96' Balzer 4x4 - Low Oil Psi

My oil psi sits at 20 psi (per the gauge) at idle. Once I accelerate goes to 40 or above. I have done a flush per the following. (127,000 miles)

Engine flush with current oil and filter, ran for 25 minutes. Drained, filled, and changed filter. Repeated process with second flush. Ran clean oil, drained, refilled with Castrol 10w30 and new filter (non fram)

No change in oil psi, remains 20 psi at idle and above 40 psi during normal driving.

Any ideas? I know with the mileage there is probably some wear, but I cut the filters open and saw no metal and picked none up with a magnet.

Is there anyway, with the exception of running a thicker oil, to get the oil psi to come up? I am a little uncomfortable with it being so low, unless 20psi is acceptable to the majority.

It's completly normal. It should idle around 20 and when driving be around 40. These 4.3 engines are weird. BTW, you could have done a search for Operating Oil PSI. but its all good

Maybe I did my search wrong, but I came up zilch with "Low Oil Pressure". Perhaps I fat fingered it in the search box.

Thanks for responding though.

It's completly normal. It should idle around 20 and when driving be around 40. These 4.3 engines are weird. BTW, you could have done a search for Operating Oil PSI. but its all good
Good bye derek. If you come back again Gary and Kathy Morgan will be notified, and the police may even show up at their house on Sycamore. Abusing the rules of this site is a federal crime, and you're damn lucky that the owner has declined to press charges thus far.

If you return, I will also post all your personal information, including home address, phone number, full name, picture, and IP address for everyone to see. (and abuse) This is completely legal, because it is information that was obtained due to things that you made public. Your return will be considered your consent to do so as well.

I'm lost!

You can find some other people's pressure readings here:
http://www.automotiveforums.com/vbulletin/showthread.php?t=571000

20 is fine at idle, the minimium idle pressure is 6 psi, you're well above that.

Ok guys I think I maybe in some trouble. Today my oil psi dropped below 18psi, actually it dropped enough that when I hit the brakes hard at a stop light, the "Check Gauges" light came on. The engine began to lope, like the computer was sensing the low pressure and was temporarily increasing RPM to keep it from stalling.

I got it home and tried to simulate the issue again by stopping hard, and the "Check Gauges" light flickered. I got out, engine running, and removed the oil cap. In aviation, if you trully had low psi, removing the cap at such a low pressure would cause the engine to die. Mine did not.

I am at a loss. Any suggestions?

I am thinking to hit the easy first, R&R the oil psi sending unit, if I can find it.

Could it be the oil pump? If so, how would I know?

It has 127,000 on hit and I have taken care of it.

Help! I am open for any trouble shooting tips that can help me rule things out.:uhoh:

Your oil pressure is well within operating parameters. Also, oil pressure will not cause an engine to stall (at least directly - indirectly it will if it vanishes and the engine siezes). You have another problem - the fact it lopes due to low speed tells me that it's in the fuel system somewhere. Have you done a pressure check on the fuel rail to ensure the pump is delivering proper PSI? It should be at least 60. Have you changed the filter lately?

Ok guys I think I maybe in some trouble. Today my oil psi dropped below 18psi, actually it dropped enough that when I hit the brakes hard at a stop light, the "Check Gauges" light came on. The engine began to lope, like the computer was sensing the low pressure and was temporarily increasing RPM to keep it from stalling.

I got it home and tried to simulate the issue again by stopping hard, and the "Check Gauges" light flickered. I got out, engine running, and removed the oil cap. In aviation, if you trully had low psi, removing the cap at such a low pressure would cause the engine to die. Mine did not.

I am at a loss. Any suggestions?

I am thinking to hit the easy first, R&R the oil psi sending unit, if I can find it.

Could it be the oil pump? If so, how would I know?

It has 127,000 on hit and I have taken care of it.

Help! I am open for any trouble shooting tips that can help me rule things out.:uhoh:

odd...mine runs at 40 idle and goes as high as 70 under heavy accelration howver if i make a quck stop mine does drop to red and check gauges ligth flicker too.. mine with a rebuilt motor with 13k miles on it and its a 95 vortec

I am not sure I see the correlation between fuel pressure an low oil pressure. I am not being a smartass or anything, I just am hoping you can expand to help me understand.

