Hi all,
My 85 245 2.3l (B230f) engine seems to run at a lower internal temperature than designed for.
Earlier in 2024 I replaced the radiator and water pump. I recently replaced spark plugs which helped getting the engine to start much faster when hot.
The car is running ok on the road with enough power to catch up with the usual traffic.
My first thought was to test the radiator thermostat. Not new. The gasket crumbled when I removed it. The thermostat was checked off the car. Seems to open at 88 deg C like it is supposed to. When I took it off it was closed but I thought that the act of removing it might have made it close. Anyway I will get a new one just because it is a cheap and easy item to replace.
Wonder next if the culprit could be the fan clutch. Anybody have experienced over-cooling due to an excessive drag on the clutch?
I know the fan on the present clutch can freely turn at rest.
Is there a way I can verify that the clutch is okay?
Maybe my temp sensor is giving a false reading on the dashboard?
I think the repair manual provides a complete graph for Temp- resistance value for this sensor. I will check.
Thanks
Richard

Measure the engine temp on the thermostat housing.

Ok I will do that.
While at it I think I will replace the coolant. The darker color seems to show it is contaminated. The deteriorated thermostat gasket and the old upper hose may have caused that.
While there is no coolant I can also check the temp sensor.
Thanks for the reply.
Richard

Still working on the cooling system. I have the Temp gauge sensor off the car. That is the one that connects to the dashboard temp needle. It has one male 1/4" tab only as positive. The negative side being the sensor body.
I now realize I apparently have no temp-resistance graph for this sensor.
I wonder if I can use the same graph that is shown in the shop manual for the other temp sensor, the one connected to the ECM. That one has two connectors. This sensor is the one located just passed the flame trap when facing the engine bay.
Let me know if you think the graph is suitable for both sensors.
The manual I refer to is the Service manual section 2:
Fuel system LH Jetronic 2.2 - B 230F engine 240 1985-19...

Thanks

Richard

The gauge sensor doesn't follow the curve used to describe the engine coolant temperature sensor for the fuel system.

The green book specifies 10% tolerance for nominal 282 ohms at 122F, 60 ohms at 212F, and 40 ohms at 248F.

I've made some notes years ago you may find helpful or confusing as hell.



The "test" of the gauge prescribed by Volvo is to substitute a 68 ohm resistor for the gauge sender and expect 3/4 deflection of the gauge. I think 100 ohms puts it right about center, what folks call 9:00.



Check the open-circuit voltage at the end of the yellow wire pulled off of the sensor terminal with key on. Should see 10.0V. Start motor, should still be 10.0V provided by a solid state regulator in the cluster.

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Art Benstein near Baltimore

A bicycle can't stand alone because it is two-tired.

Hi Art,

Thanks always for the details but I am looking at your old notes showing the analog temperature reader.
On the table next to the drawing you wrote that at 9:00 the resistance needed is 68 ohms.
In your reply you wrote: "The "test" of the gauge prescribed by Volvo is to substitute a 68 ohm resistor for the gauge sender and expect 3/4 deflection of the gauge. I think 100 ohms puts it right about center, what folks call 9:00."

Maybe you meant 40 ohms should bring the needle right at 3/4 needle travel?
And the 68 ohms is for midway travel i.e. flat at 9:00?

Hope I am not beating a dead horse but what would be a normal operating position for that needle? I thought it should go just below 9:00. About 8:45?

You know, I have been looking for 85 240 section 3 service manual. That would provide all electrical instruments info I need, and more.
I cannot seem to find a proper sourceor maybe I am not looking at the right place. Do you know how to get (buy) this manual?

Thank you again.

Richard

Looks like you found the "confusing as hell" interpretation of my 25-year old notes. 40 ohms would put your gauge in the red, assuming my memory is correct that 1986 was the first year for the temp-faker compensation circuit. Now, according to my notes and recent tests, 40 ohms would result close to 9:45 or just past "3/4" as Volvo refers.

