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This is a common misconception. Yes, most all DD do use exhaust valves, but not this early model. Look carefully; there are four rocker arms. They are connected to the fuel injectors. Additionally, in the running video, I zoom in to the exhaust manifold where you can clearly see the flames coming through the cylinder wall ports. It's a full loop scavenge system.

@@kendallmarquardt9583 learned something new today. Never knew Detroit made the 2-51 and 4-51 totally valveless for a very short period of time prior to the 60s. Interesting. Quite a special little mill ya got there. Was pretty hard to see for whatever reason the video is fairly blurry on my end. Had to look it up

@@DanWoelders-fd5zd yeah the video is quite old; camera was good back then but not comparable to today. It was fun, but I had to sell before I could do anything else with it! Thanks for the feedback!

I'm not sure, actually. I could reach out to the place the work was done and see.

@@kendallmarquardt9583upon closer inspection it looks like the front wheels are turning. They’d have to pull the fuse for XDrive otherwise.

Hey, sorry I don't have any resources for injector service

Just send them in to any diesel injector shop. There a normal unit injector many places still rebuild them there’s nothing really special about them

I have some turbo injectors off a low hour 6v53t they are freed up and had clean diesel in them engine just had water in it so it rusted the cylinders very bad

Mods were JR Automotive RaceTune 2 (mild) full delete with AAR Racepipe and catalytic converter Buzzken Exhaust to stock muffler; turbos were replaced with rebuilt (buy AARODRIGUEZ) which were factory size.

lmao ... they were made without valves and do run

This early design of the DD is similar to loop scavanging common in gas two cycle engines. But DD had to add the roots blower to get enough air moving to facilitate starting. Even with the improvement in design incorporating exhaust valves they were still hard starters.

So you’re completely unaware of how a 2 stroke works apparently. Go look at any 2 stroke dirt bike or quad engines. Zero valves.

Any sighting of parts, or rebuild tips?

My other video on this engine shows the rocker cover off, clearly viewing one rocker per cylinder, which is the injector. This design proved ineffective, thus later models had valves added. Close observation of the engine running in the video one can see the exhaust ports in action. This engine is often misinterpreted as you describe.

Wrong. It’s a 4-51. They were only produced for 10 years, they were made obsolete by the 53 series

@@kendallmarquardt9583 my appoliges i have been schooled i have been working on and still run Detroit diesels for about 38 years now and i have never herd of the 51 series engines . i am now very interested in these engines and am trying to find information on them . again my apoliges .

@@TugboatMatt my apoliges i was wrong and have learned something new . what were the 51 series found in and how many cylinders were offered .

@@crankycrow7371 this engine came from a Road grader. I came across an excellent article with more info but can’t find and will have to re-dig. I believe it said that the 51 was for the year production started and actual displacement was 53 ci per cylinder. Production ceased in ‘59 as I recall. No worries, it’s a common misconception because everyone is used to the DDs with exhaust valves. I didn’t realize how rare it was when I owned it. I’ll link the article…..when I find it again.

Hello! I cannot comment on what you could do in Cali. I recommend you contact Andrew at tunemyeuro.com which is where I got my supplies and had work done on my car. I was not subject to testing.

its already supercharged, recirculation like that wouldnt work from my understanding

Hello, I do not know that information- sorry

Hello! Sorry you caught me in the middle of moving. I’ve lots of information, photos and experiences I can share. I’m slow on posting to the channel, but if you want to PM me, email or whatever your communication of choice is, I’m happy to fill you in on all I’ve learned over four years and 100k miles. A couple sources for parts and service as well.

Hello; I can’t make the translation work for your comment/question. Please send it in English thanks.

At some point the other engine systems for intake and exhaust, will have issues to be fixed. It’s just a fact with diesel tech nowadays and you will have to decide what to do about it. Those problems forced me to research and consider the options. I went into the car purchase knowing the issues, and to me it was worth it. In my mind, a brain (chip) upgrade while may afford some performance improvement, it’s a part of the puzzle. You won’t realize the amazing potential that lies in this engine without dealing with the other things.

Exactly! You see a lot of guys out there trying to cold start diesels with the throttle in idle position. You should put the throttle in max setting while starting and as soon as it catches release the throttle.

