Ok, I've had this vehicle since new. It has 165k miles, 2WD with 4.3 v6. In the last couple years I've replaced the rearend, transmission, and water pump. Now, in the last few months I've noticed the low oil pressure issue. When started cold, the pressure is just under 20 but after warming up it drops to 15 or a little less. When I stop at redlights the pressure now drops to 0 and check gauges light comes on. Once I accelerate the pressure goes back up a bit and the check gauge light goes off. I'm really nervous driving it like this and I've gotten in the habit of pushing the accelerator a little while stopped just to keep the pressure up and the check gauge light from coming on. Is there anything I can do? I really don't want to sink anymore money into this vehicle, especially after the $1500 transmission. There's no oil leaking from the engine and I've not had to add oil or coolant at all, I check levels regularly. Any suggestions on what I could do to remedy this problem without dropping much $$$?
Thanks.

 

I would try a mechanical gauge that you know is good. Could be a bad sending unit, had that happen on a pickup several years ago, I tore id down and put in all new bearings in and still had the same thing new sending was all it needed.

 

i would try some seafoam. put about half a can of it into your oil. drive it for 50 to 100 miles then drain the oil and put fresh in. what it does is cleans all the oil passages lifters oil pump screen and just the hole engine. i did that whith a 97 jimmy with lifter noise ticking and it went away after the seafoam. but DONT forget to change your oil after 50 so miles. and with the 4.3s the oil pressure is common to drop to 10psi at a stop light and considered safe. oh and the oil sending unit could be gummed up not giving you the right reading but acutally has 40psi. so the seafoam would help.

 

Seafoam works great but with a higher mileage engine I'd be a little scared to use it. I tried it on an old honda I had yrs ago with over 200k on it. After driving it about 50miles I drained the oil and put good in. The car smoked after that. I'm assuming the seafoam cleaned out all the gunk, but some of that gunk was actually helping some of the seals in it. Either way the stuff will clean your engine out for sure.

 

So if it's a bad sending unit then does that mean the actual oil pressure is not dropping like the gauge says it is? Also, how hard is this to change? When I'm at idle at a stop light and the pressure drops to zero and the check gauges light comes on the vehicle starts kinda vibrating or idling rougher. Is that a sign that the pressure is actually dropping to zero? I may go ahead and try the seafoam this week and see if it helps.
Thanks.

 

Replace the stock oil pump with a High Volume oil pump:

Melling M-55HV - Melling High-Volume Oil Pumps - Application - SummitRacing.com


Looks like that will fit your 4.3
It'll increase psi via more volume being pushed up than a stock pump.

 

I'm having the same oil pressure problems in my 01 blazer, it started about a month ago, with only about 500 miles left til the next oil change, I used 5w 30 syn blend, thinking that the oil was too thin and that, that oil was causing the pressure to drop to zero at a stop, I changed it to 10w 30 just yesterday, drove home from my dads house and as soon as I parked in my driveway oil dropped to zero again!!! Urgh...any ideas? I've had two people tell me that it was the oil sending unit behind the distributor, which I thought was new. engine has 140k miles on it.

 

Your problem maybe your oil pressure sensor (located behind the distributor on the right side - in a horizontal position). I had a simliar problem on my 02 blazer the sensor cover cracked and leaking oil. In order to repair you have to remove the distributor. That is the only way to replace the sensor. I'm doing this repair(for the second time) at the present you - also need a oil pressure sensor socket to remove and replace the sensor. I hope this info helps.

 

Ok...I've replaced the oil sensor with a new one, however, the oil pressure still bottoms out to Zero on the gauge when the motor reaches operating temp. It does it only when I come to a complete stop. . . not only that but I have no idea on how to set the timing of the engine, the distributor was set back in, but a few degrees off so I've learned, and I don't know how to fix it nor have the money for a mechanic to fix it. On the oil problem, can it be a faulty gauge? I sure hope so, because at this time, I can't afford to pull the motor out to replace the oil pump. . .urrrgh HELP!!!

 

my blazer is an 01 Xtreme, 4.3L V6...thanks guys for your help.