Onan 4Cyl diesel 1.9L

Alrighty guys so everyone has heard me drooling over this engine the past week just waiting to dig my fingers into it and get it going for some undiscovered project or insane thing I will cook up eventually. I would just like to point out I have little to no experience with diesels so I may post here asking for help and whatnot bear with me if I do lol.



I4



Looks like it could mount up to a tranny nicely...



From what I have been digging through in manuals and what I learned from stretch when I picked it up the onan motors are rated at 30hp (Im guessing at 1800 rpm?) Are 1.9L engines that are 4 cycle

Well after I got it home and set up on some sawhorses I looked at it pulled out the dipstick the normal things you do when your curious but the oil had since turned to grease and plugged everything up and she was pretty tight didnt really wanna turn, a week passed I pulled off some of the shrouding metals and dumped some diesel in the crankcase ~a quart or so. Then this weekend came! I dug into that baby with a couple boxes of sockets and wrenches (only really needed a 3/8 1/2 and a 3/4 before I dug in I filled the crankcase with diesel to clear up some of the greasey nastyness in the oil pan then I started getting the glowplugs out!



A good comparison of before and after the shiney part was submerged in diesel a while when I had it sitting in a quart jar the top part wasnt so lucky

So I started pulling the injector lines so I could have better access to the glowplugs which were not fun getting out even with good ol wd but I got them out withough shearing anything off thank a cigrit.



Its actually pretty cool how the cylinders are set up they a twins so they are 2+2 with a split in the middle and fire 1-2-4-3 so they fire towards the middle, I thought it was kinda neat!



This one kinda sucked took forever to get the plug out because I had a tiny space to ratchet the injector fuel line is stuck so I couldnt move much not sure how to get it free but Im not gonna wrench on it unless I have to... May try tapping it with a hammer.



The injector pump thing is a tad on the rusty side Id like to pull it apart and clean it but Ill have to dig through the parts manual dont need anything springing out at me and ruining my day...



The oil cooler



Another side of the cooler with the in and out

As of right now I have her turning by hand but those are my hands and it takes a pretty good bit of torque to turn her so I topped off the crankcase in the hopes that the journals and bearings are just gummed up and need a soak. I will have to get the starter working in order to get some speed on the flywheel so the oil system gets a good cleaning but that may take a bit so for now I will just keep at her and hope for the best, though seeing as I dont have a specific need as of this moment I may do a complete teardown and cleaning just to be on the safe side and make sure I cover all bases! (And repaint her cat yellow!)

idk if you do but you have access to one but you pull injectors and pop test them for spray quality and see how many PSI until they pop.

I know a guy with a diesel shop may talk to him about it only thing is he charges me for advice :/ have to walk in with a 6 pack or he ignores me and then I only get 6 questions >.>

Honestly, I'd keep turning it till it smooth's out, drain the diesel and sludge outta it, fill it with oil and see if it will crank
It may well just start up and run

If it does, let it idle about an hour, and change the oil again

yeah I may do that depending on how it looks and feels after I let it sit full of diesel if she frees up and doesnt make any weird noises I may get her going will still have to fix the starter and get a couple batteries not sure Id be able to get her going off my truck battery

Leave the injector pump alone, they have very precise parts inside. Get it good and freed up, fresh oil and fuel, and start er up.

The firing order is no surprise at all. Every gasoline I4 I've ever worked on, fires 1-3-4-2, or 1-2-4-3. I think if they fired in straight order, it would set up a nasty harmonic.

Now... 2 stroke? Are you 100% sure about that?  Does it have a mechanically driven blower? A 2-stroke diesel of such a design cannot be naturally aspirated. Read up on the "Screamin' Jimmy" Detroit Diesel 2-strokes if you have any questions.

If it is, it's gonna sound cool as hell, but have a VERY narrow power band.

Either way, I'll be watching this closely, while working on and around the two oil-burners I picked up recently.

That thing must be heavy as HELL...

Your engine intrigued me, been searching. Found this- http://www.ebay.com/itm/engine-diesel-ONAN-4-cylinder-REBUILT-air-cooled-18-HP-1800-RPM-MEP-003A-/121107511840

I'm not sure if it's the same, but it IS very similar. Rated 18hp at 1800RPM. Fan cooled, naturally aspirated, 4 cylinder. Neat engine, but HOLY BOAT ANCHOR, BATMAN! Shipping weight... 690lbs!

Yep Doc, that's it. But, that is a military engine rating, which is way lower than actual HP.

And they are 4 stroke.

Stretch44875 wrote:

Yep Doc, that's it.  But, that is a military engine rating, which is way lower than actual HP.  

And they are 4 stroke.

