Break-in RPMs

familyman · Jul 3, 2004

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 · Jul 3, 2004

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 · Jul 3, 2004

Art,

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

Charley

familyman · Jul 5, 2004

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

dmftoy1 · Jul 5, 2004

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 · Jul 5, 2004

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 · Jul 5, 2004

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 · Jul 5, 2004

</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 · Jul 6, 2004

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 · Jul 31, 2004

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.