One other thing to note I read recently in the burned valve database that the one thing most had in common is aftermarket coolant and the speculation that Volvo coolant has been formulated to prevent hot spots in the engine.theWIFES_S70 wrote: ↑11 Sep 2017, 22:53 Hmmm... June, you're making me think I should replace my coolant with Volvo coolant.
I think I'll pick up one of these with my next FCP order.
Volvo Expansion Tank Cap 0.75 Bar (240 242 245 264 265) - Gates 1357775
https://www.fcpeuro.com/products/volvo- ... ck-075-bar
With a gallon of Volvo Coolant, about $30 bucks... Not too bad for the piece of mind. There must be some folks buying the black cap if FCP is carrying it...
I do follow most of the maintenance schedule to the letter except oil change I do at 3000 miles (synthetic) rather than the recommended 7500 and I have them drain and refill the coolant every other year or 25 to 30,000 miles or so which drives my mechanic crazy like I am wasting his time, never stated just a vibe. I don't care it's my baby and I want her to last my lifetime.wizechatmgr wrote: ↑11 Sep 2017, 23:51 June, your expansion tank is almost pornographic in its cleanliness. I have never before seen such a "nude" tank unless I was visiting the parts counter. =) It sounds like you're one of those folks that follows the factory maintenance schedule to the letter. This avoids many issues.
I think most of the folks on here that have problems encounter a car later in its life. I know mine was in pretty good shape when I bought it. If you ever get ready to sell your car, give me a message. I love buying cars previously well-loved and owned by folks like yourself that do the regular scheduled maintenance.
Wize, the point of the pressurized system is to prevent, or hold back, boiling as much as possible, no? This is probably the thinking behind using a cap with a higher PSI... It makes sense that lowering the pressure, ever so slightly will lower the boiling point (which at 254 or 274 doesn't really make that much of a difference...) but will lessen the pressure on stuff like the heater core. This is very interesting information. Especially for those who have had heater cores that perpetually weep and systems that seem over pressurized and spew coolant from the cap. I don't know if I have the time to flush my system and replace with Volvo coolant (and I already have bottles of Pentosin NF), but when I swap out my heater core and original heater hose lines, I will definitely inspect these parts (heater core, and heater hoses) since they are the only parts of the cooling system I haven't inspected and/or replaced.wizechatmgr wrote: ↑12 Sep 2017, 00:14 Just ran the math on the difference between stock and your mechanic's suggested lower pressure cap. Your cap is basically half the pressure of the other one. This sounds drastic until we run the numbers...
Your cap is ~10.8 PSI which means a 50/50 mix of coolant shouldn't boil until ~254F
The stock on mine is 21.75 PSI which means a 50/50 mix of coolant shouldn't boil until ~277F.
The thermostats open long before that so as long as you have adequate coolant flow and the cooling system is in good condition, you should be good to go.
Pretty cool document linked below for pressure vs boiling temp for both coolant and water proportions:
https://durathermfluids.com/pdf/techpap ... -point.pdf
If you look at the poly glycol concentrate listing they have - you could run that with no system pressure and still have roughly double protection. Pretty cool stuff!
Why replaced your heater core when the black cap may stop the weeping? It sure did with my 1998 V70. Volvo never had to replace anything but the cap to stop the weeping. I drove the car hard for several years after the installation of the black cap. Mine had the 2.3 hpt engine and I floored the accelerator all the time winding the tac all the way. I drive my 2004 T6 the same and no heater core weeping as of yet. JunetheWIFES_S70 wrote: ↑12 Sep 2017, 07:50Wize, the point of the pressurized system is to prevent, or hold back, boiling as much as possible, no? This is probably the thinking behind using a cap with a higher PSI... It makes sense that lowering the pressure, ever so slightly will lower the boiling point (which at 254 or 274 doesn't really make that much of a difference...) but will lessen the pressure on stuff like the heater core. This is very interesting information. Especially for those who have had heater cores that perpetually weep and systems that seem over pressurized and spew coolant from the cap. I don't know if I have the time to flush my system and replace with Volvo coolant (and I already have bottles of Pentosin NF), but when I swap out my heater core and original heater hose lines, I will definitely inspect these parts (heater core, and heater hoses) since they are the only parts of the cooling system I haven't inspected and/or replaced.wizechatmgr wrote: ↑12 Sep 2017, 00:14 Just ran the math on the difference between stock and your mechanic's suggested lower pressure cap. Your cap is basically half the pressure of the other one. This sounds drastic until we run the numbers...
Your cap is ~10.8 PSI which means a 50/50 mix of coolant shouldn't boil until ~254F
The stock on mine is 21.75 PSI which means a 50/50 mix of coolant shouldn't boil until ~277F.
The thermostats open long before that so as long as you have adequate coolant flow and the cooling system is in good condition, you should be good to go.
Pretty cool document linked below for pressure vs boiling temp for both coolant and water proportions:
https://durathermfluids.com/pdf/techpap ... -point.pdf
If you look at the poly glycol concentrate listing they have - you could run that with no system pressure and still have roughly double protection. Pretty cool stuff!
I don't know how old it is. Last time I checked it, there seemed to be coolant-colored oxidation around a few screws. And, probably the biggest reason of all is that rspi doesn't like when we play coolant roulette!
