For the love of a 520

[TJ5208 1,841]

31 minutes ago, Jeff-C175 said:

 

Do you think it makes more heat the faster you run it?

 

Do you think there would be a difference between 3000 and 3600 RPM? 

 

 

Even though my tractor has a eight speed I just pay attention to this even though I do run my tractor at some little RPMs when I don't need all the RPMs

Edited February 15, 2022 by TJ Salyers

[TJ5208 1,841]

[TJ5208 1,841]

And of course who doesn't like to hear that Onan rumble.

[jamessparks 55]

Full throttle and let it eat!!  But… anyone that wants to volunteer to mow my grass and test that speed all summer is welcome! 😂

 

[Snoopy11 5,718]

2-3.5 MPH...??????

 

My GOD...

 

To mow my yard, it would take a friggin' week... and by the time I got done, I would have to start over.

 

No thanks.

 

To me, it sounds like Toro is trying to cover their assets in case imbeciles do something stupid. These transmissions have been tested an tried at much higher Horsepower/torque levels... so it will take a whole lot more than that to convince me.

 

Furthermore, if you have ever put an oil temperature gauge on one of these engines, you know that the only time heat builds is at full throttle, 3,600 RPM. Seriously, if you let one of these engines sit an idle at 1,800 rpm... you really think they are going to overheat? Wrongo. More thottle = more fire. More fire/more friction = more heat. Basic logic there.

 

Same with the transmission, if you are dumping RPMS into the transmission, you are going to get it hotter than it would be at idle... more RPM = more friction. More friction = more heat.

 

You know what is funny... REALLY funny... is if these tractors were supposed to operate at full throttle all the time... explain to me why they have adjustable throttle rather than fixed throttle?

 

I rarely run my Duromax 457 at 3,600 rpm. Usually it sits around 1,800 at idle... and I only need to pull 2,000-2,500 to do work. 3,600 pulls like HELL. 7,500... you need a seatbelt.

 

I ALWAYS run my machines at full throttle while mowing, yes @Horse Newbie. But, it isn't necessary outside of mowing. I run WAY under 3,600 when I am traveling with my machines, because as Jeff said, it wastes A LOT of fuel.... (ask me how I know).... my machines are fuel-hogs.

 

Don

[Jeff-C175 7,206]

6 minutes ago, Snoopy11 said:

more RPM = more friction. More friction = more heat.

 

But also more airflow...

 

There must be a 'balance point' where the temperature would stabilize.

 

Does the amount of added airflow that occurs with added RPM remove the added heat?

 

How about when it's working hard and ambient temperature is high?

 

At what RPM and load conditions does not enough air flow to cool the engine?

 

 

[Snoopy11 5,718]

24 minutes ago, Jeff-C175 said:

Does the amount of added airflow that occurs with added RPM remove the added heat?

Air to fuel ratio will have a major effect on cylinder head temperatures. Really, the "heat" you think about is split into 2 portions, top-end heat... bottom-end heat.

 

The fan on our engines cools the oil (to a certain extent), thus reducing oil temperature's in the bottom end. The fan does little... to nothing for top-end heat. Again, proper air/fuel ratios will have a drastic effect on head temperatures.

 

Having said that, the cooling of the bottom-end can also be controlled (again, to a certain extent) with different weights of oil. If you put too thin oil in the engine... you are going to get extra heat.

 

Regarding airflow... I watched the temperature gauge on my 457 very closely last summer 90+ degree day. SO... what I noticed is that, when I was grading the driveway, pulling my BIG 0ZZ ripper behind the tractor, the temperature was steady at around 2,000 RPM over a period of 15-20 minutes. When I increased throttle to 3,600 RPM to go a bit faster, the engine began heating a little below +20 degrees warmer. When I backed it back down to 2,000 RPM, it cooled back down. (keep in mind, this engine did not struggle or bog down at all... ripping many inches of rock).

