Mercedes-Benz Forum banner
1 - 20 of 22 Posts

·
Registered
'04 G55 '80 280GE '99 S420 '98 E320 2011 E350 2016 GLA250
Joined
·
3,104 Posts
Discussion Starter · #1 · (Edited)
Yes, Yes, I know that as long as the "Oil Pressure Warning Light" is not Illuminated, the Oil Pressure "SHOULD" be Ok....

Still, ever since I have switched to the "Formula M" Mobil-1 (5W-40), my Oil Pressure readings have been "Nervously" Low.

I am sure the drop has been due to the Lightwer weight oil (I had previously run Only 15W-50 Mobil 1 for my Hot environment). I had switched to Formula M since I now buy it in "Bulk" for Fleet Standardization.

Anyway, to help myself sleep better at night... I wanted to PROVE the Lighter oil is the etiology. Speaking with my MB mechanic friend, he claims WHEN the Pressure Sensors start going bad... it is at the LOW-END of the Sensing range when they start to Fail. Sooooo, could my LOW Readings be related to a Sensor going Bad?

Since I'm not a "Throw-New-Parts-at-a-Problem" Kinda' guy, my Scientific Side wanted to Investigate the Differential Diagnosis of:

A- Bad Oil Pressure Sensor?

B- The Engine is NOT Creating Sufficient Pressure (ie. a Valve Tappet Oil Tube is Broken)

C- My Oil Pressure GAUGE is Inaccurate.

It looks as if the Final Diagnosis was a Slightly Screwy Pressure Sensor, So I will Plan on Replacing.


Here is the Guide for Separating out these various Etiologies, from WIS.

Please Note: This is for a M119 Engine on 1999 S420.

G
 

Attachments

·
Premium Member
Joined
·
478 Posts
As always G-AMG thank you for taking the time to do a fantastic write-up and sharing it with all of us here. You are truly one of the invaluable members and resources in our community :thumbsup:
 

·
Registered
99" CL500 , 99' CL500, 97' S500, 01' S500, 02’ G500, 09’ G550
Joined
·
2,158 Posts
Seriously G-AMG, glad you are a member... Always the most professional write-ups that I remember long after reading them, a testament to your methodology. :thumbsup::thumbsup: (two thumbsup)
 

·
Registered
1997 S500V, 1999 S500 grand edition, 2006 s65 amg
Joined
·
7,356 Posts
Nice write up. A question about the pressure level what is normal for idle and when does it need to be 3bar? I have looked at mine i know my sensor is shot because it was tested off the car and it plays around when at 1.1-1.3 it will just go down and up.
 

·
Registered
'04 G55 '80 280GE '99 S420 '98 E320 2011 E350 2016 GLA250
Joined
·
3,104 Posts
Discussion Starter · #7 ·
A question about the pressure level what is normal for idle and when does it need to be 3bar?
Hey.

You might want to re-look at the Post. I thought I was pretty clear what the "Spec" Numbers should be, in terms of RPM vs. Acceptable Pressure "Ranges".
 

·
Registered
1997 S500V, 1999 S500 grand edition, 2006 s65 amg
Joined
·
7,356 Posts
The .3 bar is considered normal for idle? That is the part that confuses me. With bad oilers my engine was running at .3 bar and now idle is roughly 1.4bar on really warm days it might drop to .5 bar. The part that confussed me was on one of the pics it had a comma instead of period.
 

·
Registered
'04 G55 '80 280GE '99 S420 '98 E320 2011 E350 2016 GLA250
Joined
·
3,104 Posts
Discussion Starter · #9 ·
The .3 bar is considered normal for idle? That is the part that confuses me. With bad oilers my engine was running at .3 bar and now idle is roughly 1.4bar on really warm days it might drop to .5 bar. The part that confussed me was on one of the pics it had a comma instead of period.
Yes, "Idle" (600-750 rpm) 0.3 to 1.5 Bars Range is Normal.

And, sorry, I "Slipped" by using the "European" Decimal, which is a "Comma".
 

·
Registered
1997 S500V, 1999 S500 grand edition, 2006 s65 amg
Joined
·
7,356 Posts
Yes, "Idle" (600-750 rpm) 0.3 to 1.5 Bars Range is Normal.