I am not sure I see the correlation between fuel pressure an low oil pressure. I am not being a smartass or anything, I just am hoping you can expand to help me understand.

Low oil pressure won't make your engine lope - if anything it will make it run smoother so long as there's enough to keep the bearings lubricated.

Low fuel pressure can make the engine lope due to a leanout condition.

There is no correlation between fuel and oil pressure, but there is a correlation between fuel pressure and the way the engine is running.

Does that help?

I am not sure I see the correlation between fuel pressure an low oil pressure. I am not being a smartass or anything, I just am hoping you can expand to help me understand.

Your oil pressure is dropping because your idle is probably dropping seeing you might be in need of a tuneup.

The pressure is tied to the engine rpms seeing the oil pump is attached to the main distributor gear.

Good bye derek. If you come back again Gary and Kathy Morgan will be notified, and the police may even show up at their house on Sycamore. Abusing the rules of this site is a federal crime, and you're damn lucky that the owner has declined to press charges thus far.

If you return, I will also post all your personal information, including home address, phone number, full name, picture, and IP address for everyone to see. (and abuse) This is completely legal, because it is information that was obtained due to things that you made public. Your return will be considered your consent to do so as well.

What is this for?

Thanks guys. Here is the plan.

First a complete tune up. Anyone got a list of minimum parts to change/replace/clean? Or the link to a previously posted list?

Second will be to test the fuel pressure at the rail. Is there a how to on that? Never done that before on a vehicle. I show no record of the fuel pump being changed, but the fuel filter was changed less than 6 months ago.

Blazerlt- That note was a little confusing from Blazee to "Derek". I assumed he was a previously banned person that Blazee was warning.

As a side note, I have noticed a slight knock coming from the front of the engine. I know poor fuel burn or low grade fuel can cause that.

Fuel filter
Spark plugs AC Delco Platinum only
Cap & Rotor
Air Filter
PCV Valve

Thanks guys. Here is the plan.

First a complete tune up. Anyone got a list of minimum parts to change/replace/clean? Or the link to a previously posted list?

Second will be to test the fuel pressure at the rail. Is there a how to on that? Never done that before on a vehicle. I show no record of the fuel pump being changed, but the fuel filter was changed less than 6 months ago.

If you look at the rail, near the point at which the fuel line attaches to it, you'll see a Schrader valve - looks like a refrigerant line fitting or a tire valve - you attach a pressure gauge to this and take the reading with the engine running (should be at least 55-58), cranking (should be at least 60).


As a side note, I have noticed a slight knock coming from the front of the engine. I know poor fuel burn or low grade fuel can cause that.

Could be a loose timing chain too, if the motor has a lot of time on it.

Could also be a slight misfire in a cylinder too.

What is this for?


Blazerlt- That note was a little confusing from Blazee to "Derek". I assumed he was a previously banned person that Blazee was warning.


Sorry for the confusion guys. He's a troll that has been banned 14 times already.

Also, the oil pump is 2 gears that mesh and as it wears the pressure does drop. Run 5w-30 not heavier so at start up the bearing get oil. If you have run low on oil or gotten it very hot the bearings gaps increase and pressure can drop as the space between increases. Then theres the lower intake leaking that can spray a fine mist of coolant inside the valley and you most often can't see it in the oil - been there several times so watch the coolant in the reservior closely - by 100k all Blazers blow this small or major and as these pressures start to drop that can be a warning sign - but not always - look at it so you don't kill the engine. Finally if an oil cooler hose is starting to leak pressure may drop so look under that Blazer and the radiator at the metal crimps on the hoses.

All great advice guys.

muddog321 - I had the intake manifold gasket changed due to that very coolant leak, which apparently I caught early enough. Since then my coolant level has stayed consistent. But who is to say I did not get any into the engine at that point to cause some premature wearing.

I am running 10w-30 now, but am scheduled for an engine oil change this week as I did a flush not to long ago and wanted to only run about two weeks and change over to Mobil Synthetic. I'll make sure to go with 5w-30 as advised. And a (Non-Fram) oil filter.

I have been all over the engine and only had one oil leak, the timing chain cover, which is a one peice, plastic, PITA to get done. When I had it off I did not note excessive play in the chain.

If it is the oil pump, am I hosed and need a new engine? I know eventually I will need a new engine, with 127,000 it is obvious it will not last forever, but was kinda hoping to get some more time out of this one.

