H3 Low Oil Pressure

[BiteEmNBeatEm]

I have a '07 H3 and recently have been getting the red low oil pressure lamp and dinging sound when come to a stop at idle. If I give it just slightly enough gas to bring the rpms from the 600-700 up to 900-1000 it will turn right off. On a cold start it doesnt seem to do it but i also noticed that the idle is a bit hight on a cold start and then in slowly drops to 600-700 rpms.

Any idea what this may be or where to start looking?

also i have never paid attention but what is the rpm suppose to be at idle?

 

[ReconH3]

Could be a worn out oil pump, or the oil that's thinned out. What's the mileage on the truck? When was your last oil change? Do you use quality oil?


"Ex Umbris Venimus"

 

[alrock]

Hmm, don't recall where my idle is either but I'll take a look tomorrow.

 

[Reloader]

The first thing to do would be to install a mechanical oil pressure test guage set up to verify if pressure is actually low or if sensor is out of wack. Alldata (or somedata as some call it) gives a spec of 12 psi at 1200 rpm. Doesn't spec if hot or cold. Old rule of thumb used to be 10 psi for every 1000 rpm. Since the H3 only has an idiot light for oil pressure monitoring, the sensor is only a switch that closes to ground to turn on the light at a preset value like 7 psi or something. They can get out of calibration considering the environment they have to operate in .I've changed many of them over the years. Several just for leaking at the crimp between metal and plastic. If you do change it , I would only install an oe one from GM as aftermarket (aka crap) ones don't seem to work as well. We've learned this the hard way with t-stats on these I-5 engines. Only use OE AC/Delco. Beats having to do it twice.
Hopefully this will be the problem. Worst case would be worn main and rod bearings allowing too much oil to wash through reducing oil pressure at lower rpm. Only way to fix is overhaul. Possibly oil pump is worn or bypass valve malfunctioning . Are you hearing any excessive valve ticking? This could be a sign of actual low pressure. Pull your dipstik and smell for gasoline as engine oil could be contaminated thinning it out. Or coolant.
Quality of oil is very important in my opinion. Quick oil change places ( or boob lubes as we call them) use really cheap oil for basic oil services regardless of what they advertise. Their oil filters are very cheaply made also. Some are used for many different applications and lack things such as anti drainback valves and have much less filter media in them. And I've cut many open over the years to prove this. Once again, OE or a premium aftermarket is the way to go. Quality oil and filters are cheap compared to replacing an engine or a transmission.
I hope its just the sending unit as that will be the cheapest thing. Sorry about the rant Good luck. Oh and the idle flare up on cold start is normal. Some cars run up to 14-1500 rpm and them settle down to a fast idle for a period then down to curb idle after they cross a certain temp threshhold. Gm vehicles monitor the time this takes and will set a P0128 code if it takes longer than the ECU thinks it should. This is all about emissions and getting the engine into closed loop asp.
No spec is supplied for curb idle but I would suspect on an I-5 engine it would be 650 to 750 rpm for a smooth idle although the I-5 has 2 chain driven balance shafts in the block driven off the crank at the back of the engine.

 

[BiteEmNBeatEm]

i am just shy of 130k miles,

I do change the oil regularly, but this last time it was done at wallyworld just for convinence.
Today I went ahead and changed it out again but that was not the issue. It seems it will only do it once the oil gets warmed up from some driving and then comes to an idle. I guess i will go pick up an oil guage at harbor freight and test it.

I am assuming that i will connect the guage where the oil sending unit is, right?

 

[BiteEmNBeatEm]

The oil pressure tester gauge I just purchased did not have a fitting that matches the threads that are at the oil pressure sending unit. So I have yet to check oil pressure.

I replaced the oil pressure sending unit with a new acdelco one, but that did not work.

Compression is as follows:
90 (closest to radiator)
110
100
120
110 (closest to firewall)
(Using a cheap harbor freight gauge)

plugs were pretty bad over all cylinders so they were all replaced and the MAF and TB were cleaned out as well. My TB was in serious need of cleaning.

 

[Reloader]

Cylinder compression really won't have much effect on oil pressure. Although yours are not consistant, 30 psi difference from low to high is signaling wear and weakening ring sealing. I would still like to know what the actual oil pressure is at say 1500 rpm cold and hot. You could try a heavier weight oil such as 10w-40 or 10w-50. But I don't know how that would affect the vvti operation. might not be a problem down there in that Texas heat.
Back to the compression thing, I like to check it on a warm engine and pull the fuel pump relay or fuse whilst running and allow the engine to stall. then pull all plugs and test . This assures no fuel is being injected into the cylinders which can wash down the oil on the walls and cause rings not to seal well while cranking giving a false pressure reading. Also I like to see what one compression stroke produces on each hole. I think that gives a more accurate pressure comparison.
Not trying to scare you or nothing but if you do need to repower, you should be able to find a good low mileage road proven ( thats what we call used) engine for about 13-1500 dollars that may already have a new head installed. Should be lots of them out there as they are used in the Colorado/Canyons also. If its the original head there will be a VIN sticker on the back of the head. If the head has been replaced the sticker will say GM replacement or something. Install time is about 13 hr by Alldata time. Last one I swapped took me about 7.5 hr but I didn't have to change much. I was impressed that the salvage yard didnt break anything and didnt butcher up the wiring. Was basically plug and play. And it had a new head already installed.Sorry about rambling on again.

