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Recently my Temperature Gauge has gone wacky. After a short amount of time the temperature goes well past the highest temperature on the gauge. There is coolant in the system, the thermostat opens at the correct temperature. I removed the water pump and it turns a little bit stiffly but nothing obviously wrong. The temperature sensor wire connector was bad and I switched out the female connector to no avail. Before I replace all three parts I thought I ask for any feedback.
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Hopefully, this will be the last question and the next post by me will be an update as to the success thanks to everyone's help. I have fixed the wires on my instrument cluster with good results. Now the gas gauge is functioning correctly. The temperature gauge is still not working correctly. It starts to rise (very little) and then abruptly snaps back down and repeats this never even getting into the actual temperature area. I'm guessing now that it is most likely the gauge itself. Could I have fried it when I put the 1973 voltage stabilizer in because it works on a higher level? Or maybe it just went bad and needs to be replaced. Will a gauge from a 1973 work if it was made for a different voltage stabilizer? Thanks so much for helping me work through this.
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I've posted this issue elsewhere also and someone said that the voltage stabilizer can be tested. He said battery voltage in 9 volts out? Is this correct? What would be the best way to do this.
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Dave;
VStab output for the 140s (VDO) instruments is 5.1V (and it can certainly be tested!)...but unless changed for an electronic one which has that as a constant output, and it is still the switching bimetallic element, that means 5.1V long-term average! It is NEVER actually 5.1V! It's either 12V or 0! See: http://www.sw-em.com/voltage_stabilizer.htm#140_VStab_Info
Good Hunting!
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Sorry for my lack of knowledge. I love my car but am not looking to be all original. I saw you say something about an electric replacement. Could you please help me understand what to look for if there is a replacement that I can put on it and how difficult that may be to do?
. Thanks.
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Dave;
All electronic VStabs are available for the 10V nominal type, so I presume someone also makes the for the 5.1V version these have a constant output at the DC level...I do not have any sources that I can recommend. Before considering replacement, I'd check output of yours first to confirm it is bad...bimetallic VStabs are highly reliable...OK I guess its 40 years old...maybe its finally given up and failed...
Good Hunting!
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This is still a battle with my gauges and I've created a new mess. I've soldered my blue wire back to the circuit board, replaced everything, and went for a test drive. The gas gauge was sort-of working and as I drove I noticed the temperature gauge would occasionally sort of click as if it wanted to go forward but then wouldn't move. After returning home I removed the cluster again and removed the stabilizer and found that the red wire was broken from its connector so now I have to fix it. When I did this I looked at the two stabilizers I have and noticed there are two different numbers on them. One is from my '72 and the other is from a '73. Which number is the correct one for my '72, does it matter? Also any suggestions on making something to replace the stabilizer holder, the rubber is shot and the stabilizer keeps falling off of the back of the dashboard. Does that affect the function?
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he voltage stabilizer fitted on the 140 (all versions) up to 1972 was 684623 and had a regulated voltage of 5.1 volts. 1973+ versions of the 140 and I think the 200 series got stabilizer 1234971 which I think has a regulated voltage of 10 volts.
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Thanks for that info. I don't see any numbers like those on my voltage stabilizers. The only numbers that are on it are printed on the side. The first one has 16/7.70 and the other has 14/10.71. both also have what looks to say Achtung Gehduse. The words are hard to read because the printing is very good. Can anyone tell me the difference? I know one came from my '72 and one came from a '73 I bought to rebuild my front end after a guy in a Toyota pickup turned in front of me and I hit him at 45 mph. Needless to say, his truck was not salvageable, it was destroyed by my tank. I just don'tknow which one is which.
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In the absence of suitable markings, and if they look the same the only option is to carry out a test to measure the output voltage. Unfortunately that is hard to do without an oscilloscope or a high end multimeter which can calculate pulse duty factor or true RMS.
You can do an approximate test with a 6 volt incandescent light bulb (one from a flashlight should do the trick - do not use an LED) and a 9 volt battery. The stabilizer is a 3 terminal device; input, output and ground which is the terminal connected to the case. To do the test, connect the 9 volt battery with + to input and negative to the case connection (ground). Connect the light bulb between the output terminal and the case connection. The up to 1972 stabilizer regulates at around 5.1 volts RMS so the light bulb should have close to normal brightness. The 1973+ stabilizer regulates at 10 volts so the output should be 9 volts which should cause the light to be really bright (just before it burns out).
