Motschrocker Posted October 12, 2015 Report Share Posted October 12, 2015 My temp gauge is not reading on my L18. I took the wire off of my temp sensor and grounded it to the negative terminal on my battery. That caused the gauge to jump to the hot so the gauge seems to work. How can i test my temp sensor to see if it is faulty? Quote Link to comment
Rick-rat Posted October 12, 2015 Report Share Posted October 12, 2015 Seems like you just proved it is faulty 2 Quote Link to comment
Stoffregen Motorsports Posted October 12, 2015 Report Share Posted October 12, 2015 The sender is probably just a resistor. Do you have a FSM? Quote Link to comment
Motschrocker Posted October 12, 2015 Author Report Share Posted October 12, 2015 That is what i was thinking. Just didnt know if there was more to it. Quote Link to comment
DanielC Posted October 12, 2015 Report Share Posted October 12, 2015 You can take a ohmmeter, and check the resistance of the sender. I do not know where, but I am pretty sure there is a chart comparing temperature, and resistance, the sender should have. Or you can just replace it. I think Datsun used a not common thread on the temp sender. You may need to get another Nissan sender. There is a pretty good possibility it is probably still available for an Nissan dealer. The sender is just a variable short to ground. It is possible the electrical connection between the sender and the thermostat housing is not being made, or the wire and terminal on the sender are not electrically connected. 1 Quote Link to comment
Rick-rat Posted October 12, 2015 Report Share Posted October 12, 2015 Too bad you are not closer, replacing an aftermarket mechanical temp gauge, (that works fine) with an electric one on Tuesday Quote Link to comment
Motschrocker Posted October 12, 2015 Author Report Share Posted October 12, 2015 The wiring in my car is a bit of a mess. It wouldn't surprise me if a connection wasn't being made. I will toy with it a bit more before buying a new one. Quote Link to comment
Stoffregen Motorsports Posted October 12, 2015 Report Share Posted October 12, 2015 Typically bad ground or seeking ground are the type of electrical problems in older cars. A bad ground could cause the problem you describe. Quote Link to comment
Motschrocker Posted October 12, 2015 Author Report Share Posted October 12, 2015 Today i tested the post the wire for the temp sender was conncted to and there was no power to it. I connected the wires to a post with power and when i turn the key on the temp gauge goes to zero. When i turn the key off the needle jumps up to what the temp probably is. Im not good with electrical but does this still sound like a ground issue? Quote Link to comment
datzenmike Posted October 12, 2015 Report Share Posted October 12, 2015 Do not touch the wire to a 12 volt source! It has it's own 8 volt regulated source and this might damage it. There won't be any power on the temp sender post. (well none with the wire off). Here's the direction of power flow... +battery... ignition switch... fuse box.... temp gauge volt regulator.... temp gauge.... temp sender.... ground. - side of battery You already touched the sender wire to the thermostat housing and got a full HOT reading so the gauge is good and so was the power to it and the ground is working... at least the thermostat is grounded. To get a reading the temp sender varies the ground. As the engine warms up the resistance to ground lowers and more current flows causing the needle to go higher. 1 Quote Link to comment
Motschrocker Posted October 13, 2015 Author Report Share Posted October 13, 2015 Alright so does this just mean the temp sender is faulty since everything else is checking out? Quote Link to comment
datzenmike Posted October 13, 2015 Report Share Posted October 13, 2015 It sure would seem so. Quote Link to comment
MikeRL411 Posted October 13, 2015 Report Share Posted October 13, 2015 In my experience [maintaining my RL411 for 48 years] the sensor is a common part number. The main difference is the SAE or Metric thread on the for a better word "collar" that holds the sensor into the head or thermostat housing. So, get a replacement unit, don't screw up the existing collar when you remove it, dump whatever collar came with the replacement and reuse your existing old collar. At least you know it is correct for the existing installation. Quote Link to comment
Motschrocker Posted November 3, 2015 Author Report Share Posted November 3, 2015 I am looking at my temp sensor and it doesn't appear to have a collar that is detachable. Id like to order a new one but i am not exactly sure what i am looking for. See the pics below for help. Quote Link to comment
Stoffregen Motorsports Posted November 3, 2015 Report Share Posted November 3, 2015 I'm not too familiar with the roadster parts, but that does not look like an OEM sender. The L series senders (as well as A series and other Nissan) have a removable metric sleeve that has threads on it and fasten it to the engine. If that one is aftermarket, it could be the reason your gauge is not reading properly. Improper compatibility. EDIT - you did say L18 right? Then that sender is positively not the right one. Quote Link to comment
banzai510(hainz) Posted November 3, 2015 Report Share Posted November 3, 2015 most times those housings cracked trying to break that 40 yr old sender out. I just have a new housing with a new sender and hex nut holder as spares to hook it up again. MY L series sender was not threaded rock auto had threaded ones and non threaded If I remember right or was Napa. Quote Link to comment
Motschrocker Posted November 4, 2015 Author Report Share Posted November 4, 2015 Yea the engine is a 73 l18. There is one sender on rockauto that has a threaded collar that is similar but i have no idea if it is the right size. My temp gauge did work ar one point. Not sure exactly when it crapped out or why. Quote Link to comment
Motschrocker Posted March 9, 2016 Author Report Share Posted March 9, 2016 I am going to revive this thread. It is almost spring and I am looking forward to driving my car. I still need to get my temp gauge working. I ordered a temp sender from rockauto, but it is not correct. As you can see in the pics above the sending unit is not original. I am not sure what my best option will be. Maybe I should just replace the whole thermostat housing? Mine currently has a water outlet, do I need to get the same. I also saw a thread where someone took the top housing off of a mazda 323 and wired the temp sender off of that. Maybe that would be an affordable option? Quote Link to comment
banzai510(hainz) Posted March 9, 2016 Report Share Posted March 9, 2016 L18? they have a sender for it. Just buy the correct one. but most cases the housings crack when trying to remove the old one then a new lower stat housing and 16mm hex nut is needed(from dealer) Quote Link to comment
Motschrocker Posted March 9, 2016 Author Report Share Posted March 9, 2016 not sure if the images above are still viewable, but the sending unit is different than others I have seen online. It does not have a detachable collar. It screws right into the housing. maybe the previous own modified the lower section of the housing to fit another sending unit? Quote Link to comment
banzai510(hainz) Posted March 9, 2016 Report Share Posted March 9, 2016 I seen 2 types One taht screws in the houisng and one that has a 16mm hex but has a coller and is threaded. Quote Link to comment
docbainey Posted March 9, 2016 Report Share Posted March 9, 2016 Looking at the one pic of the housing, it appears to be the correct housing for an L, you can see the steel collar everybody is talking about. Looks like somebody tapped the steel collar to thread in the different sensor. The piece of white plastic behind the collar doesn't belong there. Its probably all jacked up. Best bet is to get a new/used housing with the correct sensor instead of jerry-rigging it. Quote Link to comment
Motschrocker Posted March 9, 2016 Author Report Share Posted March 9, 2016 That is what I was thinking. My set up currently has the water outlet. Do I absolutely need this. I see on ebay right now they have a whole set up with sending unit, but with no water outlet. Unless someone knows another place I can get a thermostat housing? Quote Link to comment
bilzbobaggins Posted March 9, 2016 Report Share Posted March 9, 2016 Are you saying your lower thermostat housing has two ports? One for the sender and one for the coolant bypass? Its hard to tell in the photo what you have. I think I see the hard line for the heated intake manifold. Ive never personally messed with an L18. My L16 had not coolant bypass. Others delete it and drill some extra weep holes in the thermostat to get water to flow to get rid of the stagnant water. Can you get some more pics of what you have? Whats up with the stack of washers on the exhaust manifold? Quote Link to comment
Motschrocker Posted March 9, 2016 Author Report Share Posted March 9, 2016 I had this pic on my phone. It is of the dizzy but you can see to the right of the photo there is a port that connects into the hardline. Can i bypass this. Not sure about the stack of washers. Another strange thing done by the PO Quote Link to comment
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