1872 Oil Pressure Switch

[FrankF3]

My 1872 had a close call last week when my father was borrowing it to mow his lawn while his 1862 is in for repairs. (It's ironic one of the repairs on the 1862 is the oil pressure switch leaking) While he was running the 1872, the oil pressure switch let go and just about pumped the crankcase dry. It was starting to get really noisy by the time he noticed it. Since I already had the oil pressure switch in hand for his 1862, I simply used that switch to keep it going. Fast forward about a week and while mowing last night, the switch I replaced last week is leaking this week right by the spade connector. There is no oil present by the threads if the sending unit so the thread sealer I have on the threads is keep that dry.
I called the dealer and was told to check the crankcase breather for problems. I cannot see how crankcase pressure could cause the oil pressure switch to leak. The only thing connected to the switch is the oil galley which has oil pressure when running. Am I missing something here? If there's a problem with the Kohler oil pressure switches, (which at this point I am beginning to suspect) could I use an oil pressure switch from my chevy dealer? I have a chevy years ago that went well past 100K miles and never had a problem with the oil pressure switch. What do you think? What pressure does the Kohler switch indicate low pressure at?

[Sam Mac]

Put an oil pressure gage on it and be done with the problems. Crank case pressure should have nothing to do with the sender. You can relocate the hour meter under the hood and put the oil gage in the hour meter hole.

[FrankF3]

Sam, that's exactly what I told the dealer when I called about leakage on the new switch I just installed. He was pretty much adamant about crankcase pressure and the switch. I told him I don't know how that can be since the switch is connected to the oil galley. He rambled out something that if the crankcase pressure is off them all other pressures are off ??!????? Didn't buy it but stopped arguing to get a replacement switch. The gauge does sound like a good idea......

[Mike McKown]

Originally Posted by FrankF3

Am I missing something here? If there's a problem with the Kohler oil pressure switches, (which at this point I am beginning to suspect) could I use an oil pressure switch from my chevy dealer? I have a chevy years ago that went well past 100K miles and never had a problem with the oil pressure switch. What do you think? What pressure does the Kohler switch indicate low pressure at?

FWIW (), Chevy oil sending units had problems with them leaking also, just where your's is. I think the Chevy senders closed at about 5-7#'s.

The main problem that causes failure in them is heat. If you have room, use a short nipple to get the sender away from the heat. Or, just forget it and take your chances.

[J-Mech]

A "chevy" oil sending unit would be too large (not enough room) to mount anyway. I'm sure you could order one from a parts store just like the kohler one. Either way, I like Sam's idea best.

[jigbuilder]

Hmmm, sounds familiar.
Two summers ago I changed the oil/filt on my '92 1862 cub. Mowed for a hour or so and stopped for lunch. As I idled it back the M18S rattled bad. Shut it down and found oil all over the front of the tractor. A check showed no oil on the dip stick. KRAP.
The oil pressure switch let go and was leaking out the end. Put just over a quart in the engine and it fired up and sounded normal at wot and idle.
Installed a new switch and mowed for 15 min but still rattled at idle. Well the cub had mowed 3-5 acres for 20 years so figured a engine over haul the next winter so bought a new zero turn.

Messed with the cub that fall and found no oil going through the filter. Hot engine and cold filter.
Had a extra Kohler oil filter from the zero turn deal so put it on. The engine has ran perfect with no more rattling at idle or any rpm. It still runs and uses no oil as it always has.
I guess the new filter stopped flowing for whatever reason and blowed the end of the pressure switch out. Any thoughts ??

[J-Mech]

Originally Posted by jigbuilder

Hmmm, sounds familiar.
Two summers ago I changed the oil/filt on my '92 1862 cub. Mowed for a hour or so and stopped for lunch. As I idled it back the M18S rattled bad. Shut it down and found oil all over the front of the tractor. A check showed no oil on the dip stick. KRAP.
The oil pressure switch let go and was leaking out the end. Put just over a quart in the engine and it fired up and sounded normal at wot and idle.
Installed a new switch and mowed for 15 min but still rattled at idle. Well the cub had mowed 3-5 acres for 20 years so figured a engine over haul the next winter so bought a new zero turn.

Messed with the cub that fall and found no oil going through the filter. Hot engine and cold filter.
Had a extra Kohler oil filter from the zero turn deal so put it on. The engine has ran perfect with no more rattling at idle or any rpm. It still runs and uses no oil as it always has.
I guess the new filter stopped flowing for whatever reason and blowed the end of the pressure switch out. Any thoughts ??

Well, the ail pressure switch should have been able to handle the pressure. The oil pressure regulator should have opened and not let it go so high..... but, I suppose it is possible given it was old... I'm really more interested in why oil wouldn't go through the filter. Was it the wrong filter? Was it plugged? Did you cut it open to see why there was no flow? ????

[inspectorudy]

I went with the pressure gauge two years ago and it has been the solution to worrying about the light or the sender not working. Here are a couple of pictures I took of the job.

[Mike McKown]

Originally Posted by J-Mech

A "chevy" oil sending unit would be too large (not enough room) to mount anyway. I'm sure you could order one from a parts store just like the kohler one. Either way, I like Sam's idea best.

FWIW, some Chevy's use the same size/style oil sending unit as the Kohler. Should be no clearance problem.

Corvair and early V-8 SB's.

Some later engines used a larger sender that resembled a very small mushroon can.

[inspectorudy]

When I went to buy a new sending unit from the auto parts store I would always ask positive or negative ground. None of the new parts had this listed on the part box and unless you have an actual part number they cannot answer that question. It does make a difference.