Condition: at idle, stuck at big city traffic lights, the temperature gauge rises beyond the center "ideal" zone and moves over to hot.
I replaced the thermostat and it still does it. Has been doing this since I purchased this vehicle in 2003. Turning on the heat makes a bit of a difference, but the gauge still creeps up.
Was told by a mechanic that the temperature gauge is not working properly and needs to be replaced, but that it is a single piece and costs US$500+.
Looked a bit on line and i recall reading that the line between the gauge is filled with ether gas.

Any suggestions on how to fix this more economically? Not many 122s in the junk yards around here.

Your gauge is fine. I set my idle to 950 and that keeps the temp under control. It is fun to watch the gauge rise until the thermostat opens and the gauge falls again. Your water pump might be worn so that it does not move a lot of fluid, you could have a very dirty radiator (flushing the fins with a hose spray to get out any dirt might help), getting a fan shroud will direct the air through the radiator better, make sure the cap on the overflow bottle is in good shape, and just run over the slow pedestrians.

Klaus
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Did you do your Random Act of Kindness today?

If you have the stock four blade steel fan, and the engine runs at normal temperature when moving, it's the fan. Install a plastic 140 fan, and it will improve things, perhaps even fix the problem.

If it stays in the zone except when you are at an intersection your gage is fine, and your mechanic is not using his/her head to diagnose. At issue is low velocoty coolant flow at idle, all my 120s have had this after a hard run....if your choke cable is set properly the 1st 1/2" or so of travel raises the idle without making the mix richer (as it's not really a choke you know) so when it gets hot raise the idle it should cool off immediately.
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Patrick, '68 220 (used to drive 240s)

When the engine and carbs, especially the carbs, are in good condition, you can set a very low tickover speed. It's a bit of a challenge and will look good ticking over smoothly at 650rpm but won't turn the water pump very fast. If running a generator/dynamo the red light likely to be fully on as well, indicating no charge. Better to set it to 850-900 and have more water flowing round.
A poor seal on the rad cap will also put the temp up if it's losing pressure.
Check your fan belt tension too.

Totally agree, my carbs finally seal so nicely I can set the idle very low. I like the sound of the engine idling at 500-600, and as my alt can handle it usually keep it there unless it is hot out....hence the choke cable idle adjustment as required. It is not just an esthetics issue either...I figure the low idle saves gas in stop and go traffic, intersections etc...
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Patrick, '68 220 (used to drive 240s)

Very true but when running along in stop/start traffic, a 900 tickover allows clutch bite with virtually no raising of revs. I find that that with a really low tickover you tend to raise the revs too much or stall it. It's a fine art but the faster tickover makes it easier for me. Mine will run along happily, smoothly, at tickover with the clutch fully out without touching the gas pedal. That's good too.

What's the temperature rating on the thermostat? I think it should be 165*F. Most parts stores will give you the wrong one.

Also, do you a 7lbs radiator cap?

Paul

Edit: Yup! Part number for the thermostat is: 418496 (165*F)and radiator cap is: 87842 as per the greenbooks:

http://www.volvoamazonpictures.se/documents/Volvo%20P120%20P130%20P220%20(B18)%20Reservdelskatalog/Group%202b%20Cooling%20system.pdf

As I recall, I have a 4.5 lb thermostat, maybe temp is 140? don't really remember though, because I think I changed the thermostat back in '03....bought the thermostat from Rusty at RPR in Albany Calif., so i think it was the correct part.

When sitting at DC traffic lights in the summer a fast rising temp needle has always been standard on my 122. Not the most glamorous solution, but revving the engine a bit while stopped keeps the coolant flowing/fan turning and is almost always enough to maintain a safe temp. If you are idling for long periods of time in hot weather an electric push fan may be worthwhile.

Make sure that your cooling system is in tip top shape and that you do not have any air in the system.
I had an inop temp gauge in my 122, but was lucky enough to have a spare 544 instrument cluster on the shelf. I removed the temp gauge from the spare cluster, but before I installed it into the 122, I did a little calibration on the kitchen stove with my wife's candy thermometer and came up with the following results.
When the temp gauge needle reaches the 1st white line, the temp is at 167f.
When the needle reaches 1200 (straight up/down) the temp is at 180f.
When the needle reaches the 2nd white line, the temp is at 212f.
I installed a 180f degree thermostat, which seems to be operating properly, because the needle on my gauge always points straight up/down at 12 o'clock.
A new replacement temp gauge is still available for VP-Autoparts P/N673999 @ $216.00. There are probably other vendors who might have it for less. You might also check with Joe Lazenby to see if he has a working used gauge or check on ebay for a 544/122 gauge and/or complete instrument cluster.

FIRST thing I would do is get a thermometer and see how hot it is when it gets to the red.
For reasons not very clear to me a lot of 122 temp gauges indicate hotter than they actually are.
You're right that they are filled with ether, but most of it is liquid.
If it had leaked the temp would indicate lower (but it would probably have to leak quite a bit).
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George Downs Bartlesville, Oklahoma

I don't think I've ever seen my temperature gauge in what I'd consider the "normal" area of the gauge. Even after I updated the cooling system (rodded out radiator, new hoses, new thermostat, flushed block, rebuilt heater box) it does not seem to behave any differently. Just seems to always be on the hotter side. I've been told this is pretty much par for the course on these cars. The accuracy of the gauge isn't great, but the reaction time is.

Hello,

As George recommended, back up your temperature gauge by checking with another gauge.

We use a non contact thermometer to verify temperature gauges.

This is a hand held device that can measure the infrared waves at the points that you point it at.

Most radiator shops have them and you can buy cheap versions if you want to have one as they come in handy for all kinds of jobs.

FYI a new water temperature gauge is available for $236.00.

The new gauge is the B20 version.

We sell rebuilt B18 and B20 water temperature gauges for less.
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Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502

Hey Beige,
My 122 ran exactly the same. Always hot. Rebuilt radiator, heater core...still same. Purchased and installed new 180 thermostat and quality waterpump from Eric...runs dead center on gauge ever since...unless pulling 8% hills then it rises a bit and returns to center on the down hill.

I've had thermostats in 122s, 140s & 240s stick partially open.