Problem with temp gauge

[Mike F]

Hello all-

I spent the day working on the car to try to get in a position where I felt it would be safe to drive back home. One of the issues was the temperature sender. I spent time last weekend troubleshooting the problem and narrowed it down to a bad temperature sender. I installed a new one today and the gauge is still reading zero. Here is what I have done so far:

Removed binnacle, cleaned all contacts and changed all bulbs. No response.
Put new connector on wire connecting to temperature sender. No response.
Checked wire running from sender to gauge by testing it to ground, upon which the gauge spiked.

Doing all of these things are what led me to the sender being bad. I installed the new sender today and am getting the same issue: the gauge just sits at the zero mark. I know the gauge isn't stuck, since it spiked when I did the ground test, and because it "moves up" to the zero mark when I turn the key to start the car. I have a shop manual and wasn't able to find any additional insight in it beyond what I have already tried. Has anyone else run into this? Any advice you could toss my way would be greatly appreciated. I don't want to drive this car without a working temperature gauge, so as a result I have yet to be able to take the car home! :( I had hoped that this weekend would get me to a point where these bugs would be worked out.

Thanks!

[sdg3205]

Mike,

Have you allowed the car to warm up properly? My gauge works fine but takes at least 10 minutes to register anything at idle IIRC.

If you've got a temp gun, let the car idle, monitor and wait and watch.

[David T]

If the cooling system is not filled and all of the air bled out the sender won't work. It needs to be in contact with the hot coolant. Sounds like the gauge and wiring is OK. Warm up the motor until you hear the fans run. You should see the temp gauge move up to the first "tick".
David Teitelbaum

[mluder]

If the cooling system is not filled and all of the air bled out the sender won't work. It needs to be in contact with the hot coolant. Sounds like the gauge and wiring is OK. Warm up the motor until you hear the fans run. You should see the temp gauge move up to the first "tick".
David Teitelbaum

FWIW - My fans don't kick on until past the first mark and halfway to the second.

Cheers
Steve

[David T]

Depends on the Otterstat switch, the thermostat, and the calibration of the temp gauge. It does vary exactly where it comes on. As long as you know your car and what it should be doing normally. In this case he should at least see the temp gauge move as the motor warms up and definitely by the time the fans come on!
David Teitelbaum

[LEVY]

Hello all-

I spent the day working on the car to try to get in a position where I felt it would be safe to drive back home. One of the issues was the temperature sender. I spent time last weekend troubleshooting the problem and narrowed it down to a bad temperature sender. I installed a new one today and the gauge is still reading zero. Here is what I have done so far:

Removed binnacle, cleaned all contacts and changed all bulbs. No response.
Put new connector on wire connecting to temperature sender. No response.
Checked wire running from sender to gauge by testing it to ground, upon which the gauge spiked.

Doing all of these things are what led me to the sender being bad. I installed the new sender today and am getting the same issue: the gauge just sits at the zero mark. I know the gauge isn't stuck, since it spiked when I did the ground test, and because it "moves up" to the zero mark when I turn the key to start the car. I have a shop manual and wasn't able to find any additional insight in it beyond what I have already tried. Has anyone else run into this? Any advice you could toss my way would be greatly appreciated. I don't want to drive this car without a working temperature gauge, so as a result I have yet to be able to take the car home! :( I had hoped that this weekend would get me to a point where these bugs would be worked out.

Thanks!

Since everything seems to be fine, make sure you have the correct temp. sending unit. Don't know if some Volvo's are equipped with a temp. light instead of a gauge, if you installed a sending unit for a vehicle equipped with a light, it will not work.

Other possibility may be the connector at the sending unit.

