Larger Hydraulic Oil Cooler

FOURTEEN · Jun 15, 2004

"" the temp gauge on the dash reaches 240 more often than not ""

My PT-425 (new 2/4 with 85 hours) hot hydraulic temperature averages 90~100 degrees above ambient.

"Note that fluid temperatures above 82 C (180 F) damage seals, reduce the service life of the hydraulic fluid and in most cases, will cause the viscosity limits of the fluid to be exceeded. This means that the operation of any hydraulic system at temperatures above 82 C (180 F) is detrimental and should be avoided." "Continuing to operate a hydraulic system when the fluid is over-temperature is similar to operating an internal combustion engine with high coolant temperature. Damage is almost guaranteed." per Maximum Hydraulic Component Life !!

"Oil operating temperature should not exceed 200° F. (93° C.) with a maximum of 180° F. (82° C.) generally
recommended. 120° F to 140° F. (50° C. to 60° C.) is generally considered the optimum system operating temperatures. High temperatures result in rapid oil deterioration and may point out a need for an oil cooler or a larger reservoir. The nearer to optimum temperature, the longer the service life of the oil and the hydraulic components." per General Recommendations !!

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Clarke · Jun 15, 2004

My 425 66 hrs. often operates above 220 degree f with the oil cooler fan operating and the coil clean. These temperatures are measured in the tank with a thermister type electronic thermometer. Temperatures at other locations in the system may be hotter. Seems to me a lot of owners complain obout the high hydraulic temps. Seems to effect all the machines. Is this a design flaw or do you think PT tested and these temps are okay.

sg

Yardscaper · Jun 15, 2004

I did clean out the cooler today, and all that was really in there was a small layer of dust. Also, I do not have an audible alarm on my 2445 for low oil pressure or anything else. Not sure if the 2400 series diesels come with this or not, since they are not really meant to do mowing. Does anyone else have a 2445? Does it have a low oil pressure/high temp alarm??

Bill

Sedgewood · Jun 15, 2004

Not sure if the 2400 series diesels come with this or not, since they are not really meant to do mowing. Does anyone else have a 2445? Does it have a low oil pressure/high temp alarm??


I would think it would have the same setup as the 1845, since they share the same Deutz diesel and the temp sender and high oil temp/low oil pressure alarm circuitry is built into the Deutz engine. Here is a picture of the original buzzer on my 1845 just under the lip of the tub behind the left rear wheel motor. The buzzer was so wimpy you could hardly hear it over the engine roar (I could hear it buzz with the key on but the engine not running ie: low oil pressure). Given the not-so-big bucks Power Trac spent on this buzzer it's hard to imagine they would leave even that little bit off the 2445. Maybe the little feller died /forums/images/graemlins/laugh.gif

When I rewired I bought a buzzer from Radio Shack and mounted it in the dash - it's a little better but still not really loud enough.

Sedgewood

FOURTEEN · Jun 15, 2004

"" Is this a design flaw or do you think PT tested and these temps are okay. ""

I mean no disrespect to Power Trac!!!! They build a great tractor! I love mine, and don't know what I would do without it!!

HOWEVER, there are a few thoughts which, at times like these, do nudge my inquisitive nature:

1) Power Trac builds tractors from plate steel and an assortment of 'off the shelf' components. Does this make PT the ultimate source for info on the care of those various components?? Aren't the component makers more familiar with their own design and the requirements for it's longer service life??

2) Power Trac makes it's money by selling tractors. It may be counterintuitive for them to make a tractor so good that a buyer would have no incentive to ever buy another.

3) Power Trac insists that MOTOR oil be used in the hydraulic system rather than HYDRAULIC oil! Strange!! If I bought a car and the manual said to put ATF in the engine, gear lub in the radiator, and antifreeze in the transmission, I would find that strange too!!

4) If motor oil should be used in the hydraulics, why do the oil companies make hydraulic oil??

5) Are the high temperatures, increased wear, failed seals, etc accepted as 'normal wear and tear' by most owners??

6) Would longer life and less repairs in the future justify a significantly higher price tag now??

7) Look at all the benefits this hydraulic oil provides that a typical motor oil doesn't!! ATH

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Yardscaper · Jun 15, 2004

I will have to look for the buzzer tomorrow. I never heard it work from day one and never even knew that one existed until now. I will have to investigate. It is something that I would not mind having due to numerous operators. If it is not on there, I may have to figure out how to wire one in.

