Oil Pressure/White Smoke

[misfitt006]

99 Suburban LS 4x4 with the 5.7 with 109k miles.

OK so my Suburban broke down on my wife a few weeks ago, figured out that one of the catalytic converters had a catastrophic failure and came apart internally. I cut the cat off so that I could drive it the 60 miles home to save on the tow charge.

Had the cat replaced today and now I'm blowing white smoke out the tailpipe like I'm 007 throwing a smoke screen. The smoke alternates from smelling really rich to smelling like oil (pre-burn).

The oil pressure gauge is reading at or below 20 PSI and randomly (usually while breaking or stopped) completely bottoms out. I know cluster gauges aren't known for their accuracy but I also know this isn't 'normal' behavior. I also hear noise from the engine (possibly valves sticking but could also be more of a knocking sound than a clicking one). The oil is full (actually a little too full) and it went from looking like brand new oil to jet black in less than 30 days. I talked with the rep at one of the 'big name' auto parts stores and they recommended trying a 20W50 weight oil for a couple of months. Stated they have a similar vehicle with the same motor and made the switch a few years ago and hasn't had a problem since. I'm in Northern California if that matters at all. I plan to do an oil change this weekend, I also bought an oil pressure sending unit that I'll change out at the same time. Am I on the right track?

Also, and most likely unrelated, my coolant temp gauge is totally inoperative and is just bottomed out no matter how warm the engine is. The coolant hoses (supply and return) are warm/hot to the touch at running temp so I'm sure coolant is circulating. What's the easiest way to check whether that issue is the gauge itself, the thermostat, or the sending unit?

There are no codes that come up on my OBD II reader at the moment.

[MT-2500]

Originally Posted by misfitt006

99 Suburban LS 4x4 with the 5.7 with 109k miles.

OK so my Suburban broke down on my wife a few weeks ago, figured out that one of the catalytic converters had a catastrophic failure and came apart internally. I cut the cat off so that I could drive it the 60 miles home to save on the tow charge.

Had the cat replaced today and now I'm blowing white smoke out the tailpipe like I'm 007 throwing a smoke screen. The smoke alternates from smelling really rich to smelling like oil (pre-burn).

The oil pressure gauge is reading at or below 20 PSI and randomly (usually while breaking or stopped) completely bottoms out. I know cluster gauges aren't known for their accuracy but I also know this isn't 'normal' behavior. I also hear noise from the engine (possibly valves sticking but could also be more of a knocking sound than a clicking one). The oil is full (actually a little too full) and it went from looking like brand new oil to jet black in less than 30 days. I talked with the rep at one of the 'big name' auto parts stores and they recommended trying a 20W50 weight oil for a couple of months. Stated they have a similar vehicle with the same motor and made the switch a few years ago and hasn't had a problem since. I'm in Northern California if that matters at all. I plan to do an oil change this weekend, I also bought an oil pressure sending unit that I'll change out at the same time. Am I on the right track?

Also, and most likely unrelated, my coolant temp gauge is totally inoperative and is just bottomed out no matter how warm the engine is. The coolant hoses (supply and return) are warm/hot to the touch at running temp so I'm sure coolant is circulating. What's the easiest way to check whether that issue is the gauge itself, the thermostat, or the sending unit?

There are no codes that come up on my OBD II reader at the moment.

White smoke is coolant getting into engine.
Blue smoke is oil burning.

You need to check for coolant lose and intake or head gasket leakage.
Also oil for coolant or gas in it.

If it is low on coolant the temp gauge will not work right.

[j cAT]

Originally Posted by misfitt006

99 Suburban LS 4x4 with the 5.7 with 109k miles.

OK so my Suburban broke down on my wife a few weeks ago, figured out that one of the catalytic converters had a catastrophic failure and came apart internally. I cut the cat off so that I could drive it the 60 miles home to save on the tow charge.

Had the cat replaced today and now I'm blowing white smoke out the tailpipe like I'm 007 throwing a smoke screen. The smoke alternates from smelling really rich to smelling like oil (pre-burn).