The wiring diagram I have does not show wire colors on the instrument cluster so you will have to figure out the stabilizer input and output terminals from examination of the cluster connections.
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I ran the test you suggested with the flashlight bulb. I didn't have much luck telling the difference. My question is if the bulb lights up does it mean that the voltage stabilizer works? because I think I figured out which one was my original one from my car and if the test I ran shows it works than I can take that off the list. Thanks
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The stabilizer can fail in 3 ways:
- it sticks at 12 volts output
- it sticks at 0 volts output
- it regulates; but, at something other than 5.1 volts.
The stabilizer is clearly not stuck at 0 volts. If you used a 6 volt light bulb and the light bulb did not burn up, then it clearly is not stuck at 12 volts (the filament would have burned up pretty quickly). So, if the light level of the bulb seems close to normal the stabilizer is probably working at close to it rating of 5.1 volts RMS. If you have a digital multimeter that reads true RMS (or know somebody who has one) you can use the multimeter to measure the effective output of the stabilizer. Cheap multimeters generally do not read true RMS.
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Thanks for the feedback. After trying out the volage stabilizer and the new holder that I made I found that my soldering skills are at the level I thought, which is very beginner (this is my first attempt ever). My soldiers all came off so the red wire (output) and the blue(ground) came off. Now that is a bad connection. I am going to try again after another attempt.
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Those numbers look like date of manufacture so they should be the same.
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Can you post a picture of both the voltage stabilizers?
IIRC, the correct stabilizer has a bracket attached to the can.
The rubber holder is kind of important as it holds the stabilizer from hanging by the wires.
If you have the remnants of the rubber strap to use as a template, you can simply cut a new 1 out of a thick enough piece of rubber.
If you don't have the remnants, I do and I can make you a copy.
--
Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502
hiperformanceautoservice.com or oldvolvosonly.com
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Update to my ongoing dilemma. I had to make the choice to just put everything back together right now so I had the car in case of an emergency. After putting one of the other sensors I had in and putting the rest of the coolant system in place (even though I.m having to re-do it because I'm leaking around the water pump on my first try (usually for me a two or three tries before I get it right))and putting in coolant the gauge is working. I'm now guessing that my testing skills still need much much work and leave much to be desired.
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Now I've finally got the cooling system back together and think I've sealed up all leaks. I'm back to the issue with the gauge, sensor, etc. I've been switching out different sensors and voltage stabilizers without much luck. The last time I was messing with it I noticed the blue wire from the voltage stabilizer was loose. upon further inspection, it came off of the circuit board. I believe that the wire may have been coming off all along. Would that cause the gauge to malfunction if the connection was poor? I'm going to solder it back on, is there anything I should know before doing so? I'm not very skilled at soldiering.
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The gauge is powered by way of the voltage stabilizer so yes, a broken spade connector can most certainly cause a dead gauge.
Do you have a wiring diagram for the car?
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Yes I do have a diagram. The circuit board is marked where the blue wire goes so that isn't a concern. Is there anything I should watch out for when soldering the wire back on? Thanks.
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Cleanliness of the wires is important when soldering. Also, a tiny bit of flux applied to the wires will help the solder flow and adhere to the wires.
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Thank you. Now I just need to order my soldering iron.
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Cranky gauges can sometimes be caused by bad fuse connections, or a blown one of course. Cleaning all of the wire connections and the fuses themselves can often cure a multitude of faults. Instruments usually have a common earth behind the dash using a piggy back wire. It will depend on the instrument type.
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Loosen the pump bolts a bit and then put a jack under the car with a piece of wood from the jack to the pump. Use jack to push pump upwards to squeeze the seals a bit more. Tighten bolts. Do the same if you start from scratch. Use a bit of grease on the gasket to make the pump slid upwards.
