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  #46  
Old 04-07-2008, 11:03 PM
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It was nice that you assumed that we might be able to design and execute an oil level sender.... high praise...
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  #47  
Old 04-07-2008, 11:07 PM
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Quote:
Originally Posted by leathermang View Post
It was nice that you assumed that we might be able to design and execute an oil level sender.... high praise...
What about just modifying one of the ones like the SDL uses and drilling/tapping it into the side of the oil pan? Are the pans shaped similarly enough to provide a good place to measure?

I mean, we were ready to risk the car shutting itself down to save itself on a busy interstate, so surely the possibility of a hole in the oil pan starting to leak/pour won't scare anybody... after all, the sensor will tell you if the installation of the sensor failed

EDIT: we replaced my oil pan six months ago and I don't remember the specifics of the sender. But... it's a thought.
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1982 M-B 240D, odo stopped at 308,000
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  #48  
Old 04-08-2008, 12:46 AM
High River Alberta Canada
 
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O.K. lets widen the topic...

Sorry if I'm gonna confuse things
So I really like the concept we are talking about. We are trying to prevent a low oil pressure situation and this is sortta related:
There are a few guys selling 'pre-lube kits out there. The idea being that you can electrically pump up your oil pressure before you start the engine.
Here are two I've found there are I am sure lots more:
http://www.prelube.com/
http://www.varnaproducts.com/EPPump.php
One of those has a built in oil changer option... cool.
What I would like to see is an inexpensive little electric oil pump that will kick in at say1 or 2 bar (be nice if I could adjust that) ANYTIME the pressure drops.
-it would kick in when you are about to start.
-it would kick in when your very worn engine is pretty darn hot and you are at a red light and the pressure drops below...whatever and help keep your bottom end together for a few more miles.
-and I hadn't thought of the built in tap for changing my oil but put it on the list too.
Perhaps a light when it runs and a buzzer to warn of oil pressure below that..
Comments?
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  #49  
Old 04-08-2008, 09:53 AM
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Alberta, This has been discussed a lot in the archives... I am all for it... but plumbing routing in our engines is not easy to figure and execute.
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  #50  
Old 04-08-2008, 10:52 AM
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So far an approx 8- 10 pound normally closed pressure sensor for little dollars evades me. I will keep looking . Any ideals? Sources? Needed cheap. I may have to deal directly with one of the sensor manufactures to get a kind of volume price yet.
I do not care if the sensor is made in china as long as it is made well. The principal ideal behind the kit was to have everything in one package that just installs very quickly with no complications and very economical. Nice to see all the various ideals coming forward. Keep them coming.
A person can modify his kit in any way for any feature he desires. The thrust of the cheap kit is to get the alarm on as many cars as possible as quick as possible with as little effort as possible.
Procastination is dangerous and perhaps will be expensive for some. To say a proper cheap kit is overdue is understatement. I really feel this alarm feature is not really optional. Should have been offered years ago.
Hopefully with a pizzo buzzer a complete kit can be very cheap if all parts are purchased in volume. Again if possible The ideal is not to make a lot of money but to get it underway. A ten or fifteen dollar complete kit for site members would be nice. I hope it turns out to be practical. Right now it seems to hinge on the pressure sensors cost. It has to be five dollars or less in volume purchases to hit the target in my opinion.
I better go spend some more time today looking for that sensor at a reasonable cost. . Any help is welcome.

Last edited by barry123400; 04-08-2008 at 11:00 AM.
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  #51  
Old 04-08-2008, 03:17 PM
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Quote:
Originally Posted by Mustang_man298 View Post
. . . Someone mentioned wanting it to be a normally open switch that closes on fail, that's not a good setup, a broken wire or corroded contact will let you down . . .
Fail-Safe (didn't someone write a book in the '60s???)
It is certainly true that designing a completely fail-safe system that also is simple and affordable and installable by an owner (rather than designed-in by the factory) is not easy.

Then there is the question: what is the risk? How often does this happen? Is the effort better directed to performing preventive maintenance such as changing oil cooler hoses, etc?

The combination of those two items may explain why Mercedes chose to not put them on their cars.

Practical concerns
It's possible to install a low-pressure warning without putting switches and wiring at risk in the engine compartment. It can all be done in the dash.

In the case of W123 cars and others using a mechanical oil pressure gauge, the low oil pressure switch (tee'd into the plastic oil line) and all of its wiring can be behind the instrument cluster where it will be safe.

Cars with electric oil pressure senders (W124 and similar) will need a different circuit, an FET input switch, for example, that turns on a light when the resistance of the sender gets too high or low (I don't know which way it works). Using an FET will minimize the load on the oil pressure gauge circuit. This can also be safely mounted behind the instrument cluster.

