Hey Everyone,



I've gotten a ton of work done to the car over the last few months, so i'll just start with those items and lead up to the current symptom.

1982 244 DL B21F with Chrysler ignition/KJet:

prior to any work, the car had been ok during the summer as far as temps...the needle would hang out at 9:00 except when i drove faster than 70 with A/C on. It would climb to 9:30 but after I turned the A/C off it would creep back down. Slowing down also helped.

I finally got around to obtaining a brand new engine harness from davebarton.com, and though it was quite a bit of work, i'm very happy with the results. In the process of putting in the new harness, I also found a few items that either needed replacement, I broke them during teardown/rebuild, or just the old "since i'm here, might as well do it"

As pertaining to the cooling system I replaced the following within the last 2 months/1000 miles:
water pump
thermostat (87C OEM volvo) and housing
all sensors on the engine block were replaced
fan clutch (tropical)
all coolant and heater hoses
all accessory belts
OEM Volvo coolant overflow tank and cap

I also disassembled the intake manifold/throttle body and cleaned them thoroughly along with the intake ports. Cleaned the AMM assembly as well and installed a new air intake accordion hose along with all new vacuum lines. Flushed the entire cooling system with distilled water and radiator flush 3 full cycles, then filled the system with Volvo blue coolant. No leaks have been found anywhere. Have not had the system pressure tested yet.

After all that, the car began to run better than she ever has, with temps holding normally. Then out of the blue the needle shot up one day after startup and a 2 minute idle. Now it shoots up every time I start the car and stays right at a needle's width away from the red marker (or 9:30 using Art Bernstein's protractor confirmed measurements)

I replaced the new thermostat again with the same PN, no change.
The coolant sensor (yellow wire) is brand new as I stated before. I did disconnect the wire and grounded it to make sure it spiked to the red, which it did.

When i get up to 70mph, the needle stays where it is, right at 9:30. Blasting the heater makes no difference either, even when coasting down a long hill in neutral.

I've read in other posts that I should possibly consider the head gasket could have a hot spot and hasn't yet failed. I have no mixing of coolant/oil anywhere, and even after a 70mph run, I smell no hot coolant through the vents or under the hood. The radiator has a couple bent fins, but no blockages from insects and the like. Today I picked up an IR thermometer and read the T-stat housing just after a highway run. First readings were between 140-150 degrees, then I put some electrical tape over the housing and read it again. Those readings were 170-180 degrees. I also read the return hose and core area and got no suspicious readings.

It seems like the only options left are either a bad (new) sensor or gauge. Fuel tank gauge is reading accurately as a reference, and how often do the gauges really go bad? Oh, I also just read about the pressure relief pin inside the thermostat, and that it should face upward at 12:00...is this vitally important? I have no idea how it's currently situated as I've never heard about this before. It could very well be at the bottom for all I know.


Can anyone contribute any other suggestions or ideas, or am I on the right track here? I'm away from the car for a few days so I figured I would try to get some assistance from the board before I go back for the next round.

Thank you again for everyone's time and contributions.

The Brass Thing Still Valid in your year?

Got the OLD style instrument cluster? Thinks 82 was still in this config.

https://www.brickboard.com/RWD/volvo/1576097/220/240/260/280/voltage_stabilizer_gauge.html

My instrument cluster is the newer style that lasted until the end of model production. When I asked about their compensator bypass kit, the guys over at ipd said only 1986 and up have the temp compensators, so I wouldn't need the kit. Is this misinformation?

Also in reference to what Art said in the link you posted, wouldn't the fuel gauge also be reading erratically if the temp gauge or its compensator failed? It's not, that's why I'm stumped.

Your cluster does not have the temp comp board.

The little yellow sardine can looking thing that CB insists on calling a temperature compensator is a voltage stabilizer. It does affect both temp and fuel gauges. It is there to ensure both gauges get a constant 10v. And, by the way, it is not made of brass.

If the voltage stabilizer bites the dust the temp gauge will read partially warm when the engine is dead cold and it will be over the top of the scale at normal operating temp.

With a bad stabilizer the fuel gauge will also read high. A full tank will read above the full mark. An empty tank will still show 1/4 of a tank or thereabouts.


--
'80 DL 2 door, '89 DL Wagon

Yes I've been told a few times that my cluster is too old to have a temp comp board, including by the guys at IPD.

Haven't been driving the car much as of late as I'm slightly concerned with much more than short city trips, though I did install another brand new block sensor last weekend. The result of that has changed the symptom slightly to as follows...

Upon startup, the car will take a few minutes whether at idle or driving to creep up to temp, and when it does, the needle now reads slightly lower than it did before (now around a needle's with or two lower than it had been at the 9:30-9:45 mark)

It doesn't shoot straight up, and before as I mentioned, I did ground the wire and it pegs to red as it should. Wire harness is brand new.

So in conclusion, the needle still reads high, but slightly lower than it did when I had the previous temp sensor in there (which was also brand new)

Temp readings by IR thermometer are all still normal.

Next step I suppose is to pull out the instrument cluster and have a look at what's really going on back there.

there is usually no effect on the fuel reading in either the Old style with the Brass resistors or the New cluster with the Comp Board.

Note that the NEW style also has a resistor in the circuit, which is not part of the Comp Board. It is located on the rear of the cluster board. _____ in the 2nd to last PIC in Art's series It is the Black square held with a screw on one side wirh the other plugged into the white box - ITT 89 12 printed on it.
Though these rare fail.

here's Art's page --- Cleanflametrap. notes on the Fix for the Newer Cluster.

http://cleanflametrap.com/tempFaker.html

You may or may not have the thermostat clocked wrong relative to the vent hole, but if the car worked fine for a week or two and then out of the blue showed hot, I would't think that's the problem. Besides, your IR reading was reasonable.

Is it possible that the sensor wire is grounding somewhere along the way? If the gauge pegs to red immediately upon start-up, that may be a possibility, but if it takes a minute after start-up to peg then I wouldn't think that accidental grounding is the problem.

So how about that new sensor? You could test it in a pot of water on the stove with a cooking thermometer and an ohm meter. I don't know the temp vs resistance correlation curve for your car but somebody on this forum will. Have you tried using the old sensor?

earlier in that same thread.

I'm the Charlie ----aka CB

https://www.brickboard.com/RWD/volvo/1575968/220/240/260/280/1980_245_dl_temperature_guage_issue.html


The 80 has a Temp Comp Module attached to the rear of the Gas/Temp board.
It is oblong brass with blade connections...it pulls easily off the board from the rear.
Inside are common resistors...(pry back the lips of the brass shell)
what usually goes wrong when it fails, is that the Temp rises to near the Red, even though the system is just fine.