Gauges and sending unit question
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Gauges and sending unit question Hi group, Hope this is in the right section.
I have a 2005 Tahoe 5.3 motor and Im trying to hookup my 1940 Mercury gauges... The oil pressure is a 50 lb unit and Im not sure of the temp specs. I already purchased the stock gauges, and can add adapters to fit my LS, but the temp gauge is twice as long as the stock sender.
I guess my question is can I use newer temp and oil sending units, or would it be best to install the stock units, and does the degree rating of the sender matter for a sweeping L | H type gauge?
thank you.
I have a 2005 Tahoe 5.3 motor and Im trying to hookup my 1940 Mercury gauges... The oil pressure is a 50 lb unit and Im not sure of the temp specs. I already purchased the stock gauges, and can add adapters to fit my LS, but the temp gauge is twice as long as the stock sender.
I guess my question is can I use newer temp and oil sending units, or would it be best to install the stock units, and does the degree rating of the sender matter for a sweeping L | H type gauge?
thank you.
The 2005 5.3 senders will be of no use with those gauges,if you dig around a bit on the hot rodder forums you should be able to find a smaller temp sender that will work with your 1940 gauge,however you will need to tap the other cylinder head or perhaps mount it in the rad hose with an adapter.
Thread Starter
Teching In
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The 2005 5.3 senders will be of no use with those gauges,if you dig around a bit on the hot rodder forums you should be able to find a smaller temp sender that will work with your 1940 gauge,however you will need to tap the other cylinder head or perhaps mount it in the rad hose with an adapter.
(Gauge is fitted with a voltage drop 12-6v as well)
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Good luck with finding the correct sender for that gauge. Temp sender ohm ranges vary A LOT between different vehicles and there are a lot of them out there so you'll have some searching to do. Do you know the ohm range of the stock gauge?
Also, you're most likley going to peg that oil pressure gauge every time you start it. I have a 60lb gauge in my truck and it pegs when its cold.
Also, you're most likley going to peg that oil pressure gauge every time you start it. I have a 60lb gauge in my truck and it pegs when its cold.
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Gauges If you want to retain the original gauges there are companies that will convert them for you. The amps gauge will be converted to volts, gas gauge will read correct and the speedo will be converted to electronic. This isn't cheap but you will not need a bunch of gauges dangling under the dash. If you decide not to go this route do not hook up the amp gauge due to fire hazard. The old electrical system would generate 30 amps tops and the new 12 volt system with fans and a/c will be double that. The gauge just can't handle it.
Thread Starter
Teching In
Joined: Jun 2017
Posts: 43
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Good luck with finding the correct sender for that gauge. Temp sender ohm ranges vary A LOT between different vehicles and there are a lot of them out there so you'll have some searching to do. Do you know the ohm range of the stock gauge?
Also, you're most likley going to peg that oil pressure gauge every time you start it. I have a 60lb gauge in my truck and it pegs when its cold.
Also, you're most likley going to peg that oil pressure gauge every time you start it. I have a 60lb gauge in my truck and it pegs when its cold.
Thread Starter
Teching In
Joined: Jun 2017
Posts: 43
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If you want to retain the original gauges there are companies that will convert them for you. The amps gauge will be converted to volts, gas gauge will read correct and the speedo will be converted to electronic. This isn't cheap but you will not need a bunch of gauges dangling under the dash. If you decide not to go this route do not hook up the amp gauge due to fire hazard. The old electrical system would generate 30 amps tops and the new 12 volt system with fans and a/c will be double that. The gauge just can't handle it.
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As Andrew suggested -- I have all the VDO/Volvo analog gauges working on my swap by simply using the matching sender. You should be able to find the proper adapters and/or figure out how to add the appropriate sender in the right place. I have two different temp gauges, oil temp, oil pressure and the oil pressure idiot light all working just as if the stock Volvo engine was in the car. I had two bungs welded into the radiator for coolant gauges, I drilled/tapped an oil cooler fitting for the oil pressure and idiot light and was able to find the correct sender for oil temp gauge in a 16mm thread that screwed right into one of the threaded passages in the block oil casting (right above the filter). I'd post pictures -- but Photobucket is raping me right now.
Last edited by Michael Yount; Jul 6, 2017 at 07:12 AM.
Odds are that even if you use the stock sender it's going to read more towards the H than the N on the gauge since newer engines run hotter than older ones. Since the gauge just has C N and H, I would think if you know the gauge ohm readings for cold and hot, you could split the difference and come up with a sender that would put the needle in the Normal range when the engine is at operating temperature.
Got any pics of the car this is going in?
Got any pics of the car this is going in?
....and purely a guess here - but for all the newer stuff, the sender is designed to send a signal to the ECU/body computer -- and it manipulates it and sends a signal to the gauge. I know on the tachs -- it's a 5V signal. So that has to be dealt with if you're using an older tach that's expecting a 12V signal. I'd guess the same is true of the other gauges -- they're set up for 5V signals. So I'm wondering if you could use the contemporary senders with 1940 Mercury gauges at all.
However, to Nova71's point -- my car's original gauge/sender was expecting a lower operating temp than the LS3 runs at. So I had to install a small resistor in the gauge signal line to move the coolant gauge needle from the upper end of the range, to something closer to the middle under normal operating conditions. So now, when I'm under cruise and the head temps (from ECU data read) are around 195F - the gauge shows a bit below halfway. And when the fans are controlling temp (head temps around 199F-202F) the gauge reads just a bit above halfway.
However, to Nova71's point -- my car's original gauge/sender was expecting a lower operating temp than the LS3 runs at. So I had to install a small resistor in the gauge signal line to move the coolant gauge needle from the upper end of the range, to something closer to the middle under normal operating conditions. So now, when I'm under cruise and the head temps (from ECU data read) are around 195F - the gauge shows a bit below halfway. And when the fans are controlling temp (head temps around 199F-202F) the gauge reads just a bit above halfway.