A Detroit Diesel whatever series starts in full fuel even when the throttle is in the idle position. When the engine turns over and starts, the flyweights in the governor fly outward and slow the speed down to where the throttle lever is at when it starts. It’s best in cold weather to hold the stop lever and crank the engine over a bit and then let the stop lever go, doing that creates heat in the cylinders first then letting the stop go let’s fuel to be injected into a warm cylinder, resulting in a faster start. If you don’t do this your injecting maximum cold fuel into a cold cylinder. A lot of people in cold weather use either on a hard starting engines and only make things worse because they spray too much in the intake and ends up breaking the top rings when whatever cylinder fires first.

@@harryward1608 That makes sense now that I think about it. I am most familiar with Macks, which were externally injected and you had to hold the throttle down to get full fuel. Thanks for the clarification.

@@harryward1608 qwantoz hp ??

No. This is a 4-51 the 51 series does not have valves.

No sir, the 51 series did not.

No...The 51 series did not, they were *loop scavenged* with Intake AND Exhaust PORTS much like a normal 2-Stroke gasoline engine (but with crankcase oil instead of premix), and the injection system was designed to spray the fuel upward against the head, not into a piston bowl...Now, the 53/71/92/110/149 Series were *uniflow scavenged* with Exhaust valves.

@@misters2837 qwantos hp ??

@@vilivuorinen8096 qwantos hp ??

There is very little soot -- unless you are accelerating hard, or if something is out of whack. I also use cetane boost in the fuel as it gives a cleaner burn which further reduces soot. Yes, it smells diesel. But it's worth it..... You can get the downpipe without the cat, and it saves some $$ but I wanted it to cut down on the soot.

@@kendallmarquardt9583 Hey Kendall. I've got a 2012 35d as well, thinking about some modifications. Is there a strong smell in the cabin with the windows up while idling? Also, what did this end up costing? thx

@@mrschlister8729 There has almost always been the cabin smell. Sometimes I use recirculate, then not an issue. The cause is the small turbo to manifold gasket which was replaced with the turbos, but bolts came loose (not my work) and blew it out. So if I replace it, likely will solve the problem. Cost, parts and tune for the delete, about $3400. Plus I bought a 6000 lb scissors lift as I didn't want to do this on jackstands. When this job is done, it will show other problems, oil leaks and the turbo seals were leaking. Also there were other sensor problems I didn't want to take the time to fix so I sent it off to have whatever else it needed done. This included reman turbos, oil lines, gaskets and a couple of injectors and some other miscellaneous parts. All said and done, about $7 k. Ran it on the dyno, 590 ft lbs and 364 HP at the wheels on a hot humid afternoon on straight fuel. I get 26 mpg. Have a bad injector to replace now. 228k miles all worth it. You are in command of the road in this car.

Just a little, if you have the windows open around town. I’m considering a muffler delete as you really don’t hear the exhaust note. Hoping to put a microphone back there and one in the engine bay for a future video.

This early design was very similar to a gasoline powered two stroke in that there are ports in the cylinder walls on opposite sides. One for relieving exhaust and the other set for admitting fresh air for combustion. The exhaust ports in this video are visible with flames. The addition of actual exhaust valve(s) similar in function to a four stroke engine was made to more efficiently move gasses through the engine. However, more mechanisms mean more complexity and more weight. But, it did improve performance.

It's not crankcase scavenged, there's a roots blower for scavenging. And he's talking shite, it has valves. Google it if you want to see how exactly it works. Some Turner diesels or the Sachs D500 engines, now that are actually valveless, port controlled two-stroke diesels. Turner usually with a blower and conventional sump lubrication, the Sachs with crankcase scavenging and total loss lubrication. Shit just gets burned together with the diesel fuel, and surprisingly they don't smoke that much, usually even way less than a gasoline two stroke with 2% premix. Maybe the right oil is able to ignite in a diesel cycle or they just need way less than a conventional gasoline two-stroke, idk.

If it is truly a 51 series and not a 53 then no it did not have valves. Plenty of info out there about them. They were not produced for a long time as the 53 series quickly replaced them.

