Help guys.. 92 sel 600 oil pressure question. - PeachParts Mercedes-Benz Forum

will70724 · #1 11-14-2007, 11:54 PM

Hey guys, hopefully you can help me out. I have a 92 sel 600. I just noticed a little while ago that my oil gauge isnt moving. I was driving and it would stay on 0 so I pulled over and reved the car up and when i brought it up to high rpm's the gauge went up. So I took it on a longer street and got on it and when i got on it when the rpm's high the gauge went up, but as soon as it shifted gears t he oil pressure droped back down to 0.

So basically my car isnt getting any oil pressure besides going high on the rpm's. Also I just noticed I'm about 800 or so miles over my due oil change, I have no idea how I missed that.

But I'm wondering do you think the oil filter might be cloged and that's whats causing no pressure at low rpms?

So I have a few things I'm thinking it can be.

1) oil filter cloged.
2) oil sending unit not working?
3) or something very bad?

Any suggestions or any idea what it sounds like? Should I change the filter and just see what that does? Should I risk driving it on the freeway to the shop I take my car to?(about 60 miles away) or what should I do??

Thanks in advance.

Jim B. · #2 11-15-2007, 12:14 AM

It should be at 3 bar (top bar) all the time, except that while idling in traffic it might drop to 2 bar, then go back up to the top when you get back up to normal speed again.

When you checked the oil on the dipstick, was it low on oil? You DID check the oil, right?

Did the "low oil" orange dash light come on, in the car?

Did you see anything like oil dripping

PS: Will, you were missed on the recent Diesel Drive, up this way, and I hope you can make the next one......

will70724 · #3 11-15-2007, 12:24 AM

I know it stormed so hard here that day i couldnt make it, and my friend that was going to go backed out t he night before it sucked. I defintely defintely want to go on the next one.

And the oil level is perfect not low at all, and the oil light is NOT on. And its not overheating or making any knocking noise?? So Im wondering what it is?

wbrian63 · #4 11-15-2007, 08:23 AM

My '92 300SE did that recently. Simple fix - a new oil pressure sender.

I have no idea where it might be on a V12 - mine was easily serviced from the top of the engine - it attaches to (or right next to) the oil filter housing.

mbdoc · #5 11-15-2007, 08:29 AM

On the W140 chassis, the warning lamp for low oil pressure comes on at 0.3 Bar (approx 5psi). If that lamp didn't come but the gauge dropped to ZERO, I would think that the sender IS the problem.

IS the engine noisy?? if you remove the oil cap with engine running, is there oil being sprayed??

#6 11-15-2007, 08:43 AM

If you truly have low oil pressure the motor should *REALLY* be protesting! If not, it is almost assuredly the sender.

FWIW I have never even heard of any MB motor suddenly losing oil pressure unless maintenance was utterly neglected for a very long time.

will70724 · #7 11-15-2007, 08:48 AM

Im always a little paranoid but it really sounds like it's just the oil pressure sender. The car doesnt get above 80 degrees c. So its not getting hot or nothing and the car is fairly quiet, and its not sluggish or nothing. So Im praying its just the oil pressure sender and not something drastic.

If the car was really losing pressure the car would overheat and be very loud even while in the car right?

Thanks in advance.

will70724 · #8 11-15-2007, 08:58 AM

By the way heres a diagram of the oil filter i just dont see where the oil pressure sender would be? I guess I will have to take everything off to see it.

Edit is it the braided hose that runs under the oil filter on the picture captioned with now to the oil filter? it looks like a hose that runs into some sort of unit? Hard to tell though?

http://v12uberalles.com/changing_oil_filter.htm

mbdoc · #9 11-15-2007, 10:12 AM

Figure 62 is the sending unit

will70724 · #10 11-15-2007, 07:12 PM

Thanks for t he diagram, the shop I go to called me back today and he says pretty much its nothing to worry about ( well not like t hat) but nothing to worry about as far as the pressure goes. He said just to double check under the oil cap to see if theres pressure.

But since it doesnt get hot and not making noise its most likely the oil pressure sender

Brett San Diego · #11 11-16-2007, 02:03 AM

Quote:

Originally Posted by will70724

Thanks for t he diagram, the shop I go to called me back today and he says pretty much its nothing to worry about ( well not like t hat) but nothing to worry about as far as the pressure goes. He said just to double check under the oil cap to see if theres pressure.

But since it doesnt get hot and not making noise its most likely the oil pressure sender

Probably the sender, but could also be the wiring. Here's a very good read. It's a long story, but a very good DIY diagnosis and documentation of the fix. Worth reading every word. Anyone with a pre-96 V12 needs to be aware of this thread.

http://www.benzworld.org/forums/w140-s-class/1332584-oil-pressure-zero-starter-wont-go.html

Posts 62-65 document oil pressure sender diagnosis and replacement.

Brett

will70724 · #12 11-16-2007, 03:25 AM

Good pics, Im almost 100 percent sure its the oil pressure sender. NOw I'm debating if I should replace it myself or take it to the shop I trust.

I live out in san francisco and have no where to do this, so if I were to do it, I would have to find a part store with the part, drive to parents in vallejo, and figure out how to replace it.

Any suggestion on how much the part would be?

And also a suggestion of how long the sender would take to do?

Brett San Diego · #13 11-16-2007, 02:41 PM

Quote:

Originally Posted by will70724

Good pics, Im almost 100 percent sure its the oil pressure sender. NOw I'm debating if I should replace it myself or take it to the shop I trust.

I live out in san francisco and have no where to do this, so if I were to do it, I would have to find a part store with the part, drive to parents in vallejo, and figure out how to replace it.

Any suggestion on how much the part would be?

And also a suggestion of how long the sender would take to do?

According to alldatadiy.com: $78 part, 0.9 hrs book time.

Brett

will70724 · #14 11-16-2007, 03:52 PM

Hmmm ok. so basically if i do it i would save like 100 bucks ( shop price)

Anyone done one of these pressure senders? Is it worth doing it on my own or is it better to just pay the 100 bucks?

lesrrt · #15 11-16-2007, 04:38 PM

If A 100$ is all they charge you that is. Easy. Take off the drivers air box assembly: there are 2 10mm fasteners that holt it on. This is after of course you removed the black cowling panels that cover the hyd fluid tank. Remove the hose clamp via the throttle assembly and leave the MAF sensor side on. Unplug the MAF sensor and the one sensor in front, or IAT temp sensor. Now remove the black metal top radiator support; there are 6-10mm bolts, real easy. This will allow you to lift the entire air-box with the rubber intake boot hose and front inlet plastic horn attached as one unit. When you get this out, you can see the oil pressure sending unit under that assembly; it should have a green wire. Also like Brett said above, read the posts. Your wiring is probably shot. If the wire loom crumbles in your hands, chances are you will see naked wire that had its plastic disentegrate via the heat. You could probably access this unit from under the car too if you had real small hands I guess. Good luck and save your $