Oil alarm buzzer triggered while dipstick shows full

[Jim M.]

Anyone else experienced this ? What might cause this ?

 

[alrock]

Bad sensor? It's located right above the oil filter and fairly easy to change. But what concerns me a bit is what you posted in your other thread about using a quart of oil every 500 miles. Perhaps someone else can recommend how to measure the oil pressure in the H3. Is it on a standard scan tool?

 

[Jim M.]

Sorry for the confusion.....the oil consumption problem of a quart every 500 miles was on my previously owned 2006 H3, not my current 2009 H3.
Two different vehicles. This alarm issue just showed up on the 2009.......and no signs of excessive consumption.....dipstick shows full after 1500 miles since last change.
Thanks for the sensor suggestion.

 

[08H3]

Sensor is cheap and likely the issue. I would definitely start there.

 

[rascole]

Ditto above.

 

[Jim M.]

Thanks guys . Absolutely the logical place to start.....and hope its as simple as that. Thanks for the input. Can't believe I missed the obvious. Another example of why it's great to bounce these things off others.

 

[Jeepwalker]

Um ...not to throw cold water ...but how about genuine low oil pressure? That's a real possibility. These Atlas engines are famous for low oil pressure at high miles. If it weren't for that and a couple other things, the engines are robust enough to probably last forever. An oil pressure test is the logical place to start IMO. Could have a weak oil pump, clogged oil pickup (with bits of broken chain tensioner plastic), leaky pick-up tube gasket (was a common thing), worn cam chain tensioner, or worn bearings. Or (more than likely) all of the above. If you go to change the oil press sensor, I'd invest a little time and at the same time while you have it off, perform an oil pressure test. Then you're not guessing and can plan what your next steps will be. You need a certain uncommon metric adapter to do it. I just made one out of a drilled/tapped large metric bolt (cut down short). But you can buy off ebay not that much. Do a search on the forum what the size is. Parts stores rent oil pressure testers ..some do anyway, but like I say, you'll need to come up with the right adapter. An oil pressure tester is a good tool to have in the tool box. Make sure you bleed the air out of the pressure tester hose to get a 'true' reading.

My H3 is running around 9-11 psi at hot idle, foot on the brake (in gear). At road speed it stays at ~25psi (hot). That's low, but still within minimum engine requirements. I've seen engines with as low as 4 psi at hot idle and they ran fine for many years. In fact I had a ford years ago which the oil tester gauge didn't even register at all!! Ha ha. At hot idle. And yet it ran fine for years. Sometimes on mine, in the summer, it dips down below that, probably to 8 and sets off the low oil pressure alarm. Not often but it does. I tested mine with a verified Winters 0-30 psi gauge (LOL!!) and cross checked it with a 0-60 psi verified gauge. People get freaked-out by low oil pressure, but you'd be surprised how long an engine can last on relatively low oil pressure. Mine's probably been like that for years. Regardless, I plan on pulling it's 3.7L I-5 in the spring and rebuilding it.

It's worth bearing in mind pressure gauge acccuracy isn't linear. They are designed to be most accurate within a certain range, usually falling in the 70-80% of it's entire reading range, and less accurate outside of that range. A good gauge comes with a spec sheet which will give the tolerances in certain psi ranges. So, if you rented a 0-200 psi chinese oil pressure gauge at a parts store that's been dropped and beaten around for years, and the gauge needle read super low on your PSI test, bear in mind, that's at it's least accurate reading range. And 0-200 is way too high of a scale unless an engine has good solid oil pressure in the 50+ psi range. The accuracy on such a gauge could be off quite a bit in fact. That's why i put a new, calibrated, 0-30 psi gauge on my H3's engine to get what I hope was a quality reading in the 10psi range. Anyway ...something to be aware of. Maybe you'll get lucky and your problem is a failing oil pressure switch.

Let us know what you discover.

 

[Jeepwalker]

If I recall it's an M16 x 1.5 thread adapter. Like I said, make sure whatever oil tester kit you get has some adapter to fit. I cut & tapped a metric bolt (see pic). Easy to do. Or just buy one (link below). Same for an LS so if you know a mechanic they may have one you can borrow.

https://www.amazon.com/Pressure-Sensor-Adapter-Mechanical-Engines/dp/B09WR4L712/ref=asc_df_B09WR4L712/?tag=hyprod-20&linkCode=df0&hvadid=616267171621&hvpos=&hvnetw=g&hvrand=15456720785250089677&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1027853&hvtargid=pla-1730317269779&psc=1

 

[Jeepwalker]

Awwww shucks! LOL Here you go! After this pic I re-bled the air out of the hose. It seems to hold to 10-ish at hot idle (AC on ...hot summer day, in gear (worst case)). 25-28-ish at 60mph. Not great but probably been like that for at least a few yrs. She rattles a little on start-up too. Come spring I'm planning a refresh on her. Life finds a way.