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So now for an update. I ignored the wishes of the Missus and put house repair on hold to look through my parts. I found another voltage stabilizer and two water temperature sensors (one coming out of my spare engine) With them and the original parts in the car and the spare dashboard cluster I found earlier. I swapped out the temperature sensor, put both found ones in boiling water and the temperature gauge did not move. I swapped out the voltage stabilizers and with the original one the fuel gauge went to full and slowly went to empty (the tank is full). With the other 2 Voltage stabilizers, the fuel gauge worked perfectly but the temp gauge didn't move. I tried every combo of sensors and voltage stabilizers and no response from the temp gauge. I then did the same process with the other dashboard gauge cluster and had the same results. I also tested the resistance of the other 2 temp sensors and the multimeter measured around 27 on both (as opposed to the 5.1-6 on the original one). I also looked at fuses and they seem o.k, but I'm not sure which fuse I'm supposed to be looking at.
This all leaves me at a dead end. Either both the temperature gauges are bad, the wire is bad or I didn't look at the correct fuse (or at it). Any help?
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Check for voltage to your gauge.
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So here is what I have now done. I'm not very educated on the testing of electrical parts yet so please take that into consideration as to what I tried. With the coolant sensor still in the back of the engine block, I set my multimeter to the lowest Ohm setting (200) and it showed a 1 on the screen. I then put the black probe to the body for ground and put the red to the male part of the electrical connector on the sensor. It took some moving the probes to get a steady reading. At first, it would show numbers in the high 100's then go back to 1. After trying to find a steady reading I managed to get a reading of about .5 and .6. There is no coolant in the engine at the moment because I unwisely panicked and went to check the water pump and thermostat before being smart enough to ask questions here first as to what to check. It's about 45 degrees right now so that is the temperature of the sensor. Does this information tell me anything? Thanks again to everyone who is helping to learn how to work on my car.
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Yes, that information is useful and seems to confirm the sensor as defective.
A "1" on the display of the meter when the probes are not connected to anything means something like "over limit", so in that setting anything over 200 Ohms.
I always check the meter and probes first by firmly holding both probes together. The resulting reading should be very low, like 0.1 or 0.2 Ohms. Anything much higher and you must check the leads and connecion to the meter first to pevent false readings.
When all is well, then I would expect to see a much higher reading than 0.5 or 0.6 ohms through the sensor, even at 45 degrees ambient...uhm... ah 7.2 degrees C.
The way you describe the method of taking the measurement sounds OK to me, so I'm not doubting the values you measured.
Now I'm working from a 200-series here, but it seems like Volvo used the same sensor (Volvo part# 460191) from 1967 right up until the last 240s in 1993, so what I write below should apply to your car as well. However, I can't be 100% sure so anyone more knowledgeable, please chime in!
One of the tests Haynes says to do in the 240 is to shortly (max. 2 seconds!) ground the temp wire coming from the cluster at the sensor side and see if the temp meter in the instrument cluster deflects to full scale high (ignition on, engine off).
If it does, then wiring and instrument are deemed OK.
If it doesn't, then wiring and instrument must first be checked.
At such a low resistance as 0.5 - 0.6 Ohms, that basically equates to grounding the wire and I would expect to see a full scale deflection. This could be intermittent, hence the symptoms you described when you started this topic.
Since there is a warning to only shortly ground the wire from the temp gauge, to prevent damage to the instument, I would check the instrument too. If this erratic behaviour of the coolant sensor lasted long enough, it might have caused damage to it. Hopefully not, though.
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Being a solo mechanic, and not learned in electricic testing, what is the best way to perform this test. With such a short time I'm not sure how to work at the sensor and see the guage together. Do I set it up in the engine compartment then go into the car and turn the ignition on for 2 seconds?
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Yes, that is how I would do it.
Given the results described in your next post, you need to eliminate possible causes one by one.
If the fuel gauge is working correctly, then it is reasonably safe to assume that the voltage regulator is fine too. Next step: the wiring.
Note, in a previous post, you wrote .5 to .6 Ohms, now it is 5.1-6?
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It does look like the sensor has a little chip in the ceramic around the male connector. At this point I think I'm going to go ahead and change the sensor. The sad thing is that I probably have 1 or 2 in all of the parts in my garage but it may not be reasonable right now for me to search. I'm re-siding my house and need to finish before any more winter weather so it looks like a purchase is the most reasonable option. Thanks for the help.