A second set of rings on the bottom of the pistons. When the piston is at top dead center the oil rings are still below the intake port

@@heinzhaupthaar5590 You're the only one talking "shite" the 51 series is NOT THE SAME as the 53 Series... This Video is of the 51...Which ONLY has the Unit Injector in the cylinder head, it has Exhaust Ports and Intake Ports much like the Fairbanks-Morse 32 Series engines, but unlike the F-M engines this one doesn't use crankcase intake pressure for scavenging, it uses the Roots Blower...

The exhaust has been modded with Buzzken downpipe with catalytic converter (free-flow). The ECM was re-programmed with JR Automotive Racetune 2.0; not a chip. Dyno results on a hot humid day were 364 wheel HP and 590 wheel torque; without cetane boost. It sets you back in the seat, nicely.

@@kendallmarquardt9583 Nice man, how many kms do you have on yours? Im thinking of buying one with 220k kms in great shape. I test drove one with 360k kms a month ago and it felt like a brand new truck.

@@lomparti I have 360.5 km on the car now. When I bought it 4 years ago it had 219 km. Know that you will have to deal with the emissions system at some point! But yeah, the build quality is so stellar that anything else feels like a tin box. I have the M sport style 300 wheels with the super wide rear wheels with Continental Extreme Contact. It's so comfortable to drive that there is less fatigue on long drives. You are truly in command of the road. I have driven cross country and also into the woods of northern Wisconsin on forest access roads hauling equipment around. It is a very nice work truck. I get a solid 26 mpg having all the fun I want. I have spent about what I purchased it for in repairs and service, but for the age and mileage, it's needed maintenance. Keep that up and it will run forever.

The diesel is a completely different animal. The emissions system is very temperamental and at some point requires major service. I would recommend becoming fully educated on the issues and solutions before diving into one. That being said, for me, the rewards were worth it. I have spent as much getting things sorted out as I paid for the car initially, but people don't want to deal with these issues so it makes it less of an investment to start with.

@@kendallmarquardt9583 Hey, yeah I've am fully aware of the diesel and all, the emission system was going to be deleted for sure (doing ABC delete for tuning and sound). It was more regarding catastrophic issues I 'm afraid of like on the N54 if you don't fix a specific oil leak for example it can make the belt shred into the motor. Or like quirks like that.

@@JackRR15 What I experienced was once the backpressure was released, the weakness of the oil seals in the turbos showed up which is characteristic. Turbos were replaced along with valve cover gasket (blowing oil all over the place) . I did have the harmonic balancer replaced as well with the Fluiddamper, since the OEM one can go to pieces and since I was that deep into it, what the heck. They also put a special clutch on the alternator. BMW had a recall for idler pulley, which made me nervous taking it to the stealership!

@@kendallmarquardt9583 Ok thank you for the info, really like the car. Think I'll definitely get one now.

@@JackRR15 I highly recommend Andrew Rodriguez at TuneMyEuro. Great info and videos. Tell him I sent you!

I did full delete, added an AAR Race Tube, Buzzken Exhaust downpipe with catalytic converter, JR Automotive Racetune 2.0. The tune was a full ECM reprogram. Shout out to Andrew Rodriguez, https//:www.tunemyeuro.com where I got the supplies. I did the upgrade work, but eventually sent the car to him as there were sensor faults I didn't have time to chase, and there were oil leaks and the turbos needed to be replaced. He ran it on his dyno too. This was at 186k miles. Now have 209k, no issues. Just reliable fun.

This one was reportedly out of a road grader; serious work you bet!

It's a Tuxedo MR6K-38 mid rise scissor. 6000 lb capacity. Makes a nice additional workbench. But to put both cars in the garage I have to back over it which is a bummer. But it sure is handy.

quantos hp ?

@@aliriogomes5451 I don’t know.

qwantoz hp??

Tom Christman.... Sorry, that is Not true... the series 51 engines were Very fuel efficient and the fishermen (most all of the 4 cylinders were marine apps for small commercial fishing boats) back in the day, loved them for their reliability and fuel efficiency.

@@Romans--bo7br Yes they were fuel efficient compared to a gasoline engine, but obviously Detroit didn't pursue that way of producing their engines. You'll notice that there are no 2 stroke Diesels made this way anymore. The only valveless 2 stroke made now is the opposed piston-like Fairbanks Morse and Achates (excited about this engine!).

I've got a video of that somewhere..... but no, the only rockers on this motor were for the injectors. If you watch carefully in this (crude) video you can actually see the exhaust ports being lit up when I shoot in the manifold. I'll see if I can find the old "pre" start video when I first got the motor. Long time ago...

