Oil Pressure woes

[paintballrocker]

Ok guys so '02 s10 4.3, 160,000 mi.

Normally at 190* it will idle around 600 with 25-30psi oil pressure and climb to around 40-45ish while driving. Ive had a slight lifter tick for the last 10,000 or so but it has never gotten worse.

Today while driving it dropped to around 2-10psi at idle warm, setting off the check gauges light.and would only climb to about 30 while driving under load (I was hauling some lumber). The few times it did dip to around 0 for a second or two while going to D to R or to P. Never ticked any worse than normal or knocked.

So i drove right home making sure to hold the brake and give it slight gas at stops to keep it up around 20psi. Right away I changed the oil and filter, i always use 5w-30 non synthetic. Started it up and hard normal psi for a cold start, sightly above 40. Went for a drive but once it warmed up it would drop down to close to 0 and trip the check gauge light.

Now I am at a loss, do you think it is the pressure sensor/sender or the pump going out?

Also not sure if it matters but I changed my upper and lower rad tubing cause they were leaking and changed the thermostat to a stock replacement 190* one. After doing that maintenance I noticed it is warming up real quick, but does not go over 190*.

[paintballrocker]

also the oil was only a month old, no shavings or glitter. just little black sludge particles ont he last few drops. So the lack of metal in the oil makes me think it is not bearings (either main or cam)

[HenryJ]

How many miles on it?
Might be worth putting a good gauge on it to REALLY check the oil pressure?

[paintballrocker]

the truck is going to get pressure tetsed with a mech gauge on friday. I hope it is the sensor or maybe the gauge motor as the gm dashes are known to fail. I really really hope i am not heading towards a rebuild at onl 160,000

[HenryJ]

Any leaks at the pressure sender?

[paintballrocker]

Havent checked yet, but thats a good idea. I already ordered a new sensor even though im not pressure checking it till friday.

Depending on what the pressure check says and if the new sensors fixes anything, i might change up the oil to a 10w-30 or 5w-40 and see if the thicker oil helps at all.

From my research the sensor/sender unit will cutoff the fuel pump at 4psi or lower, so when my gauge dipped down to zero i dont believe it was truely zero since it didnt shut off.

[HenryJ]

I don't recall, but there may be separate sensors for the oil pressure and fuel pump cut-off. I would have to dig into the books that I let go to find out though

[AVTekk]

Did you get it fixed? Usually the sender is the culprit.

[paintballrocker]

not yet. I had to work this weekend so my truck actually went to a mechanics shop for the pressure test. they said to change the, which i already ordered. so im just waiting for that to get here.

Any advice or tipsfor changing one out? I know its behind/below the distributor

[ApproachMedium]

Most likely that sensor is your problem. My first first gen S10 behaved almost exactly the same, and it was the oil pressure sending unit. They are usually wired directly to the FPR on most GM cars, however I would have to double check the schematics on an 02. Most likely if they are not directly tied together, they probably are signaled via the computer if the oil pressure drops to cut the fuel pump.

[paintballrocker]

yes, from what I researched it cuts out the fuel pump relay at pressure below 4psi

[paintballrocker]

So I pulled the pressure sensor, it was leaking out the back of the sensor where the plug goes. Put in a new ACDelco sensor and so far oil pressure is back to normal, idles at 20psi and goes to 40 under load.



Im guessing a seal inside the sensor went out causing it to leak out of the back

[HenryJ]

Sounds very reasonable. Glad you fixed it!