Greetings,

Problem - in the last couple of days, oil temp is reading very high, between 220-260F. Has typically read around 180-210 max, so it's a bit concerning.

Only recent work is replacement of OD solenoid with dremeled out. Problem appeared before this work.

Coolant temp reading is normal (hair below 9am) and cooling appears to be working - top hose is too hot to hold on to, lower hose is warm, but can be held while engine is running fully hot (i.e. while oil temp shows 260F). Coolant gauge has been de-liared, and shows actual coolant temp, unmolested by regulator.

Oil pressure appears normal, 2 bar at idle 900 RPM, 4+ bar at 4000 RPM.

Oil is 10W-30 Mobil 1 Full Synth; when problem appeared, oil was at -1/2 Q.; filled now.

All gauges appear to be working correctly, so I'm wondering where to start...

I've read in another post that the senders can go bad, so I'm wondering if they send bad info, or simply stop working...? Anyway, some suggestions from the collective brilliance of the board...

Thanks,

Lanval

Hi Lanval,
Quick test you can do to verify if oil is at 260 is to boil up some water not much, just a cup full and take it quickly to the car so it is at boiling point whn you get there, yank the dipstick and put the oil end into the oil. If the oil is at 260 I suspect you will reboil the water around the dipstick end for a few moments.

Another simple test is to get a cooking thermometer and put a small dab of high temp grease or heat transfer compound on it and touch it to the oil sump and hold it there till it stops rising a cruder still test is to spit on your finger and put that on the oil pan (you need to lay on the ground and reach under. If the oil inside is at 260 it will boil off.

The fact that your top and bottom hoses to the rad show a big difference and you have not reported water loss from boiling says to me that you radiator thermostat is working otherwise you would be boiling off water and your gauge would show way high (especially since you have as you say de-liared the gauge).

For checking the water temp gauge ground the lead from the gauge and it should read full scale with the ignition on. then put a 68 Ohm resistor in series with the lead to ground and it should read about 3/4 on the scale, that verifies the water gauge.

The oil temp gauge I have on my 245 uses a brass sensor screwed in place of the sump drain plug and a single wire runs back from there to the gauge in the dash. I have seen on the net the resistance readings for the sensor at various temperatures but cannot remember what they were.

I strongly suspect that there is either a part short on the cable from the gauge to the sensor or the sensor or gauge is faulty.
Cheers,
Charlie

Having re-read your original post, I would immediately suspect your oil temperature gauge.

You report NO other symptoms of excessive temperature, and you've made an honest instrument out of your coolant temp gauge. Your oil temp would not go up 40-60 degrees without having an associated increase in coolant temp.

My suggestion is to pull the temp sensor and gauge check it independently.
--
Thank goodness we don't get all the government we pay for. -- Will Rogers

UPDATE

Checkpoint Charley and Smitty -

Thanks. I went to Sears and bought an IR thermometer, which showed the following temps, while the engine was running, and the oil temperature gauge read 260+:

Coolant Hose at the exit point from the block (top hose) = 189F
Coolant Hose at the entrance point to the block (bottom hose) = 164F
Oil Pan under car, next to drain bolt/oil temp sensor = 185F
Oil Dipstick on measuring point = 137

That last one is kind of suspect, I think - not sure how tight the reading can be, but that's a little spot to be measuring. Anyway, the rest of the numbers fit with the coolant gauge, so it's pretty clearly, the sender, wiring or gauge itself.

I'll take this opportunity to change fluids, and then take a run at the gauge. Thanks for all the help.

Thanks for the feedback!

FWIW, the IR thermometers will vary depending on the emissivity of the target. A highly polished metallic surface will give a different reading than a flat black plastic surface, even if both are at the same temperature.

Also, of all 4 measuring points, the dipstick has the least mass and so will give up its heat the quickest... that might account for the low reading.

