Oil pressure switch?

[AwesomeJ10]

My '88 GW came with an oil pressure switch. This is wired into the ignition circuit and the switch closes when it receives oil pressure correct? I believe the idea is to cut the ignition circuit if there is no oil pressure - a safety thing. Kills the engine if there is no oil pressure. Can also contribute to 'slower' cold start ups on a worn out engine that takes a while to develop pressure.

I don't have this wired up on my FSJ's. I believe they will start 'faster' without the switch because it doesn't have to wait on oil pressure to start firing the plugs and the injectors.

What are everyone's thoughts regarding oil pressure switches? Good idea? Bad idea? Why?

[Stuka]

I was not even aware grand wags had such a thing. Even most newer vehicles don't have them.

I do not think they are a bad thing, but if you keep up on your oil, not a needed thing either. Unless of course you have some major failure where all the oil drains out quickly. Like you hit the oil pan on a rock or something.

[oakknoll]

I have these switches on my small engines (Honda, Kohler, Kawasaki). They often don't work correctly. They either fail and won't allow the engine to start, or they kill the engine when working on a slope. I have disconnected them without causing engine damage. I've never heard of one in an automobile engine, especially a Jeep. I would be interested to hear if anyone else has one.

[ClovisMan]

I thought the point of them was to be wired into an e-pump circuit in case of rollover, etc.?

[pyro]

i was under the impression that an "oil switch" was another name for "sending unit". at the local auto parts place they list the sending unit as a switch.

[RustyJoe]

From the factory, at least my 89, has a switch (sending unit) near the oil pressure gauge sending unit. This switch was used to turn on the electric chock after oil pressure is started, not for stopping the engine. This was to keep the electric choke from pulling off too quickly, especially if you sit with the key on for a while before starting the engine. Is this the switch you mean??

Russ

[adzam]

From the factory, at least my 89, has a switch (sending unit) near the oil pressure gauge sending unit. This switch was used to turn on the electric chock after oil pressure is started, not for stopping the engine. This was to keep the electric choke from pulling off too quickly, especially if you sit with the key on for a while before starting the engine. Is this the switch you mean??

Russ

Yah it's for the electric heater in the black choke cover. it's not connected to the ignition in any way.

[AwesomeJ10]

I should take a pic. The factory oil pressure switch is located right where the oil pressure sending unit it. They tee off of each other. Removing it from the waggy allows for much faster cold start ups.

Just wondering what everyone's thought was?

I'm thinking about tying it back into my TBI harness to cut power to the ECM when there's no oil pressure. I can see how this would be handy during an accident.

[chevelleguy]

From the factory, at least my 89, has a switch (sending unit) near the oil pressure gauge sending unit. This switch was used to turn on the electric chock after oil pressure is started, not for stopping the engine. This was to keep the electric choke from pulling off too quickly, especially if you sit with the key on for a while before starting the engine. Is this the switch you mean??

Russ

Yah it's for the electric heater in the black choke cover. it's not connected to the ignition in any way.

X 3

[lindel]

Welcome Sir! Glad you made it over!

[letank]

From the factory, at least my 89, has a switch (sending unit) near the oil pressure gauge sending unit. This switch was used to turn on the electric chock after oil pressure is started, not for stopping the engine. This was to keep the electric choke from pulling off too quickly, especially if you sit with the key on for a while before starting the engine. Is this the switch you mean??

Russ

2X, the only issue is when the switch fails, it tends to deactivate the choke heater circuit and your choke not fully open or close... and the engine will die.... useful when you run out of oil... but bad when you failed to realize what is happening... I ran out of gas again.... Mine is acting up, and is jammed open.... I really need to change it, but with our mild weather it starts most of the time at first crank.

[wedgetail]

I've never heard of one in an automobile engine, especially a Jeep. I would be interested to hear if anyone else has one.

I know for sure old landcruisers have them. Newer ones I'm not so sure, but I'd bet they do as most things stay the same (with 40 and 70 series anyhow). I'm not completely sure about them, but I think on the whole I like the fact they're there. Especially when someone borrows it... They work with a capacity as a timer for starting so will kill the engine if pressure isn't up after 10 seconds or so. Then kill it immediately if pressure drops when running. Problem is when the vehicle is old, cap is worn and oil pressure is lower (like 350k km +) it can mean starting takes two or three attempts to start when it's been sitting a couple of weeks unless you rev the piss out of it.