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98 S70 N/A: Question about coolant and expansion tanks

Help, Advice and DIY Tutorials on Volvo's P80 platform cars -- Volvo's 1990s "bread and butter" cars -- powered by the ubiquitous and durable Volvo inline 5-cylinder engine.

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theWIFES_S70
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Re: 98 S70 N/A: Question about coolant and expansion tanks

Post by theWIFES_S70 »

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.
Image

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...
Retired:
1998 Volvo S70, N/A, 5-speed, 187K
2007 Volvo S40, 2.4i, 5-speed, 121K
2015 Volvo S60, T5, 85K

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wizechatmgr
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Post by wizechatmgr »

Couldn't hurt to give it a try...
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In order to learn how to fix something, you must first learn how to break it.
1999 V70 XC AWD 2.4 T -- ~231k miles
1998 V70 2.4 NA -- ~184k miles

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Post by wizechatmgr »

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.
Wisdom requires knowledge as a prerequisite, but knowledge can be developed due to a lack of wisdom.
In order to learn how to fix something, you must first learn how to break it.
1999 V70 XC AWD 2.4 T -- ~231k miles
1998 V70 2.4 NA -- ~184k miles

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June
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Post by June »

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.
Image

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...
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.

I understand various coolants react to different materials ie copper, aluminum, and certain plastic as well as the silicates protect the water pump in our cars whereas other coolant has no silicates like Dex cool plus different heat transferring abilities.

Volvo coolant is only $20 at my dealership for one gallon concentrate. June
My Volvo cars owned
1989 740 GLT ordered
1994 850 4door standard shift ordered
1996 960 ordered
1998 S90 ordered totalled after 3 weeks
1998 V70 GT dealer stock car
2002 S80 T6 ordered totalled
2004 S80 T6 dealer stock car and current car owned

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June
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Post by June »

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.
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.

The tank has never looked dirty, nor has the coolant ever changed color. June
My Volvo cars owned
1989 740 GLT ordered
1994 850 4door standard shift ordered
1996 960 ordered
1998 S90 ordered totalled after 3 weeks
1998 V70 GT dealer stock car
2002 S80 T6 ordered totalled
2004 S80 T6 dealer stock car and current car owned

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wizechatmgr
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Post by wizechatmgr »

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!
Wisdom requires knowledge as a prerequisite, but knowledge can be developed due to a lack of wisdom.
In order to learn how to fix something, you must first learn how to break it.
1999 V70 XC AWD 2.4 T -- ~231k miles
1998 V70 2.4 NA -- ~184k miles

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theWIFES_S70
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Post by theWIFES_S70 »

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!
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.
Retired:
1998 Volvo S70, N/A, 5-speed, 187K
2007 Volvo S40, 2.4i, 5-speed, 121K
2015 Volvo S60, T5, 85K

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Post by June »

theWIFES_S70 wrote: 12 Sep 2017, 07:50
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!
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.
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. June
My Volvo cars owned
1989 740 GLT ordered
1994 850 4door standard shift ordered
1996 960 ordered
1998 S90 ordered totalled after 3 weeks
1998 V70 GT dealer stock car
2002 S80 T6 ordered totalled
2004 S80 T6 dealer stock car and current car owned

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theWIFES_S70
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Post by theWIFES_S70 »

June wrote: 12 Sep 2017, 08:13 Why replaced your heater core when the black cap may stop the weeping?
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! :lol:

You have, however, sold me on Volvo coolant, June. The black cap, too! No reason to go with anything else really.
Retired:
1998 Volvo S70, N/A, 5-speed, 187K
2007 Volvo S40, 2.4i, 5-speed, 121K
2015 Volvo S60, T5, 85K

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Post by rspi »

I apologize for not reading all of the post but that really looks like oil. I would thing that either the engine is somehow leaking oil into the coolant system, or it's transmission fluid getting in through the rad. The thing about that is, if it's manual, there is NO connection to the transmission. If it's NA there is no oil through the radiator.

Send an oil sample to Blackstone labs. They will at least be able to tell you if there is coolant in the oil.
'95 855 T-5R M, Panther - 22/28 mpg, 546,000 miles
'95 955 T-5R Yellow Wagon, Lemonade, 180,000 miles
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