Oil & Fuel TC33D oil light at low RPMs?

[BigE_]

Thanks everyone.

Fullpull, yes, I tried two different gauges with the same results, and the sending unit is brand new.

Jinman and IH3444, thanks for the suggestions. I have the service manual for the tractor (well worth the $100), which makes finding all the various parts much easier.

I stopped in at the dealer this morning to pick up a different qd o-ring and they suggested cleaning the filter in the oil pan as well.

I'll do the easy stuff first and then drop the oil pan, but my bet is on the oil pan filter.

Why? The oil pressure goes down as the oil heats up. Now, as the oil heats up, the viscosity is increased, so if there was a problem with the rings, bearings, etc., the higher viscosity would help seal these better, thus increasing pressure. The same deal would go for the pump.

Conversely, if there is an obstruction in the path before the pump, higher viscosities would tend to plug this further, thereby lowering the oil pressure as it heats up. Given that there is a filter before the pump...

Of course, I'm no mechanic, just trying to apply physics and common sense to the situation.

I've got company coming to visit tonight, and tomorrow is my son's birthday, so its looking like Friday would be the first day I'd be able to work on the tractor again.

Regards,
-Steve

 

[jinman]

Why? The oil pressure goes down as the oil heats up. Now, as the oil heats up, the viscosity is increased, so if there was a problem with the rings, bearings, etc., the higher viscosity would help seal these better, thus increasing pressure. The same deal would go for the pump.

Conversely, if there is an obstruction in the path before the pump, higher viscosities would tend to plug this further, thereby lowering the oil pressure as it heats up. Given that there is a filter before the pump...
-Steve

Steve, I think you have that heat/viscosity thing backwards. As oil heats up, it thins out (viscosity decreases) and the pressure drops. If your rings/cylinder walls were worn, the decreased viscosity would cause the engine to smoke more as it warms up. If the bearings were worn you might hear knocking or more engine noise.

Those of us with a pressure gage for oil pressure know that it is always higher when the engine is cold. As the engine heats up and viscosity drops, the pressure always goes down slightly.

I still strongly recommend checking that pressure relief valve before doing anything else. Your pressure would react exactly as you describe if it relief valve was being held open by a glob of guk.

 

[BigE_]

Jinman,

It makes sense to me that oil thins out as temperature increases -- I've seen it first hand. I'm looking at Oil Viscosity and the Multigrades section.

"Multigrade oils typically begin as base oils, such as 10W. Then viscosity-index modifiers (polymers) are added in an effort to stabilize the viscosity. This allows a 10W40 oil to flow like a 10W at cold temperatures and a 40W at higher temperatures"

This is what was confusing me, and I think they might it backwards. I'm running 15W40, and based on the above, the viscosity should increase as the temperature goes up.

No visible engine smoke except when first starting, so that is a good thing.

After changing out the oil, the engine did appear to be quieter at higher RPMs. At first when I was checking the oil pressure I thought I hadn't run throttle up to the proper RPMs.

I'll see if I can find 30 minutes to check the pressure relief valve tonight. It would be *really* nice if that fixes the problem.

 

[dqdave1]

I would check the pressure relief also. Located by oil filter. Did you add any type of cleaner to old oil? If you did I would discard oil in it now as it has some cleaner in it also. If you did not add cleaner; you could save the oil. You may want to dump the oil and fill with kerosene and let it sit. If pickup screen is clogged, this may unclog it. I find it highly unusual that a machine with this amount of hours would have bearing problems; which it may be. Hour meter may be way off.

 

[BigE_]

Tonight after the kids were in bed I got some time to work on the tractor. I've attached a few pictures. All I had with me was the cell phone, so pardon the quality.

It took me a while to find the oil pressure relief valve, even though I had pictures of where it was supposed to be. I finally took off the FEL, and that made life a lot easier.

Removal of the 7308 loader took a while to develop a technique, but here's what I finally puzzled out (no manual for this). Only managed 1 scratch....

1.) Find a nice level place to park the loader, OUT OF THE WAY OF THINGS (mine currently isn't)
2.) Raise the loader and completely dump the bucket
3.) Lower the loader to the ground
4.) Set parking brake, get off tractor and remove pins from the quick detach
5.) Move the levers so that the flaps loosen up and lower / flop loose.
6.) Remove any straps holding the hydraulic hoses in place
7.) Raise the loader and slowly start backing (take off the parking brake) at the same time
8.) After the loader is off and on the ground, shut off the tractor
9.) Move the loader control joystick around in a circle a few times to equalize pressure
10.) Detach the quick disconnects and put the covers on

Things I learned:
If you can't get the quick disconnects to re-connect, a LIGHT tap with a hammer on the male end will relieve some of the pressure and let you reconnect. It will also spray hydraulic fluid on the tractor and you if you aren't careful.

Level ground is important. That's why I got the scratch on the hood.


OK, on to the oil pressure relief valve. As you can see from the attached picture, it well behind quite a few things. At a minimum, it looks like I'll have to detach what looks like an oil temperature line, remove the dipstick, and remove the fuel filter and sediment bulb. I'll probably have to remove the oil filter as well, which will probably mean draining at least some of the oil.

I tried to get a crow's foot back there, but my biggest (22mm) wouldn't fit on the bolt. I'd love to be able to remove what looks like the main hydraulic line, but something tells me I'd likely make a mess doing that. True?

Since it was 10:30 at night (beautiful out with the full hunter's moon, though), I decided to call it a night and come on inside.

 

[jinman]

Are you sure that's the relief valve? I'm not saying it is not, but I see something else in your picture that looks more like the relief valve. It's below and slightly to the right of your oil filter. Don't know...just lookin' over your shoulder.

 

[jinman]

Well, I went back and looked at the NH diagram on the website and I think you are correct. I'm attaching the diagram with the relief valve being item number 38.

Darn! I posted the wrong diagram! To make it worse, I can't delete that last post because only a few of TBN's buttons work on this machine. Don't know why...I can't even edit a message. I know how...the buttons are just dead. They all work on my computer at work, so I'm sure it's a problem here only.????

see new attachment...

 

[dqdave1]

I don't know about you, but anything I want to remove is always located in a position that requires removal of many things. I have never had to remove the oil pump either but I am sure it will be a challenge. For the bright side; you will provide all of us with valuable information.

 

[BigE_]

I have the exact opposite problem: the buttons all work at home, but only a couple work at work, so I know how it goes.

I got a couple more to work correctly by setting all my security settings to default (from high) and disabling my ad blocker, but I still can't get the formatting buttons to work. (Tools --> Internet Options --> Security)

If that isn't the pressure relief valve, then I don't know where it is. I was looking at the same picture you posted. I'll take a better picture later on today. Found my camera.

 

[BigE_]

That bolt you see below and to the right of the filter holds the hydraulic diverter valve in place. (At least I think that's what it is called). Large hydraulic line running to it, small ones going away from it.