has no such de-rating and can run forever and a day at maximum output. That's why the seemingly low hp rating of 140 or so. Commercially it may be rated at 200, but then only for short periods of time. That's my uderstanding and phone calls in the past to Hercules have backed it up. Its rating is "continuous".

My heaviest use of the truck was during the cross country trip last year when I hauled the 9,000 lb trailer to Nevada and run it daily at high rpms including in low gear pulling some 27,000 lb up and over the Rocky Mountains. The engine never complained. Burned over 300 gallons of veggie oil and biodiesel on the trip as well.
The image below shows the rig at the beginning of the trip. The dolly was off-loaded in Arkansas at Jason's.
I did have an undetermined problem with the IP, which was cured with the replacement of the hydraulic head in Joplin MO with a lot of help from the people of this forum, btw.
Coming back from Oklahoma, the truck hauled the 16,000 lb xm757 with other cargo totalling 37,000 lb. The hills along I-40 in Tennessee are something else!
I did have a problem with the FDC, which started to leak fuel into the engine oil on the haul from OK (based on the rate of leakage, measured later), accelerating a "knock" from the engine.

IMHO, the greatest danger to the engine is overrevving it when engine braking on long downhill runs.
The exhaust brake on my truck was a source of comfort to say the least coming down from Nevada into California. The engine was never overrevved and it never overheated, although I did remove the radiator cover for parts of trip, hauling the xm757 among other.

For diesel engine ratings go here and see where your engine fits in:
www.cat.com/cda/files/88766/7/LECW2462-07.pdf

I understand that max power may not be developed at max rpm, but thought that the rating thing could be interesting to add to the mix.

I have no technical information to add to this but I'm one of those crazys that run the truck 55 all day long and do the occasiona 60 MPH blast to pass something. No problems ever.

It is a strange feeling to pass anything other than a refueling depot in a Deuce

Every so often it happens!

TM9-2320-361-10 page 1-17

[Vehicles- All] ... With Maximum Payload and Towed Load - 45mph, With maximum Payload only - 56MPH

the greatest danger to the engine is over-revving it

Click to expand...

Connecting rod stress increases exponentially with RPM's. The reversal at TDC is hard on rods, and rod bolts. They're in tension where metal is weakest. Handling power is easier as the rods are very strong in compression.

For the LDS465-1 w/two hole nozzles (from the chart, page viii, LDS troubleshooting manual, in resources):

Best fuel economy - 2000rpm (increases dramatically above 2400rpm)
Best Torque - 1800rpm (torque down only 1% at 2000rpm, maybe down 10% at 2400rpm)
Least smoke - 2400rpm to 2600rpm (couldn't care less)
Best HP - 2600rpm (though only 4hp more than 2400, maybe 13 more than 2000rpm)

So, what's best? U decide. But-
High engine speeds increase ring wear (also exponentially)
Moderate engine speeds are better for loaded bearings than low rpms.
Cold starts, warm-up, stop and go is harder than an expressway.
A well maintained engine can stand up to severe duty better.
Running 2600rmp w/no load (M/T, flat land...) is not constant WOT. It is less stressful than, say, a long grade w/10Tons.JimK

Has anyone had a multifuel fail because of ring wear? From what I've read or seen broken rods/low oil pressure/worn bearings causes a mulitfuel to fail. Anyone had a rod fail without warning(no knock, no drop in oil pressure)?

Dennis

Has anyone had a multifuel fail because of ring wear?

Click to expand...

wear tends to be progressive

Ths was emailed to me by one of the Steelsoldiers members the last time engine life was discussed:

Hi Jason,

I tought to use the PM as a lot of guys don't want to hear what I say about their revered multifuel motor.

Let me start with the history of it. MAN in Germany designed it many years ago in response to ideas of using any petro fuel without regard. The original engine was licensed by Hercules back in the 60's, and production of the Hypercycle LDS427 was fielded to the military.

The criteria was it HAD to fit in the footprint of the old Reo Gold Comet 331 gas 6. Keep in mind the Comet was a legendary, proven powerplant taken from Reo's successful line of road trucks. It was at the top of the curve in smaller displacement truck engines back then. TACOM tried a lot of different off-the-shelf engines with varied results.

At the same time, the 5-ton line went from the Continental R6602 (602CI) gas six to the Mack ENDT-673 turbodiesel. It was very successful, but very expensive on acquisition.

Nonetheless, the multifuel was pushed by pork barrel money with lots of hype rather than objective testing. It did fit the M35 with little modification. BTW, the first model had a turbo that actually made boost.

The truck was successful, but poor habits led to turbo failures and the military went back to Herc for a fix. It led to the naturally aspirated 478CI LD-465. This is where I believe the design was fritzed, as all the 465 series had the habit of tossing pushrods and tossing 3&4 rods without warning.

Another note to ponder: all mechanically injected Diesels will run on jet fuel, kerosene, burner oil, and a host of other petro fuels with no big deal. If the fuel pump is equipped with hardened parts, it will run without galling the injector plungers on regular gas in a pinch. The only difference on the Hypercycle is the little pre-combustion chamber the injectors squirts into so as to get things burning completely before flowing into the cylinder. Sort of a compression wasting device if you just run it on Diesel. The multifuel went through many revisions, from the 427 to the last, the LDT-465-2 in the Ford M656 5-ton. Different head gaskets, different pistons, different cooling nozzles for the pistons, different timing, injectors, turbos, gaskets. All were tried chasing the elusive longevity found in other engines, never to be had.

As I noted, I witnessed a LOT of these engines with a common failure on the bottom end. Also find that the engine was unsuccessfully marketed for years commercially. Nobody bought them for reasons industrial or vehicular. Given the choice of better proven designs I don't blame them.

I brought up the DT466 as it is a smaller engine than most, and being SAE spec, the rear mountings and housing are the same as the multifuel. It would fit within the limited real estate of the G742. A Cummins 5.9 would be a good choice as well, with the turned up version easily surpassing the best multifuel. Not cheap, but it all depends on whether you want to have it driving reliably a long time or keep it original and be married to rebuilding the engine on a regular basis.

SAE designs are such that no matter who makes it, parts will fit together with little hassle. I.E., any SAE #3 sized bellhousing will accept any #3 transmission. Within the series, the mounting holes and such will be the same as well. A #4 is little, a #1 is large in the scheme of things.

I hope this helps and answers some questions for you.