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Old 09-05-2020, 03:40   #16
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Re: perkins 4-108 Break In after Rebuild

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Originally Posted by patagonik View Post
Buen dia,me dedico a la inyeccion diesel por eso puedo aconsejarlo.
Si su motor echa humo(sobre todo cuando esta frio)en ralenti es muy posible que este atrasado.Seguramente esta un poco mas silencioso que lo normal.
Ud puede girar la bomba inyectora aflojando los 3 tornillos que la sujetan sin temor,nada se va a romper.En el cuerpo de la bomba inyectora hay una chapa de aluminio con una flecha que indica la direccion de giro,usted gire el cuerpo en el sentido CONTRARIO a la flecha y pongalo en marcha a ver si nota diferencias.
El perkins tiene tambien otra forma de corregir la puesta a punto:
En el frente del motor(la distribucion) hay una tapa de chapa o una bomba de agua justo enfrente de la bomba inyectora .quitela y se encontrara con el engranaje que acciona la bomba inyectora.En el centro de este engranaje hay 3 tornillos que permiten mover el centro del engranaje (incluso tiene una marca para tomar como referencia)afloje los 3 tornillos y mueva el centro del engranaje PERO EN ESTE CASO MUEVALO EN EL SENTIDO DE GIRO QUE INDICA LA CHAPITA DE LA BOMBA) y pruebe el motor.
Le dejo mi correo si tiene mas dudas ,estoy en la patagonia argentina
dieselesquel@live.com.ar
Saludos y no tenga miedo que es facil

Good morning, I am dedicated to diesel injection so I can advise you.
If your engine is smoking (especially when it is cold) at idle it is very possible that it is running late, it is probably a little quieter than normal.
You can rotate the injection pump by loosening the 3 screws that hold it without fear, nothing will break. In the body of the injection pump there is an aluminum sheet with an arrow that indicates the direction of rotation, you rotate the body in the OPPOSITE direction to the arrow and start it to see if you notice differences.
The perkins also has another way to correct the set-up:
In the front of the engine (the distribution) there is a sheet metal cover or a water pump just in front of the injector pump. It will meet the gear that drives the injector pump. In the center of this gear there are 3 screws that allow moving the center of the gear (it even has a mark to take as a reference) loosen the 3 screws and move the center of the gear BUT IN THIS CASE MOVE IT IN THE DIRECTION OF TURN INDICATED BY THE PUMP FLAP) and test the motor.
I leave you my email if you have further questions, I am in Argentine Patagonia
dieselesquel@live.com.ar
Greetings and don't be afraid it's easy
Thank you for you insight. I am going to double check all connections and then adjust the timing. I think you are probably correct and my timing is a bit retarded. Your explanation of the timing adjustment was very helpful-will report back once I have given this a try. I did carefully time the engine, but it was my first time timing a diesel so I was concerned that I might have set it up incorrectly. The good news is, I set it up ok-it just may need adjustment.
Thanks again,
Jim
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Old 09-05-2020, 03:48   #17
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Re: perkins 4-108 Break In after Rebuild

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Originally Posted by oldcal46skipper View Post
We use what we call a "Miss a sippi Dynamometer" that is a piece of 2" X 4" wood that we place under the output shaft coupling and lift against the coupling until it ignites.
That is an indication that the gear is not slipping.
When the wood starts to burn, that is an indication the gearbox is not slipping.
Its a good thing the transmission and coupling are off the engine or I would probably try this and burn down my very old barn! Right now it's just the flywheel attached to the crank, so no load. I think it will be really impossible to load it without getting it in the boat. I'm just trying to address all the gremlins before I drag it across town and reinstall. Once it's installed in the cave and launch I can put it under load until the river boils
Sent you a pm with my email-btw.
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Old 09-05-2020, 04:05   #18
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Re: perkins 4-108 Break In after Rebuild

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Put it in the boat and run it hard to seat the rings, if the timing is retarded it wonít make good power and will be smoky, but will be quiet, but it wonít hurt anything, just wonít make good power.
If too advanced it will rattle like a cold motor even when hot and too advanced can cause damage.
However having just been rebuilt smoking is sort of normal as the rings havenít yet seated, and they donít seat until itís put under a load as then the cylinder pressure is higher, strong load results in very high cylinder pressure, this blows the rings out to the cylinder walls and that makes the seat well.
Way back when and even to this day Aircraft engines used to be run in on Non detergent oil,for the life of me I canít imagine why, I wouldnít use non detergent oil, but would do my first oil change very soon, the reason is, is because any metal that is worn off is come so very soon and you donít want that wear metal staying in the oil, so first change 5 hours max.
Now it wonít kill it if you donít, but believe itís best to.

You did have the injectors overhauled didnít you? If not then that could very well be the cause of smoking.
This is a great post-thank you. About the injectors....they were running when I removed them and so I used them again without testing When I asked a shop about testing them they didn't seem to either want to or felt it was a waste of time. I distinctly remember they said they either work or don't. But wait...it gets better. The boat also came to me with four new injectors in a vacuume sealed bag. Rather than use them, I installed the old because "they either work or they don't" and the old ones had been working.