@Mr Sunshines... if YOU were paying attention to what DRNEGOLICIS was saying... He was referring to the series 53 & 71 engines having exhaust valves. He even said in his closing sentence that "I'd like to see a valveless design, what's under the valve cover?".

Hekili..... Unlike the other series of GM Diesels (they were Not marketed as Detroit Diesel until mid-1965), the Series 51 engines (only inline, 2 & 4 cylinder versions made) were numbered by the first year of production, whereas the other 5 series were numbered by the ci displacement per cylinder.... ie: 53, 71, 110 etc. The 2 cylinder series 51 was used mostly in smaller generator & welding sets and occasionally in irrigation pump systems, whereas the 4 cylinder series 51 engines were largely used in marine applications in smaller commercial fishing & crew boats, etc. and were revered for their fuel efficiency and reliability. They also were the only GM Diesel series that was Loop Scavenged ("Day Cycle" - valveless), but did use a Roots-type Blower (Non-pressurizing, positive air displacement) to provide air for combustion and scavenging. The other 5 series were all of the Uniflow design (aka Clark Cycle) utilizing Intake ports in the cylinder liner and exhaust valves only in the head (both, 2 & 4 valve heads were available for the Series 53 & 71 engines up until around 1964 or 65, after that... the heads were available with 4 valves per cyl. only.

Getting to close to the exh ports and that thing backfires, ouch

a oil sump like a 4 cycle

The sled engines are loop scavenged and make well over 3hp/cubic inch, just look at the Rotax 850 ETEC with direct injection. But the uniflow 2 strokes were probably faster accelerating and were easier to tune, not sure.

bruce, pull your head out. this is a diesel engine running in this video.

I love these old high tech 2 strokes they are awesome, all I have is a boring old fart omc rotary sled motors,

qwantos hp ??

These are blower loop scavenged..not uniflow..only made 2-51 and 4-51...anyone who thinks this isn't true hasn't opened up one of these odd pieces of DD engineering.

M Shultz-Very true my uncle has one sitting in his shop on a homemade stand with very low hours its an odd but cool piece of iron...only thing that that rocker assembly works Is the injectors!! Not a lot of these around running that ive seen or heard of anymore except for on here.

Not this one and an850 ETEC rotax has a sliding variable exhaust valve and it produces much more power for it size than any 2 stroke detoit. These were great engines for its time but they would melt with the HP per cubic inch of a modern 850 Rotax Etec as they produce nowhere near the power for ther size as a moderns Rotax engine can. Todays 2 strokes are way more powerful!

but they don't make 1/3 of the torque as these did or do...

I wished that I’ve known it was for sale if would had brought it asap

Bruce Miller: you don't mix the oil like a 2 cycle engine

I think he meant low ash motor oil..All the 2 cycle detroits perform the best with monograde 30 or 40 weight low ash motor oil. they slobber much less with that inside of them rather than something like rotella 15w-40...lol

They do burn some of it though as it works its way past the ports

They do burn some of the oil up

+Turbo617 Is this literally all you do? Sit at your computer and shit on everyone else's videos and forum posts?

+Turbo617 Since I am unaware of the depth of your knowledge of Detroit Diesel engines, I won't focus on an explanation in that direction. What you can not see, however, is that I had in fact, plugged the holes and filled the water jacket during the running process and subsequently drained it off afterwards just to see how much it warmed in the two to three minutes of running. There was hardly a change in temperature, most likely because that there is so much iron in those engines it takes forever to warm them up. The exhaust manifold never warmed either. I had a dump truck with a 500 c.i. DD and it would take 8 miles of driving under load before it would throw any heat.

***** Turboshit.

Just think if DD would have used a regular injection pump (like a Bosch rotary) you could have had a complete "flat head" with just water and injector holes. I even thought about an 8 port pump running half crank speed (for durability) and DUAL alternating injectors per cylinder...when one injector fails you only loose 1 power pulse out of 2 crank revolutions...its not a simple as the rack and rocker injection...but more precise.

If I remember correctly These engines had 54 Cubic inches per cylinder They were called 51 Series because they were introduced in 1951

It looks like plasma coming out of the exhaust ports.