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Possibility of replacing thermostat without coolant flush? Advise Please 850

Hi,

I've just realized that my thermostat was gone and will try to replace it with the new one after I get the part according to what I'm advised by you fellow board members. I've looked at the instructions in volvospeed. There it is said that I need to flush the coolant. Is this the only way to go? Is there any other way to go around without the coolant flush? BTW, What type and amount of coolant to use if I have to flush the system?

Also I remember having two type of thermostats (185 F/195 F) from previous posts. Which one do you think I should get? Any extras to buy before I start?
Where to buy? And please lots of advices of your experience replacing it.
Thanks a lot in advance,
Ihsan 95 850 N/A 103k.








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    Possibility of replacing thermostat without coolant flush? Advise Please 850

    Some folks have posted that a little fluid will leak out if you don't drain the coolant down some. I flushed mine when I did the t-stat because it had not been done in a while. Haynes has capacities but I bought one gallon of Volvo coolant and it was enough (mixed 50/50). I did not drain the fluid out of the block because I could not reach/open the drain. I have seen opinions both ways about which t-stat to use. Conventional wisdom would say to get the cooler one but some folks have posted that the engine runs better with the hotter one. I got mine at the dealer along with the coolant- not worth mailorder for such a small ticket item. Two words of advice- Don't strip the petcock at the bottom of the radiator if you drain the coolant- be easy on it as it is plastic. Also, if you didn't already, invest in a set of torx drivers. The torx on the t-stat housing has been stripped by many as it is pretty tight and I think you have to access it at an angle. Good luck.








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      Possibility of replacing thermostat without coolant flush? Advise Please 850

      Thanks for the advise Wayne,

      I already have a torx bit set, but I don't think I have 40mm one as the volvospeed says. I need some other parts also, I think i'll get them from an online retailer. My dealer is a bloodthirtsty wallet lover :).
      Thanks again.
      ihsan








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        Possibility of replacing thermostat without coolant flush? Advise Please 850

        Genie;

        Get the set of torx sockets at AutoZone....they work and a lot cheaper than those that Sears sells for an arm and a leg. Good luck!








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    Possibility of replacing thermostat without coolant flush? Advise Please 850

    You don't absolutely have to flush the coolant when replacing the thermostat. You will lose a small amount, however - maybe a cup - just add some to the expansion tank when you're done. I think the recommendation to flush the whole thing is based on the fact that it's probably a good time, based on general age and miles, to do that job also. But you don't *have* to.

    Gerald C








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      Possibility of replacing thermostat without coolant flush? Advise Please 850

      Thanks Gerald,

      I think for the time being I'll only change the thermostat and leave the flushing part for a later time as I'm fighting over my way with a graduate thesis.
      Ihsan








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        Possibility of replacing thermostat without coolant flush? Advise Please 850

        Hi Genie,

        Just to recap on your dilema i unfortunately put my t-stat in the wrong way :-(. So i jacked up the car up on the side on the expansion tank and undid the bolts again. I took the coolant top attached to the pipe quickly and placed it in the right direction!!!

        So be sure you check which way the ARROW is pointing on the t-stat when you remove and replace with the new one.

        Mark.
        uk voc 94 850glt 2l 20v 192k...
        --
        Mark in the UK.








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          Possibility of replacing thermostat without coolant flush? Advise Please 850

          Dude,

          Just splurge the 30 bucks and flush the fluid while your at it. Gives you piece of mind and will save your engine in the long run. Put that 6 pack back on the shelf, open your books and study with piece of mind.

          Just my 002

          Yall come back and see us now ya hear...








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            Possibility of replacing thermostat without coolant flush? Advise Please 850

            Certainly an intertesting theory. Is this an opinion or do you have data to back up the part about it saving the engine in the long run?








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              Possibility of replacing thermostat without coolant flush? Advise Please 850

              Dude,

              Frequent engine repair and failure can be traced to improper or non existent engine cooling water treatment. Rust, scale, mineral deposit and deterioration of seals are the result of improper or no treatment in the cooling system.

              From the time the coolant is introduced into any type of engine it starts a gradual degradation process into corrosive acids. This degradation is a function of time, temperature and the types of metals used in the engine and components construction. Once the coolant turns acidic all engine metals start to dissolve. The results are leaking water pumps, heater cores and radiators.

              With the increasing number of aluminum engines and components the corrosive process is accelerated since the coolant degrades much faster in contact with aluminum than in typical cast iron engines. During the preventive maintenance of any engine, in addition to the freezing point, the pH value of the cooling system should be checked.

              Most automotive manufacturers provide in the vehicle manual information about the suggested mileage or time to change the coolant. However it is important, because of the different climate and operative conditions, to measure the pH of the coolant every time the vehicle is at a scheduled service.

              Extensive testing has shown that a coolant pH below 8.3 pH is not acceptable for use in engines due to its corrosive nature. The correct pH value should be maintained between 9.5 - 10.0 pH. Below 9.0 pH it is advisable to flush the cooling system and refill with a new coolant solution.








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                Possibility of replacing thermostat without coolant flush? Advise Please 850

                I'm not questioning the desirability of periodically replacing engine coolant. Didn't realize that was your point since the original poster didn't mention when his coolant was last replaced. Could have been yesterday, or could have been years ago. My question pertained to your comment about the desirability of replacing coolant whenever the thermostat is changed.








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                  Possibility of replacing thermostat without coolant flush? Advise Please 850

                  In fact,

                  I had it replaced March 2002. That's why I don't want to get into doing that again. In a couple of months I'll graduate from the grad school and have lots of time to do the extras. I think a coule of months wouldn't kill my engine.
                  ihsan








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                    Possibility of replacing thermostat without coolant flush? Advise Please 850

                    This is only my opinion, but I do have a fair amount of auto maintenance education and experience. I wouldn't worry about replacing the coolant for at least a couple more years. If you're not going to keep the car for a few years beyond that, don't ever change it.








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                      Possibility of replacing thermostat without coolant flush? Advise Please 850

                      Thanks,

                      I remember reading something like "The coolant better be changed once in every two years" That's whay I had it planned to change it next March actually. And that's why I posted the question if it is requirement to change coolant with thermostat.
                      ihsan







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