I am also suspecting the oil psi sending unit, but do not know how to troubleshoot it other than R&R it and see what happens. Any advice there?

Thanks,again guys, this forum has saved me allot of money....:grinyes:

No, I have 4 Blazers and 20 psi is common at idle and the engines will go over 200k easily so relax - drive on!

Well gentlemen...today as I pulled off the freeway my truck engine made wicked noises and the oil pressure sank to the redline. The knocking in the engine became worse. I managed to nurse it to the shop I usually take it to. The mechanic that usually works on it is confident that by engine has let go.

I won't no more until he gets it apart, but says it will be easy to tell if it has let go.

He is telling me that worse case scenario I am looking at a NEW chevy crate long block and labor. His guess was on the high side he said, but in the neighborhood of $3500. Again that is NEW with a 36000, 3yr warranty. I am sure a rebuilt engine would be cheaper, but a limit 12 month warranty.

I am not made of money, but I can manage a new engine.

My question is ...now....would you reccommend a rebuilt or should I go with the added warranty of the new?

I bet you blew an oil cooler line.

Also shop around for a crate engine install. Might be even cheaper.

Don't go by one guy's quote.

I wish it were that easy. No oil leaks from under the vehicle. I will definately get a second opinion.

I am interested to hear what it was. I am thinking a spun bearing, maybe a rod bearing. Please post after you get results. A good reputable engine rebuild shop can rebuild an engine and you could get many, many trouble fee miles. That being said, a new engine from GM is probably the best out of all options, because its new, but it costs more.

As we get deeper into the cause when the lower intake bolts were torqued if they went to 36 ft lbs (95 down) or the 96up 12 ft lbs? GM has a bulletin on this and if the higher torque is used on the 96up it pulls the block together and can spin the main bearings. Just thinking cause if no leaks and the leaking manifold could have done damage too so no positive way to tell if you did not do the work yourself unless the shop remembers.

I will poke around and ask what the torque was. Better yet, when the motor is out I may take my torque wrench over there myself and check to see what it was torqued to. Do you have that GM bulletin number? Not that I expect to find it torqued wrong, but if I do I would definately like some back up data to bring to them. Maybe then I get a little finacial help from them.

Question - Does anyone know what a new chevy crate engine would cost and what chevy references as the amount of labor to R&R?

I am going to research myself as well, but I was hoping someone on here would know. I want to make sure I am seeing a fair quote for the engine and labor. I am going to call the local chevy dealer as well and see what they would charge, obviously higher than anyone else, but at least it gives me a worse case scenario to gauge my shop by.

Thanks guys and I will repost on here as soon as it is confirmed what let go in the engine.:banghead:

Wow good luck with this problem and keep us updated on what it is, I am really curious what the hell is happening!!!

post 1 oil pressure concern
post 7 lower pressure & drops when braking
post 14 slight engine knock
post 22 lower presure, louder knock

I wish I or someone would have checked oil level or advised to stop driving until cause of presure drop was found , look into the suction side of pump and/or oil level for cause. Sorry it is too late.

Trust me I looked at the oil level on more than one occasion. My theory, when I had the coolant leak 3 months ago and had the manifold gasket replaced, it was already too late. I envision coolant got into areas that it was not supposed to and that is when the trouble began.

I had a choice. New truck (4x4 SUV) = $800 per month payment, increased insurance, $600 per year registration (Arizona sucks), for 5 glorious years.

or

Keep my Blazer and put some money into it to make it a solid driver. In the end, because I crunch numbers all day for a living, it was cheaper to keep the blazer. I know I read allot people on here sometimes regret they ever bought a blazer, but mine has been good to me. It is a little long in the tooth and now is going to need some TLC.

I'll let everyone know what the final outcome is on the old engine and again appreciate everyone's help.:banghead:

I was a bit luckier than you a week ago. When I rounded a corner I saw my "check gages" light on. I mistook it for the "check engine" lite becuase of a mioss I had been having and after stared at it for a few minutes it dawned on me what it was.

Anyways I checked gages and seen oil gage was down almost to bottom, I too figured "sending unit" or gage, rolled the window down to listen to engine and all seemed normal.

When I made my right turn, my pressure came up and then back down. When I stopped I noticed oil smell and heard engine knocking. UHoh.

