Power steering issue

I'm curious what is considered "overheating"? Does it get so hot the oil boils over? I think P/S systems, like all hydraulic units, run warm. I always ran ATF and on older trucks, I don't recall a filter on the P/S.

 

Filter's in the reservoir.

 

Most anything after 2000ish. Went to straight 15w40. I don't exactly have a answer why. I didn't see a problem with either.

 

the resevoir on my peterbilt says only use dexron III . didnt know u could use regular 15-40 woulda been much cheaper then that atf

 

Well that's a surprise to me. My 2000 I switched to 15w40 years back when I had system torn down.


Like I said, I can't exactly give a better answer. On how or why. Sorry, and I have experienced no issues. Maybe other know more. It was pretty standard practice in my experience.

 

I always thought it was the older Trucks that used motor oil. Not all, but some. The idea was if it leaked into the engine, it’s only oil. I always used the latest greatest Dextron. To me hydraulic oil makes sense. Never heard of a PS cooler.

 

I'am not a expert on all the systems .. the Peterbilt's are what I'am most familiar with
The older systems like on the 359's & early 379's All recommended the use of ATF
The later 379 & 389 all Recommend Dexron III just rebuilt a system on a 07 379 last week the parts person at the Peterbilt dealer said ( some shops and customers use hydraulic oil. But our shop use's Dexron III
Just like what @D.Tibbitt said there is a sticker.on alot of Reservoirs on the Peterbilt's I've been around that says Dexron lll
1 thing is for sure every system has a filter .. that is a fact that was a Discussion on TTR a couple weeks ago about that

 

Gear and pump manufacturers offer multiple fluids that are approved for use across many applications. I too remember many older trucks with engine oil, especially twin gear systems with the larger reservoirs.

I think ATF is a good choice especially for colder climate.

Back in the 90s we had a Chevy WT with 5speed trans that failed early in life. Local rebuilder told us to switch the lube from ATF to 10w30. Never a problem after and it shifted so much better than it ever did from new.

I don’t think the fluid type will fix the OPs issues, agree we need more info.

Good discussion….

 

How is it overheating? What are the symptoms? I've seen bad ground issues use the steel braided pressure hose as a ground. Burnt up the hose over the course of a day

 

IIRC Dexron 3 is equal to about 8 weight engine oil. It will flow a lot nicer than 15W-40 in the cold.

I was told a long time ago that if you mix ATF with engine oil in the power steering it'll take out seals. No idea how much truth is in that and I've never verified it. Could just be an old wives tale for all I know.