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

[prwood]

Some of you may be have noticed that issues with the cooling system are the #1 most common problem I've posted about with my V70 here in this forum:

2017: Diagnosing low coolant: viewtopic.php?t=81752
2018: Radiator replacement: viewtopic.php?t=84915
2018: Need recommendations on upper radiator hose: viewtopic.php?t=84563
2019: Low coolant, high coolant temp, no cooling fan: viewtopic.php?t=89827
2020-2021: Occasional coolant reservoir boilover: viewtopic.php?t=96125

When I look at the pattern of the above threads, I can see that I've essentially been replacing bits of the cooling system over the past few years: top radiator hose, radiator, coolant hose at the exhaust end of the PCV assembly, coolant hose from the thermostat to the PCV elbow. I had also replaced the coolant pump a while back when I did the timing belt. Now over the past month two additional leaks have developed: the coolant reservoir and the upper radiator hose (again). The coolant reservoir split on a top seam in the plastic right next to the cap. I replaced the coolant reservoir, and within days, the top coolant hose split. For the moment I have it duct taped, which holds until the temperature gets up over 210. It seems that I am essentially chasing a coolant pressure problem from one weak component to the next. At this point, the only coolant system pieces I haven't replaced are the hose going from the coolant reservoir to the engine block, and the hose going from the radiator to the engine block, and of course the engine block itself.

A blown head gasket has always been one of my suspicions. In the past I've performed a block leak test using the OEMTools test kit and fluid, and it did not indicate the presence of any exhaust gases in the coolant. After the most recent issue with the coolant reservoir and upper radiator hose, I decided to run that test again, and it again came back clean. However, I didn't have time to get the engine heated up past 200F since it happened just before we were leaving on vacation (thankfully not one where I had to drive my car). We're back now, so I tried again, and this time I let the temperature get quite a bit higher. I had ensured that the coolant level in the reservoir was 3 inches below the tip of the test tube. For most of the test, when drawing air through the test tube, the fluid remained blue. Unfortunately, when the coolant temp reached 200F, the coolant started expanding rapidly and pushed its way up into the test tube and mixed with the test fluid. I'm not quite sure how to interpret the results: There *was* a color change in the test fluid - normally the test fluid is blue and is supposed to turn yellow if exhaust gas is present. My coolant is green. In normal color mixing, if you add green to blue you'd get teal, but the fluid turned a more yellow-green color.

I'm not sure if I should interpret these symptoms as a blown head gasket, or as something else.

Any advice or further information or tests I could run?

[jonesg]

In a nutshell, your head gasket is fine.. it passed the block fluid test.
Coolant bottle cracks are predictable. I changed mine when I saw chalky residue on the outside.
I would check the elec cooling fan at the radiator, vida can power it up.
Otherwise its probably mostly all from normal aging.

[prwood]

Hmm, ok. I had to wipe my VIDA VM off of my laptop a while back due to storage space and OS issues. I just tried setting it up again today using a VM from volvodiag.com, but this new VM is having some difficulty recognizing my DiCE via USB. That is probably an issue for a separate thread. I do know my cooling fan is coming on sometimes, although I'm not totally sure if it's coming on as often as it's supposed to.

I have ordered a replacement upper radiator hose to replace the one that just split a few weeks ago. Genuine Volvo this time so hopefully it will hold up.We'll see what happens once that is replaced.

[firstv70volvo]

Hmm, ok. I had to wipe my VIDA VM off of my laptop a while back due to storage space and OS issues. I just tried setting it up again today using a VM from volvodiag.com, but this new VM is having some difficulty recognizing my DiCE via USB. That is probably an issue for a separate thread. I do know my cooling fan is coming on sometimes, although I'm not totally sure if it's coming on as often as it's supposed to.

I have ordered a replacement upper radiator hose to replace the one that just split a few weeks ago. Genuine Volvo this time so hopefully it will hold up.We'll see what happens once that is replaced.

Something to watch for is getting the radiator clamp in the right place. The Volvo radiator top outlet neck isn't very long and there's a narrow gap near the metal tabs that hold the end tank to the core. I had a problem getting the clamp down far enough and behind the lip in the upper outlet that keeps the clamp and hose from coming off. My hose would pop off and the only solution that worked for me was a 45.5mm Oetiker stepless clamp. These clamps are narrower than the screw type clamp so I could push it in closer to the radiator and get it behind the lip of the outlet neck. The Oetiker clamps are also constant tension clamps that hold better over a wide temperature range. These clamps aren't as convenient and reusable as a screw type clamp but I couldn't keep the upper radiator hose reliably on any other way. I did have an aftermarket radiator, which may have added to the problem though. I do think constant tension type clamps work better for radiator hoses like the round or flat spring type or the Oetiker clamps.

This is a picture from one of the previous threads you listed, the narrow space between the outlet neck and those metal bend-over tabs is where I had a problem pushing the clamp in far enough.

IMG_0296.jpg (130.66 KiB) Viewed 941 times

[jonesg]

A $10 torque app will allow you to watch the coolant temp on the fly.

https://www.amazon.com/Launchh-Professi ... 192&sr=8-5

[prwood]

My father-in-law suggested that there could be a problem with the thermostat - perhaps it was not opening and letting coolant into the radiator. Yesterday, I did some testing using my OBD monitoring app to monitor the ECT temperature reported by OBD, and an infrared thermometer to measure surface temperature of the radiator. I found that the radiator stayed at ambient temperature until the ECT reported approximately 175 degrees F, at which point the radiator temperature started to climb. This is quite a bit lower than the 195 degrees F the thermostat is supposed to open at, which makes me question the accuracy of various parts of the system:

- is the infrared thermometer reading and reporting the temperature correctly?
- is the thermostat opening at the correct temperature?
- is the ECT sensor reporting the correct temperature?

I've used the same infrared thermometer to take readings in other settings (e.g. boiling water, cooking food, ambient temperatures inside the house), and it's usually correct within a couple of degrees. I have replaced both the ECT sensor and the thermostat in the past, but it's been quite a while on both of them.

Any thoughts?

[scot850]

When was the thermostat last replaced? On an 01 I believe it is easier than the later versions. When I worked with a Volvo shop foreman who I totally trusted, he recommended swapping the thermostat every 3 years which is about the lifespan of the coolant.

If you have no idea when it was last changed, it is probably a good idea to eliminate it as a cause.

As to the infrared temperature measurements, they are reading the external temperature and not the internal temperature. The only time you may get the temperature closer to normal expected temperatures is after a goo long run when the parts get more time for heat soak.

Neil

[jonesg]

A few of the problems can be traced to that leaking coolant bottle, pressure loss causes higher temps.

I had a bad signal wire at the fan plug end, tracked it down with a signal tracer (fox and hound) , 5 minute solder job and the coolant fan works again, seems to turn on around 220F. I was getting overheat whilst sitting at idle, driving would force air through the rad and cool it down, fixing the fan solved it.
I'm not sure you a problem other than aged hoses which were subjected to higher than normal pressure for a while.

[abscate]

I’ll take some shots of my LPT and see what temp the thermostat opens

[jonesg]

pressure test can show problems with engine cold.