And, sorry, I "Slipped" by using the "European" Decimal, which is a "Comma".
Man on this forum you never need to say sorry. You are one of the kings of DIYs i just got a bit confused and it it was another form of measurement. I must say thanks for these threads. Especially the 722.6 thread with the pressure spring.
 

·
Registered
99" CL500 , 99' CL500, 97' S500, 01' S500, 02’ G500, 09’ G550
Joined
·
2,158 Posts
Yes, "Idle" (600-750 rpm) 0.3 to 1.5 Bars Range is Normal.

And, sorry, I "Slipped" by using the "European" Decimal, which is a "Comma".
hahaha a European in Texas... somehow that made me laugh.
 

·
Registered
2001 CL500
Joined
·
1,707 Posts
Thanks for sharing!:)
 

·
Registered
1991 R129 500SL
Joined
·
2,021 Posts
Thank you for sharing :thumbsup: + :bowdown:

Slightly OT: My R129.066 has a defective oil pressure gauge on the instrument cluster, as it only reads between 1.8 to 2.5 bar. This happened after I removed the "white face" stickers that I placed (trying to "upgrade" the instrument cluster look).

Is it possible to replace with a new gauge from MB (if at all available) or do I need to send it to a place for recalibration? Any suggestions would be highly appreciated.

Thank you in advance!
 

·
Registered
'04 G55 '80 280GE '99 S420 '98 E320 2011 E350 2016 GLA250
Joined
·
3,104 Posts
Discussion Starter · #16 ·
Thank you for sharing :thumbsup: + :bowdown:

Slightly OT: My R129.066 has a defective oil pressure gauge on the instrument cluster, as it only reads between 1.8 to 2.5 bar. This happened after I removed the "white face" stickers that I placed (trying to "upgrade" the instrument cluster look).

Is it possible to replace with a new gauge from MB (if at all available) or do I need to send it to a place for recalibration? Any suggestions would be highly appreciated.

Thank you in advance!
Hmmmm, if the incorrect Readings ONLY started after you removed the Instrument Cluster..what "i" would do as a first-line repair.... Would be to remove the cluster, and thoroughly clean all of the applicable contacts(making sure they are shiney on both sides), and apply a dab of Dielectric Grease to keep out all of the heat/humidity/salt in your Phillipine environment.

G
 

·
Registered
1991 R129 500SL
Joined
·
2,021 Posts
Thank you G, for the advice in using dielectric grease on the contacts...will definitely try that on the weekend!

Just thinking out loud, but if it were "a problem with the contacts", would it still work at all as against it working partially within the 1.8 to 2.5 bar range?
 

·
Registered
'04 G55 '80 280GE '99 S420 '98 E320 2011 E350 2016 GLA250
Joined
·
3,104 Posts
Discussion Starter · #18 ·
Thank you G, for the advice in using dielectric grease on the contacts...will definitely try that on the weekend!

Just thinking out loud, but if it were "a problem with the contacts", would it still work at all as against it working partially within the 1.8 to 2.5 bar range?

Remember, the gauge reading depends on RESISTANCE... If you have a small amount of corrosion on the contacts, this will alter the "True" resistance being sent by the Pressure Sender, and yield a False Indication.

Bottom line is: it is a FREE first-line check, prior to blowing any money.
 

·
Registered
99 S500-W140-175k, 01 ML 320-W163 300k, 94 E420-w124-129k
Joined
·
434 Posts
Great info on low oil pressure, Thank u for this G-AMG!:thumbsup:
question,. is too high of oil pressure bad as well for the M119 machine? reason i ask is because i have a M119 with 120k miles on it, i am running mobile 1 5-30 synthetic, at start up, cold; idling my needle is right at 3. once engine reaches 80c marks from idling for a while, needle will drop down right above the 2 mark, when i rev engine up it hits 3 and stays there. Does my machine have problem or is this ok? The time my pressure dropped to 1.5 was when i had a blown cam oiler.
 

·
W140 Moderator
"CHRIS" Merc 92 600SEL / Sold > 93 600SE / 93 S500 / 89 560SEL / 413CDI / B180-CDI /A170-CDI
Joined
·
7,798 Posts
As usual a 100% spot on and beautifull DIY by you G-AMG ,love it but then , if I only had those TOOLS you have .
Can you make a quick one of how to take a V12 engine out ,lol.:thumbsup:
 
1 - 20 of 22 Posts
Top