LEVY

[Mike F]

Thanks for the info everyone. I suspected that perhaps I wasn't letting the car warm up enough (fans didn't kick on), so I fired it up this afternoon and let it idle for a while. The fans never came on, so I took it for a quick drive around the block. Not once did I hear the fans come on. This is odd, since the fans seemed to be working properly when I drove it the roughly 35 mile trek from the PO's house. I jumped the otterstat wires to double-check that the fan itself hadn't pooped out, and it came on. Still no movement whatsoever from the temp gauge. Coolant then began running out from the hose on the overflow tank, so I shut it off. I suspect that perhaps there may still be air in the cooling system, is it reasonable to think that this may be the cause of both problems (no temp gauge, and no fans)? I purchased the new sender from John Hervey (and it looks identical to the one I removed), so I have no reason to think that it's the incorrect part. I couldn't fool with it any more; had to come home. I'll go back next weekend and fiddle with it some more. I plan on doing a coolant flush and perhaps replace the rubber radiator hoses. It looks as though some have been replaced and some are still original. I'd feel more confident if the originals were out, and when the coolant is drained seems like the perfect time to do it. One question about the otterstat- in all of the pictures I have seen (as well as the workshop manual) the otterstat is oriented such that the connectors are facing DOWN (towards the ground). Mine is the other way around, with the connectors facing UP (towards the engine cover). Is there any reason that the PO/PO's mechanic of choice would have done this? Is there any consequence to it? It got me thinking that if my coolant level is low or there is air in it, if the otterstat isn't at the BOTTOM of the pipe it may not be in contact with coolant. Just a thought. Anyway, thanks for all of your help so far. I'm looking forward to getting this sorted out!

PS- If there is anyone on here in the Pensacola/Pace/Milton, FL area that feels like tinkering on it with me, let me know! I plan to be back over there next weekend and if I can't get any resolution with what I plan to do I'd be open to some local suggestions! :wink:

[DeloreanJoshQ]

I have the same problem that just started happening with my temp gauge a month or so ago. The gauge stopped working and if I tapped the binnacle it would pop back up. This worked for a while and then finally my hitting of the binnacle no longer solved the problem. My fans cycle on and off and after testing the sending unit, there was no response from the gauge, so I am looking at getting a new gauge. I was planning on replacing them all anyway, since I have faded lettering and hashes on all of the gauges.

[DeLorean03]

Wow, another DeLorean in the Panhandle. I lived there in Pensacola from 1989 - 2011; got my car in 2003 til nearly July 2011 with only Casey and myself down there. Now there's like 4-5 of you in that area.... what a bummer.

Do you have any kind of air-bleeder kit installed on this cooling system? You need to if you don't. If there's air in the system, you may not have hot coolant getting to the temperature sending unit.


One place - it's called the DeLorean air Bleeder for $19.95

SpecialTAuto (http://specialtauto.com/delorean-parts/Keep-it-cool.html#Delorean : The Fan Fix Dual 2 x 2 .)

Other place is Toby at DMC-NW:

Click here (http://www.delorean-parts.com/Merchant2/merchant.mvc?Screen=PROD&Store_Code=DPNW&Product_Code=K1017DP&Category_Code=9475)

[Mike F]

I just ordered the bleed kit from DMC-NW about ten minutes ago!

[DMC5180]

You need to turn the otterstat pipe over to face down. The reason is to avoid a potential air pocket formation in the otterstat port.

[mluder]

I have the same problem that just started happening with my temp gauge a month or so ago. The gauge stopped working and if I tapped the binnacle it would pop back up. This worked for a while and then finally my hitting of the binnacle no longer solved the problem. My fans cycle on and off and after testing the sending unit, there was no response from the gauge, so I am looking at getting a new gauge. I was planning on replacing them all anyway, since I have faded lettering and hashes on all of the gauges.

Mine's doing the same thing. Looks like I may need to replace as well. I'm going to try cleaning the contacts first.

Cheers
Steve

[David T]

The early cars had the Otterstadt switch facing up. You need to cut the pipe and modify it so the switch is on the bottom. If the temp gauge never moved either you still have air in the system or when you installed the sender you used a LOT of teflon tape. That sender needs to be electrically connected to the block.
David Teitelbaum

[DMC5180]

The early cars had the Otterstadt switch facing up. You need to cut the pipe and modify it so the switch is on the bottom. If the temp gauge never moved either you still have air in the system or when you installed the sender you used a LOT of teflon tape. That sender needs to be electrically connected to the block.
David Teitelbaum

That would be the early cars with the pipe that ran behind the A/C compressor before VIN 1233, His VIN is later. But you never know what PO might have changed.