Up at the top of that note page is a test circuit using a 68 ohm resistor and variable voltage supply -- just to measure current vs needle deflection, because current is what is actually measured by the gauge.

Go to https://ozvolvo.org/archive/ Type 1985 or TP30808 into the search bar.

I don't know of any section 3 manual for 1985 describing the gauge calibration as was done in the older manuals for section 3 group 38 (instruments). I do know the temp sender and gauge sensitivity was not changed since those years even though the scale's legend changed in '81 as well as the reference regulator. (lookup TP11402) Page 60 is where the resistance numbers from Volvo appear.

Best download anything pertinent to your car while it exists on line.


--
Art Benstein near Baltimore

Time flies like an arrow. Fruit flies like a banana.

Hello Art,

Got it.

I take Volvo never mentioned what a "normal needle deflection" should be if all components are per spec? What would you say should be that position?

I have downloaded the TP30308 and TP11402. I will study the info.
Before writing to you about manuals I have found this site: volvo240-260.com
In there exists a section called "Green Book". This is where I found the TP 11050 1 1975 240 Section 3. You probably know about all this.
Thanks for the information.

Thank you for your help a million times. You should start a car manufacturing company.
I would be your first customer.

Richard

Normal. What a concept. I pulled out a 240 Volvo Owner's Manual (from 1983) and on page 6 it says "The gauge pointer should remain inside the black range during normal operation" followed by what you should do if it repeatedly moves into the red.



This overlay image helps to communicate needle position exactly.

Normal for my 89 sedan daily driver (all of the cars I drive have had the TempFaker removed if so equipped) is 9:00 after the warm-up cycle is done. When cold, like winter-cold, it is like 7:30 or below for a half mile or so of my trip downhill to town. During that first opening of the thermostat I catch the needle cresting 9:15 before settling back to 9:00 where it remains as long as the motor is running.

Normal for my 89 wagon -- dump runs and lumber fetcher -- is about 8:45. When I'm really cold in that car (wagons have more to heat) I dream about maybe changing the thermostat and flushing the heater core. But the seat heater works.

Our 79 244 runs about 8:40, but the heater is plenty warm. I can't even tell you which thermostat temps are in those three 240's I drive without some research into old repair history. I'd be concerned if the needle never made it past 8:30 maybe. Like is the tstat broken and wide open. Or the temp sender crusty with deposits? But after years of driving things that were not Volvo and having their heads off after overheating symptoms, I'm happy to have these Volvos that don't need head gaskets and the like, and have us running in the red and losing coolant on the Bay Bridge.
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Art Benstein near Baltimore

In democracy it's your vote that counts; in feudalism it's your count that votes.

Ha! Looks like there is a lot of freedom from the manufacturer's view.
Thanks for sharing what your actual Volvos are doing. It will help me figure out if my engine is running below operating temp.
You have done more than enough on this topic.
I am going to do my homework on the car and provide feedback later.

Thank you!!.

I like "...in feudalism it's your count that votes".

Richard (near Saint Louis)

I did not mention other reasons for "temperature lower than expected." One commonly reported reason is rich fuel/air mixture, something I've not experienced from the gauge being low symptom. In other words, the more obvious indications were horrible fuel consumption, or in the later cars, emissions fault warnings from OBD, or oxygen sensor failure. For the LH2.2 1985 model, I'd expect stinky exhaust, black plugs, and poor MPG would be your signals for that malady.
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Art Benstein near Baltimore

A chicken crossing the road is poultry in motion.

