Hydraulic problem followup

A case of STP?

F. George McDuffee fired this volley in news: snipped-for-privacy@4ax.com:

Or just some higher-viscosity oil designed for worn systems.

A 25% drop in pressure cold-to-hot could be anything, not only the pump, and _including_ the pressure relief valve spring. But it could just be worn-out oil.

Lloyd

Yes, you got it all nailed down.

This is a great plan. Check out the engine's main seal at the same time.

I was in to a hydraulic shop have a cylinder repaired on my backhoe just last week, what they told me is that with pumps they don't actually rebuild, instead they simply replace the worn parts with new or remanufactured, which in your case are probably about as commonplace as they get.

IMHO, you're penny wise and pound foolish to not replace the releif valve when you are there. A relief valves gets HARD use on an open center system and is a common failure component. Its a high labor/low cost item to replace later.

But then, I tend to do a lot of rebuilding when I tear a tractor down. This has REALLY reduced my breakdowns.

Same applies to old hoses that bend often.

Breakdowns cost 5 times the cost of repair

In many cases a (whole) lot more than that.

The tractor doesn't use or leak oil from the engine. Eric

In my case any rebuild would be as you describe. Aside from the end plates that seal against the gears, which I may fix myself. But I'm betting that just installing new parts will be cheaper. Eric

Then I guess I'll replace the relief valve too if it is likely to be a problem. Eric

If I made money with my backhoe then I would be buying new tires for it too. And I would replace a couple worn cylinder seals. But this machine just gets used by me to do chores on my 10 acre parcel. It is fun and relaxing. Most of the hoses have been replaced in the last few years, but there a couple that were pretty new when I bought the backhoe and they won't be replaced by me unless they fail. Eric

Repeat after me, Unka.

STP is not oil.

STP is not oil.

STP is not oil.

STP is not oil.

STP is not oil.

STP is not oil.

STP is not oil.

STP is not oil.

STP is not oil.

STP is not oil.

STP is not oil.

STP is not oil.

I ran my old '61 mini on STP with SAE50 oil added to it for several months untill I could tear the engine down and rebuild it. Started with SAE50 and a can of STP. Added a quart of #50 every 30 miles or so, and another can of STP every couple of quarts. It was nasty stuff to drain when I pulled the engine. (and reallynasty stuff drained out of the exhaust when I stood it in the corner. The Mini had 196000 miles on it when I bought it - I think 214,000 when I rebuilt it. It was getting 50MPG of gas and about 120 MPG of oil (if you can call the thick mixture oil). The rings were very fragile with no tension when I tore it down (most snapped like glass). Strange thing, with that mileage, it went together with standard size rings and bearings, right in the middle of spec for fit. Just a deglaze on the cyls.

If you have to split the tractor to get to the pump, don't cheap out on the seal. Unless it has been replaced at some point in the not too distant past you would be well advised to replace it while it is apart. Be a real bugger to NOT replace it and have to split the tractor again next spring when you need the tractor - because the seal is leaking.

STP is good stuff, but it's just a chainmaker for the oil, keeping it in film, like Slick50, which adds slickery to it, too.

Honey-oil. I think another product had the Motor Honey name, way back when.

Yeah, amazing!

I had a 1959 Austin Healey Sprite in 1962 and since STP had recently come on the market, I decided it might be good for the Austin engine, SO I added the proper amount.

Next time I changed the oil and filter, all the STP was in the oil filter housing. It would not pass through the oil filter cartridge, which was not paper, like today, but some type of rag material.

I never tried STP again in any vehicle.

Paul

One of the first things I would check is the screen on the pickup line in the tank. You could have stuff clogging up the filter after the machine runs for a while and then falls off the filter when the machine is shut down. So simple to check, so expensive not to.

John

Haven't done a Case, but on Johne Deere, Ford, and International the pickup screen comes out with the drain plug. I always put a magnet in the oil drain stream. Then fish it out when drained. You can see if you got soemthing coming apart by the amount of steel you found.

Karl

I've seen exactly this on an auto transmission - proper line pressure at startup, but as soon as you rev it a bit, it sucked the crud to the screen and lost pressure.