 

THEREFORE... in my humble opinion, the fans on our engines are sufficient for both lower and higher RPMS respectively.

 

As for load. The less power you have, the more demand for power increase, and thus the more strain the engine is going to have (obviously). But what this really means is that the rod is rotating on the crank... pressing on the crank (for lack of a better term) THAT much harder. It is working to perform in a scenario in which a bigger engine... wouldn't even bog down.

 

When a small engine is struggling, it will certainly increase temperatures. THUS... why in these engines, you will get less heat by increasing RPMS than leaving it at, say 2,500, and letting it strain.

 

Any of that make sense. A bit easier to demonstrate in-person...

 

Don

 

Edited February 15, 2022 by Snoopy11

[Handy Don 14,124]

54 minutes ago, Jeff-C175 said:

 

But also more airflow...

 

There must be a 'balance point' where the temperature would stabilize.

 

Does the amount of added airflow that occurs with added RPM remove the added heat?

 

How about when it's working hard and ambient temperature is high?

 

At what RPM and load conditions does not enough air flow to cool the engine?

 

I'm prepared to accept the manufacturer's engineers' expertise on this one and follow the guideline they published in the OM. 3600 RPM for working and governed idle of 1100-1200 for cool down.

Some years back a member instrumented a P220 to get head temps for the front and rear cylinders (to attempt to add real data to the anecdotal "high rear cylinder failure rate" commentary). If memory serves, both heads were stabilized at very similar temps in the mid-300º Fahrenheit range running at 3600 RPM under load in warm weather with the standard tins (including the oil filter gasket). Temps spiked briefly to upper 300's immediately after shutdown and then cooled. His conclusion was that if there was premature failure on the rear cylinder, it wasn't related to head temps.

Edited February 15, 2022 by Handy Don

[TJ5208 1,841]

50 minutes ago, Snoopy11 said:

Air to fuel ratio will have a major effect on cylinder head temperatures. Really, the "heat" you think about is split into 2 portions, top-end heat... bottom-end heat.

 

The fan on our engines cools the oil (to a certain extent), thus reducing oil temperature's in the bottom end. The fan does little... to nothing for top-end heat. Again, proper air/fuel ratios will have a drastic effect on head temperatures.

 

Having said that, the cooling of the bottom-end can also be controlled (again, to a certain extent) with different weights of oil. If you put too thin oil in the engine... you are going to get extra heat.

 

Regarding airflow... I watched the temperature gauge on my 457 very closely last summer 90+ degree day. SO... what I noticed is that, when I was grading the driveway, pulling my BIG 0ZZ ripper behind the tractor, the temperature was steady at around 2,000 RPM over a period of 15-20 minutes. When I increased throttle to 3,600 RPM to go a bit faster, the engine began heating a little below +20 degrees warmer. When I backed it back down to 2,000 RPM, it cooled back down. (keep in mind, this engine did not struggle or bog down at all... ripping many inches of rock).

 

THEREFORE... in my humble opinion, the fans on our engines are sufficient for both lower and higher RPMS respectively.

 

As for load. The less power you have, the more demand for power increase, and thus the more strain the engine is going to have (obviously). But what this really means is that the rod is rotating on the crank... pressing on the crank (for lack of a better term) THAT much harder. It is working to perform in a scenario in which a bigger engine... wouldn't even bog down.

 

When a small engine is struggling, it will certainly increase temperatures. THUS... why in these engines, you will get less heat by increasing RPMS than leaving it at, say 2,500, and letting it strain.

 

Any of that make sense. A bit easier to demonstrate in-person...

 

Don

 

And that's what I meant and also it'll help your engine run longer without having to struggle all the time. And also helps to keep carbon off.

Edited February 15, 2022 by TJ Salyers

[Snoopy11 5,718]

Well, first you said:

17 hours ago, TJ Salyers said:

I run my machines at Full throttle all the time because if you don't it could cause overheating because these are air cooled engines so you're taking air away from the engine which cools it.