Also, I would expect Air pockets in the cooling system to cause a Very hot reading and indication of low coolant. I'm not completely sure which way the temp gauge works, But he said, the gauge Pegged out when the terminal was grounded. (UP or DOWN?) I'm assuming he means UP. This seems to be just to the opposite of the Oil and fuel gauges. Those peg out when the circuit loses ground.

[LEVY]

That would be the early cars with the pipe that ran behind the A/C compressor before VIN 1233, His VIN is later. But you never know what PO might have changed.

Also, I would expect Air pockets in the cooling system to cause a Very hot reading and indication of low coolant. I'm not completely sure which way the temp gauge works, But he said, the gauge Pegged out when the terminal was grounded. (UP or DOWN?) I'm assuming he means UP. This seems to be just to the opposite of the Oil and fuel gauges. Those peg out when the circuit loses ground.

Temperature sending unit and otterstadt need to be in direct contact with coolant fluid to work, specially the otterstadt that is mounted away from the engine.

No cooling fluid means the sending unit will think the engine is cold.


LEVY

[DMC5180]

Temperature sending unit and otterstadt need to be in direct contact with coolant fluid to work, specially the otterstadt that is mounted away from the engine.

No cooling fluid means the sending unit will think the engine is cold.


LEVY

He also mentioned he let the engine get hot enough to push coolant out the overboard hose. I have a hard time believing there is a huge amount of air trapped in the Right Head and still be able push coolant out.

I have to believe it's and electrical issue until proven otherwise.

[DMCMW Dave]

A blown head gasket will push coolant out the overflow And the sender will see steam which is hotter than the coolant

[Ron]

I'd re-do the test but ground the wire right to the case on the sending unit itself. If it maxes the needle, you were the lucky one in a million to get a bad new unit.

( I liked the heat gun idea too...)

[Mike F]

A blown head gasket will push coolant out the overflow And the sender will see steam which is hotter than the coolant

Geez, hopefully it's not that!

Yes, the gauge pegged UP when I grounded the wire. Next time I am with the car (will not be until Friday night unfortunately) I will try grounding the wire right to the casing of the sensor. Knowing my luck, I will have the one-bad-in-a-million sensor (why can't I have that kind of luck with the lottery?). My otterstat pipe does not appear to be one of the early ones (looked on DMCH diagrams for comparison). It looks as if the PO simply turned the pipe around for reasons unknown. As far as the air trapped theory, I agree with you DMC5180 in that you would think it would cause the temp to go UP rather than not register at all. That is how it has worked for every other car I have ever wrenched on. I was kind of grasping at straws there, since I can't think of any reason why this isn't working. I feel like I have worked down the line and eliminated every other possibility, particularly since I was able to run that ring terminal to ground and it pegged the gauge. It seems like if THAT works it would be something before that in the line, which at that point the only things left are the sender itself and the coolant touching it on the other side.

Let me toss this out there...the sensor relies on the block into which it is threaded for a ground. Is it conceivable that the ground for the block itself has gone bad? Maybe corroded or otherwise providing enough resistance that the sensor isn't getting a good enough ground to function properly? If that were the case, however, wouldn't there be more things than the temp gauge not working properly? Just a thought...

[Bitsyncmaster]

If your starter works, the block is grounded pretty good. The temp sensor would still work fine even with a few ohms of poor ground but the starter would never work with that.

You could measure the resistance of the sensor at the block. Then you should measure that same value up at the gauge. I have a spare sensor I can measure, it's one from Special T.

[DMC5180]

David T's Theory of too much TFE tape on the sensor is plausible if it's a ground issue.

