Hello All. I want to change the thermostat in my 1987 Volvo 240DL(107,000 miles). I understand I have choice of 2 different ones : One is 190 degrees F and the other is 197 degrees F . I am in central NJ. A hot summer day here would be about 95 degrees F and a cold winter day about 8 degrees F . Since it doesn't get all that hot here I am inclined to go with warmer 197 degree F thermostat. Is this correct choice ?? Next question is I was told that I don't have to drain out coolant(or if I do drain I don't have to drain very much out)to change thermostat since it is up high. Is this true ?? Thanks in advance for your replys and advise.

As a side note, purchasing a thermostat with a small "air release" hole at the top (your local Napa Auto Parts store sells these) will keep an air pocket from preventing the thermostat to open. If you have been having intermittant overheating problems in the past go with the cooler thermostat... if your engine has been running cool go with the 197... personally I have used both and notice very little difference.

Have fun, and remember to clean up spilled coolant!

-Flup

If your coolant is less than 2 yrs old it's OK to reuse it. If not, drain it all, run some Prestone HD Rad Flush through (instructions on the bottle), and refill with new coolant 50/50 with distilled water.

To save your coolant undo the block drain in behind the back of the exhaust manifold - 13mm open-end wrench. I loosen it a little and put a 1/2-inch heater hose over the end, open it further by hand, and then undo the reservior cap for faster flow. This directs all coolant into the catch pan I put below for less mess, saving it if that's the idea, and easy disposal if not. This will drain more than enough coolant to do a non-messy t'stat replacement.

To change coolant you'll need to undo the lower rad hose to get all the old coolant out. This will result in a gusher of coolant out onto the engine splash pan and a fair bit will spill onto the ground. Coolant is highly toxic to small animals, especially cats, so catch what you can and clean up the rest.

When you install the t'stat place it so the little hole near the rim is at the highest position. After running the engine to full temp to test the t'stat and check for leaks, let it cool fully and check the reservoir - it will probably need a top-up.
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Bob (son's 81-244GL B21F, dtr's 83-244DL B23F, 'my' 94-944 B230FD; plus grocery-getter Dodge minivan, hobbycar 77 MGB, and a few old motorcycles)

Additional Heads-up. These thermostats area bit different then American cars. These thermoststs have a rubber gasket on them No paper gasket on the Housing. It's obvious when you take it apart just thought I'd throw that out to you.
After doing the T stat, start the engine and as it gets close to temperature grab the Top hose with both hands and squeeze and release it fast. this will help purge the trapped air in the upper hose. Watch your Temp. gauge because if the air is trapped the temp will shoot up.
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'75 Jeep CJ5 345Hp ChevyPwrd, two motorcycles, '85 Pickup: The '89 Volvo is the newest vehicle I own. it wasn't Volvos safety , it was Longevity that sold me

Yes and yes. Use the higher temp thermostat, since in our generally moderate and definitely humid environment, it helps the engine work more efficiently. It also helps drive off accumulated water from the oil, reducing sludging inside the engine.

And yes, it's right up top on the engine, right in front. One of the easiest things to get at actually. New thermostats will come with a new o-ring seal - there's no other gasket. Clean up the sealing surface and the water neck well before reinstalling. You will lose a bit of coolant, nothing much you can do except put a wide pan under it. If the factory splash pan is still in place, you can just put your pan under the back corners to catch the coolant as it drains out there. A big pile of old newspapers under the whole thing would be a great idea too, that'll prevent staining the driveway or sending any to the storm drains.

You don't need to remove the top radiator hose for this job, just the 2 10mm nuts and the lifting eye on the front of the engine. However, just go easy when folding back the hose. The plastic tanks and water nipples on the original radiators are very fragile. Don't flex the thing any more than necessary to remove the thermostat. And don't be surprised to find green, yellow, sticky, grey crud in the housing. Just clean it all up and observe orientation of the old thermostat when installing the new one.

Good luck!
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Rob Bareiss, New London CT ::: Roterande Fläkt Och Drivremmar!

"And don't be surprised to find green, yellow, sticky, grey crud in the housing."

This is just why you should take this opportunity to drain the coolant out (drain valve at right rear lower side of engine. The coolant is anti-corrosion for the whole cooling system and heater core and lubricant for coolant pump, and these characteristics only last a couple of years. Flush water through engine block coolant channels when drain is open, but don´t run engine with water only in there, since then the pump gets no lubrication.

If you want to clean out thoroughly, run with new coolant for a a couple of days and then drain again, and replace a second time with new coolant. Always use 50/50 blend with water.

Gustafkalle

I believe that you would want the higher temp thermostat.

You will lose maybe a pint of coolant when you do the change, so you do need to put a pan under it to catch that. I don't think it's worth draining more out from the bottom to avoid that, but that method would be a lot neater since the spillage from the top where the thermostat is does run all over the place on it's way down.
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Andy in St. Paul. '89 244 147K mi, '91 745 Regina 202K, '87 245 lost to rust at 225K