I'm not sure if this will be of any help, but here are temp gauge sensor Ohms from AllData for the mid/late-80s 240s, distinguishing between earlier and later sensors. They don't give the values for lentil soup, just water ;)

"https://charm.li/Volvo/1985/240 L4-2.3L SOHC VIN 88 B230F/Repair and Diagnosis/Instrument Panel%2C Gauges and Warning Indicators/Temperature Sensor %28Gauge%29/Testing and Inspection/"

There's quite a tolerance range for the earlier ones that includes values you noted. They also note a later sensor as '87-on, yet on Genuine Volvo parts sites I see the p/n 460191 temp gauge sensor has fitment listed for 240/740s from 1975 through 1993?? The voltage stabilizer temp compensation board was introduced in 1986, although I've always suspected some were earlier, perhaps non-North American ones. My '85 240 out of the Halifax plant didn't have one. Anecdotally, some '86-on didn't have the board, but they were troublesome early on, so it's hard to know what a PO did. On Dave Barton's page, he notes an '88 Euro cluster that didn't have the board connector. I also see a note on IPD with a comment about an aftermarket 460191 temp sensor from FAE that read very differently from the Volvo one.

I've got a 940 running a bit cool at the moment, so need to check out my thermostat at some point soon.

Oh, and Art, that reminds me that I've been meaning to thank you. That '95 940 recently had a dead speedometer. Thanks to your speedo writeups and pics I was able to spot the problem. It was a rotted trace much like the one you found on that '93 Yasaki speedo you stripped down. A couple of nearby solder joints were slightly corroded, so I had reflowed them, but it was only after seeing your pic that on closer inspection under magnification I noticed a nearby trace was corroded right through. A nearby capacitor didn't look like it had leaked and its solder joints looked okay, but I replaced it anyway. My ESR meter wasn't working so I couldn't easily check it and the other caps (just got myself a new one as a Christmas present). Next time it acts up I'll check the caps, but in the meantime the speedo is all back with a jumper around the break and working fine.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

"confusing as hell" continues...

I'm confident in assuring our North American followers the Volvo parts reference is correct; that the sensors/senders are the same (460191) 75-93 in the 240. I think AllData got some 7/9 info into that page where the second set of numbers for 87- are listed. Way off for any 240 in our market.

You know the 7/9 series Dave, when did those sensors change? Were they not two-pin sensors for the temp gauge at some point? Maybe 87-?

ESR meters. With those old Yazaki repairs I did, I measured ESR the "old fashioned" way using a function generator and an oscilloscope. But then a few years later, I got a Christmas present from a fellow Brickboard friend: A "tester" kit in a clear lucite case with a ZIF socket to plug all manner of components into. Reads out capacitance and ESR right there on its display. Wow!

I assume the '95 Yazaki speedometers are built similar to the 93-94 on a single sided board. It still mystifies me that Yazaki got seemingly exclusive rights to capacitors formulated to plan obsolescence so quickly, not only losing value but destroying everything else around them! Never seen anything like it.
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Art Benstein near Baltimore

A backward poet writes inverse.

Art, that Alldata page of ohms for the gauge temp sensors is indeed a mixed of 240 & 700 info. The same tables appear in a TB post I saw.

The upper table is for the single pin sensor, 460191. The resistance range is approx. 60-250 Ohms depending on hot or cold. It was used in all 240s/260s from '75 right through to '93. Volvo NA Parts fitment says it was also used in the 760s ('82-on) and early 740s ('84-'87). It's not clear exactly which 700s used it, but I believe it would be those with a VDO cluster and gauge.

The lower table is for the two pin sensor, 1362645. The resistance range for that one is approx 150-550 Ohms. It was used in the later 700s, all 900s and the early S/V90s. IPD says it was '87-on 740 and '88-on 760, plus the 780. Volvo NA parts says it was also used on some early 740s ('84-'86) and some early 760s ('82-'87), again without being specific as to which ones, but I believe it would be those with the Yazaki cluster and gauge. 240s never had Yazaki gauges, while 900s did and the later 700s were a mix (if you look at the green electrical manuals).