I just went and grounded my terminal and it does not move from rock steady ZERO. When the Key is turned from OFF to ON the needle will move UP to the ZERO mark and stay there even with it grounded. I did this test without disconnecting from the sensor, I just clipped a test lead to the stud and grounded the other end. This leads me to believe you have a bad gauge.

[Ron]

David T's Theory of too much TFE tape on the sensor is plausible if it's a ground issue. That is why I suggested going to the sensor case... (been bit before! lol )


I just went and grounded my terminal and it does not move from rock steady ZERO. When the Key is turned from OFF to ON the needle will move UP to the ZERO mark and stay there even with it grounded. I did this test without disconnecting from the sensor, I just clipped a test lead to the stud and grounded the other end. This leads me to believe you have a bad gauge.
Had me going for a minute...You must of done something wrong...I just double checked it- with key at RUN, and a test lead from the sensor terminal (still connected) to the block, or even the quarter panel, the gauge maxes out...

EDIT: [deleted bad info]

[Mike F]

David T's Theory of too much TFE tape on the sensor is plausible if it's a ground issue.

I just went and grounded my terminal and it does not move from rock steady ZERO. When the Key is turned from OFF to ON the needle will move UP to the ZERO mark and stay there even with it grounded. I did this test without disconnecting from the sensor, I just clipped a test lead to the stud and grounded the other end. This leads me to believe you have a bad gauge.

My gauge moves to the zero mark when the key is turned from off to on as well. I have not tried grounding the stud with the terminal still attached to it. When I tried grounding it, I always did the terminal itself off the stud. If the gauge is bad, wouldn't it NOT respond the way it has with regard to pegging out when the terminal is grounded (given that the temp sender works by providing a decreasing resistance to ground as it heats up)?

I appreciate everyone's help and patience with me as a DeLorean newbie. I'd be quite lost without the support. It's just frustrating that the car is 100 miles away and I have to wait a week at a time to try these tips, and then only get a day or so at a time with it. I think I have drawn a line in the sand here...if I can't get this cooling system issue sorted this weekend I'm going to bite the bullet and have the car towed home. That way I will be able to poke around as much as I need to. I was hoping to be able to DRIVE it home, but I guess that's how it goes!

[DMC5180]

That is why I suggested going to the sensor case... (been bit before! lol )


Had me going for a minute...You must of done something wrong...I just double checked it- with key at RUN, and a test lead from the sensor terminal (still connected) to the block, or even the quarter panel, the gauge maxes out...

Memory trick: If you ground the terminals on a D, (F)uel (F)alls and heat rises...


I just checked again with a different test lead and still can't get the needle to move from ZERO. I suppose there could be too much oxide/tarnish on the sender stud, but I also went to the bare terminal body.

[Ron]

Try grounding the LightGreen/Blue wire in the White 7 pin bulkhead connector -- same wire.

[DMC5180]

Try grounding the LightGreen/Blue wire in the White 7 pin bulkhead connector -- same wire.

I tried this (back probed) and nothing changed. Then I unplugged the connector, "BOING" straight UP with the lose of ground. This confirms the Oil, fuel and Temp gauge needles will peg out with "loss" of ground.

[Ron]

I tried the temp again (and fuel sender)-
I had the fuel sender backwards, it is the light that shows empty when you ground it. (Full and Fall made for a bad memrory trick, DUH.... anyway, I edited out the bad info above...both easy to see in my own post here here (http://dmctalk.org/showthread.php?1246-Fuel-Sending-Unit-A-look-Inside) ) :blackeye:

But I still get 260+ when grounding the temp sensor???

[DeloreanJoshQ]

Try grounding the LightGreen/Blue wire in the White 7 pin bulkhead connector -- same wire.

Thanks for the idea!

I unplugged the white bulkhead connector and replugged it back in. I put pressure on it towards the "peak" where the temp gauge wire connection is and the gauge works! Now I need to see if it will hold or if it will lose contact again. Any ideas on how to keep the connection from loosening?

[DeLorean03]

Yes,

Take the carpeted backboard off from behind the driver and psgr seat. Unhook your battery.