The oil pressure gauge is reading at or below 20 PSI and randomly (usually while breaking or stopped) completely bottoms out. I know cluster gauges aren't known for their accuracy but I also know this isn't 'normal' behavior. I also hear noise from the engine (possibly valves sticking but could also be more of a knocking sound than a clicking one). The oil is full (actually a little too full) and it went from looking like brand new oil to jet black in less than 30 days. I talked with the rep at one of the 'big name' auto parts stores and they recommended trying a 20W50 weight oil for a couple of months. Stated they have a similar vehicle with the same motor and made the switch a few years ago and hasn't had a problem since. I'm in Northern California if that matters at all. I plan to do an oil change this weekend, I also bought an oil pressure sending unit that I'll change out at the same time. Am I on the right track?

Also, and most likely unrelated, my coolant temp gauge is totally inoperative and is just bottomed out no matter how warm the engine is. The coolant hoses (supply and return) are warm/hot to the touch at running temp so I'm sure coolant is circulating. What's the easiest way to check whether that issue is the gauge itself, the thermostat, or the sending unit?

There are no codes that come up on my OBD II reader at the moment.

first the cat failure at this mileage means your engine has big problems. unburned fuel usually causes this.

my first guess is the head gasket/heads are / have failed. check compression.

check oil pressures. if the pressures are below 20 psi I would unload this vehicle.

If you can do it install a scrap yard engine of this model year.

with 109,000miles and these failures the vehicle has not been properly maintained.

you do oil changes ? who's oil and viscosity ? what filters used ? what coolant used ? when do you change coolant ?

at 100,000 miles these vehicles are just beginning on their life cycle. many get well over 200,000 miles .

[misfitt006]

Originally Posted by j cAT

first the cat failure at this mileage means your engine has big problems. unburned fuel usually causes this.

my first guess is the head gasket/heads are / have failed. check compression.

Ok compression check looked good. I got between 100-120 psi off the first rotation and was hitting 180 by the 4th rotation on all 8 cylinders.

Originally Posted by j cAT

check oil pressures. if the pressures are below 20 psi I would unload this vehicle.

I don't have a mechanical oil pressure gauge to do the check so I'll go get one tomorrow. I did a complete oil change (nothing unusual about the look of the oil, no water/coolant/etc) and replaced the sending unit today but was still getting the >20psi on the dash gauge at idle. I'll get the mechanical gauge tomorrow to verify that the dash gauge is accurate.

Originally Posted by j cAT

with 109,000miles and these failures the vehicle has not been properly maintained.

you do oil changes ? who's oil and viscosity ? what filters used ? what coolant used ? when do you change coolant ?

at 100,000 miles these vehicles are just beginning on their life cycle. many get well over 200,000 miles .

I've only owned this thing for about 6 weeks so I have no idea about the maintenance history. At some point someone has converted it from DexCool to traditional green coolant. I am hoping that whoever did it A) knew what they were doing, and B) Did it correctly. The coolant looks pristine though so there's no indication that it's dirty/old/etc. When I did the oil change I went with 10w30. I got the oil at Oreily's and went with their brand oil and filter (on sale for $13). I'm usually a Quaker State guy but money is tight and I plan to change the oil out again in >3k miles so I went with the store brand.

On the temp gauge issue, I pulled the temp sensor plug and checked it with my test light. I got good current there and the needle on the dash moved from dead up to zero (basically it wiggled a little bit) when I grounded the plug with the test light. So I'm assuming the gauge is good so maybe the temp sensor is bad? Could it be the thermostat?

[j cAT]

Originally Posted by misfitt006

Ok compression check looked good. I got between 100-120 psi off the first rotation and was hitting 180 by the 4th rotation on all 8 cylinders.



I don't have a mechanical oil pressure gauge to do the check so I'll go get one tomorrow. I did a complete oil change (nothing unusual about the look of the oil, no water/coolant/etc) and replaced the sending unit today but was still getting the >20psi on the dash gauge at idle. I'll get the mechanical gauge tomorrow to verify that the dash gauge is accurate.







I've only owned this thing for about 6 weeks so I have no idea about the maintenance history. At some point someone has converted it from DexCool to traditional green coolant. I am hoping that whoever did it A) knew what they were doing, and B) Did it correctly. The coolant looks pristine though so there's no indication that it's dirty/old/etc. When I did the oil change I went with 10w30. I got the oil at Oreily's and went with their brand oil and filter (on sale for $13). I'm usually a Quaker State guy but money is tight and I plan to change the oil out again in >3k miles so I went with the store brand.

