Situation No. 1
You are ready to perform the first hydraulic fluid change on your 2-year-old utility tractor. You are new to farm machines since you grew up in town but married a farm girl. Thinking that hydraulic fluid is all the same, you go to the local “big box” rural retailer and buy the least-expensive hydraulic fluid. The label says it meets all standards, so you felt good about the purchase. You now brag to the other guys at a meeting about how prudent you are with your money and that there is no need to buy hydraulic fluid from the dealer. This is what they say:
A: Farmer A says you need to get the fluid out as soon as possible since it does not have all the additives the tractor manufacturer wants.
B: Farmer B says you were smart – all fluid is the same.
C: Farmer C tells you that it will be fine if the label says it meets all standards.
D: Farmer D believes you never need to change the hydraulic fluid. It is a scam to get your money.
Situation No. 2
You are adjusting the valves on your tractor, and when you get to cylinder No. 3 exhaust, it is very tight. The specifications are 0.020-inch and 0.025-inch, intake and exhaust, respectively, cold. All the other valves were around 0.005-inch loose. The valve in question had only 0.015-inch clearance. It was 0.010-inch tight. You have never seen that before. Since you are friendly with the guys down at the tractor dealer, you run it past them. These are the responses you receive:
A: Mechanic A tells you that it is normal to find a tight valve occasionally. He says just loosen it up and forget about it.
B: Mechanic B is very concerned. He states that if the lash was correctly set the last time, then the valve is pulling through the cylinder head.
C: Mechanic C says Mechanic B is wrong. If the valve is pulling through the cylinder head, the lash would be loose.
D: Mechanic D claims the rocker arm is bent or failing, and the lash is tightening up.
Answers
Situation No. 1: Farmer A is correct. There is no industry standard for hydraulic or what many call tractor fluids. Even though the container says it meets specific manufacturer standards, that is only partially true.
Most, if not all, equipment companies do not publish all their standards and often require dedicated additives to work with the components in the hydraulic system.
Farmer A gave excellent advice: Drain it out and put the proper fluid from the dealer in the tractor.
Situation No. 2: Mechanic B is correct. The engine is suffering from valve seat recession, and the valve is starting to pull through the cylinder head.
If left unchecked, the valve will usually extend enough that the rocker arm will interact with the retainer, and the lock will come off. When this happens, the valve will drop into the cylinder and usually destroy the engine.
It is crucial to be aware of any differences in clearances, etc., when working on any engine. That is why I check the lash first and then adjust. Unfortunately, some people loosen up all the valves first. If you do this, you can never detect valve seat recession.