Bill

Sedgewood · Jun 16, 2004

If it is not on there, I may have to figure out how to wire one in.


These "before" and "after" wiring logic diagrams I drew up during my fire damage rebuild may help. The senders are behind the left side panel you remove to blow the cooler out, just forward of the alternator. Get a loud buzzer - maybe a backup alarm. I may try one of them next - my Radio Shack buzzer is barely audible.

Any thoughts on why backhoe work would generate the high temps you are seeing? I have found that nothing I do creates anywhere near the heat that mowing does. And you seem to be seeing the same high temps I have experienced while mowing. I wonder if the tight engine compartment on the 2445 is restricting oil cooler air flow too much.

What hydraulic oil temps are you seeing? From all I've read, anything over 180 degrees leads to shortened component life, 160 being a good operating temp. Just where is the hydraulic cooler mounted on the 2445? The 1845 cooler is mounted on the underside of the engine cover and exhausts out the top.

Sedgewood

duane · Jun 16, 2004

Yardscraper,

Are you using full throttle when using your backhoe. Just a thought. The oil flow through the hydraulic cooler comes from the charge pump (integral inlet pump to the variable volume piston tram pump). The charge pump is a fixed geroter type pump, and volume increases with RPM. The greatest amount of cooling for the hydraulic circuit is at full throttle. After working the unit hard, sitting at full throttle with no tram action and the PTO off, the hydraulic circuit should cool down. It may take some time. If you have a surface thermometer, take a reading on the inlet/outlet pipes to/from the hydraulic cooler. You should see a temperature difference. I get about 8 – 10 degrees. If you do not get a temperature difference, then you have an oil flow problem (oil filter clean?), the cooler is dirty/fan ineffective or a combination. If I remember pictures of your model correctly, the hydraulic fan/cooler is up front where it can get a source of un-preheated cooling air. On the PT400 series models, the fan/cooler is on top of the engine bay cowl where it pulls from the engine compartment. Some of the engine bay heat invariably mixes with the ambient air which preheats it some prior to going through the cooler.

As you have noticed, as the hydraulic oil heats up, the tractive torque diminishes. The hot oil thins out and passes through the wheel motor clearances with less pressure drop, thus less effective mechanical torque is delivered. The only way to combat this is to lower the hydraulic oil temperature, or use a higher weight oil that remains thicker at higher temperatures. (i.e.: a synthetic 5W-50). Another hydrostatic manufacturer recommends 10W-30 for regular duty, and 5W-50 for ground engaging work that can create some significant heat. I would love PT to incorporate a 2 speed wheel motor design operated from a hydraulic solenoid that would change the range. Other hydrostatic manufacturers have hydraulic heat issues as well, but having 2 or 3 speed ranges maintains tractive torque. It would be more complex and costly on the PT because of the all hydraulic design. Hope this helps, sometimes I babble too much!

Keep us posted.

dannygw · Jun 16, 2004

( The only way to combat this is to lower the hydraulic oil temperature, or use a higher weight oil that remains thicker at higher temperatures. (i.e.: a synthetic 5W-50). )
For anyone interested in synthetic oil for either hydraulics or use in their engine, Checker Auto Parts has Castrol Syntec 5w50 (and other weights) on sale this week for $3.99/quart. I plan on using the Syntec 5w50 when I change engine oil. As Fourteen suggested in an earlier post, I plan on using it in almost every engine I own. It may seem expensive, but it is really cheap insurance against engine failure due to high temps.

IrTxRx · Jun 16, 2004

As a hopeful futur PT owner, with all accompanying new buyer jitters, I must say this "oil temp" discussion has me a little nervous. Oil at 180 when it should not be above 160... who cares. Oil at 200, 220, 240 with everything appearing to be in proper working order makes me a little worried. Especially since it appears to affect performance /forums/images/graemlins/blush.gif!!! It also is a little concerning to me that it appears to affect all makes and models /forums/images/graemlins/confused.gif.

Could all PT owners who have no trouble with oil temp please make a very boring post saying all is OK with their machine /forums/images/graemlins/smile.gif
Thanks