Dyno test before and after engine rebuild?

[bw77]

A question for those who rebuild farm/heavy equipment engines - is it common practice
to dyno test the machine before and after an engine rebuild?

I was thinking back to when I rebuilt farm tractor engines, many years ago,
in a small shop. We did not have a dyno to test the engines, and looking back
I thought it would have been a good thing to have.

Edit: I have in mind machines with a PTO that would not need a wheel type dyno.

 

[Highbeam]

It is not normal to dyno test an engine at all. Only the enthusiasts and motorheads. I would love to tune an engine on a dyno but they are expensive to rent or buy.

 

[RobSmith]

"seat of the pants" dyno usually tells how much better an engine is after a rebuild.

 

[A_Pmech]

With farm tractors? Not that I've seen.

A dyno run is a routine part of a pre-buy inspection for a class 8 truck. Any decent truck dealer will allow you to take a truck you're interested in to the shop for a run. I'm sure many have failed the test, been rebuilt and tested again.

 

[Wastedwagesracing]

The use of a PTO dyno is pretty common on farm tractors. I'm not so sure about the use of it prior to a rebuild. I think it's more used for tuning the fuel systems after repairs.

 

[bgott]

We used to dyno tractors after rebuilds when I worked at an IH dealership. Basically it was to run the engine in under load to seat the rings.

 

[A_Pmech]

We used to dyno tractors after rebuilds when I worked at an IH dealership. Basically it was to run the engine in under load to seat the rings.

What kind of dyno did you use? Some kind of PTO eddy current brake?

 

[509frank]

Worked at JD dealership in central PA. I never ran a tractor on a dyno befor a rebuild but always after. We would start out with the engine running and the pto shaft running at 540 rpm or 1000 rpm depending on model of tractor. We would then put a 20 to 25 percent load on the engine and let it run for about 15 to 20 min. at this point we would remove the load and pull the throttle wide open. The pto shaft would then be running about 600 or 1100 depending on tractor a 50 percnt load of rated horse power would be applied and ran for 15 min at this point we would add load untill the pto rpm was down to 540 or 1000. this would be full hp . Our dyno was basicly a hydraulic pump. there was conversion chart for pressure the pump made given the rpm of pto shaft=horse power. AT least thats how I remember it it was 22 years ago.

found this image on the net but is what we had at the JD dealership.

FRank

 

[A_Pmech]

found this image on the net but is what we had at the JD dealership.

FRank

Interesting...

Thanks for the info FRank.

 

[sdguy55]

Dynoing a diesel after a rebuild is always a good idea. Break in the motor. Otherwise try and find an implement that will sufficiently load the engine down

Sent from my SAMSUNG-SGH-I897 using Tapatalk 2

 

[bgott]

What kind of dyno did you use? Some kind of PTO eddy current brake?

Water brake. You hooked a water hose up to and away you went!

http://en.wikipedia.org/wiki/Dynamometer#Water_brake_type_absorber

 

[larry_g]

Not sure how common it is these days but years ago quite common. M&W was one of the major players. The above vid shows one in operation. Search M&W dyno to see more.

lg
no neat sig line

 

[danlolasdad]

http://www.land-and-sea.com/tractor-pto-dynamometer/tractor-pto_dyno-video.htm

 

[Racecarl]

I dynoed very few tractors before an overhaul, but I dynoed EVERY one after. Loader tractors were dynoed twice as long as a field tractor, mainly because loader tractors spend a lot of time idling around or being used under light loads.

 

[HTGTS350]

When I worked for Caterpillar a post rebuild dyno test was a necessary part of the warranty program, many small problems can be discovered on a dyno before they become large or catastrophic problems in the field.

 

[plewlandsbob]

I am an agricultural tractor mechanic. We use our dyno, to test engines after a full rebuild, or a major repair. We also dyno every new tractor we put out and put a print out of results, in with the ops manual. Every trade in gets dyno'ed as well. It is extremely useful when investigating claims of lack of power.
Our dyno is connected to the pto and is basically a large generator and a big element like an electric fire to create a load. It has its own built in computer and printer to work out max hp, torque. Cost around 40 grand , 6 years ago.

 

[mustanginky]

i can vouch for the auto tinkerer's here. every time i make a significant change on my blown mustang, it sees the dyno. but that is mainly to make sure the a/f ratio's stay within a safe range. also, in this day and age of computer controlled this and that, it's the only way to tune the car. so to keep the a/f ratio and timing tables safe and most efficient, i have to take it to the dyno.

in the implement world, i can imagine it would be a great tool to break in an motor and seat the rings. i can also imagine it would be used to detect problems prior to going out and working.