Thanks for clearing that up. I was a little stymied over the 2-stroke thing. And with a size and displacement like that, I fugred it was good fr more power. Actually, knowing how torque and power curves tend to work- I wonder (aloud) if its 18hp@1800RPM, but 30@3600 or similar. Perhaps the "key" to the higher power, is higher RPM. A hp "rating" is not necessarinly the PEAK, buy at "rated" RPM- in this case, 1800 for generator duty.

lol I stand corrected! on a number of fronts lol so yeah Ill try working on the diesel today a little more isnt much I can do with the massey atm pretty cold out and snowing pretty good so we will see what happens :p

I tried to spin the onan this morning I think it is just to cold to be trying to work on it did not want to move so I think I need to wait till it warms up so I dont hurt myself

mill spec ratings are usually 80% of one half peak HP... at least, that's what it was in '85 in the missile field. Doc was also spot on about the @ a specified RPM... ratings were application specific most times. (application specific rating supercedes the proofload rating)

meaning... if generic motor was ordered for the military, the contractor would give the hp and torque ratings.
Military proofload specialists would test the engines, and rate them at 80% of one half the peak hp.

Later, when the engine was mated to a support or weapon system, The motor would be tested again at the required RPM for that piece of equipment, and yet ANOTHER HP rating would be associated with the motor.

The same motor, on a different piece of equipment, with different operating rpm, would have a completely diff HP rating. It made it dang difficult for the engine mechanics to ID the correct engine to order parts if the NSN (national stock number) was missing.... a fairly common occurrence on equipment that had seen combat duty. Add in that the same, lets just say, Genset may have 3 different engines that COULD be on it.

well from what I know of the vw 1.9L (which have smaller bores) they produce 100hp at somthing like 4200 rpm but are turbod so I am kinda wondering if this is around 50-60 at 3600 torque should be pretty beefy though when she is running I may get with someone that has a dyno and check the numbers

Ok so in my search through the huge ass file known as the onan master manual (thanks lawren) :p I found a little part about the starter specifications and reads as follows: 7.2 volts 390 amps this leads me to believe that I could use a regular car battery at 12v and 950 amps... however the starter says it is 24v so I am clueless...

Moose, that just means that the equipment it was on used a 2 battery 24 volt starting system. The starters are application specific. The specs given by the manual show what onan provided for it, and what is required to crank it. a single battery should crank it fine.

cool

It will not crank on 12v, or will crank very slowly. Starter is wired for 24v. Hook two car, or lawn mower batteries in series. Also, I'm sure you could take the starter to a place that rebuilds them, and get a 12v, or have that one rewired. Also, glowplugs will be 24v.

didnt know they could be rewired might go that route because I like that it was made here in ohio

Yeah, sorry I wasn't clear... I meant that a 12 v starter would have plenty of capacity to crank the diesel. 12v on a 24 volt starter would cause an over amp, and under rotate prob. These came originally with a 12 v starter, the 24 was application specific. The 7 v rating that the manual specifies is the minimum required to turn the motor at sufficient speed with the 12 v starter...

The fact that it is a 24v starter lends credence to the mil application likelihood, as the tech orders for diesels in the military use indicate 24v starting systems. (the battery boosters the military employs for diesels are 24v... they didn't want the average 18 yo 1 striper running out and hooking a 24 volt booster to a 12 v starter)

Lawren Wimberly wrote:

The fact that it is a 24v starter lends credence to the mil application likelihood, as the tech orders for diesels in the military use indicate 24v starting systems. (the battery boosters the military employs for diesels are 24v... they didn't want the average 18 yo 1 striper running out and hooking a 24 volt booster to a 12 v starter)

I suspect the 24v mil spec also has much to do with the fact that voltage and current are inversely proportional (see Ohm's Law). Any electrical device will require HALF the current at DOUBLE the voltage, and therefore be TWICE as efficient.

Getting the starter rewound might be an option. OR- a 24v mil spec starter might be a desirable thing on an open market. You could maybe sell it for more than it would cost to buy a 12v starter for your application.

Regarding the glow plugs- Since they are simple resistance units, you MIGHT be able to just use them as is, but it will take more power and time to glow them. OR- sell them as well...

That might be a good idea we know it works because stretch got it spinning just didnt throw the gear out was all so might just be the rust I will have to pull it off and clean it up see if that helps

Most military equipment is 24v.  This is a military engine, I bought it from the government surplus, and fits the MEP-003 generator.  Easiest thing to do is use two batteries in series, and use it on 24v.  Remember, the alternator on the engine is 24v too, and will charge two batteries.  Only thing you might add is lights, and two 12v lights can be wired in series, to run on 24v.

I do have a the 12v version of this engine, it uses a different starter, starter location, alternator, glowplugs, fuel filter, and oil filter.

While we had it here, we attempted to spin it over with the starter.  If you remember, I used my military crane truck, reason is, it's 24v also.

And yes Doc, one of the biggest reasons is the wiring only needs to be half the size of 12v systems, to carry the same wattage.

works that way with AC too... thus the industrial equipment usually runs 440 and 16 guage stranded wiring. I agree with stretch about keepin it 24 v, it'll be cheaper to add a battery than to convert. I suspected it was a milspec, stretch confirmed it.

started cleaning up some rust on the starter then it started raining/snowing so didnt get much done on the engine it moves about .075" now though so were getting there its froze up anymore!