You'll need two people for this. One person holds all the wires for the white bulkhead connector in place with a good secure hold. The other plugs the bulkhead connector back in. Since you got one person holding the wires and pins in position, the connection should be secure when the other person plugs the female-ended bulkhead connector back into place.

That's how I solved the problem where my brake lights kept turning off due to a loose connection in the black bulkhead connector.

[Ron]

Sounds like the connections need cleaning (or one of the two is pushing the other out of its plug).

[sdg3205]

My temp gauge is doing odd things.

Initially it was pegged at 12. I cleaned and checked the bulkhead connection which seemed fine. I also verified the connection at the gauge behind the dash was good. Still read at 12.

Then I removed the wire from the sender and placed it on the block to ground it. Now it pegged hard at 1:30, or the 'p' in temp. If I am correct, this means the bulkhead connection is in fact good. Does this mean the gauge and the sensor are both bad? Is there anyway that the gauge is mounted upside down since its 180 degrees off?

Thanks!

[Ron]

Did you notice what the gauge did when you disconnected it?
Disconnected, it should go max one way -- Grounded, max the other way.
Sounds like you may have a bad sender or the feed wire grounded (you may have just grounded it better by shorting it to the block...). I'd guess sender, if you didn't have other problems (see below).

I think it might be a good idea to merge this and your instrument panel indicator threads together -- Let me know!

[sdg3205]

Hey Ron,

The only time it ever moved was when I first properly grounded it. It pegged to 1.

If I disconnect it from the sensor or ground the gauge doesn't move.

[Mike F]

If your gauge is pegged and not moving at all, you may want to see if the needle itself is in fact stuck. This happened to me on my fuel gauge when the sender was disconnected once and the car was powered up (which caused the gauge to peg hard downward). The violent spiking of the gauge to a position that it normally never goes to got it stuck. In order to free it I took the trip reset button apart (carefully!), and using a thin piece of thermocouple lead I fished through the reset shaft hole and ever so gently touched the gauge. It freed itself immediately and has worked fine ever since. This may be worth a shot for your temp gauge.

When my temp gauge was inop it ended up being a bad sender, however the needle itself was free to move. It would move up to zero when the car was turned on and would spike when I grounded the wire at the sender, so I concluded that it wasn't getting the right signal. The replacement sender finally fixed it.

[Ron]

Agreed. I got away with slapping the binnacle for a while, "for being ugly", then Eroc hooked me up.

I'd pull its fuse, just for GP, lol

[sdg3205]

So, while the binnacle was out I gave the gauge connections a thorough cleaning. Then I removed the lense and reset the needle in case it was in fact stuck.

Then I re cleaned the bulkhead connection and grounded the wire to sender to the block instead.

I plugged it back in and when I turned the key it sped over to 1pm again and pegged hard at 1pm.

Thoughts? Ideas?

[David T]

Disconnect the wire to the sending unit at the sending unit and try again. If it pegs out again there is probably a problem with the connection between the gauge and the sending unit.
David Teitelbaum

[sdg3205]

Can I run a looong wire from the sending unit right to the gauge?

[DMCMW Dave]

Can I run a looong wire from the sending unit right to the gauge?

Worth a try or take the gauge to the back of the car and use clip leads.

[sdg3205]

This is how I tested the gauge today.

I ran wires directly to the terminals that the circuit board travels to just prior to the temp gauge, which is the battery gauge that works perfectly.

I ran a dedicated wire to the black harness which goes to the sender.

I turned the key... No change. I went to the sender and moved the wire around. I could see tiny little sparks when I put it I the block as a ground. Obviously has current, but no change in the gauge when grounded or not.

Is it time to blame the gauge as faulty?

18554

[sdg3205]

18555

Where the gauge sits.

[Ron]

This is how I tested the gauge today.

I ran wires directly to the terminals that the circuit board travels to just prior to the temp gauge, which is the battery gauge that works perfectly.

I ran a dedicated wire to the black harness which goes to the sender.