 

[Reloader]

Any news? Just curious.

 

[H32NV]

SAME ISSUE. SAME EXACT SYMPTOMS. And when I check it if the oil is hot, it shows A FULL QUART LOW. When I let the engine idle and cool down, it's DEAD NUTS ON FULL. WTH? I'm gonna pull the pan and look at the pickup tube. Not assuming it's the oil pump yet, but it would fit the bill. that or the pickup tube. or a dirty oil filter, which I just changed and still have the same issue. BTW, the oil pump comes with the front cover for the motor on the I5. GMpartdirect has it for $100 and the new front cover seal is $8. I think a new pickup tube is around $35

*My compression is 110-120 all the way around.* - EDIT

-Rob

 

[BiteEmNBeatEm]

I ended up replacing the oil pressure sending unit and used an oil flush and have been running rotella t6 oil and issue is gone. I'll be switching back to a regular synthetic oil here soon I just wanted to have the t6 detergents help clean up inside the engine. All is good now.

 

[Pmedic920]

I ended up replacing the oil pressure sending unit and used an oil flush and have been running rotella t6 oil and issue is gone. I'll be switching back to a regular synthetic oil here soon I just wanted to have the t6 detergents help clean up inside the engine. All is good now.

I have the same issue. I'm going to replace the sensor first. Can you tell me where it is on the h3? Scale of 1-10 how difficult was it? Any special tools required? Thanks for any info you can provide.

 

[DJinCO]

Rotella T6 is a great oil for cleaning.

 

[Pmedic920]

I have the same issue. I'm going to replace the sensor first. Can you tell me where it is on the h3? Scale of 1-10 how difficult was it? Any special tools required? Thanks for any info you can provide.

Bump

 

[Xscorex]

The exact thing happened to me right after getting my oil changed at jiffy lube. I put one bottle of Stp oil treatment in to thicken my oil and the light fluttered on here and there. I put two in and the light went away. I have 140k on my engine. Jiffy lube put in 5w30 but it must have been tbin or something.

 

[Best4x4]

My 07 H3 Adventure was having the "Oil" Message and the warning light illuminate after I finished installing a new Silla Radiator. It would go on/off whenever it wanted to, at idle, at speed, or shortly after cranking the H3. I knew I wasn't having an actual oil issue because the engine wasn't knocking and the oil level was spot on. I decided to replace the oil pressure sensor, and immediately after I unplugged it I knew it was faulty. Fresh clean oil started to drip out of it so it had internally gone bad. I replaced it with a BWD brand sensor (haven't ever had an issue with them on other rigs), and the install took maybe 15 minutes to install once I located it. A deep 1 1/16 deep socket is all you need to remove/install the sensor which is located directly above the oil filter on a 3.7L.

 

[Baitcaster]

A new member here but having the same problem with my 2007 H3. It has 99,000 mi. on it and out of the blue it oil light started coming on. I have changed the oil and water pumps, the rod bearings, bypass valve, cleaned the oil pick up tube, the pan, changed the clutch fan, thermostat, drive bell, replaced all of the fluids and though I always use prem. oil and filters, went to Valvoline 10w-30 Racing synthetic with a Bosch filter and still having the problem. I did check the oil pressure when it started and it was losing oil pressure - thus the basic overhaul of the lower. After everything, it initially seemed to take care of the problem and had oil pressure and initial testing the light didn't come on, but took it for a longer run today and the dang light and alarm came back on. But like others on here posted, just a little fuel and it cuts off. I can't figure this out for nothing. I really don't know what the heck to do next. Help!!!!

 

[Luis Rodriguez]

same issue. Same exact symptoms

 

[Lunesta2]

I had this problem. I just changed the oil sensor and it went away. You can unplug it and see if there is oil on the connector. If there is it's bad. If not change it anyway. It's cheap and easy

 

[alrock]

http://smile.amazon.com/ACDelco-D18...447214813&sr=1-5&keywords=oil+pressure+sensor

 

[kilroy]

Is it just me or does there seem to be one recurring thing mentioned in this thread? If anyone has missed it in the past our I5's do not like full synthetic after having spent any amount of time running on Dexos. Have the smoking at start-up issue mentioned relating to full synthetic multiple times / places.

 

[Lunesta2]

Been running full synthetic for 10 years on mine now. I don't even change my oil unless it says change oil.