Break-in RPMs

[familyman]

Somewhere in our friendly forum I remember somebody saying that during engine break-in not to exceed 2000rpm. The ever helpful and sometimes poorly translated Kubota manual says not to run the machine at "high or excessive speeds", whatever that means, for the first 50hrs. At 13hrs I have consistently kept engine speeds below 2000rpm but I wonder if it wouldn't be wise to occasionally venture higher. Any ideas?

Charley

 

[art]

I'd highly recommend maxing the RPM some during break in as well as thru it's whole life cycle. It is important to vary the throttle during break-in.

 

[familyman]

Art,

By "maxing" do you mean the rated rpm, or highest rpm on the tach? For how long? Thanks for the input.

Charley

 

[familyman]

Are there any engine builders/rebuilders out there with diesel experience who can shed some light on break-in?

 

[dmftoy1]

Just my .02

I don't think it's going to hurt you to run the machine at PTO speed (either 2500 for Mid Mount or slightly higher for the rear pto). If it was a problem with these tractors then they'd tell you not to use the PTO's for the first 50 hrs either.

I bought mine to mow and brushhog and it's been run at "high" RPM's since day one. I did and still do try to vary the rpm's slightly as i'm operating it.

Regards,
Dave

 

[mathteacher]

My dealer and the service man that I went to school with said that if you vary the RPMs every 10 or 15 minutes by 100 or 200 RPMs that you could run it at PTO speed. He also said that keeping it under 2000 isn't as good for it as vary the RPMs every few minutes.

Donald B.

 

[California]

Another opinion, maybe this will shed some light on the question.

From 'Breakin Period' in the manual for my early Yanmar:

"Ideal conditions for breaking in a tractor engine would require operating the tractor at full engine speed under 75% of full load for approximately the first 100 hours."

Also
24 hp @ 2400
max fast idle, and max road speed: 2600
full throttle full load 2400
pto 540 @ 2200

 

[ZackaryMac]

</font><font color="blue" class="small">( "Ideal conditions for breaking in a tractor engine would require operating the tractor at full engine speed under 75% of full load for approximately the first 100 hours." )</font>

This also goes along with what my father-in-law says. He's been rebuilding tractors for 40 years (mainly Massey Ferguson), and he says the same thing. He also rebuilds other diesels as well, such as skidders, dozers, saw mill engines, etc. I went in his garage one day, and sitting on a stand was a 6V71 (I think) GM diesel (big). He had it turned up pretty good, so I asked him what he was doing. He said he just finished rebuilding it and running it for a couple of hours. I said why is it running so fast, he said that diesels should be run in at their operating rpm, but not under full load right away. He has an excellent reputation, so I'd say he knows what he's talking about. This motor ended up back in the sawmill it came from.

I hope this helps a bit.

 

[familyman]

Thanks to everyone for the advice. 16hrs now and I'm sure it's time to wick it up. I'll be sure to vary the speed. Most of my work has so far invoved the BH which doesn't seem to load the engine too much, and I always give her 5 mins. to warm up. Some day I'll load up some photos of "the great pumpkin" at work.

 

[nharrold]

I discussed this question just yesterday with the head mechnician at my Kubota dealer, as I have a new 7800 and wanted to know what speed I could run the 72mmm at during the break-in period. He told me to just go ahead and run it at regular operating speed, taking care to vary the RPMs frequently during the break-in. But he said that there is no need to run the machine at reduced revs.

 

[markls8]

Here's an interesting technical link on this topic. It applies to motorcycle engines specifically, but you can generalize some of the principles to diesels I think. Hope this helps. http://mototuneusa.com/break_in_secrets.htm

 

[familyman]

Thanks for the great article. I posted this a while ago, so I was surprized to see a new reply.
In one of my previous posts regarding engine oil change I expressed my opinion that a very early oil change on a new machine was good medicine -- this article supports that approach.
Another article by a Harley engine builder (American Iron magazine??) also stated that several hard acceleration/deceleration cycles on a new motor, after warmup, is the best way to seat the rings for long engine life.
However, 2 problems come to mind regarding our low rpm diesel engines:
1. Are they machined or designed any differently with regard to fit and metallurgy than high rpm gas engines?
2. High load/rpm conditions are not always feasible, depending on a persons specific applications for the machine.
Thanks again, and any other info would be appreciated.

Charley

 

[dmftoy1]

Well I'm definately not any form of expert as far as engine break-in, but I can tell you a story about our visit to the Navistar plant in Indy. When they were building the 7.3L engines for Ford they would run each engine for a few minutes checking all it's vitals, etc and then the thing would be "stress" tested. If I remember right they were running it's redline for something like 10-20 minutes. If everything checked out at the end of the run then it was packaged for shipping (after it cooled down).

We went back and did the plant tour again last spring (and they were building the 6.0L ). They don't do this any longer (except on randomly selected engines). They had some cool robotic test harness that attaches itself to the engine (all ports, etc) and they can cycle everything on the engine without having to run it like they did the 7.3's.

Anyway, I've run mine (by necessity) at 2500 rpm when mowing since new, and so far so good. I did send a sample of my oil to blackstone for testing at 100 hours and they said the engine looked to have broken in well with low wear metals, etc.

Have a good one,
Dave

 

[_RaT_]

My Kubota manual for my L3830 simply states to keep the engine under maximum engine RPM (translates to "pedal to the metal") for the first 50 hours. With almost 300 hours I have yet to see the need for WOT. PTO speed is below WOT. 2000 RPM is to low for a little engine working a mower and in most folks opinions I would bet they would conclude that lugging a diesel would not be beneficial, particularly for a brand new engine. Get your new engine up to PTO RPM.

 

[Rowski]

Great info in this thread.

I'm getting my new tractor soon. I have about 25-30 hrs of field mowing to due. So i searched the TBN and found this thread.

My question:

Is the break-in different for a turbo diesel and the turbo itself?

Some of the grass I will be cutting is very tall and thick. I suppose I could slow my speed down to put less load on the engine?

As mentioned I don't have my tractor yet so no owners manual.

 

[JerryG]

<font color="blue">Is the break-in different for a turbo diesel and the turbo itself?</font>
The only thing that you need to do different, is to make sure to let it idle for a minute or so, before shutting it off. The bearings in the turbo need to cool down some. If they are shut down hot, the oil will coke on the bearing and make rough places. That will destroy the bearings.