I turned the key... No change. I went to the sender and moved the wire around. I could see tiny little sparks when I put it I the block as a ground. Obviously has current, but no change in the gauge when grounded or not.

Is it time to blame the gauge as faulty?

18554No. It takes 3 wires to run the gauge, one for power, one to pull it low (a separate ground), and one to pull it high (the sensor wire, which the sensor grounds in varying amounts depending on its temp). It's a balancing act... If the ground at the gauge is bad, the ground from the sensor will peg the gauge.
Since you had a slew of bulbs that had to be cleaned, I'd guess the ground for the temp gauge might be the
problem...but not sure because you never answered what happens when you remove the sensor wire and NOT ground it to the block...

[sdg3205]

No. It takes 3 wires to run the gauge, one for power, one to pull it low (a separate ground), and one to pull it high (the sensor wire, which the sensor grounds in varying amounts depending on its temp). It's a balancing act... If the ground at the gauge is bad, the ground from the sensor will peg the gauge.
Since you had a slew of bulbs that had to be cleaned, I'd guess the ground for the temp gauge might be the problem...but not sure because you never specifically answered what happens when you remove the sensor wire and NOT ground it to the block...
,

Yes I did. Post 33. If the sender wire is Not grounded to the block or put back on the sensor nothing happens.

I'm a little confused. There are three terminals on the gauge that are used. Two share with the battery gauge (power and ground) and the 3rd is the sensor wire which is now connected directly to the black plug. Isn't this exactly what you just described?

[Ron]

Sorry, I misread where you removed "it" from ground...

Yes, same thing. But just because the Volt Gauge is getting the separate ground, it doesn't mean the Temp Gauge is. You would need to bring ground right to it to be sure (...I suspect the connection is bad. It would act exactly like what you are saying.)

sorry so slow to answer, I'm on a stupid IPad and it is barely in range.....

[sdg3205]

Sorry, I misread where you removed "it" from ground...

Yes, same thing. But just because the Volt Gauge is getting the separate ground, it doesn't mean the Temp Gauge is. You would need to bring ground right to it to be sure (...I suspect the connection is bad. It would act exactly like what you are saying.)

sorry so slow to answer, I'm on a stupid IPad and it is barely in range.....

It's all good Ron!

I'm going to try a few other options.

[sdg3205]

This is the hard ground and 12v at the gauge.

18556

Stand by...

[sdg3205]

This is the 12v and variable ground sender wire grounded to the block.

18557

[sdg3205]

Here is the 12v and variable sender ground with the sensor wire properly secured to the sender.

18558

[Ron]

If you now remove the connection from the sender off of the gauge and confirm the ground goes away from the gauge, the gauge should then swing the other way. Otherwise, I would say it is gauge time (but check it just like you did with it totally removed before ordering ;-)

EDIT: If it falls after removing the sensor wire connection from the gauge, at the gauge, it has a short to ground....

[sdg3205]

If you now remove the connection from the sender off of the gauge and confirm the ground goes away from the gauge, the gauge should then swing the other way. Otherwise, I would say it is gauge time (but check it just like you did with it totally removed before ordering ;-)

EDIT: If it falls after removing the sensor wire connection from the gauge, at the gauge, it has a short to ground....

Ron!

Here is the last picture.

This is 12v and the variable ground to the sender.

0 v when the sender wire is hanging in the breeze in the engine bay. NOT grounded to the block and NOT on the sender itself.

18559

[Ron]

Looks like gauge time to me man...

[sdg3205]

Agreed

[sdg3205]

Replaced gauge tonight and works perfectly.

[DMCMW Dave]

I've seen a couple where the gauge itself is fine but the shunt resistor across the back (the colored looking piece of ceramic) has opened up. With the shunt open the meter will work but will be horribly inaccurate (a fuel gauge with an open shunt will read empty when empty but about 1/4 when the tank is full).

Part is not available separately but scroungers might have them. The color is the calibration value.

[sdg3205]

Thanks dave. It would be nice to fix it and have a spare.