Buzzers
For a gasser, the buzzer at startup would be a momentary thing -- just until the engine fires and the oil pressure builds up. For a diesel, having a buzzer sounding continuously during pre-glow will quickly get old, I think. If the buzzer is loud enough to be heard over road noise, stereo, etc, it will be really annoying in the driveway with the engine not running. How about a flashing red LED? Some pretty bright ones are now available.

An interesting discussion. Keep it up!

Jeremy
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  #52  
Old 04-08-2008, 05:34 PM
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Quote:
Originally Posted by Jeremy5848 View Post
Fail-Safe what is the risk? How often does this happen? Is the effort better directed to performing preventive maintenance such as changing oil cooler hoses, etc?
Buzzers
- just until the engine fires and the oil pressure builds up. For a diesel, having a buzzer sounding continuously during pre-glow will quickly get old, I think.
Jeremy
If there is anything I don't want in my circuit it is a field effect transistor ! LOL. You would then need something to protect it ...like backwards mounted Zener diodes... etc... just more things to fail.... LOL

That is why I suggested the button to keep the noise off during that time...

I don't know what the ' field of study' is... lets call it ' ergonomic attention span for Mercedesapians. But any light is less effective for speed of grabbing attention to an serious mechanical fault than an auditory BUUUUUZZZZEEEERRRRR.... I suppose if being precise...as I always am... auditory is redundant in that sentence.
LOL
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  #53  
Old 04-09-2008, 12:49 AM
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Quote:
Originally Posted by kerry View Post
Here's a low oil pressure/high coolant temperature kit. Do people think it could be adapted to our engines?