On the temp gauge issue, I pulled the temp sensor plug and checked it with my test light. I got good current there and the needle on the dash moved from dead up to zero (basically it wiggled a little bit) when I grounded the plug with the test light. So I'm assuming the gauge is good so maybe the temp sensor is bad? Could it be the thermostat?

I would next pressure check the coolant system. some heads have had cracks that caused coolant to enter the intake. not in oil crankcase or a head gasket.it was a manufacturing defect.

could also be that the intake gasket is leaking causing coolant to enter the intake.

still though if the oil pressures drop to zero and you use a pressure gauge to confirm then you got screwed on this one ...

[misfitt006]

Ok here's an update on my situation. I've done the following:

Changed oil pressure sending unit and got the same results

Installed a mechanical oil pressure gauge to verify problem wasn't with the dash gauge, it confirmed bad oil pressure

Did a compression check and all 8 cylinders are getting ~100-110psi off the first rotation and maxing out at ~200-210psi

Dropped the oil pan (Holy crap what a pain in the ass!!) to check for a clogged pick-up tube

Rebuilt the oil pump since I was already in there just in case (new gears, pressure relief valve/spring, shaft retaining sleeve)

Verified that the supply and return lines coming off the oil filter housing were not clogged (blowing through them showed no restriction)

Put it all back together and started it up. Had great oil pressure on the cold start (~20-30psi at idle) but as the engine got up to temperature the oil pressure just dropped until it was at zero again. When given gas the pressure will rise, but as soon as I take my foot off the accelerator it just plummets. It is also still blowing white smoke out of the exhaust and the exhaust smells really rich which I know is almost always unburned fuel and it's also throwing a P1345 cam position sensor code.

I don't have an air compressor so I haven't been able to do a leak down test. The oil looks 'normal', no chocolate milk looking oil and no 'waxy' buildup on the inside of the oil fill cap. I used 10W30 instead of the 5W30 it calls for when I filled it after putting it all back together.

On a side note, changed out both temperature sensors and the thermostat and the temp gauge on the dash is working now.

[rustydogy]

I would go with j-cAt & MT 2500 ,,your oil pressure is way to low at 109xxx that motor should be 40-50 cold and 20-30 hot ,and assuming you did right by rebuilding your oil pump , then you have the start on major internal damage already , white smoke is water/antifreeze , black smoke is gas you said it smells rich , that could be because of many other things , since your not putting out black smoke ,I would pressure test the radiator to 16-18 lbs and watch it , it may drop a little in the first couple of minutes but pump it back up and watch it for 10 15 min, if it drops you have a leak in intake , cracked head , head gasket At any rate I think the 1 who sold it to already knows what's going on with it,,,,,,,,,,,,,,,,, good luck

[j cAT]

Originally Posted by rustydogy

I would go with j-cAt & MT 2500 ,,your oil pressure is way to low at 109xxx that motor should be 40-50 cold and 20-30 hot ,and assuming you did right by rebuilding your oil pump , then you have the start on major internal damage already , white smoke is water/antifreeze , black smoke is gas you said it smells rich , that could be because of many other things , since your not putting out black smoke ,I would pressure test the radiator to 16-18 lbs and watch it , it may drop a little in the first couple of minutes but pump it back up and watch it for 10 15 min, if it drops you have a leak in intake , cracked head , head gasket At any rate I think the 1 who sold it to already knows what's going on with it,,,,,,,,,,,,,,,,, good luck

I agree with this ... my guess is the crank bearings are shot. and the intake manifold is leaking coolant into the intakes. you for sure got screw with this one.

coolant will damage the converters.

good luck .

[Levithan9]

A a professional auto tech, I can tell you that your engine is on a 1 way ticket to the scrap yard.

With the info you've provided, I can determine that either your bearings are shot or the clearances of the bearings are WAY over spec. If I were you, I'd start thinking of a few things:

• New / Used engine
• Getting rid of the vehicle
• Getting drunk to help offset the feeling of getting screwed over

I'm sorry to say, but these are the facts of life. Stop dumping money into it, cut your losses, and run like hell....