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I guess you must have a rather large collection of parts...
Luckily these sensors are not rare or expensive.
In the meantime I suggest you perform a quick check of the instrument as described in my previous reply to rule out (or confirm) damage to it (and/or the wires).
Good luck!
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So now I've tried to test the temperature sensor using boiling water and had zero response on the gauge, it doesn't move at all. I had another voltage stabilizer in my collection of extra parts. I switched out the stabilizer and now the fuel gauge works but still no response from the temperature gauge. I put the old stabilizer into the spare instrument cluster and the fuel gauge works sometimes and sometimes not, so I'm pretty sure the old voltage stabilizer is bad, but now need to figure out the temperature issue. I'm concerned that the wire may be bad since I did have to change the female fitting to the sensor due to the fact that the original was barely holding on. The wiring diagram in the Haynes has the sensor connecting to the fuel gauge than the temp gauge, how would I run a new wire, or is worth getting a new sensor?
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Did you overlook the fact that the water temperature sensor needs to be grounded for the gauge to operate properly?
I believe you aren't reading the wiring diagram correctly. The wire from the water temperature sensor is connected only to the water temperature gauge via the PC board on the back of the cluster.
However, the output wire from the voltage stabilizer does go to both gauges also via the PC board.
On more than 1 occasion, erratic or non-functioning pre-1973 140/164 water temperature and/or fuel gauges has been caused by loose mounting nuts and/or corrosion between the mounting nuts, washers and PC board.
--
Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502
hiperformanceautoservice.com or oldvolvosonly.com
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Coming in late here. When this sort of thing happens I always start by checking and cleaning all of the fuses. Surprised that Ron didn't comment on that. Hi Ron.
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Derek;
For the 140s, where the Fuseblock is located in the relatively cozy passenger compartment, cleaning conical fuseends and mating contacts is not even something I think of first, but you're right...after so many years, it certainly wouldn't hurt to do some PM on those connections to assure a reliable power connection! Thanks for the reminder, and keeping me honest...peer review is good!
Cheers
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Before you get into the wiring....
Have you checked the resistance through the sensor? Haynes says it should be about 200 ohms at room temperature but they don’t give any resistance values for higher temps.
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Thanks for the idea. I'm still a little uncertain with my electrical testing skills. What would be the best way to test the resistance of the sensor. Is it connected to the car at the time? It's cold outside so would the sensor need to come inside for room temperature? What is the best setting on the Ohm Meter and where do the probes go? Sorry for the questions but I want to learn as much as I can to keep my car on the road, I have loved it for almost 20 years now.
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Dave;
I'd verify the accuracy of the indicating system, before actually suspecting Cooling Sys...by pulling the Sender and putting it into a bath of known temp (including a chassis connection for a single wire Sender!), and seeing what the gauge does with Ign ON. If gauge is still wacky, check your VStab..Gauge reading high is a symptom of VStab not cycling. See: https://www.sw-em.com/voltage_stabilizer.htm#140_VStab_Info
Good Hunting!
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If the VS is bad, it should also affect the fuel gauge.
Has any work been done to the cooling system recently?
If not, you should try to determine if the engine is actually overheating or if the gauge needs further attention.
--
Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502
hiperformanceautoservice.com or oldvolvosonly.com
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No work has been done on the cooling system lately. There has been an issue with the fuel gauge also. I ignored the fuel gauge issue until I received replies to this question. My old fuel sender went bad and I replaced it with one from a donor car I had for other issues. The replacement one never really worked right (after about 60 miles it went to empty, I'm guessing the same issue with my original in that the wound wires were breaking)so it failing to me was just a matter of time. I'm checking to see about the reaction from the gauge to boiling water. I lucked out and found another dashboard panel in all of my acquired spare parts relatively easily, so might just switch it out and see if it helps.
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When both the temp and fuel gauges act kooky then the voltage stabilizer becomes a real suspect as it is associated with power to both gauges. On a ‘72 140 you should find it attached to the back of the instrument cluster via a floppy rubber attachment.
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Thanks for the input, please see my new comment and if you have any ideas please let me know. Thanks again for the ideas
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