[2001 V70 2.4T] Coolant Wars: The Coolant Strikes Back

[jonesg]

go to napa and get block tester fluid kit or order from amazon, it detects exh gas in the coolant.

https://www.amazon.com/Block-Tester-BT- ... 130&sr=1-2

I don't think its the head gasket, you're getting an over temp warning. But the fluid will prove it..

Does the elec cooling fan function when the AC is turned on ?
Was it running when the over temp warning came on?

What is the coolant temp running at ?
get a $10 ELM327 for android phones to get an eye on coolant temp.
they also have similar for iphone.

https://www.amazon.com/Mestart-Enhanced ... prsubs_1_t

[prwood]

I have done the block test a few times previously. Ran the engine at idle until ECT got up over 200 F (probably 20 minutes or so) and did not see any change in fluid color when drawing air into the test tube. The only thing I did notice was that when I revved the engine at idle up to 4000 RPM, a *whole* bunch of bubbles were pushed through the test fluid. The color didn't change, but there were definitely lots of bubbles caused by something. Not sure if that's normal. So unless I'm operating the tester incorrectly, it doesn't seem to indicate a head gasket leak.

The engine cooling fan does operate when the AC is on, though I'm not sure it operates constantly when the AC is on. Is it supposed to run 100% of the time when the AC is on?

The engine cooling fan does seem to kick on around 226 F and kick off around 220 F pretty reliably.

I was not driving the car on Sunday when the latest boilover occurred, so I don't know the status of the fan or the exact engine temps at that time. My wife just reported seeing steam from under the passenger side of the hood (near the expansion tank) and the high temp warning on the dashboard, pulled over, and shut off the car. I arrived and didn't find any leaks, just the apparent boil over from the expansion tank. I replenished the coolant and drove home. Later that evening, however, I was driving the car again and monitoring the coolant temperature, and the temperature got up over 225 F (it got as high as 231 F), and didn't start going down which it normally would when the fan kicked in. At the time I wasn't able to exit the car and check the fan since we were on a time sensitive errand, but I suppose one might assume the fan wasn't kicking in if the temperature wasn't going down. What I did was turn on the heat to full blast until the coolant temperature started dipping down closer to 221F.

I do have an OBD monitor which I connect to from my phone and use to monitor coolant temp. Typical behavior is that after about 20 minutes of warming up, the coolant temp seems to settle into a cycle of 200 F - 225 F, with the engine cooling fan kicking on, cooling down the engine, kicking off, and the engine warming back up.

Here are some charts I gathered on a longer drive a few weeks ago. You can see it settle into the above mentioned coolant temp cycle after 20 minutes. The other factor is that driving at highway speeds usually cools the engine down without the fan needing to kick in, but unfortunately this car is most often used for lots of stop-and-go city driving with long periods of idling, so the cooling fan is probably being called on more often.

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[02V70]

When I had a head gasket leak, there were bubbles in the coolant the whole time. It's interesting you have it only at 4k rpm. Maybe a small head gasket leak? Does your exhaust steam at 4k rpm. The test should show if they were exhaust gasses, but since it didnt, maybe the cooling system wasn't burped properly since the last time you lost coolant and there were air pockets.

[prwood]

When I had a head gasket leak, there were bubbles in the coolant the whole time. It's interesting you have it only at 4k rpm. Maybe a small head gasket leak? Does your exhaust steam at 4k rpm. The test should show if they were exhaust gasses, but since it didnt, maybe the cooling system wasn't burped properly since the last time you lost coolant and there were air pockets.

It doesn't steam at 4k rpm, although admittedly I don't bring it up to 4000 rpm that much in practice. Usually only if I'm doing it on purpose as a test, if I'm quickly accelerating onto a highway, or starting up a very steep incline.

Can anyone confirm all of the conditions under which the engine cooling fan should turn on, and when it should turn off?

If anyone has any other tests I can try, either driving tests or diagnostics in the driveway, I'm all for it.

Also if there is any additional data I could provide from my OBD reader, I can gather it. I have the following available via OBD:
- Distance traveled with MIL on
- Engine coolant temperature
- Engine RPM
- Fuel system status
- Intake air temperature
- MAF air flow rate
- OBD Module Voltage
- O2 sensor 1 wide range current (mA)
- O2 sensor 1 wide range equivalence ratio
- O2 sensor 2 bank 1 short term fuel trim
- O2 sensor 2 bank 1 voltage
- Short term fuel % trim - bank 1
- Throttle position
- Timing advance
- Vehicle speed

[jonesg]

so its air pressure, not exh gas, thats good.
thermostat installed correctly ?
I believe there's a weep hole on the thermostat flange which must be positioned on the high side to prevent air pocket in the housing.

check under front floor mats for coolant.

with engine stone cold in the morning remove the coolant cap, is there any residual pressure present ?
Air is compressible, fluid isn't, any hiss indicates air in the plumbing.

I would also consider the water pump, if fluid is starting to exit the weep hole air may be getting into the system.

I recall my elec fan comes on at 220 and goes off at 190, that was sitting idling on hot day without AC.

When the elec fan was not functioning the temp gauge on the dash, whilst sitting at idle, started to climb into the upper half, but driving 200 yards quickly brought the needle down down again, that was in warm not blistering hot weather.

you can test the cooling fan in vida , it has several speeds given in percentages.
The different speeds might be for when the AC compressor cycle on and off.

