Oil Pressure Problems, and Possible Oil Pressure Switch Replacement?

[zsiya]

Quick question: When I remove my old switch, will I have a stream of oil coming out? I won't be changing the oil as it was just changed. DIC said "stop engine" twice in the past month and seems the switch may be the culprit as the engine still has oil.

'02 EXT LT
I6
63,000 miles

 

[IllogicTC]

Quick question: When I remove my old switch, will I have a stream of oil coming out? I won't be changing the oil as it was just changed. DIC said "stop engine" twice in the past month and seems the switch may be the culprit as the engine still has oil.

'02 EXT LT
I6
63,000 miles

Just because there is 7 quarts in the sump doesn't mean it's getting up and around properly - this is key to understand! If you'd still like to try replacing your oil pressure switch first to ensure it's not the issue, you may get a bit of oil coming out of it but it won't be (or shouldn't be) a whole ton. Having a 1-quart bottle on hand to replace any potential loss should be more than enough as long as you give sufficient drain time.

It's also interesting to note that the oil pump was redesigned for the 2003 model year. I find this important to note as it must have been enough of a problem to immediately do a redesign on it. Consider getting your oil pressure actually tested (not the faux reading the PCM gives for the I6) as you may have a simple crappy switch, or you may have a serious problem. Not trying to send up alarms, just trying to be cautious. And 63k miles is a nice low number for a vehicle that old, my 05 has 107k

And it's a stupid question but you just never know - did you make sure to change the filter along with the oil?

I'd also like to welcome you to GMTNation. Make sure to stick around, you never know if something else will crop up and between all of us we've seen probably every issue ever to happen on a TrailBlazer or Envoy

 

[zsiya]

Yes, the filter was changed. With a redesign that early, was there a recall or TSB to look for?

 

[IllogicTC]

Yes, the filter was changed. With a redesign that early, was there a recall or TSB to look for?

Not that I can remember. I do have a tidy little collection of TSBs, too. Speaking of which, if you'd like to have a look, they're hosted here: https://mega.co.nz/#F!NhxTCQ6R!zc6F2JWbC1yj3KdqoajX6w You can get them freely on the PC, on a phone will require the MEGA app if you're into that.

I knew it was a dumb question but trust me, you never know you are certainly welcome to try swapping out the switch and seeing if that makes any sort of difference, but I would still err on the side of caution and also have the oil pressure tested. The stupid Kent-Moore (Spent-More) "official" tool from the service manual is crazy expensive. Like $70 I think it was just for the adapter, that's not including the gauge. I'm sure there are cheaper alternatives to be had if you'd like to test the pressure yourself. If you're married, it's a great excuse to expand your toolbox.

 

[gmcman]

When I pulled my switch the oil just dribbled a little, a paper towel will suffice.

 

[zsiya]

Not to beat this horse, but two more questions: (1) this happened twice. Both times it was less than a mile from home and the engine was still "cold". Does that sound more like a switch? And (2), if it is the pump (still thinking positive!) are there other things to look for aside from the actual pressure test?

 

[IllogicTC]

Not to beat this horse, but two more questions: (1) this happened twice. Both times it was less than a mile from home and the engine was still "cold". Does that sound more like a switch? And (2), if it is the pump (still thinking positive!) are there other things to look for aside from the actual pressure test?

Not really beating a horse as we don't know if the oil pressure gremlin is dead yet

The engine temperature may have something to do with it (oil thickens as it warms up, make sure you're using 5W-30 and not 0W-30) and as far as I know the pressure test could shed a ton of light on things, or maybe it will show absolutely nothing and you end up out-of-pocket because your truck decided to play nice. I'm not sure that the engine temperature alone would really affect the switch, but I'm not entirely sure.

I'm going to modify the thread title to include the oil pressure issue, should get some more people peeking in and helping out.

 

[Mark20]

Not really beating a horse as we don't know if the oil pressure gremlin is dead yet

The engine temperature may have something to do with it (oil thickens as it warms up, make sure you're using 5W-30 and not 0W-30) and as far as I know the pressure test could shed a ton of light on things, or maybe it will show absolutely nothing and you end up out-of-pocket because your truck decided to play nice. I'm not sure that the engine temperature alone would really affect the switch, but I'm not entirely sure.

I'm going to modify the thread title to include the oil pressure issue, should get some more people peeking in and helping out.

