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

[jonesg]

" 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."

Someone used the wrong size torx bit , its no biggie.
any decent tech can easily get those bolts out even if completely stripped out.
I did it on my bike transmission bolts with a shake and break in an air hammer.
The nuclear option is to weld a nut to the torx bolt head and remove with a socket.

[abscate]

Those thermostat bolts respond well to 30 seconds of propane heat and a brand new sharp Irwin extractors tool bit

Order new ones from FCP , of course.

[prwood]

I checked out the fan signal wire the last time I was digging around in there. The wire coming from the fan control module was in decent shape up to the connector, but the wire on the harness side was just hanging on by a thread right at the connector. Right now I have the whole thing wrapped in electrical tape, but I'm guessing the degraded condition of the wire could lead to spotty signal from the ECU to the fan? If I just unplug it, but leave the main fan power cable connected, will the fan default to stay on? It might be time to visit a junkyard and snip the harness-side of the connector off from another P2. It looks like this model of fan was only used in 2001-2003, so I'm assuming I'd need to take it from one of those models? https://www.fcpeuro.com/products/volvo- ... oe#fitment

The ECT sensor wiring seemed to be in good condition, and that sensor was replaced within the past 6 years. It seems to give sensible readings via OBD.

If you were to define a "red alert" level for ECT readings, where would it be?

[jonesg]

I checked out the fan signal wire the last time I was digging around in there. The wire coming from the fan control module was in decent shape up to the connector, but the wire on the harness side was just hanging on by a thread right at the connector. Right now I have the whole thing wrapped in electrical tape, but I'm guessing the degraded condition of the wire could lead to spotty signal from the ECU to the fan? If I just unplug it, but leave the main fan power cable connected, will the fan default to stay on? It might be time to visit a junkyard and snip the harness-side of the connector off from another P2. It looks like this model of fan was only used in 2001-2003, so I'm assuming I'd need to take it from one of those models? https://www.fcpeuro.com/products/volvo- ... oe#fitment

The ECT sensor wiring seemed to be in good condition, and that sensor was replaced within the past 6 years. It seems to give sensible readings via OBD.

If you were to define a "red alert" level for ECT readings, where would it be?

thats where mine failed but I was able to solder in a 2 inch repair section.

either disconnect the battery, cut the plug off and take it with you to hollands.
or de-pin the purple wire from the plug and fix it. I'd do option 2.

the "stay on" failure mode only occurs when the onboard relay fails.
A bad or missing signal doesn't trip the fail safe mode.

I guess the danger temp is whatever number starts blowing various hoses and fittings.
So it depends on the condition of your particular system, mine was venting coolant at the cap and also blew the hose clamp at the radiator. I didn't catch on for a while, by the time I started to monitor the temps it was fixed, now the fan comes on around 225.

but alls well that ends well. you found the underlying culprit.

[abscate]

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.

Jonesg for the win!!

( searching for Volvo horns)

260F is where I would eject the warp core. That’s approaching the bp of 50-50 coolant at 16 psi pressure , so bad things happen at higher temps than that

Jimmy57 , our resident Volvo tech, has endorsed Valvoline Maxlife synthetic ATF for the P2 chassis. That’s a real cost effective ATF you can get on Amazon for a few bucks a liter if you wait like a lioness , to ambush the prey

[prwood]

How do I "de-pin" the wire from the plug and reattach it? There seems like plenty of slack in the wire if I can figure that piece out.

[dikidera]

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.

Jonesg for the win!!

( searching for Volvo horns)

260F is where I would eject the warp core. That’s approaching the bp of 50-50 coolant at 16 psi pressure , so bad things happen at higher temps than that

Jimmy57 , our resident Volvo tech, has endorsed Valvoline Maxlife synthetic ATF for the P2 chassis. That’s a real cost effective ATF you can get on Amazon for a few bucks a liter if you wait like a lioness , to ambush the prey

Depends where, for me Mannol ATF 3309 is the cheapest. A couple of bucks per liter. Now it may not be quality, but when the radiator is broken and my tranny is running on milkshake, it's pretty cost effective.

[prwood]

I just had a bit of a "duh" moment. I recently purchased a pack of fully insulated disconnect terminal pairs to repair the connector for the alternator exciter wire. Like this:

Screenshot 2023-08-22 at 3.22.54 PM.png (119.07 KiB) Viewed 598 times

Is there any reason I couldn't snip off the Volvo connectors and replace them with a set of these?

Edit: it seems that the main benefits of the Volvo connectors are having more rigid protection around the connector, and having a fitting to attach it on the fan shroud.

[02V70]

If the Volvo connectors are broken, I don’t see why not as long as they fit.

[jonesg]

smear of dialectric grease seals the deal.