[abscate]

Your temperature readings look ok and aren’t indicative of anything major. If you do have a slight leak which doesn’t let the system come up to pressure, you will see some steam. Cycling between 225 and 190 might be a bit higher than normal , I’ll try to check my 2005

I believe AC enabling will always induce low fan speed, also to be confirmed

Really appreciate how you core dump your info and data on these issues, Peter. Your threads always swell the Collective Brain of knowledge

[dikidera]

You don't need to have bubbles in the expansion tank to have a bad head gasket. I didn't and my radiator blew a hole the size of a golf ball when I held the RPM at 5000-5500 for 10 seconds. But I did fail the block test when I had done it(so I knew what was going to happen sooner or later) and it's usually very indicative.

I live in a hit climate and my S60 does go to 105c at 40c ambient temp, but WILL drop as soon the fan kicks in, which on my old S40 P1 and S60 P2 always happens at 105c.

The S60 P2 models will have a vertical needle unless the temps reach over 120c, this is confirmed by a few independent people.

As for the air, I find our Volvos very very difficult to bleed out the air. I had the need to flush my coolant system a few times these past few weeks, just so I can rule out or confirm an issue and air being trapped is my biggest concern.

[prwood]

Here are some graphs of OBD data from a drive I took on Thursday.

The first one is a drive from Salem down to Woods Hole with a stop shortly into the drive to get some dinner at a drive-thru. Drive time total was about 1 hour 50 minutes for 104 miles (167 km). ECT held steady around 190F (88C) while driving on the highway, thanks I assume to the wind-cooled engine - no need for the engine fan to kick in. However, you can see an alarming jump in ECT at the point where I got off the highway for dinner after about 10 minutes of driving at city speeds followed by 20 minutes of driving at highway speeds. I watched as the ECT quickly crept up from 190F (88C) to over 240F (115C). I got a bit nervous waiting for the fan to kick in to cool it down, so I forced some cooling by turning the heaters on full blast and waited for the heat to come down before I got back on the highway. I suspect that the engine fan didn't come on when it was supposed to, since typically it comes on between 226-230F (108-110C). Unfortunately I wasn't able to get out of the car and verify whether the fan was on since I was in a drive-thru line at the time.

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The second graph is from the drive home from Woods Hole to Salem. Drive time total was again 1 hour 50 minutes for 93 miles (149km) (different route!). This time there was no alarming jump in ECT - it held steady around 190F (88C) on the highway, and did start to creep up again after getting off the highway, but didn't have the chance to get high enough for the fan to attempt to kick in before I got home.

IMG_2040.PNG (362.23 KiB) Viewed 445 times

It's been 1 week since we had the coolant boilover incident. Since then I haven't lost any coolant, although there have been a couple of points where the ECT gets alarmingly high and the fan doesn't seem to be cooling it down when it should.

It seems like either something is happening in the engine that makes it heat up so much that the fan can't keep with it, or the engine is operating normally and the fan is failing to kick in when it should.

Any thoughts on next steps for diagnosis?

P.S. Despite all the coolant issues, I still have to say I absolutely love crusing down the highway in this car. It's so comfortable and drives so smoothly, even after all these miles and other issues. City driving is less pleasant due to the bumpy city streets around here... the suspension is old and rattly, and all the worn plastic bits inside the car rattle and shake. But on nice smooth highways it's a pleasure.

P.P.S. @jonesg to answer your earlier questions:
- No coolant on the floor mats - heater core appears to be functioning properly as when I switch the climate control to heat, plenty of heat is pumped into the cabin (and the ECT goes down).
- I don't hear any hiss when opening the coolant cap with a stone cold engine.
- I replaced the water pump when I did the timing belt at 200k miles (it's about 270k now).
- I'm not sure if the thermostat is installed correctly. I was going to replace it a little while back when I replaced the expansion tank, but the thermostat housing bolts were stripped so I couldn't remove it.

[abscate]

Those aren’t crazy numbers, 240 F isn’t high for a heat soaked engine coming down to idle. With AC on the fan should be on so you might have a seized fan or relay wiring problem there.

There is a really good Volvo mechanic named Rachel down there….plus Corvair and Beetles!

[jonesg]

I'd say it looks like , as abscate says, a cooling fan problem. Its not kicking in.
it works when the ac is on but not when temp commanded. if that is so then its the ...I don't know which sensor is responsible, the one next to the thermostat maybe.?

check power and ground at the fan plug, you should also get a low computer v reading on the signal wire (purple ?), maybe 2 to 5v.
12v power is always on, switched by grounding done in the relay which is usually built into the fan housing.
but yours is 2001 so it might not be integrated like my 04.

If yours has the bosch controller on the fan its designed to fail on at 100% speed, its better to have it run constantly to a flat battery than blow the cooling system and head gasket.

as you aren't having that problem ,again, its indicating the temp sensor or signal wire. Temp sensor sends signal to the ECM , it comes out of the ECM in the small purple wire. I found my signal wire dead at the fan, I snipped it near the ECM and put a signal on it , then just used a cheap fox and hound circuit tracer to find the break. Replaced the bad section and repaired the wire I cut with heat shrink and liquid tape, alls well now.

Just below the pass side headlight, find the large main loom, find the purple wire and try a piercing probe to see if theres any signal coming out the ECM. From there it goes to the power distribution box above the ABS pump, you can backprobe the plug at the box.
just keep chasing it.

Vida was telling me "signal missing" , I forget what the actual fault code was for the fan. But it did indicate a fault.


you should also be able to check the temp sensor circuit with a meter.