 

Then:

 

16 hours ago, TJ Salyers said:

I do run my tractor at some little RPMs when I don't need all the RPMs

 

So... that is why we are discussing...

 

I thought it was obvious, but if I run my mowers at 2,800-3,000... and try to run through tall/thick grass... it is going to bog down...

 

Don

 

[TJ5208 1,841]

1 minute ago, Snoopy11 said:

Well, first you said:

 

Then:

 

 

So... that is why we are discussing...

 

I thought it was obvious, but if I run my mowers at 2,800-3,000... and try to run through tall/thick grass... it is going to bog down...

 

Don

 

That was with my old tractor I sold to you because I didn't need all the RPM just to drive around. But with my 520 I like to keep it full throttle.

Edited February 15, 2022 by TJ Salyers

[Snoopy11 5,718]

1 minute ago, TJ Salyers said:

I didn't need all the RPM just to drive around.

That makes sense.

 

Certainly not trying to nit-pick, TJ...

 

3 minutes ago, TJ Salyers said:

But with my 520 I like to keep it full throttle.

 

I usually keep my zero turn at full throttle as well even when traveling. If I don't... it is SUPER slow.

 

Really just an interesting conversation. I think, it all depends on the machine and what you are using it for.

 

Don

[TJ5208 1,841]

13 minutes ago, Snoopy11 said:

That makes sense.

 

Certainly not trying to nit-pick, TJ...

 

 

I usually keep my zero turn at full throttle as well even when traveling. If I don't... it is SUPER slow.

 

Really just an interesting conversation. I think, it all depends on the machine and what you are using it for.

 

Don

 I've been keeping my tractor Full throttle is because I need to get this carburetor

cleaned out but now I have the carburetor almost taken apart. Probably after I get the carburetor cleaned out I'll run a little slower.

[kpinnc 14,663]

37 minutes ago, Snoopy11 said:

Really just an interesting conversation. I think, it all depends on the machine and what you are using it for.

 

Most, dang near all 520s are hydros. Those require a minimum of half throttle just to keep the hydro cool and happy. An Onan P220 should make huge oil pressure even at idle, but it will get hot in a hurry.

 

Probably best to run 2/3 to full throttle all the time. Flathead Kohler with a manual tranny? You can putt putt all you want with those.

[Snoopy11 5,718]

1 minute ago, kpinnc said:

require a minimum of half throttle just to keep the hydro cool and happy

And moving....

 

Don

[kpinnc 14,663]

4 minutes ago, Snoopy11 said:

And moving....

 

If you think of the pressure and heat generated by the slippers or the ball ports on a hydro (depending which you got), and then remember what happens when you skate a flat file across a ball bearing- you'll want all the oil squirted into those pumps you can get. 

 

That's my theory and I'm sticking to it! 

Edited February 15, 2022 by kpinnc

[Snoopy11 5,718]

1 minute ago, kpinnc said:

you'll want all the oil squirted into those pumps you can get

 

AMEN!!!

 

Don

[WHX?? 51,865]

Have one or four myself Never dreamed I ever have even one! Was up to a six pack at one time but a bad axle and a motor too expensive to rebuild turned her to parts to keep the others running.

Edited February 15, 2022 by WHX??

[Horse Newbie 7,395]

5 hours ago, Snoopy11 said:

I ALWAYS run my machines at full throttle while mowing, yes @Horse Newbie. But, it isn't necessary outside of mowing. 

What @Snoopy11 ?…did I say something ?

[Jeff-C175 7,206]

5 hours ago, Handy Don said:

I'm prepared to accept the manufacturer's engineers' expertise on this one and follow the guideline they published in the OM.

 

Me too Don, and my questions were more or less rhetorical.  Hopefully helping some to see the 'bigger picture'.

 

But, the bottom line is that there is likely VERY little difference, cooling or lubing, if any, between operating at 3000 vs. 3600 RPM.