--
Thank goodness we don't get all the government we pay for. -- Will Rogers

hello lanval,

the oil & water temps should alternate a little between each because of heat transfer. good start suggestions from the others.

another idea, does your a/c fan still work?

try taking the wires and hooking it up to a rocker switch inside the car or wire it up where it will start when the engine starts--you could put a delay relay on where the fan starts about 8-10 sec after the car starts.

for a 92, a 2 row rad should be enough, and the oil temp shouldn't go over 100C (212 F), at least mine doesn't in texas' heat & humidity (92 wagon ~155k miles).

i notice down here near houston, it's the humidity that really heats up the oil. drier days seems to keep the oil & water temp down (quicker heat transfer).

if you wire your a/c fan up, be sure to use a relay near the fan. write back if you are not sure how to do the wiring. you can pick up those metal bosch relays for free just about any j/y.

regards,
byron golden
86 245
92 245

BCG,

Nah, the AC auxiliary fan is gone - I took it out about 2 months ago. The AC stopped working earlier, but I was going to re-wire the auxiliary fan to work off a manual switch. But as it turned out, the AC was semi-working (no cooling) because I turned it on, and could hear the pressure switch trying to turn the aux. fan on. The aux. fan was dead. Also, the car ran fine w/o for about 8 weeks, so I'm thinking maybe the issue is with the sender, the cooling sys, or the oil transfer sys.

I checked the coolant, and it doesn't appear to have oil in it, but it should be changed. The oil doesn't appear to have water/cooling fluid in it, but I didn't run the engine to see if it would froth - I will do that in the next few minutes.

I will do a drain and fill on the radiator, new thermo and drain and fill on the oil, and see what I get. I do have some Mann oil filters, and the filter currently on the car is not a Mann, so that bothers me.

I'll also check the oil temp sender/wire, and if possible, find a way to check the oil temp independent of the gauge.

Thanks,

Lanval

hello lanval,
what you mentioned is a head gasket leak--oil in the rad water, coolant in the oil. i don't think that would be an oil temp problem, perhaps.

also, these engines hold up better than we think--so a mann filter over the long term will help the engine, a poor filter won't hurt the car in the short run.

could be a bad temp sender, if it's old. you can buy a new one at different places, write back for p/n info and what works.

the sender wire that came with the gauge has a hard plastic cover so the wire should be protected unless it's on a hot part of the engine and partially melted it.

my 86 245 oil and water temp was getting pretty hot, but before i correctly traced the problem (air leaks raising my combustion temps and created high nox and melted my cat), i put in an aux fan, tropical clutch, oil cooler setup (using a volvo oil cooler and tstat sandwich plate), and a 3 row rad.

my oil never gets above 100C (212) in my 86 245.

again, my 92 245 has a normal setup (2 row rad, normal fan clutch and an a/c fan) and never approaches 100C.

could you have air leaks, but you said your water temp never goes up.

have you thought about removing the temp compensation board and jumping pins 1 & 3 to give you a real-time water reading? that way you can watch your actual water needle move at the same time with the oil temp gauge. if your water needle goes up to about, maybe 10 o'clock position or higher where normal 9 oclock, along with the oil needle, then you know your water and oil are getting hot.

it then may indicate air leaks, causing a hot engine (leaner) and possibly make you fail emissions testing. if you have a california car with an egr, it might hurt it, but i'm not sure about this point. with a 92, and air leaks, it will probably give you codes.

a 92 should be pretty cool running.

regards,
byron

One other thing to consider is the gauge wiring. Does the indicated oil temp change when the turn signal is on or the lights are switched on or off?

I'll second this. Check the wiring to the sensor and the contact at the sensor itself, it lives way down at the bottom of the car, so it's easy to get yucky.

-Ryan
--

Athens, Ohio
1990 245 DL 133k M47, Cibié E-codes, Now with working wipers!
1991 745 GL 290k (Girlfriend-mobile)
Buckeye Volvo Club

What is the ambient temperature when this happens? Are you driving at high speeds, or in stop-and-go city traffic, with the A/C on? The stock radiator is undersized for this engine, which becomes very evident when it is under load. Oil is also used to cool the engine, and if your cooling system is not doing the job properly you will see an increase in oil temps. How old is the t-stat, hoses, fan clutch etc?

