Posted: Tue Jul 09, 2013 10:32 am Post subject: m38 Fuel Sending Unit
Howdy. Newbie here. Just bought a 52 M38, Canadian Military. It's modified with 77 Buick 231 V6 and 11" brake upgrade. Looks like most the gauges are not working. Since it was 24V and is now 12V, I need to assess what I have. I would like to get the fuel gauge working. Right now the gauge reads full all the time. I will likely order a 12V dash gauge, and would like to get a new sending unit (gasket leaking) however I cannot find any info on the voltage of the sending units. Would 800201 here:
http://www.willysjeepparts.com/Fuel_Tank_Gauges.htm
be the original 24V?
Any other place to find a 12V sending unit?
Just go to the VDO and Stewart Warner web sites and order 12 volt parts that are meant to be used together. Since you are now 12 volt there is no reason to use any 24 volt parts. Also there is no reason to buy expensive civilian 12 volt gauges and senders when the mechanical oil pressure, water temp are all you need for those two. The gas gauge is where you want to buy a matched pair of sender and gauge from a quality brand.
The situation here is unlike the situation discussed down the page further where a member wanted to get a new gauge to work with his 24 volt sender in a 12 volt system.
Bottom line, when exact correctness for shows is not a consideration and you have converted the jeep to 12 volt then the simplist most reliable set of gauges will be a volt meter, a mechanical oil pressure and water temp, and a matched brand new set of fuel gauge and fuel sender from a reputable manufacturer. This combination will give you years of trouble free reliable service. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
Hi Wes. Thanks for the reply.
The VDO site is too intimidating to navigate. I am trying to match a 12V sending unit with a 12V gauge, however the sending unit on the military m38 has some variations that need attention - like the arm length and reversed polarity (this is supposition from my forum reading). Generic solutions require more thought and this is where I need more detailed assistance. I thought another member might have been down this path already.
As I have had several direct emails regarding my post (please post your responses here so everyone can benefit), I need to clarify:
Where do I find a 12V sending unit with float and gasket to match the m38 gas tank? If a generic option is available, has anyone successfully done this?
however the sending unit on the military m38 has some variations that need attention - like the arm length and reversed polarity (this is supposition from my forum reading).
They are both negative ground. There are no reverse polarity issues with stock Willys jeeps.
Quote:
Where do I find a 12V sending unit with float and gasket to match the m38 gas tank? If a generic option is available, has anyone successfully done this?
Many have been down the same road. There are no aftermarket 12 volt senders out there that fit the fastener pattern of the M38's tank. To match any after market sender to your current gauge requires knowing all about your current gauges electrical system. If you know nothing about the internal operations of the current 12V gauge you have you cannot select a sender for it. Some gauges read full with high resistance and empty with low resistance and others read the opposite, full with low resustance and empty with high resistance. If you have a quality 12 volt gauge then give us the manufacturer's name and part number/model number and we can help you. If it is a cheap gauge with no numbers to ID it with then you should follow my original advice and buy a matched set gauge & sender from a reputable brand and drill the sender to match the M38 tank's screw pattern. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
They are both negative ground. There are no reverse polarity issues with stock Willys jeeps.
I was too hasty in my description. It's the resistance (ohm range) that is reversed, not the polarity.
Quote:
Many have been down the same road. There are no aftermarket 12 volt senders out there that fit the fastener pattern of the M38's tank. To match any after market sender to your current gauge requires knowing all about your current gauges electrical system. If you know nothing about the internal operations of the current 12V gauge you have you cannot select a sender for it. Some gauges read full with high resistance and empty with low resistance and others read the opposite, full with low resustance and empty with high resistance. If you have a quality 12 volt gauge then give us the manufacturer's name and part number/model number and we can help you. If it is a cheap gauge with no numbers to ID it with then you should follow my original advice and buy a matched set gauge & sender from a reputable brand and drill the sender to match the M38 tank's screw pattern.
This is good advice Wes. I have not removed the existing gauge or sending unit to know the ohm range - or whether its actually worked on this 12V rebuild. I have lots to discover with this new purchase. I believe that the gauge worked before, so it's likely a 12V one.
What would be be a drawback of using the 12V sending unit meant for the CJ2A/CJ3A with the matched 12V gauge?
What would be be a drawback of using the 12V sending unit meant for the CJ2A/CJ3A with the matched 12V gauge?
I assume you are talking about an aftermarket 12V unit for a CJ2A/3A since those two jeeps came stock as 6 volters. The only issue would be drilling the sender lid with holes to match the M38 tank screw pattern. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
I assume you are talking about an aftermarket 12V unit for a CJ2A/3A since those two jeeps came stock as 6 volters. The only issue would be drilling the sender lid with holes to match the M38 tank screw pattern.
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