I thought oil thins as it warms up?

 

[IllogicTC]

I thought oil thins as it warms up?

Nope, multi-weight oils are one grade at "winter" temps (I assume 0 Celsius), and another at 100 Celsius. 0W-30 would have an SAE viscosity of 0 in the winter, and 30 when it's warmed up. The idea is to cover a wide range of operating conditions. You'd need a thinner oil when it's cold out to make cranking easier and to help get oil up and flowing more quickly from a cold start. Back in ye olde days, the "straight-weight" oils were common, and you'd switch between your summer oil (like SAE 30), to winter oil (10W, for example).

And a fun fact: Tar pitch has a viscosity about 230 billion times greater than that of water.

 

[coolasice]

Nope, multi-weight oils are one grade at "winter" temps (I assume 0 Celsius), and another at 100 Celsius. 0W-30 would have an SAE viscosity of 0 in the winter, and 30 when it's warmed up. The idea is to cover a wide range of operating conditions. You'd need a thinner oil when it's cold out to make cranking easier and to help get oil up and flowing more quickly from a cold start. Back in ye olde days, the "straight-weight" oils were common, and you'd switch between your summer oil (like SAE 30), to winter oil (10W, for example).

And a fun fact: Tar pitch has a viscosity about 230 billion times greater than that of water.

I do believe you have this stated incorrectly... multi weight oils Thin less at Higher temperatures, thus a 0w-30 would have say a thickness of 40 at 20C and 10 at 100C, while a straight weight oil (30w) will have a thickness of 250 at 20C and 10 at 100C (taken from http://www.bobistheoilguy.com/motor-oil-102/)

Oil does thin as it warms up, but will thicken over extend time/use

 

[IllogicTC]

I do believe you have this stated incorrectly... multi weight oils Thin less at Higher temperatures, thus a 0w-30 would have say a thickness of 40 at 20C and 10 at 100C, while a straight weight oil (30w) will have a thickness of 250 at 20C and 10 at 100C (taken from http://www.bobistheoilguy.com/motor-oil-102/)

Oil does thin as it warms up, but will thicken over extend time/use

It may be backwards, my explanation. I had done some more searching after posting and had read more on it, but never got around to editing or adding another post. As I understood it, the multi-weights were supposed to exhibit a lower viscosity at lower temperatures (temp is never stated in my research) and the higher number is the viscosity expectation at 100 celsius. It's interesting that they post a thickness of 10 @ 212 fahrenheit as that doesn't exactly coincide with the SAE numbers on say SAE 30 (straight weight)

 

[coolasice]

It may be backwards, my explanation. I had done some more searching after posting and had read more on it, but never got around to editing or adding another post. As I understood it, the multi-weights were supposed to exhibit a lower viscosity at lower temperatures (temp is never stated in my research) and the higher number is the viscosity expectation at 100 celsius. It's interesting that they post a thickness of 10 @ 212 fahrenheit as that doesn't exactly coincide with the SAE numbers on say SAE 30 (straight weight)

The numbers are not the viscosities, the numbers listed on the bottles are what the oil represents, a 0w-30 will have the same viscosity of a 0-weight oil at 20C and the same viscosity of a 30weight oil at 100c

 

[IllogicTC]

The numbers are not the viscosities, the numbers listed on the bottles are what the oil represents, a 0w-30 will have the same viscosity of a 0-weight oil at 20C and the same viscosity of a 30weight oil at 100c

But in a way DOES represent relative viscosities in a sense.

 

[coolasice]

SAE J300 states it all.

 

[ChrisinVictoria]

I f you are still concerned about your actual oil pressure let me tell you what I did. I took my old sender and tore the plastic off until I had just the metal left. drilled in a 1/4 inch and then tapped it so a fitting for a lube gun would fit. Bought an 18 inch line and a cheap $10 gauge that also fit the line. Screwed the sender back in and I could look at the gauge as the engine was running and had someone accelerate. No stepper motors or false readings. And yes I had low pressure but within GM's incredibly low specs. I think I got the idea from that other site.

 

[Texan]

For the record, could you please post the psi's at idle and 2000 rpm at operating temp.

 

[ChrisinVictoria]

It has been 2 years since I checked mine. I don't remember what it was. I has since swapped the engine. GM specs for an 02 are 85kpa (12 PSI) at 1200 RPM ,at opearating temperature, with 5w30 oil. That's pretty low.