Long story short and more embarrassing, I unevenly tightened down on two of the old injector brackets when reinstalling-the bracket castings cracked. They are cast iron and brittle and frankly they seem like a horrible design almost designed to fail. They seat against the tapered injector barrel to push it into the block but the brackets themselves are designed not to contact the block. No problem, I have the vacuume bagged new ones that came with the boat.
So I have two new injectors and two old injectors installed in a newly rebuilt engine. Typing this I feel really cheap...

So is it true, they either work or they don't? Have I just admitted on the forum that I' m a noob?
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Old 09-05-2020, 06:14   #19
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Re: perkins 4-108 Break In after Rebuild

[QUOTE=Ecos;3135391]
Quote:
Originally Posted by a64pilot
Way back when and even to this day Aircraft engines used to be run in on Non detergent oil,for the life of me I can’t imagine why, /QUOTE

Because there are anti friction additives in compounded oils. With the RMS finish required for aircraft cylinder walls, you need some wear to break them in.
Maybe, but the same engine with a turbo it is recommended fo break them in on Ashless Dispersant oils, meaning detergent oil.

I think it’s because aircraft piston engines are 70 yr old designs and that was how it was done then, and nothing has changed.

What is RMS finish? Aircraft cylinder walls are honed very rough when compared to modern automotive designs.
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Old 09-05-2020, 07:11   #20
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Re: perkins 4-108 Break In after Rebuild

What is RMS finish? Aircraft cylinder walls are honed very rough when compared to modern automotive designs.[/QUOTE]

RMS is the roughness, (root mean squared.)
Chromed cylinders would never break in, if you didn't use straight oil for a while.
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Old 09-05-2020, 07:41   #21
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Re: perkins 4-108 Break In after Rebuild

Chromed barrels were sort of a failed experiment just like it was for other engines as well, it’s apparently still allowed but most avoid it.
Energy saving oils are an automotive thing, I don’t believe it ever made to it Aircraft or Diesel oil for that matter, I don’t know why
https://club.mobilindustrial.com/glo...-conserving-ii
I do know that wet clutches don’t work well with the energy saving oil, and many motorcycle owners have switched to Diesel oil for that and other reasons.

However all that aside, a piston engine is a piston engine for most intents and purposes. For those breaking in an engine, this article may be if some interest, maybe not on what kind of oil cause that’s not an issue with Marine Diesels, but pay attention to the power setting recommendations and why, the why is most important.

https://www.lycoming.com/content/har...t-engine-break
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Old 09-05-2020, 08:00   #22
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Re: perkins 4-108 Break In after Rebuild

[QUOTE=a64pilot;3135656]Chromed barrels were sort of a failed experiment just like it was for other engines as well, itís apparently still allowed but most avoid it.

Chromed cylinders work great and they have for at least 65 years. There is no other way to re-size a worn out bore either.
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Old 09-05-2020, 08:10   #23
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Re: perkins 4-108 Break In after Rebuild

Regarding timing adjustment-is it ok to slightly adjust while Perkins engine is running.? Would be nice to hear and see change while making slight adjustments. Have scribed marks of existing orientation to block
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Old 09-05-2020, 09:47   #24
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Re: perkins 4-108 Break In after Rebuild

The engine is going to smoke some until the rings seat. It should be run under load. Get it in the boat.
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Old 10-05-2020, 02:54   #25
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Re: perkins 4-108 Break In after Rebuild

Good Morning Cruisers & Boaters. I had promised to post my "Rebuilt Diesel Boat Engine Procedure", but my good old PC died after only 10 years and I'm having difficulty finding some data. My good old Chevy truck is 21 years old and still going strong. My Cal 46 "Satori" is 53 years old and still perfect,IMHO the best Cal ever built!


How come 'puters don't last very long ? The Perkins 4.108's I rebuild are 40 years old or older.


Since I don't want to offend this great forum's leaders and the OP, I will start another thread with the "Break In"procedures we have used for over 15 years and 200+ Perkys
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Old 29-05-2020, 15:05   #26
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Re: perkins 4-108 Break In after Rebuild

Because it's good to get follow up when a member asked for help here is a quick Post to finish up this thread-fuel pump timing was the cause of the smoking-not rings needing seating. After rotating the pump the smoke disappeared and the engine sounds great. Goes in the boat tomorrow and will then get to run it under load.
When rebuilding I followed the static timing and fuel pump timing check process in the manual-the fuel pump index lined up perfectly when #1 piston was .120" before TDC but it ran smoky nonetheless , turned the pump 1/4" and it ran perfectly-no smoke . Hope this helps someone else struggling with a smoky Perkins.
Thanks again for all the suggestions!
Jim
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Old 29-05-2020, 16:22   #27
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Re: perkins 4-108 Break In after Rebuild

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Originally Posted by jpendoley View Post
Because it's good to get follow up when a member asked for help here is a quick Post to finish up this thread-fuel pump timing was the cause of the smoking-not rings needing seating. After rotating the pump the smoke disappeared and the engine sounds great. Goes in the boat tomorrow and will then get to run it under load.
When rebuilding I followed the static timing and fuel pump timing check process in the manual-the fuel pump index lined up perfectly when #1 piston was .120" before TDC but it ran smoky nonetheless , turned the pump 1/4" and it ran perfectly-no smoke . Hope this helps someone else struggling with a smoky Perkins.
Thanks again for all the suggestions!
Jim
for the followup.
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