http://www.moyermarine.com/cgi-bin/shopper.cgi?search=action&category=KTAS&keywords=all&template=Templates/B000_storebuilder.html
It looks to me like it could. The "Bare Bones" type kit was around $38 (it looked like oil sending unit, buzzer and the high temp sending unit in the kit).
I would assume that the are all NPT type threads on the sending units.
You would have to find a place drill and tap in the sending units. The high temp one would be the more difficult one to find a place to do this. You could get a piece of pipe (tapped for the fitting) a to install like one of those lower hose type block heaters but put it into the top radiator hose and not have to do any drilling on the engine.
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  #54  
Old 04-09-2008, 01:02 AM
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Originally Posted by leathermang View Post
If you already have one you don't need another one....
LOL
If the factory put one in...then you have already paid for it...and they made provisions for it fitting into some space...
After the fact working is very different...
And inside the pan is a very harsh working environment.... for something you really want to be able to count on...
Concerning the Low Oil Level light/sensors. The Low oil Level indicator would tell you if there was a leak in your oil system but would not tell you if there was a drop in your oil pressure. Example: if you oil pump stoped working you would still have a pan full of oil and the Low Oil Level indicator would never go on.
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  #55  
Old 04-09-2008, 01:11 AM
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Originally Posted by Diesel911 View Post
The Low oil Level indicator would tell you if there was a leak in your oil system but would not tell you if there was a drop in your oil pressure. Example: if you oil pump stoped working you would still have a pan full of oil and the Low Oil Level indicator would never go on.
I am only for the low pressure buzzer... simple, easy to make... and will tell you if you run out of oil just as if oil is not being pumped properly... like you dropped your oil pickup into the bottom of the pan... oil level will be fine...but pressure will immediately be affected...
There is also the problem with the warning level... how much oil is up in the system when operating as compared to the resting level ? Are we talking a float type system or an electrical sensor ? How much mist inside the pan would it take to give a false sense of security to the electrical sensor type ?
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  #56  
Old 04-09-2008, 02:07 PM
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Found one source for the 10 lb sensors. The ten pound trigger level seems sane to me. Still under one bar. They have to be custon calibrated. They are also a fixed calibration I believe during production. The units that we can change the calibration ourselves are too expensive I believe for the target price.
Asked for a quote for the first hundred and they are preparing it now. If the quote is within reason I will buy them. If not seek other sources. Since they are american made I believe delivery time hopefully will be short. The specs like overpressure and operating temperature limit are also good for our application. Kind of a stock item with custom tuning.
This is the item that concerns me the most. Current rating for the pizzo buzzer is no problem either with this unit. Rated as an industrial unit for cycle life as well. So no problems there. It is the right sensor for the application. Certainly not garbage either.
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  #57  
Old 04-09-2008, 02:32 PM
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Originally Posted by barry123400 View Post
Found one source for the 10 lb sensors. The ten pound trigger level seems sane to me. Still under one bar. They have to be custon calibrated. They are also a fixed calibration I believe during production. The units that we can change the calibration ourselves are too expensive I believe for the target price.
Asked for a quote for the first hundred and they are preparing it now. If the quote is within reason I will buy them. If not seek other sources. Since they are american made I believe delivery time hopefully will be short. The specs like overpressure and operating temperature limit are also good for our application. Kind of a stock item with custom tuning.
This is the item that concerns me the most. Current rating for the pizzo buzzer is no problem either with this unit. Rated as an industrial unit for cycle life as well. So no problems there. It is the right sensor for the application. Certainly not garbage either.
If the above dose not work out; I had been thinking the if a restricted fitting was put in the sensor oil pressure circuit you might be able to adjust the pressure that that sets the sensor off.
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  #58  
Old 04-09-2008, 06:54 PM
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Originally Posted by Diesel911 View Post
If the above does not work out; I had been thinking the if a restricted fitting was put in the sensor oil pressure circuit you might be able to adjust the pressure that that sets the sensor off.
Remember you have no constant flow so the pressure will equalise. A restrictive device might get you there but the loop would have to flow under pressure all the time. Otherwise just a delay in reaching pressure and a slow bleedoff would result. Very slowed up response to what was occuring.
From my limited search so far pressure devices are quite a big buisiness in the industrial realm. Generally as they are sold you can pay big dollars for a self adjustable one. Or have them custom calibrated in special orders. Cheaper is the operative word for these.
The second item is the operational enviroment to consider. Oil gets hot and the device must be happy at 120 pounds pressure load as well. Sensor cycle reliability has to be well beyond usage profiles. ..I do not think american engines have the bypass pressure set as high in the oil pump either. Or more likely the american oil pumps have generally been of lower volume designs. Generally mercedes survives at high speed by paying attention to their oiling system designs.
There seems to be no other valid so called standard pressure device except the automotive ones at down around five pounds. I too think they are not ideal. Yet far better than nothing.
If your pressure is dropping you want the sensor to get the message as soon as possible. So as little restriction as possible. Time is of the essence here. If your oil level is getting pretty low and you take a corner you might get a beep for example. The oil gauge has too much inertia to preform this function usually. Or the event goes unoticed. As little delay in the system is important to assure this feature as well.
As soon as you go upwards in pressure past ten pounds the switch opens. Since this is a custom deal I would really preffer to calibrate it at 1 bar or about 14 lbs. There are some tired engines out there though. So I will try 10lbs and test it to make sure it is not too high for the average 123 car. I am pretty sure it will cover more than 90 percent of them.
Just gives perhaps a little more time in event of a failure if a higher pressure switch is used. Depending on the severity of the leak or problem of course.
In most cases it will save your engine. It is not just the oil coolant hoses to fear. A sudden motor oil leak anywhere on a trip could do you in. A lot of engines have been damaged by the oil change plug not being tightened over the years alone. Or blowing an oil filter off. Even just leaving the oil fill cap off. The second example is not a concern on 123s. It would take dynamite. Yet you could still develop an oil filter container seal leak suddenly.
For the high or overheating temp I will make it customer adjustable though. Or this is the thought now. It will probably land up working off of the present temp gauge sender. That is a little down the road though at present. Simple as possible consistant with not being a pain in the posterior. I am determined to do it properly. Otherwise my remaining life might be spent answering emails.
No return price quote on the 100 sensors yet. I hope they are sharpening their pencils. If I can just get an oem price we are away to the races. Keep the ideals coming. All viewpoints are worth examining by everybody.

The only advantage I have if it is one. I have owned multiple diesels with these devices..Most where more sophisticated. Believe me when I say they do their job and earn their keep.

Last edited by barry123400; 04-09-2008 at 07:42 PM.
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  #59  
Old 04-09-2008, 07:46 PM
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Not 100% sure I'd want one that bottomed out at 1 bar or even close to it. The owners manual specifies anything down to 0.3 bar is acceptable, maybe a tad lower..... after a long, hard, hot, fast run on the interstate, in the summer, my first stop-light after I take an off-ramp easily drops the oil pressure down to half a bar or less... it's back up once things cool off, but I'd hate to have the alarm going off in the meantime.

1 bar = about 14.5 psi

0.3 bar (the first time I would ever consider installing a buzzer) = 4.4 psi.
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1986 M-B 300SDL, retired due to rust and electrical problems. Donated engine to:
1987 M-B 300SDL, odo dead. New project.
1982 M-B 240D, odo stopped at 308,000
1982 M-B 300SD, 175,000
1989 Dodge Ramcharger, 87,000 - 4wd, 318
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  #60  
Old 04-09-2008, 10:07 PM
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I thought that one bar was the lower limit suggested...
but my question is why don't you put a new oil pump on it... since you see it very low at higher oil temperature..
OR at least check to see if the oil pressure valve on the back of the pump is working correctly...also the thermodynamic bypass at the filter ?
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