 

[bmcutright]

I just noticed that I'm having this problem. 04 4.2 I6, noticed that the oil pressure gauge on the cluster drops to 20 then to 0 then back to 20 when parked/sitting at idle. Give it a little gas, goes right to 40. This is after the engine has completely warmed, driven 20 miles, plus 90 degree day here in Florida, noticed when I returned home. When the oil PSI gauge goes low, sets off the Check Gages light. No signs of anything wrong (abnormal vibrations, engine has enough oil, etc). How would I check the PSI, besides the PCM? Oil has about 2000 miles on it, per the sticker from the dealership, however the dealership didn't seem to notice the tread had worn off the insides of the front tires, so hard to trust them.

 

[IllogicTC]

You can't even check it via PCM. The I6 is literally, "there's enough pressure," or "there's not enough pressure." The gauge is an extraordinarily-glorified dummy light and they would have been better off (and possibly saved the inattentive their engine) just putting a big lamp in there where the gauge is.

You'd have to get a pressure test kit that fits on either on the oil filter or the oil pressure switch.

 

[bmcutright]

Could this be a problem with the sensor? Gauges? Actual oil pressure? And how do I go about diagnosing it? Anybody have somewhat rare (once every 2 weeks) problem like this?

 

[lint]

I just noticed that I'm having this problem. 04 4.2 I6, noticed that the oil pressure gauge on the cluster drops to 20 then to 0 then back to 20 when parked/sitting at idle. Give it a little gas, goes right to 40. This is after the engine has completely warmed, driven 20 miles, plus 90 degree day here in Florida, noticed when I returned home. When the oil PSI gauge goes low, sets off the Check Gages light. No signs of anything wrong (abnormal vibrations, engine has enough oil, etc). How would I check the PSI, besides the PCM? Oil has about 2000 miles on it, per the sticker from the dealership, however the dealership didn't seem to notice the tread had worn off the insides of the front tires, so hard to trust them.

Same thing but with 3000 miles on oil ,Just started about 2 weeks ego . I have no rattle at zero on gauge so i cant see it being no oil pressure, I guess its time for me to start at the gauge and work to the engine or start at the engine and work to the gauge Thankfully its warm again .I haven't even looked for the sending unit yet or even what it is called in this SUV .

 

[bmcutright]

I'm hoping it's an instrument problem, but i've watched Apollo 13 too many times to think it's "only instrumentation"

 

[coolasice]

Same thing but with 3000 miles on oil ,Just started about 2 weeks ego . I have no rattle at zero on gauge so i cant see it being no oil pressure, I guess its time for me to start at the gauge and work to the engine or start at the engine and work to the gauge Thankfully its warm again .I haven't even looked for the sending unit yet or even what it is called in this SUV .

could just be a bad stepper motor if they were never replaced?

 

[lint]

could just be a bad stepper motor if they were never replaced?

That's what I hope ,and that would be nice, I have been on here for years and the old site and heard people talk about stepper motors and replacing them but never looked for to see the location I was going to start looking for a good post on here this Saturday, But if you know of a good post with pic's of the stepper motor and location please post a link , any help would be appreciated . and sorry for getting off the post direction. But I thought that was where it was going . to begin with.

 

[Hatchet]

Does the DIC(if you have it) light up with low oil pressure? or does the gauge just go down and back up?

That's what I hope ,and that would be nice, I have been on here for years and the old site and heard people talk about stepper motors and replacing them but never looked for to see the location I was going to start looking for a good post on here this Saturday, But if you know of a good post with pic's of the stepper motor and location please post a link , any help would be appreciated . and sorry for getting off the post direction. But I thought that was where it was going . to begin with.

The stepper motors are what the needles are attached to on the cluster.

 

[lint]

Does the DIC(if you have it) light up with low oil pressure? or does the gauge just go down and back up?




The stepper motors are what the needles are attached to on the cluster.

the only light that comes on is the ''check gauge'' light no code. or anything else ... yup gauge goes down once warm at idle ''started to worry me at first'' ,then sometimes jumps around just like bmcutright posted. it goes up some and down like touching two wires together and letting them go before it reaches above 20 or 30 off on ,on off ''sometimes''
the oil gauge '' I use the word loosely'' does read good oil pressure normally .