Which gauge a 700 had would likely vary by assembly plant and chassis number, meaning model and where/when it was assembled. Fastest way to be certain is to reach under the manifold and check the connector, and maybe confirm that by looking at the instrument cluster to check that it's VDO or Yazaki (Yazaki has a space bar separator for the odometer tenths digit, the VDO odometers have no bars between the digits).

The '95 940 Yazaki speedo is extremely similar to the '93 one, but they managed to use a few less components. Both the Yazaki cluster and the gauges are becoming more troublesome than they should be as they age. The soldering isn't the best, so you get corrosion. The flexi plastic PCB circuit boards on these Yazaki clusters are prone to damage, the screw contacts are prone to oxidation and of course soldering is very difficult to re-flow without burning through the plastic. I'm increasingly hearing of problems with the speedos going dead as they age past the 25 year mark. The capacitors probably aren't the highest quality and will slowly start to fail. Very few speedo repair places are familiar with them or even want touch them. With labour costs these days it's hard to justify sending them out for repair, so used seems the way to go. I'm also increasingly hearing of people finally wanting to say good-bye to their 700/900s when the gauges start going dead. If I hadn't been able to repair mine, the thought was crossing my mind that it was high time to move on from that car.

As for ESR meters, those little multi-function testers with the ZIF socket are indeed amazing. The one I got is the popular little LTC T7 model. It can do way more than capacitor ESR. They can do resistors, capacitors, inductance, thyristors/triacs, diodes (double/Zener, incl breakdown voltge), transistors (NPN/PNP), small battery volts/AmpHrs, even has an IR decoder. It automatically determines which type of device you've plugged in and the orientation of the leads is unimportant and with test leads can do in-circuit capacitor testing. It's self-calibrating, auto-off and USB rechargeable. I got the full kit in a plastic case, with three test lead clips, USB cable, a test capacitor and a test diode and pin bridge. On an AliExpress Black Friday sale, I got it for under $15, delivered. Typically they're more like $50 and on Amazon a fair bit more. There's also an older T1/TC1 model (slower and a bit less capable) and a newer T7H model(same, but faster measuring). Before I got it, I checked out reviews and also a video done by a tech who compared it to high end pro-meters made in Europe and was suitably impressed with both the sensitivity and accuracy. Biggest problem with the one from China is there's no instructions, but you can find them elsewhere online. I used it to quickly check out some Christmas light bulbs.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

Hello Art,

Good to read a message from you. I was hoping I could get your most valuable attention once more.
Thank you so much for your reply.
On the Temp gauge sender:
I did not realize it was receiving a 10 Volt reference voltage from the cluster. I will check to make sure it is getting this signal as well.

About the coolant temp sensor for the fuel system: Is there a reference voltage sent by the ECM? Is it 5 Volts when not connected to the sensor? The manual does not seem to elaborate much on this sensor besides giving a full Temp vs resistance curve.

I hope you can enjoy Christmas / New year week.

Note: This 85 245 Volvo is still up and running. Love this car. Manual transmission. Verrry useful and the least of my troubles compared to other cars I own. I heard those redblock engines almost never fail. Masterpiece of drivability, longevity, simplicity and usefulness. I don't really care about modern cars. If I can find another 240 with good body I will probably buy.

Richard

Thank you for the kind words Richard.

You're right, the ECU temp sensor gets measured using a regulated 5V source, so you can backprobe that wire to the ECU's pin 2 (comfortably from inside the cabin by the way) to watch its performance during the engine warmup, thus verifying the sensor's stability over the range and all the wiring.

Here's the circuit for the LH2.2 -544 ECU. Yours may be an earlier version, but I believe the circuit for this function is identical. It uses the same sensor as the 83/84 LH2.0 system used, single element one of the two pins grounded.



So, if you disconnect the wire and measure the voltage, you'll see a little less than 5 volts due to the voltage divider fixed at the ADC input.

Hey, it is good to see the Brickboard functioning again!!
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Art Benstein near Baltimore

What's the definition of a will? It's a dead giveaway.