I got out and seen whole side of blazer had been "oiled". It turns out I had blown a cooler hose and after retracing my steps later on I saw where it had started leaking and stopped, it took about a mile to pump it all out and thenI drove it 2 miles after that.

I had to pour a gallon into it to find the leak, made a mess on my work parking lot, a bunch of phone calls and a bummed ride to get the line set, filter, oil and fixed it in the parking lot. I was good to go in about 5 hrs and smiling becuase I had hoped the engine wasn't hurt from starving oil.

One of my co-worker drove in in his brand new avalanche and smiled when He told me that his (old payment from 04 tahoe) onlt went up $3 per month.

I smiled again and said that my payment this month was $51 for oil line and $6 for oil and filter and having to lay on back on parking lot, lol.

Yours had oil in pan, but for some reason did pump any pressure, restriction, crack, pump not spinning, ect. I am sure the mech will find it.

Upon inspecting the engine it was determined the main bearing was extremely worn out and that the oil pump gears were extremely worn as well.

Well I learned a few things from this. First, my shop are rip off artist. If you live in AZ, avoid Gruelich's Auto Repair. They told me they would put nothing less that a new crate motor in and quoted $4900.

Based on this I called 4 different repair shops which included the local chevy dealership. ALL quoted me a hell of a lot less. I called my shop and spoke with the manager who got offended I would even think of asking for other opinions. Well I explained to them I had chosen to go with a company called "Engine House" because of price and warranty. Remaned engine with 4 year 60,000 warranty. He immediately began talk allot of trash about this other shop. In my line of work that can only mean two things, one the other shop really sucks, or two, the other shop is stealing all the business because they offer a good reliable product and back it up with a solid warranty.

I won't bore you will the details, more a vent I guess. Even the Shop you thought you could trust, may not be trustworthy at all.

I am getting my toy back with a solid engine. How do I know "Engine House" is good an not another rip off artist? I work for an airline, and ALL of our ground vehicles have their engine rebuilt by EH. 150 rebuilt engines, onlyone sent back for warranty.

Next stop, more horsepower, better gas mileage, and a smile on my face.

You are a smart man. I respect that.

He was all pissed because he was caught ripping you off. Like a thief will carry on when he get's caught stealing.

People with a warranty usually means they have a quality product.

Hey all-
Just an update.

Truck is done and I am VERY happy:grinno: with the decision to go with Engine House here in Phoenix.

Rebuilt engine - 3 year, 50K warranty.
New Cap/Rotor/Plugs/Plug wires.
New oil and filter (although it is break in oil, after 500 miles they change it to Mobil 1 Synt for free)
Radiator flush - Although I had this just done :frown:
New upper and lower fan shrouds. Both were junk and I had it on the list to do. But as the shop was there anyway they changed it and only charged for the parts.
Serp Blet Tensioner - Junk - replaced and only charged for the part.
Tranny mounts - Again only charged for parts as they had to drop the tranny for engine R&R.
Harmonic Balancer - Old one was chewed up. Material only again cause they were in the area.

Originally quoted at $2800, but with the additional parts came to $3000. I'm not made of money, but it will be good peice of mind to know the truck is virtually new under the hood. All Line Replacable Units (Sorry I am in the aviation industry) like the ALT, Starter, A/C System - I just replaced myself.

Now the big question - Do I squeeze some mroe HP out of it??? LOL!!! Seriuosly though I would not mind an Edlebrock Intake or some other nick nacks to get a little more HP and Gas Mileage<<<<is that an auxymoron??

Thanks for all the help guys and if you are ever in Phoenix, or move here (Reference Hell for weather in the summer) I would highly reccommend Engine House.

I would wait for at least 1000 miles before you tinker with it.

Also, I would replace the tranny fluid and installa new filter. That alone will free up some power when you put some nice fluid in there and an unrestrictive filter.

Go and get a complete fluid change (T-Tech) and then go and get the filter swapped on. If you only drop the pan, you will only be getting less than 40% of the new fluid.

Good advice BlazerLT. I am thinking about going with full synthetics all around. Meaning, engine, tranny, differentials, etc. I am reading up some different type fluids out there and allot of the website point back to AMSoil. Have you, or anyone else, used these? I am curious and I know in the forums you get allot of real world experiences. You know how each manufactuer toots their own horns that their product is the BESTEST EVER!!