 

And maybe... just maybe... they want  you to run it spherical objects to the wall so that it wears out faster and you have to buy a new one from them!

(I don't think that's true, but just sayin')

 

3600 is more or less 'red line' on these engines.  How long would someone drive their car at red line and expect it to last?

 

The main reason, IMHO, and it was stated in the operator manual when MOWING, to run full speed, is for the blade tip speed and QOC.

Truth be told, I see very little difference between 3000 and 3600 RPM as far as that is concerned also... on MY TURF.  YMMV.

 

One last thing... if anyone can provide an explanation of the following:

 

 

Why is this so?  I presume this is only for a HYDRO trans?  Not enough fluid flow causes damage to what parts?  The slippers?  Or ???

 

 

Edited February 15, 2022 by Jeff-C175

[Snoopy11 5,718]

1 hour ago, Horse Newbie said:

What @Snoopy11 ?…did I say something ?

I was referring to post #47, chum...

 

22 hours ago, Horse Newbie said:

So you’re saying run it at max rpm while mowing ?

 

 

Don

[Handy Don 14,124]

1 hour ago, Jeff-C175 said:

One last thing... if anyone can provide an explanation of the following:

 

 

Why is this so?  I presume this is only for a HYDRO trans?  Not enough fluid flow causes damage to what parts?  The slippers?  Or ???

Since we're guessing, I'll play along 

First, to me this is an "edge case" scenario. As in people repeatedly slamming the motion control back and forth (full reverse full forward ==> wheelie?) or pulling a very heavy load at a low engine speed. (Note, this does not mean mowing heavy grass or blowing heavy snow--the mower and blower are driven directly via a PTO, not through the transmission. It might be when plowing really heavy snow.)

Second, I'm gonna assume that at lower input speeds to the transmission, that there is correspondingly less power driving the pump, and less "max pressure" available to the hydro motor as well as less cooling air from the fan.

So, if now the pump/motor is being taxed with heavy friction due to lots of fluid resistance it starts generating heat that cannot be dissipated quickly and so up go its internal temps. It these temp rises cause further friction, possibly to higher than the engineered range for safe operation, it could reach a tipping point where the friction become so great that the pump motor seizes. I would consider this "extensive transmission damage."

 

Notes

• on all heavy equipment with significant hydraulics, there are separate engine and hydraulic oil cooling systems AND temperature gauges and warning lights for the hydro system
• on 520's (at least on the one I got) there is a temp sensor on the transaxle that lights a warning light on the dash if it gets too hot

So that's my 2¢. 

Edited February 16, 2022 by Handy Don

[kpinnc 14,663]

I think all we can do with these hydros is make "educated guesses". As an Engineer myself, I'm regularly shocked at what triggers warnings like the one Jeff has in the thread. 

 

We all know that none of these machines are new anymore. Some folks babied them and maintained them religiously- but most didn't. They worked the absolute crap out of them to the point of abuse and only thought about maintenance when something broke. We often inherit what's left over...

 

Oil qualities have changed for the better. We can order the most oddball grade by the case now and have it delivered on Sundays. When these machines were built, and the manuals written, that was not the case.

 

So while we have some challenges sometimes, we have better tools for preserving our machinery than people had 30-40 years ago. For me at least, the manuals are just a starting point now. We have to make the best decision we can. 

 

Fresh 15w50 oil won't harm an Onan with 1000 hours on it. Old black 30w half full will.  Ask me how I know... And somewhere between half and full throttle will be sufficient for a hydro if you keep fresh oil and clean filters and cooling fins.

Edited February 16, 2022 by kpinnc

[RED-Z06 2,582]

On 2/12/2022 at 6:13 PM, Horse Newbie said:

After not starting my 1994 520H for about 1.5 months, I need to install a primer build on mine. It was slow to start today.

I need these wheel covers

[Jeff-C175 7,206]

14 minutes ago, RED-Z06 said:

I need these wheel covers

 

I need two sets!