New oil cooler lines are now on my shopping list for this weekend...

I like this idea, couldn't you put some sort of contacts behind the oil pressure gauge behind the cluster? That would make it that much closer to the ignition switch for lockout purposes.

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http://i106.photobucket.com/albums/m...73378_30-1.jpg

I am posting this again as I think my soulution is simple and has been in my car working since the date of the origional thread:
Low oil pressure alarm for 617.952

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84 300D, 82 Volvo 244Gl Diesel

Hey i was wanting to know what do i need to do if i ever want to install one for my 300SD, since mine has an electronic oil pressure sensor...

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Current Garage
2008 Mercedes GL320 CDI 188k mi Repair/Work in progress
1994 S350 160k mi Garage Queen & prepping for repairs
2005 E320 CDI 203k mi Healthy & Daily Driver
1994 S350 357k mi Retried as parts car
1984 300TD 214k mi Blown OM617 Poss OM603 Swap??

Sold
1987 300SDL 200K+
1994 S320 181K mi
2008 E320 Bluetec 127k mi
1999 S420 130K mi
1980 240D 360k mi
15+ Others that has come, stay and gone

GONE, BUT NOT FORGOTTEN
1995 E320 SE 220k mi
1984 300SD 350k mi

The method I used in my old Thread will work on Cars with either Mechanical or Electronic Oil Pressure seneors type gauges. As, takes the pressure from a different area.
Low oil pressure alarm for 617.952

At present there is no "bolt on" type setup so that you can add your sending unit into the area where the Oil Pressure gauge tubing or the Oil Pressure sending units screw in.
This is why I decided it was easier for me to remove the top Oil Filter Cap and drill and tap it to fit the sending unit. The only caution is that you need to drill fom the inside out so you can avoid the Casting Webs in the top of the Oil Filter Cap.

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84 300D, 82 Volvo 244Gl Diesel

O.K. You've got your Oil Pressure (AND maybe Coolant OverTemp) kit contents
in hand and you're itching to "Get Wrenching"...

WRONG!

Nice man @ MBNA in Montvale,N.J. Re-Confirms FSM's Specifications for OM602.962
(Your engine's Specs may be different)
Oil Pressure(s) at IDLE and at 3,000 RPM.[He's got the same info as the FSM]

"Oil Pressure at idle MAY drop to 0.3 Bar"
"Oil Pressure should instantaneously increase with RPMs to 3.0 bar at 3,000 RPMs."

(0.3 bar is "Around" 4.35114 PSI)
(3.0 bar is "Around" 43.5114 PSI)

The Cole Hersee OP offers at least 3 different OP Switch(S):
A 3-7 PSI switch as offered in the M40177BP kit.
A 6-12 PSI switch, #8601.
A 8-12 PSI switch, #8643.
The last two would have to be ordered separately from the "Kit".

(Or other fine Marine Engine Warning System offering)

The New Zealand Electronic, Digital Gauge from CruzPro, the OP60, is almost infinitely adjustable.
(And would most likely work with existing VDO sensors)

NOW, HERE IS THE CONUNDRUM:

[Forgetting for the moment the fact that the CH unit may not go low enough for FSM specs at idle]

If you are using the IDLE PSI figure as your low OP Alarm...It is entirely
within the realm of His Most Obfuscatory, Lord Murphy's, Power to allow
an Oil Pressure Anomaly at high engine speeds.
(without proper notification by the OP Alarm,'Cause you've still got above
the Minimum OP)
'Resulting in Engine Damage and You None the Wiser!

[Horrible analogy ,It is possible to "Beat the Airbag" in a Modern Vehicle IF
You Are Not Wearing a Seatbelt...The Seatbelt provides just enough
"Slow Down" time for your Noggin...So that the Airbag may Deploy.]

Scenario "On the Road":
You're romping along at 2900 RPMs and the OP drops to 13 PSI...
(WHAT IS THE REAL,MINIMUM OP NECESSARY TO PREVENT DAMAGE
@ HIGH RPMs ???????)
You get no OP Alarm, because the 13 PSI is above Low Setpoint.
BY The TIME You DO Get An Audible It May Be Too Late...

Please,
Someone Play DA and Correct me!

__________________
'84 300SD sold
124.128

You make a good point concerning Oil starvation under load and no alarm sounding; but with no alarm at all my Wife would drive the car until it could not be driven any more. And after it died She might try to start it. At least with my mininum alarm I have some hope that there is something left to fix.

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84 300D, 82 Volvo 244Gl Diesel

hello, i had a problem during decelerating right turns, i also had noticable dings and dents in my oil pan (apox 1"deep). i finally pulled the oil pan and found the pickup tube/screen was cracked from one of the oil pan impacts!!!!!i replaced this part from my doner car and now pressure stays at least @ 2 bar minimum. Bill

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Gretchen 1981 240D 4-spd 213,000 mi
1979 240D 4-spd 298,000 mi parts car

1994 BMW 325is
1991 Dodge turbo diesel
1997 ford expedition

BILL

Bump, bump...any more on this NEEDED protection alarm.

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1985 300D, 250k
1980 300SD, 180K

There are many out there, the variable is cost and quality.


Low oil pressure alarm
http://www.google.com/search?q=Low+oil+pressure+alarm&rls=com.microsoft:en-us&ie=UTF-8&oe=UTF-8&startIndex=&startPage=1

Right now someone on another current thread is examining a comparison op amp approach. This is a good ideal as rpms pick up the alarm moves to a higher pressure alarm threshold status. Simular to volkswagons two stage system but better. Also easily tailored to you cars individual needs.

The tachometer signal is being utilized or investigated as the input for comparison. Nice sensible approach in my opinion. This is for the electric gauge senders.