 

[AtlWrk]

The "check gauges" light and "Low Oil Pressure" DIC message are triggered by commands from the PCM when it detects a genuine problem: either actual low pressure or a flakey switch (more likely).

A bad stepper motor itself cannot trigger those warnings.

 

[Hatchet]

The "check gauges" light and "Low Oil Pressure" DIC message are triggered by commands from the PCM when it detects a genuine problem: either actual low pressure or a flakey switch (more likely).

A bad stepper motor itself cannot trigger those warnings.

That's what I was getting at. Great minds lol.

Mine did the same thing shortly before I lost the engine. When I replaced it we opened the bottom and the oil pick up had slot of metal shavings restricting the flow. Not saying this is what is happening here. Just giving my experience. I would check the switch at the oil filter. Also at next oil change, check the old oil for metal, just in case.

 

[lint]

That's what I was getting at. Great minds lol.

Mine did the same thing shortly before I lost the engine. When I replaced it we opened the bottom and the oil pick up had slot of metal shavings restricting the flow. Not saying this is what is happening here. Just giving my experience. I would check the switch at the oil filter. Also at next oil change, check the old oil for metal, just in case.

wow you are just full of uplifting news sorry to here that ,I have put probably 50 motors in ,in my life but i don't want to start on one of theses lol hopefully its a electronic problem .'' hopefully ''

 

[lint]

The "check gauges" light and "Low Oil Pressure" DIC message are triggered by commands from the PCM when it detects a genuine problem: either actual low pressure or a flakey switch (more likely).

A bad stepper motor itself cannot trigger those warnings.

Thanks AtlWrk hopefully flakey switch Just cant see how the motor doesn't start to rattle with pressure at zero. so hopefully not pressure.

 

[bmcutright]

That's what I was getting at. Great minds lol.

Mine did the same thing shortly before I lost the engine. When I replaced it we opened the bottom and the oil pick up had slot of metal shavings restricting the flow. Not saying this is what is happening here. Just giving my experience. I would check the switch at the oil filter. Also at next oil change, check the old oil for metal, just in case.

Makes me want to change the oil early just to check it for metal shavings. Is the oil psi switch easy to change?

Was it an actual loss of oil pressure that caused you to lose the engine? Were there other symptoms we should look for to diagnose and prevent losing our engines? Maxed out my credit score just to buy the damn thing, can't dump much more in if it becomes a money pit.

 

[Hatchet]

My cylinder number one wasn't getting oil anymore and caused the bearing to go dry and detonate.

 

[bmcutright]

Using a word like"detonate" has me more worried that there may be more going on than just a bad switch. Were there other symptoms I should watch for? (Noises, etc.)

 

[04TBlazerLS]

New member, first post:

Yesterday, I rigged up a manual oil pressure tester, to check the actual oil pressure readings at the oil filter. The testing was on my 2004 Trailblazer LS with a I 6 / 4.2L engine @ 118,000 miles. I had installed a new oil pressure switch/sensor, but the dashboard oil pressure gauge would still drop to a zero reading intermittently. The engine never made any unusual noises (from lack of oil) at highway speeds and no warning lights came on.

These are the actual manual oil pressure gauge readings using the tachometer at normal engine temperature:
700 RPM (idle) - 19 PSI
1200 RPM - 38 PSI
2000 RPM - 52 PSI
2500 RPM - 66 PSI

I was pleased with the results.

 

[Mooseman]

If you're not getting a message in your DIC to stop the engine, then it could be the stepper motor in the gauge itself that's dying.

 

[IllogicTC]

If you're not getting a message in your DIC to stop the engine, then it could be the stepper motor in the gauge itself that's dying.

If you don't have DIC, there's a yellow lamp in the upper left that shows a picture of a needle on a gauge, which would be the other indicator that there's an oil pressure issue (well it just means check gauges, which means you'd look to see which one is reading bad).

 

[04TBlazerLS]

Never had a stop engine code on the instrument panel.

It surely is an electrical problem in my case. With the new electrical oil pressure switch/sensor removed from the vehicle and the wiring harness disconnected, the oil gauge would still move from zero, to 40 psi, when the engine was fired up. The above faulty oil pressure reading occurred when I was manually testing the oil pressure with the adaptor screwed into the opening where the oil pressure switch/sensor was removed.