Not such a good day today

[jeeper]

I live in the country. We have several "seasonal roads" around here. A seasonal road is much like a two track. It does have gravel in spots but is mostly just dirt. Or maybe I should say ruts. It is graded by the county once a year usually in the spring. The road is not maintained in winter months.

I took a ride down one of these trails for fun today. When I got about half way down the trail I noticed my oil pressure dropped down to almost zero. When I rev the engine up the pressure goes up to about 30.

I just installed a new sending unit on Friday. When I started the cold engine this afternoon I had about 40 psi. After the engine cooled down this evening I tried it again and had about 30 psi at idle until it warmed back up. Then it dropped back down to just over 0.

I'm guessing my bearings are worn. I'm going to try using 15w40 or maybe straight 30 weight.

This was a temporary engine anyway but I'm not ready for it to fail just yet.

Anyone have any suggestions?

[randyscycle]

Before you do anything, install a mechanical gauge and see what its really doing......

[jeeper]

Thanks Randy. I need to locate one of those. In the mean time I got to thinking about this. Maybe you can correct me if I'm wrong.

My engine came out of a 1993 chevy. It has a gauge sending unit by the oil filter. It also has a oil pressure switch near the distributor. I have my electric fuel pump running in series through that switch. If there is no oil pressure I would have no fuel pump running.

So my question is at what pressure does that switch turn the fuel pump on?

I'm assuming I need at least 4-5 psi to activate the switch?

So if my gauge is reading 0 but my fuel pump is still running my gauge has to be off by at least the amount of pressure needed to activate the oil pressure switch?

[kwai]

I use 20W50 high mileage valvoline in my wore out sbc 350. Fixing the oil leak on the oil pressure guage, keeping the oil full (it does exactly as you describe when it's 2 quarts low) and using the heavy weight oil give me good consistent 50 psi oil pressure.

[O.D. Fever]

Sometimes the oil filter will implode, same causing low oil pressure after warm up. Its cheep , just change it and see if it is the cause.

[Don Cavey]

Sorry if this is somewhat OT.

Thanks for the answers. I have a similar problem with my 96 Jeep Grand Cherokee. I went to 20W50 a few years ago and it helped. But it is doing it more this summer than before. I may have changed the oil and put the recommended 10W30 in and that would be the answer. As for the filter, I will make sure it is a good one like Purolator or NAPA. I will bet the bearings are worn (170,000 miles, 318 CID).

[randyscycle]

No matter where the sending unit is in the oil galleries, it should get the same pressure reading, so if you have low pressure at the sender, you'd likely have low pressure at the switch that controls your fuel pump too.

Any auto parts store that sells the cheap gauges should have a single oil pressure gauge. Just buy the line kit and install it temporarily and route it out onto the hood or somewhere you can see it when you drive and go out for a ride until everything is nice and up to temperature. See where your pressure is then.

Ar e you running an electric gauge currently? If so, I'd ditch it anyway for a mechanical one just for peace of mind.

[Tyson]

My 95 ford ranger had oil pressure problems too. Turned out the oil pan gasket deteriorated and all the little rubber parts found there way into the pan. The screen on the oil pick up was so clogged that it wouldnt let any oil through. I replaced the pick up tube and I now have a consistant 50psi

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[Don Cavey]

My 95 ford ranger had oil pressure problems too. Turned out the oil pan gasket deteriorated and all the little rubber parts found there way into the pan. The screen on the oil pick up was so clogged that it wouldnt let any oil through. I replaced the pick up tube and I now have a consistant 50psi

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Thanks. That's good to know. A friend of my, a retired automotive machine shop owner, suggested getting a high volume oil pump in lieu of an entire engine rebuild. So, if I go that route, I could "kill two birds with one stone" as they say...

[jeeper]

Thanks. That's good to know. A friend of my, a retired automotive machine shop owner, suggested getting a high volume oil pump in lieu of an entire engine rebuild. So, if I go that route, I could "kill two birds with one stone" as they say...

I don't know if it is true or not and don't want to spread false information but am curious what others think about High volume pumps?

I've read on other sites that a high volume oil pump is a bandaid at best and can actually cause more damage to the lower end at high rpm's. My understanding of what I read was that a high volume pump can actually pump the whole oil pan sump up to the top of the engine too fast leaving the bottom end without oil.

No matter where the sending unit is in the oil galleries, it should get the same pressure reading, so if you have low pressure at the sender, you'd likely have low pressure at the switch that controls your fuel pump too.

So at what pressure does an oil switch activate?