The same system could be implemented on the mechanical gauge cars by installing an electrical oil pressure sensor as well on the car. For the cars with automatic transmisions. I have always felt the system could be left shut down by using the contacts on the transmission lock out system. Just a dollar relay should accomplish that rather than doing it electronically. This way the average guy can install the system and perhaps even repair it with a little help.

You could still check the system out periodically by turning on the key and engaging a transmission gear. Since there is no oil pressure it should alarm. Most people do not like an annoying sound while waiting to get their engines started. Or need the distraction.

Since you put your car in neutral or park before shutting down there would also be no noise. On the highway especially you want to know when the pressure has dropped below thirty pounds on the average example right away.

When driving under many conditions I have found it impossible to monitor the oil pressure gauge. Or at least as constantly as it should be observed with those oil cooler lines. If a line blows off a fitting because of rotting rubber etc. In most cases the engine will pay the price in my opinion before you notice it. Without a proper alarm you at least should have reasonably current oil cooler hoses. The older hoses have been the most prevelant problamatic disaster area with these cars.

I like your idea of using the NSS to silence the alarm when you're not moving. The flashing LED (I like both) could be allowed to flash in neutral or park as it would be less annoying than a beeper.

Adding the system that KarTek and I are designing to a car with a mechanical gauge (W123, etc.) would not be difficult. All you'd have to do is to tee the oil line behind the instrument cluster and install an electric sender.

Jeremy

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

Barry,

Where ,Please.
Thanks.

YES,(Holy Grail of OP Alarms) setpoint increases/decreases with RPMS !
[AUTO-MATICALLY]

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'84 300SD sold
124.128

Oil pressure alarm
http://www.peachparts.com/shopforum/diesel-discussion/259067-oil-pressure-alarm.html#post2270534

Low oil pressure alarm for 617.952
http://www.peachparts.com/shopforum/diesel-discussion/214443-low-oil-pressure-alarm-617-952-a.html#post1771056

Warning Buzzer for Low Coolant/Low Oil Pressure
http://www.peachparts.com/shopforum/diesel-discussion/225033-warning-buzzer-low-coolant-low-oil-pressure.html#post1883983

Low oil pressure indicator
http://www.peachparts.com/shopforum/diesel-discussion/135438-low-oil-pressure-indicator.html#post996180

Unbelievable!!!#!@#!@
http://www.peachparts.com/shopforum/diesel-discussion/56600-unbelievable-%40-%40.html#post339806

The latter part of the first item Mr.Hunter lists is where the ideal of a differential system development is listed. Somewhere or other I saw a refference it may still be moving forward.

I may have a quick look to see if the old volkswagon distinct two stage system can be transplanted. . This might be the quickest and cheapest route. Depends how they have it wired in. It works really well in my experience.

There would be a lot of missing systems in junkyard volkswagon diesels if it is practical. At least the price would be right as well. I have good volkswagon wiring diagrams so I can soon post an opinion.

Much depends on how they lockout the high pressure warning at low rpms. If it is a signal from the alternator we would be in luck. About the same alternator on mercedes I think or hopefully close enough.

For those not familiar with the volkswagon system. Below an arbitrary value. Probably two thousand rpm the normal idiot light dominates. Probably set to trigger at five pounds or less. At 2000 rpm and above the alarm is armed. .

Any oil pressure less than 1.4 or 1.8 bar triggers an alarm that will relieve any form of constipation . The sensors we need can be harvested easily and cheap from junk volkswagons.

I can look up what models have the 1.4 bar and the ones that have the 1.8 bar sensors in their high pressure warning. Their low oil pressure sensor is .3 bar and is common to all their old models I believe. This information I just gathered from my volkswagon service maunuals.

I only experienced the high pressure alarm once after driving through a deep puddle. Once was enough. There was no way you were going back to volkswagon and attempt to tell them you never noticed and fried your engine under warranty. I thought for an instant the dive alarm had sounded on a U boat. In my opinion 99.9 percent of volkswagon diesel drivers have never heard that alarm fire.

Actually it could be somewhat like an episode of the twilight zone.You are cruising around 100 miles per hour in your 240d. Possibly down a mountain. Your sterio with a five hundred watt amplifier covers or is attempting to cover the cars background mechanical noise.

The oil pressure declines with a burst oil cooler line or whatever and the dive alarm sounds. After you get the car stopped your passenger asks if there is any toilet paper but you cannot hear him. The sudden lack of noise in itself has impaired your hearing temporarily.

Okay all kidding around aside. After the tach amplifier there is a rising voltage with rising rpm. With a high impedance input circuit monitoring it so the tach reading is not disturbed . Beyond a certain voltage the higher pressure oil sensor circuit installed is armed. .Of course as soon as the rpms and voltage drop off it drops out so that circuit no longer is armed. The threshhold can be set with a simple potentiometer.

When the relay output device drops out it can arm a bright red light much lower pressure circuit by its default contacts. As long as the circuit is turned on with the key there should be no issues. Or that low pressure circuit can be setup just self standing.

I like this better than the volkswagon setup because of it's simplicity. The only fly in the ointment is your tach must be functional. Anyone with a little time can look up the electronic chip with a very high input impedance able to throw a small relay. The threshold enabeling is specified in the schematics presented so there is no design issues that occur to me. Someone will have to plot the output voltage range of the tach amp as well.

This could fly and possibly as simple as it gets. I have been looking for simple and trouble free. The ideals are just slow to form. I was always concious I might find something simpler than this but doubt it now.

Barry,
(AND Thanks, Hunter)

Practical ! Fairly Simple.
[Being the electrical/cpu dinosaur that I am,the synapses will have to "Chew" on the comprehension]

I wouldn't even mind wearing a set of hearing type protectors at startup if
the Alarm sounds as part of a Self Test !

__________________
'84 300SD sold
124.128