What weight and type of oil do you run in this car? How long since the last oil change? Oil level on the dipstick when the engine is stone cold?

None of the factors you mention result in significant change - stop N go, freeway, ambient from 60-80F, AC doesn't function. All result in the same high temps. Freeway keeps it a little under 260 oil temp.

Oil is 10W-30 Mobil One full synthetic, changed more than 6 months ago, though less than 3000 mi. Haven't checked oil cold, but at (more than) fully hot, appeared normal.

Since car is a 92, and radiator appeared to be working fine until recently, I'll assume that car SHOULD cool, but may not be now, due to a blockage or some other random problem. Coolant itself is oldish, but remains more than min in overflow. Haven't checked for oil in coolant, that's on today's list.

Best,

Lanval

Can you verify the oil temp with an external gauge?

260F is pretty darn hot. But the fact that it drops slightly under 260F on the freeway, and doesn't change otherwise, points to a problem with the cooling system. The system is not circulating enough coolant at low engine speeds, OR you are not moving enough air through the radiator due to blockage/deposits. How old is the waterpump?

It wouldn't hurt to replace the thermostat at this point, and completely flush the system (remove lower hose and freeze plugs in the block).

Just to be clear, it slowly moves up to 260, and from there, will move up and down slightly - freeway = below 260, maybe down to 230; sitting in traffic rises back to 260. Doesn't seem to go above that, regardless.

I don't have a way to verify the oil temp, and if I didn't have the gauge, there would be no other indicator. Pressure+idiot light are normal, coolant shows normal (and also appears to be working correctly). I may buy a laser temp thingy today, and fluids will be changed.

Are the freeze plugs replaceable? Seems like I read they aren't, but not certain. I'll check the Bentley for procedure.

Thanks,

Lanval

I would check the thermostat first - replace it with a new or known good one.

I disagree with the statement about the radiator being "undersized." I live in Gilbert AZ and creep in traffic on days when the ambient temp is 115F and the surface temp on the pavement is 150F. Stuck in traffic with the AC on, once my cooling system was up to snuff (new OEM rad + waterpump)I've never had a cooling problem.
--
Thank goodness we don't get all the government we pay for. -- Will Rogers

Smitty, you mean the coolant thermostat, referenced in section 260 1-6 of the Bentley, correct?

Since the coolant temp shows normal, but the oil temp shows high, if the coolant thermostat IS bad (that is, giving false readings) then I still have a problem, I think - since the oil temp is WAY high. Maybe there is something wrong in the radiator, though it seems to be working...

Thanks,

Lanval

Hi Smitty,

What year is your Volvo? I haven't owned a 240 newer than 1986, so I can't say if the radiator was improved in later years. Mine had a Bridgestone ("Volvo") radiator with an aluminum core and plastic "side tanks." Dual row. I bought this car with 40,000 miles, and even when it was "new" ambient temps over 90-95F with the A/C running put the temp gauge to about 1/8" under the red zone. I would also see an increase in coolant temp when climbing grades at highway speed.

Replaced the stocker with a 3-row Nissens 5 years ago and I have never seen the temp gauge creep above 9 o'clock since. It usually rests somewhere around 8 o'clock when the ambient temp is below 85F and A/C off.

Mine's a '92... rad has the aluminum core with plastic end tanks. I had cooling problems shortly after moving here, and after much deliberation about 3-row brass radiators I took a chance with an OEM-type from fcpgroton. I believe the manufacturer is Nissens as well. But I took the opportunity to flush the whole system and put in new hoses and t'stat, and haven't had any cooling problems since (3+ years now).

FWIW, when I pulled the old rad, I hosed about 10 pounds of gunk out from the cooling fins. I didn't have the time or inclination to see if that would have made a difference, but I'm sure it would have helped.

On a side note, I guess I was seduced by the claims for Dexcool and used that for coolant. 15 months later I noticed some coolant weeping from the t'stat housing, and when I opened it up I found the t'stat seal had nearly disintegrated. OK - time to flush thoroughly and say goodbye to Dexcool. Back to Prestone.
--
Thank goodness we don't get all the government we pay for. -- Will Rogers