Won't tinker with it for awhile. Want to good break in.

Thanks~

Glad to hear you are happy with the results

I've been using Amsoil products for about 12-15 years and the only complaint I have is the 2 stroke oil should not be called 100:1, it is a bit misleading.

I've used the autofluid, engine oils, grease, filters, ect. Mostly use the 15w40 marine oil for old stuff. If I had built a new engine I would use the 0w 30 with tight clearances.

As far as amsoil being the best, well, I don't know about that. We had used mobil 1 for many years and was happy with it also.

Thanks for the feedback. I belive after the break in period I will run Mobil 1 oil and filter. It seems to be a highly reccommended oil and is readily available.:rolleyes:

Yea, Mobil 1 is good and if you shop right and hit some sales you can get it for cheap.

My oil psi sits at 20 psi (per the gauge) at idle. Once I accelerate goes to 40 or above. I have done a flush per the following. (127,000 miles)

Engine flush with current oil and filter, ran for 25 minutes. Drained, filled, and changed filter. Repeated process with second flush. Ran clean oil, drained, refilled with Castrol 10w30 and new filter (non fram)

No change in oil psi, remains 20 psi at idle and above 40 psi during normal driving.

Any ideas? I know with the mileage there is probably some wear, but I cut the filters open and saw no metal and picked none up with a magnet.

Is there anyway, with the exception of running a thicker oil, to get the oil psi to come up? I am a little uncomfortable with it being so low, unless 20psi is acceptable to the majority.
Don't EVER use Engine Oil Flushing treatments!! They do more damage than any ills they may cure. Any vehicle that see regular oil changes will never need (or benefit from) an engine flush. This stuff is solvent, it thins oil out terribly, (that's why the label says not to drive the vehicle during the procedure). I would bet this is what ate your main bearings up.
Stay away from this crap, they shouldn't be allowed to sell it. Anything that could possibly be so sludged-up that this stuff would help, is gonna be junk anyway. Glad to hear about your positive experience with Engine House, thanks for sharing it with us. I hope to help someone avoid creating a problem by using engine oil flush. I ruined a good engine 25 years ago by using it, and following the directions exactly. Never again! And this stuff is made by good companies, too - they respond to demand. If folks were all educated against using it, the demand would disappear, along with this evil potion... It is snake-oil!

Don't EVER use Engine Oil Flushing treatments!! They do more damage than any ills they may cure. Any vehicle that see regular oil changes will never need (or benefit from) an engine flush. This stuff is solvent, it thins oil out terribly, (that's why the label says not to drive the vehicle during the procedure). I would bet this is what ate your main bearings up.
Stay away from this crap, they shouldn't be allowed to sell it. Anything that could possibly be so sludged-up that this stuff would help, is gonna be junk anyway. Glad to hear about your positive experience with Engine House, thanks for sharing it with us. I hope to help someone avoid creating a problem by using engine oil flush. I ruined a good engine 25 years ago by using it, and following the directions exactly. Never again! And this stuff is made by good companies, too - they respond to demand. If folks were all educated against using it, the demand would disappear, along with this evil potion... It is snake-oil!

There is nothing wrong with an engine flush if it is performed properly and the engine is kept at idle for the time frame. It causes no damage and does a good job at cleaning some of the sludge in your engine.

Most engine oils won't keep your internal engine clean so a small scubbing for 20 minutes or so will doo no harm and can clean out the lifters nicely.

I agree with BlazerLt, I do not belive this is what caused my problem. The root cause, after seeing some of the stains on the torn down motor was the coolant leak that occured at the intake manifold. This is why it is VERY important to do routine inspections on your vehicles. Had I caught this early enough I may hav prevented the issue which led to the engine main bearing frying.The core engine was not taken care of by me since birth, the way my current engine will be. While I agree that consistently changing your oil and filter with quality products will only server for a positive purpose, down the road a flush maybe in line to simply get a good cleaning. As BlazerLt stated, in the engine and ONLY at idle for the reccomended time. Followed by drain, flush, drain, and refill.At least thats the way I understood it and did it myself. But it most certainly did not cause my issue.

Where are these photos of the engine?

My engine?? Noting special about it, other than it is LOOOOWWWW MILES!!!:grinyes: