Pagoda SL Group

W113 Pagoda SL Group => General Discussion => Topic started by: Mike Webster on September 23, 2005, 08:30:32

Title: gas gage - sending unit confusion
Post by: Mike Webster on September 23, 2005, 08:30:32
Pagoda Scholars,

I have a 230sl (built in December'65) which was restored about 5 years ago. My problem is my fuel gage is reading empty when the tank is more than half full. Thinking I may have a crud problem, I removed and cleaned the unit (it's the cylindrical style). Every thing seemed to be in order so I reconnected the unit and found the same result. After researching this site I thought I had had a sending unit for a 280 so I purchased a new 230 VDO unit for $150.00 made for chassis numbers #008954 and newer (mine is 014654). It appeared identical to my old unit, but what the heck, I bought it so I put it in. Same result except I'm now $150.00 poorer. Now, I think I have may a 280 fuel gage with a 230 sending unit. Before I go off and spend another $150.00 for a new 280 sending unit, does anyone have any ideas?

Mike from Detroit
230sl DB180 silver/red
Title: Re: gas gage - sending unit confusion
Post by: jeffc280sl on September 23, 2005, 10:41:06
Hi Mike,

Does you fuel gauge read full when the tank is full?  I'll assume yes.  The problem may be a matter of electric resistance.  As you know the cylindrical sender has a float.  This float is supposed to move up and down with the fuel level in the tank.  As the fuel level drops the sliding contact on the side of the float ioncreases resistance.  As this happens voltage drops to the gas gauge and the needle falls.  Let's assume for the moment that the problem is not with the sending unit.  I would check the wiring from the sending unit to the gauge with an ohm meter. There are 3 wires on the sending unit.  One goes to ground, another to the low fuel light and the third to the fuel gauge.  Fuse 5 feeds the other side of the low fuel light and gauge.  There is a large connector under the driver dash that feeds the instrument cluster.  Sorry I don't know the wire color or number of the gas gauge stuff.  I would check all of the wires and measure the resistance between the connector for fuse 5 and the gas gauge.  As the you move the float up and down the meter should change.  Does this happen?  What are the readings when the gauge is up (full), 3/4, 1/2, 1/4 and all the way down (empty)?  If the readings are good I would say the gauge is inaccurate.  Maybe dirty?  Clean the pins and connector well.



Jeff C.
1970 280SL 4-speed
Title: Re: gas gage - sending unit confusion
Post by: JimVillers on September 23, 2005, 12:19:24
I also just bought a sending unit for my "1967" 230SL (built in 1966).  The part number I received is 110 542 12 04 64.  The "empty" resistance between pin "G" and the brass pin is 65.5 ohms.  The "full" resistance is 4.6 ohms.  

I have not installed it yet so I don't know if it will work correctly or not.  If yours is the same, I'll just plug it into the connector to check the gauge compatibility.


Jim Villers
190SL, 230SL 5-Speed, 190E 2.3-16 Kompressor
Title: Re: gas gage - sending unit confusion
Post by: jeffc280sl on September 23, 2005, 12:44:58
Thanks Jim,

That's great information to know.  Do the readings track nicely between full and empty?  Assuming yours is good, at half full Mike's could be reading 65 ohms which would indicate empty on the dash gauge.  If so, its the sending unit.  I suspect Mike's sending unit should read something like 35 ohms at half full.  If so, I'd check grounds, connectors, wiring and lastly the gauge.  You know how hard it is to pull the center cluster and what other jobs it leads to while out.

Jeff C.
1970 280SL 4-speed
Title: Re: gas gage - sending unit confusion
Post by: JimVillers on September 23, 2005, 19:17:42
Jeff ... It is hard to tell the readings at "half" with the unit not installed in the tank.  I can measure the resistance as the float moves from one end of the cylinder to the other but I can't see the float to estimate where it is.  My assumption is that the resistance change is linear from empty to full.

Jim Villers
190SL, 230SL 5-Speed, 190E 2.3-16 Kompressor
Title: Re: gas gage - sending unit confusion
Post by: hauser on September 23, 2005, 21:10:40

I'm not sure if this helps but when my gauge went bad I was getting a reading of 3/4 when it was just about empty.  The times that I would fill up it would still read 3/4.  Once the new gauge was installed the problem was cured.

1969 280sl 5 spd
Gainesville, Fl.
Title: Re: gas gage - sending unit confusion
Post by: ja17 on September 23, 2005, 23:10:16
Hello Mike,
I think some of the early cars had the lever type sender. These do not interchange. I am not sure whene the break point was. Of coarse as hauser states, it may be the guage in your case also.

Joe Alexander
Blacklick, Ohio
Title: Re: gas gage - sending unit confusion
Post by: German Dude on September 24, 2005, 04:40:10
Mike,
I have a 64 Pagoda. I did have the cylindrical shaped sender in it too. It showed empty when the tank was full, and slowly crept up when driving. An empty tank would produce a half full showing.

I am sure the cylindrical style sender is the problem. You need to put in the old-style sender which has an external float. I put one in and it worked like a charme. Installing is the easiest job you can think of - just make sure the tank is almost empty. Well, you have done it before so no need to tell you how.

I have now a working gauge which bounces happily at turns - just the way it is supposed to be.

You should be able to sell off both cylindrical senders and get a float sender without having to shell out too much money on top. SLS will sell it to you.

Juergen
64 230SL #2933, 4sp, signal red, white hard top
93 Citroen XM station wagon
Title: Re: gas gage - sending unit confusion
Post by: A Dalton on September 24, 2005, 07:52:23
>> Mike,
I have a 64 Pagoda. I did have the cylindrical shaped sender in it too. It showed empty when the tank was full, and slowly crept up when driving. An empty tank would produce a half full showing.
>>

 Correct. The early .042 used the external float/arm and these had a circuit that used higher resistance at full/lower at reserve.
 Resistance specs. for early units are:
 Full-180 ohm, +12/-2
 1/2-100 ohm, +/- 5
 Reserve-10 ohm, +/- 4
Title: Re: gas gage - sending unit confusion
Post by: Mike Webster on September 24, 2005, 08:51:40
Pagoda Scholars,

Thanks so much for you're input. Some of my findings:
1) I really beleive I don't have a wiring problem because all the wires appear to be new, everything else works fine and the readings are consistent.
2) I thought I had a cylindrical style sending unit because thats what it shows in my 230 BBB parts book. Upon looking further investigation, I found that my book is a Janurary 1967 edition, which superceeds the December 1964 edition (rookie mistake). Since mine is a '66, I beleive Juergen and Joe are on to something, mine should be a float style sending unit. Oh, those dreaded engineering changes!!

Since my car is restored, I don't know if it has the origional tank. Before I go SLS and purchase a float sending unit, would it be possible someone could provide these answers:
1)Is there a difference between earlier and later tanks?
2)Is the mounting flange and the connections the same for a float style vs. a cylindrical style?

Mike (still confused in Detroit)
1966 230SL DB180 silver/red
2005 Chevy Impala (great car, no kidding!!)
Title: Re: gas gage - sending unit confusion
Post by: A Dalton on September 24, 2005, 09:04:54
The sender unit change on .042 was at chassis 008954 and on.
 Up to then should have the exterior float system.

 These early units can be diagnosed by simply unplugging the sensor and substitute a 100 ohm resistor [ Radio Shack] from the gauge feed wire to ground . The gauge should then read 1/2 full.........
 That should be terminal G at sensor
Title: Re: gas gage - sending unit confusion
Post by: A Dalton on September 24, 2005, 10:12:06
Later unit , if anyone is looking..

 http://cgi.ebay.com/ebaymotors/MERCEDES-108-109-111-113-FUEL-LEVEL-SENDING-UNIT_W0QQcmdZViewItemQQcategoryZ34198QQitemZ4577742595QQrdZ1
Title: Re: gas gage - sending unit confusion
Post by: hands_aus on September 25, 2005, 06:13:13
Arthur

Did the 'early' 250SL have the external float sender or the cylindrical sender?

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto
Title: Re: gas gage - sending unit confusion
Post by: A Dalton on September 25, 2005, 08:16:16
quote:
Originally posted by hands_aus

Arthur

Did the 'early' 250SL have the external float sender or the cylindrical sender?

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto



 cylinder style... [only early 230 used ext. float.]
Title: Re: gas gage - sending unit confusion
Post by: German Dude on September 26, 2005, 01:01:12
Mike,
the connections are the same.
You have 5 or 6 small bolts there. Fits like a glove.

I am positive all you need is an external float sender.

Best,

Juergen
64 230SL #2933, 4sp, signal red, white hard top
93 Citroen XM station wagon
Title: Re: gas gage - sending unit confusion
Post by: Mike Webster on September 26, 2005, 06:52:32
Jurgen,

 
Another rookie question, who is SLS? I tried Google, and I get no hits.  

Mike


Title: Re: gas gage - sending unit confusion
Post by: A Dalton on September 26, 2005, 08:17:45
http://www.sls-hh-catalogue.de/bin/dbframes.phtml?mid=IN02

 Item #3 ..part 247016

 The gasket is the same for either unit.  The float goes to the right of the tank. The bolt pattern is off-set for this orientation.
Title: Re: gas gage - sending unit confusion
Post by: Mike Webster on September 26, 2005, 12:27:24
Thanks for the info, I ordered the part from SLS. Will keep everyone advised.

Mike (a little less confused in Detroit)
Title: Re: gas gage - sending unit confusion
Post by: rwmastel on September 26, 2005, 15:07:29
quote:
Originally posted by German Dude

I am positive all you need is an external float sender.

But Mike's VIN ends in 014654, so according to info in this thread, his car would use the cylinder style not the external float style.

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420
Title: Re: gas gage - sending unit confusion
Post by: hands_aus on September 26, 2005, 19:06:28
Arthur,
Thanks for the info.

Just checked/cleaned mine because the gauge shows almost empty when half full.

This is a 108 replacement sender because the sender that was in my car was way too short.
This unit is about 40mm longer and I still have the problem.

Still not accurate but I have been living with it for 2 years now and know how it works.

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto
Title: Re: gas gage - sending unit confusion
Post by: A Dalton on September 26, 2005, 19:42:05
BS
 Is there a part# on the sender.

 All the 108 senders I see are the same # as 113 cyl type.
Even the 4.5
Title: Re: gas gage - sending unit confusion
Post by: hands_aus on September 27, 2005, 00:17:39
quote:
Originally posted by A Dalton

BS
 Is there a part# on the sender.

 All the 108 senders I see are the same # as 113 cyl type.
Even the 4.5


Arthur,
I had another look, there were no MB numbers but this is what I found.

OLD cylindrical SENDER that was originally in CAR

TOP MARKINGS

VDO      nur f Benzin

11  66   <<is this the make date?    
21/169  
LENGTH   150mm

RESISTANCE  WITH FULL TANK   59.4 Ohms
RESISTANCE  WITH EMPTY TANK   118.4 Ohms


NEW cylindrical SENDER FROM 108

TOP MARKINGS
VDO   
xxx  73   
21/293
673

LENGTH   190mm  approximately

RESISTANCE  WITH FULL TANK   4.5 Ohms
RESISTANCE  WITH EMPTY TANK   65.5 Ohms

Neither of these senders give me a correct reading that is why I asked about the 'EARLY' 250sl and the float type sender.

There was a discussion about this some time ago and it came out that the gauges were different for the different types of sender.

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto
Title: Re: gas gage - sending unit confusion
Post by: German Dude on September 27, 2005, 03:18:50
Rodd,

I know that with respect to the VIN, it should be a cylindrical sender. But the symptoms are identical to what I experienced, hence my confidence. I even get the red low fuel warning light - which kind of made me happy.

Juergen
64 230SL #2933, 4sp, signal red, white hard top
93 Citroen XM station wagon
Title: Re: gas gage - sending unit confusion
Post by: Mike Webster on September 27, 2005, 08:48:50
Pagoda Scholars,

I beleive Jurgen's suggestion will work.  After I install the float unit, and if it works, I'll offer my slightly used cylindrical unit free as a token of my thanks to anyone who needs it.

I'll keep you posted.

Mike in Detroit
Title: Re: gas gage - sending unit confusion
Post by: n/a on September 27, 2005, 11:35:44
I'm quite certain the float sender will solve your problem.  I had this exact problem with an early 1964 230sl we had.  When I installed the float sender, everything was perfect.  It is possible that somewhere along the way someone swapped out your gauge to be the early type.

don't always trust the VIN

-Lewis

'66 230 sl 113042-10-016238
'67 Saab Sonett II #43 of 258
'69 Porsche 911S
'00 Saab 9-3 viggen conv
'02 Saab 9-5 aero
Title: Re: gas gage - sending unit confusion
Post by: A Dalton on September 27, 2005, 12:06:04
As Lewis points out..With these cars being as old as they are, if you are not the original owner or know the history well, it is difficult to tell what parts have been changed, re: tank/sender/gauge.
 As I posted earlier  ,if a 100 ohm  test resistor in place of the sender registers 1/2 tank on the gauge, your fuel level indicator system should be coupled with the earlier external float sender unit.

 Resitance specs are from  '59 BBB
Title: Re: gas gage - sending unit confusion
Post by: Mike Webster on September 27, 2005, 13:05:04
A Dalton

Yoe hit the nail on the head. I am the second owner of this "restored" car. God only knows what parts are in it.

Mike in Detroit
Title: Re: gas gage - sending unit confusion
Post by: Mike Webster on October 24, 2005, 07:47:42
Scholars,

I finally received my new float-lever style sending unit from SLS and installed it Saturday. When I turned the ignition on the gage read empty on a 3/4 full tank. So I took the unit out and manually moved the float while a friend observed the fuel gage and found the gage reads full when the float is in the empty/down position, and empty when the float is in the full/up position. I am now the proud owner of two new VDO sending units, neither one getting the job done. Any ideas?

Mike in Detriot
1966 230sl silver/red
Title: Re: gas gage - sending unit confusion
Post by: A Dalton on October 24, 2005, 08:08:39
Do you have any in between readings when you go through the range??
..if not [ reads full or empty only] , then I think you may have the wires crossed at the sender for the gage feed and the reserve lamp feed .. that would explain the full/empty only readings when operating the float by hand.
 So, check my first queestion and post finding...
Title: Re: gas gage - sending unit confusion
Post by: Mike Webster on October 24, 2005, 08:29:37
A Dalton,

Yes, the indicator moves up and down the range of the gage with corresponding movement of the float, only in the opposite direction. However,I cannot recall the low fuel light comming on (I know that the light does work). Anyway, if the wires are crossed, why does the cylindrical style work?

Mike
Title: Re: gas gage - sending unit confusion
Post by: A Dalton on October 24, 2005, 09:09:50
<<why does the cylindrical style work?

>>

 If the cyl works , why are you using another style???

 Do you have an ohm meter???
Title: Re: gas gage - sending unit confusion
Post by: Mike Webster on October 24, 2005, 10:06:51
A Dalton,

This is what happens with the cylindrical style unit. With the tank full, the gage reads full. After running about 100 miles, the gage shows half full. At 200 miles, the gage shows empty, with the low fuel light on. At the pump I check my fuel usage aginst the odometer and the car runs about 18-20 mpg. Assuming the tank is 17 gallons, the tank should rum empty around 300-340 miles.

Mike
Title: Re: gas gage - sending unit confusion
Post by: A Dalton on October 24, 2005, 12:10:58
I see .. that seems a little different than your other post, but I do believe I have some info for your problem..
 First of all , all 65/l tanks take the float/rod sender unit. All 82/l tanks take the cyl unit.
 Second , you can not use a cyl sender with an early gage and vics/versa..
 So, you have a 65/l tank with the newer sender and gage , which will work, but will not be accurate/calibrated to a 65/l tank, as they belong in an 82 l tank..
 .. That is why I mentioned using a 100 ohm test resistor back in place of the sender unit in an earlier posting.. if that resistor test results made the gage register 1/2 tank, you then would know  you have the earlier float system and that you also have verified the earlier gage calibration...

Title: Re: gas gage - sending unit confusion
Post by: Ben on October 25, 2005, 03:24:47
But 17 gallons is 65 litres !

 
quote:
This is what happens with the cylindrical style unit. With the tank full, the gage reads full. After running about 100 miles, the gage shows half full. At 200 miles, the gage shows empty, with the low fuel light on. At the pump I check my fuel usage aginst the odometer and the car runs about 18-20 mpg


........my own 230SL behaves pretty much in the same manner, though I normally get the fuel light "on" at about 215 miles and can stretch maybe 240 from a tank !

Regards,
Ben in Ireland.
'64 230SL 4sp.
Title: Re: gas gage - sending unit confusion
Post by: hands_aus on October 25, 2005, 06:28:33
one gallon = 4.5456 liters
65 liters = 14.3 gallons (imperial)

I think the floater sender unit is from a sedan of the same period.
I vaguely remember this info from a previous discussion either on here or the old Yahoo site.

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto
Title: Re: gas gage - sending unit confusion
Post by: Ben on October 25, 2005, 07:52:25
quote:
one gallon = 4.5456 liters
65 liters = 14.3 gallons (imperial)



......Bob my 230SL owners manual states 14.2. Imp. Gallons/17.2 US gallons/65 litres !

If you made a mistake whilst calculating mpg figures you could end up with quite a difference in range in you Pagoda !

Regards,
Ben in Ireland.
'64 230SL 4sp.
Title: Re: gas gage - sending unit confusion
Post by: hands_aus on October 27, 2005, 03:54:44
True Ben,

Your original post mentioned 17 gallons = 65 liters and I assumed you would be thinking imperial gallons not US gallons, because the discussions on here always refer to the tank as being 18 gallons (obviously they mean Imperial gallons)

I made a spread sheet in which I enter 'liters used' and 'distance travelled in miles' and it converts to liters/100km, km/liters, MPG Imperial, MPG US, miles to KM, US gallons, IMP gallons.

It is very informative.

I always think in Imperial MPG for my 250SL and Km/liter for my Toyota Corolla.

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto