What Ohm is the stock temp gauge

[1970 CST Short Wide]

I want to see if I can fine a temp sending unit that will work with the stock temp gauge in my LS. I need the Ohm's of the stock gauge Any help would be appreciated
Thanks
Steve

[mongocanfly]

My ecm reads off the stock LS sending unit on drivers side head up front....for my gauges I simply ran it to the passenger side head in the back and put the gauge sender there and then to my stock gauge.

[68c10airstream]

If you can do what i did, the front of the water pump has a raised round boss, drill and tap for the stock temp sender. Only thing left is the ls motors run hotter that the 60's did so once my ls was warmed up the temp gauge read 3/4 scale and i wanted 1/2 scale at 200 degrees F. So i cut the sender line and installed a variable resistor and dialed it from 3/4 scale back to half scale (added resistance to skew it colder). Removed the variable resistor and read the value and i think it was 4 ohms. Went to radio shack and bought a 4 ohm 1/2 watt resistor and soldered it inline with the sender wire. When the engine is cold its a little off calibration but to me the most important area is being able to read if it gets hotter than 1/2 scale now. I pull the old airstream in 100 degree temps and it gets just past 5/8 scale. Mission accomplished.

[mongocanfly]

68c... my factory water pump, had that boss you are talking about...that's where I ran my steam line to...but when I replaced my waterpump due to a seal leak the replacement pump didn't have that boss on it..

[68c10airstream]

I had to replace my pump also but i think i dropped my year of engine from 2001 down to 1999 to get the boss i think. On the second try it was perfect, even came with a thermostat already installed.

[mongocanfly]

That's good to know... I just told them I needed a w.p. for a 2002

[1970 CST Short Wide]

Originally Posted by mongocanfly

My ecm reads off the stock LS sending unit on drivers side head up front....for my gauges I simply ran it to the passenger side head in the back and put the gauge sender there and then to my stock gauge.

That's where I plan to put it but need to know WHAT sender to use. I believe the plug in the head is metric?

[mongocanfly]

Yes that plug is metric..I had the autometer LS kit that goes from metric to standard but the only adapter I used for the oil sender..I used a mechanical temp gauge instead of electric...I drilled and tapped mine to fit it..

[68c10airstream]

1970 cst short wide, just to keep things clear if i understand correctly, and the info you were looking for, the stock sender is a SINGLE wire terminal sender, with the head of the terminal looks like the head of a nail. I reused the 1968 sender into my ls because the stock sender and dash gauge are basically matched. I was a dealer mechanic and specialized in electronic and drivability issues. As stated earlier in my post i knew what to do to rescale it cooler to achieve that half scale i was shooting for.

I will go over this as these 2 words get thrown around a lot and even sound similar.

sender= single wire terminal usually creating a variable ground (through the body of the sender) to drive a dash gauge.

sensor= usually 2 terminals screwed into the block creating a varying resistance proportional to temperature and this internal circuit is insulated from ground. This is typically used for a ecm/pcm. The ecm/pcm puts out a low voltage signal to go through the sensor and return back to the ecm/pcm to used for fuel trim, etc.

Someone here went through a very detailed factory dash/sender description (t bone i think) and was good info to figure out how to match them up.

Just source a factory 1967-72 v8 coolant sender and figure where you want to thread it into. Not to confuse you but when i did my inline resistor (4 ohm) as a different approach i believe a person could use the stock sender in the ls with the stock dash gauge, leave the plastic lens off of the stock cluster and when your engine is completely warmed up remove the needle and reinstall where you want it.

Remember that if you do use the 67-72 stock sender, shine up the "nail head" of the sender to get the most accurate reading. Living up north in the salt bed i fixed many 70's-80's stock dash gauge for reading an incorrect cold value. About every one i fixed was simply sanding the nail head shiny again and the dash gauge read correctly again.

i hope my long winded (typical for me) doesn't upset any one, but electrical issues upset many and i only want to help. Thanks for being patient.

[davepl]

I seem to post this about once every two weeks. Does no one search anymore?

[1970 CST Short Wide]

Originally Posted by davepl

I seem to post this about once every two weeks. Does no one search anymore?

Forgive my stupidity but what is this trying to tell me. My main ? was what are people doing to use stock temp gauge with LS motor?

[davepl]

Originally Posted by 1970 CST Short Wide

Forgive my stupidity but what is this trying to tell me. My main ? was what are people doing to use stock temp gauge with LS motor?

No idea, but the subject is "What ohm is the stock temp gauge" so I posted a table of ohms vs temp, which makes sense to me. If you knew the ohm/temp mapping of sensors, you could pick one that matches.

You'd need an LS sender that had the same range, or drill and tap an LS water pump for out sensor, to use our gauge. I wound up going the latter route and tapping the pump for my sender (but in my case it wasn't the giant 13/16" sender, but that can still likely be done).

Now that you have this info, what sensor are you planning to run? Or do you know?

[68c10airstream]

In this post (#7) you said you wanted to put a sender in the back of the head, was the threaded hole metric (yes) and what ohms does it need to be??

When i did my temp sender work about 4 years ago i too was looking for a single wire metric threaded sender matching the stock 1968 sender ( as i believe this is what you want) i gave up looking because i couldn't find a SCREW IN MATCH UP to fit my needs.

My original 1968 v8 temp sender is pretty big and decided to try and fit it into the engine somewhere. I looked around and found someone screwing in the 68 sender into the boss on the front of the water pump. I was sold.

It's a little big and ugly and would have preferred a small metric threaded sender matching the stock sender values threaded into an available hole in the side of the head but that wasn't out there and i even searched a bit about a year ago to tidy up my big ugly sender but didn't find it , hence my posts

I have read many of "davepl"'s posts and he brings a fantastic level of technical info and is a great asset to this forum.

I'm a little hesitant to throw this possibility out there on the chance of confusion, but there is a slim possibility of a 80's vintage gm engine small metric threaded temp sender in a gm vehicle that has a vintage style analog dash gauge, possibly monte carlo?? You would have to have the sender and the little square voltage resistor board that sits piggyback behind the monte carlo's temp gauge. They are a matched pair. Install both, sender in your ls engine, and remove the 68 square board behind the stock 68 gauge and then install the 80's square board onto the backside of your 68 temp gauge.

Just trying to help, electrical issues are probably the most challenging, but i like the challenge. Get with "tbone" as he does dash work and maybe by now something has worked.

[68c10airstream]

Well i spent some time in the old books at a real parts store and i ordered a temp sender which may be an almost drop in small replacement sender of the same values. I ordered it and should have it installed next weekend and will give feedback then. It will thread in the corner of the cylinder head by removing the factory 12x1.5mm plug. It will require opening up the 12mm hole up to 14mm but it's the same thread pitch (1.5) so this should be able to be done with a 14mmx1.5mm tap by hand. It's a low profile sender that takes a spade terminal and if this works it will be very easy to do and will occupy less space than the factory temp SENSOR in the opposite cylinder head corner, (the SENSOR has 2 wires and it is used by the pcm for coolant temp info).

[1970 CST Short Wide]

Originally Posted by 68c10airstream

Well i spent some time in the old books at a real parts store and i ordered a temp sender which may be an almost drop in small replacement sender of the same values. I ordered it and should have it installed next weekend and will give feedback then. It will thread in the corner of the cylinder head by removing the factory 12x1.5mm plug. It will require opening up the 12mm hole up to 14mm but it's the same thread pitch (1.5) so this should be able to be done with a 14mmx1.5mm tap by hand. It's a low profile sender that takes a spade terminal and if this works it will be very easy to do and will occupy less space than the factory temp SENSOR in the opposite cylinder head corner, (the SENSOR has 2 wires and it is used by the pcm for coolant temp info).

Ill be watching this very closely , waiting on a brand and part number. Hope it works

[davepl]

I guess I wasn't clear but what I was getting at was you could take my chart for our truck's gauge (the one I gave you) and then google around for charts of different LS sensors, and if you got a match, screw it in and you're done!

Here's one from a 2005 Silverado just as an example - this one is NOT a match, but it's one of maybe twenty that came up under Google Images for "LS coolant sensor temps vs ohms".

If you can find a match, and it's an LS sensor, you should be able to use it without any drilling, tapping, electrical adapters, or other gee gaws.

I can't promise there IS a match, but if there is, and you happen to find it, be sure to post because we could all make use of it. Odds are the 69 Camaro guys figured this one out about 10 years ago though...

[solidaxel]

Following this one for my 78 Silverado

[1970 CST Short Wide]

Originally Posted by 68c10airstream

Well i spent some time in the old books at a real parts store and i ordered a temp sender which may be an almost drop in small replacement sender of the same values. I ordered it and should have it installed next weekend and will give feedback then. It will thread in the corner of the cylinder head by removing the factory 12x1.5mm plug. It will require opening up the 12mm hole up to 14mm but it's the same thread pitch (1.5) so this should be able to be done with a 14mmx1.5mm tap by hand. It's a low profile sender that takes a spade terminal and if this works it will be very easy to do and will occupy less space than the factory temp SENSOR in the opposite cylinder head corner, (the SENSOR has 2 wires and it is used by the pcm for coolant temp info).

Any Luck??

[68c10airstream]

Part is in route. I'll let the cat out of the bag and tell you is a "ts-249" temp sender. It's for a 77-86 bmw application and it's very close to a match al least from my research. My truck is somewhat apart as i upgrade to a larger output alternator, and changing over to hydroboost and a steering gearbox upgrade/replacement, so it's a little involved. Google ts-249 images and i purchased it from amazon. About $20.00 in my hands.

i crossed over a ts-6 spec over to the ts-249

[1970 CST Short Wide]

Originally Posted by 68c10airstream

Part is in route. I'll let the cat out of the bag and tell you is a "ts-249" temp sender. It's for a 77-86 bmw application and it's very close to a match al least from my research. My truck is somewhat apart as i upgrade to a larger output alternator, and changing over to hydroboost and a steering gearbox upgrade/replacement, so it's a little involved. Google ts-249 images and i purchased it from amazon. About $20.00 in my hands.

i crossed over a ts-6 spec over to the ts-249

I work part time at an auto parts store, is the brand called Standard? I'll order one tomorrow and try it also. We can compare results later

[68c10airstream]

Standard and 4 seasons/everco should be the brands that work. Just match the bmw application. bmw's part number is 6211-0788-115

[68c10airstream]

Remember this isn't a perfect drop in. The 12mm hole needs to be opened up to 14mm. If it doesn't work out you will be leaving it into the head as a plug. Before my install i was going to let it sit on top of the motor in my cold garage overnight and compare resistance against the oem 1968 sender, then remove the 1968 sender if it matched resistance and put the bmw and the 68 sender in water with leads attached to the body of each (ground) and leads attached to the sender terminals and warm the water up to 200 degrees and see how close they match up. If close then it will remove the plug and tap the hole larger and i will be done. I believe the 14mmx1.5 is the same as a popular spark plug thread so buying the tap is a nice addition to my tool box.

[1970 CST Short Wide]

Originally Posted by 68c10airstream

Remember this isn't a perfect drop in. The 12mm hole needs to be opened up to 14mm. If it doesn't work out you will be leaving it into the head as a plug. Before my install i was going to let it sit on top of the motor in my cold garage overnight and compare resistance against the oem 1968 sender, then remove the 1968 sender if it matched resistance and put the bmw and the 68 sender in water with leads attached to the body of each (ground) and leads attached to the sender terminals and warm the water up to 200 degrees and see how close they match up. If close then it will remove the plug and tap the hole larger and i will be done. I believe the 14mmx1.5 is the same as a popular spark plug thread so buying the tap is a nice addition to my tool box.

Do you have any specs on the bmw sender? What made you go with this one, what numbers are you using

[68c10airstream]

http://67-72chevytrucks.com/vboard/p...ictureid=23241 Hopefully this is an image out of the standard motors spec sheet. When i removed my stock 1968 sender it slipped out of my hand and fell onto the floor. I think it's messed up. Any way i put the new bmw sender (ts-249) into boiling water at 200 degrees F and it showed 90 ohms resistance. PERFECT!!!. I got out my variable resistor and dialed in 90 ohms resistance, installed it inline between the sender terminal and ground and turned my key on and it showed mid scale temp reading. From memory this is the value i remembered fron a few years ago. I can't run my engine now because my alternator isn't back yet and i'm not finished with my hydroboost changes but by installing my 90 ohms resistance inline i'm simulating a 200 degree F engine. Looks like i'll be tapping my 12mmx1.5 hole up to 14mmx1.5 soon!!

So there is the answer to the ls engine swaps that use a stock 67 and up standard motors ts-6 temp sender and are looking for a low profile replacement sender to thread directly into the head without adapters is the TS-249 temp sender. I have NOT tapped my head yet but has seen people drill the 12mm x 1.5 hole pretty large so i feel the tap should work very easily. It's only going 2mm larger in diameter, that's 1mm wider on each side of the hole!! I'll be trying the tap job later in the week when i get a chance!!

[1970 CST Short Wide]

Before you go drilling your cyl head, I found one that's a fairly good match
Factory spec is 368 Ohm's at 100F and 80 Ohm's at 220F
This one is 372 Ohm's at 100F and 40 Ohm's at 220F AND its 1/8 pipe AND they make an adapter. (Speedway Motors). We're working on it and will let you know what we find
NAPA Part # is TS6035SB