 

[Jeepwalker]

Sorry, brain-fog, I mis-typed (can't edit my earlier post): My 0-60 psi ga is Winters. 0-30 is a Carbo (ebay/China) gauge. Seems like a nice gauge tho. But start with a 0-100 psi. If yer oil pressure is real low then move to a lower psi gauge for greater accuracy if you need to. B/C on start-up cold oil pressure can spike a lot till engine speed settles down and oil warms up. Then the fun part occurs as the gauge starts dropping and you wonder how low it'll go!! he he. https://www.ebay.com/itm/184659379178

Best of luck!

 

[Jim M.]

Wow....lots of good info....quite the education ! Thanks. Sensor has been ordered and on the way. Also having a low idle issue (that I've never experienced on my other H3) where it starts out just fine at start up (approx 1K rpm) but then drops to around 500 rpm after warm up and a few miles......and stays that way at each intersection. Irritating steering wheel shimmy and rattle until I get idle to about 800-900 where I think idle should be. Tried throttle bottle cleaner and a shot of Sea Foam but no change. Any tips on how to get the idle up ? Could the one issue be related to the other ?

 

[Jeepwalker]

Also having a low idle issue (that I've never experienced on my other H3) where it starts out just fine at start up (approx 1K rpm) but then drops to around 500 rpm after warm up and a few miles......

What's yours idling at? So did you clean the throttle blade off real well? And the IAC? Any codes? The throttle blade and bore have to be very clean.

I guess.... like always, start with the easy things: Might ohm-out the temp sensor with a VOM and compare it (cold reading & hot reading) with a temp/ohm chart. Sensors can 'drift' and the computer 'could' think it's a different temp than it is (screwing up the fuel ratio). Also could be a vacuum leak ..intake, hose, etc (get a vacuum gauge). If you have to remove the plugs, might want to do a compression test on it. Parts stores rent out compression gauges for free (deposit). These Atlas engines often burn a valve in the center cylinders. Mine has low cylinder compression too on one of the center cylinders and I suspect its a valve issue. If it idles too long under certain circumstances it'll give a high mis-fire count. But usually not. Again ...why I need to do a refresh on er..

Have you tried to clean off the Mass Air Flow sensor? It's worth a shot. I've had MAF's which were on the very low end of 'good' but caused operation issues (not on an H3). But after I replaced the reading was in the normal range and engine ran great. Ohm out the coils ...ensure they're good. Visually inspect for traces, etc. Look plugs over carefully. I'm just throwing out possibilities here.

Oh also. I just remembered: On the H3's it's real easy to fold the rubber intake boot under itself at the throttle body, when installing. A guy/mechanic/tech could easily do it and not even know it. Mine was like that when I bought it. Even when the clamp is tightened, a little air can slip past the poor seal and spoof the engine into the wrong air/fuel ratio. It's worth a look. Not sure what the shimmy is. Have you checked the engine mounts? Open hood, put in gear (foot on the brake) and give it some throttle. Watch the engine to see if it 'rocks' up. Put it in reverse, and give some throttle (foot on brake) ...and watch engine. Engine mount failure is somewhat common on these.

Do you have a decent OBDII scanner?

 

[Jeepwalker]

Oh, btw, the knee-jerk reaction is to go to a thicker oil in the event your engine does have low pressure (we don't know that ...but just speaking out loud for the sake of the topic). But don't. Or don't add 'much' thicker oil. Atlas engines, like many engines these days, have oil squirters for the cylinders to lubricate them. They require a thin enough oil to properly squirt. Engines get ruined, or live a short life when guys start playing backyard alchemy with oil weights. But then again, at 25-28 psi, IDK how much squirting comes out of my engine's either?? If so ..does it make it to where it needs to be? IDK that either.

 

[Jeepwalker]

Yeah, 500 is low. I think mine idles ~650 if I recall. Was the idle always low?

You probably need to scan for codes and start with basic troubleshooting, ground zero and work out from there. Otherwise it's just a scatter-gun approach.

But hey, here are some scatter-gun ideas LOL: Cam phaser working? ..missing cylinder?, compression low?, low vacuum, Bad coil/plug? etc (??). PCV valve or the PCV hose? MAF, IAC, O2 Sen, Plugged cat? Corroded ECU?? I'm probably forgetting some things. This is almost a separate topic from oil pressure.

 

[Jim M.]

Thanks Jeepwalker. Looks like my works cut out for me. Yep, cleaned the MAF sensor (just cleaned, didn't replace with new) and was headed for the IAC valve next. No CEL , so didn't check for codes. Working on my '52 Buick today, so........I'll start following your suggestions tonight or tomorrow. Thanks for all the insight, and devoting all the time and effort to send me in the right direction .....on BOTH issues. Much appreciated !