Draining and refilling coolant questions

johnwartjr

Registered User
Greetings

I've drained and replaced coolant before, and I've also been known to take the easy route and let the dealer do it.

I think my SC is probably due for a coolant drain and refill, since it's starting to get cold here, and I want to do it before I either freeze rolling under the car, or have to deal with snow.

I've read tidbits here and there that the SC engines have a different coolant changing procedure than many vehicles, and that a flush is probably a bad idea.

Anyone care to comment on the procedure? How you've done it? Anything else you replaced at the time of the coolant flush? Thermostat? Radiator Cap? Would a flush using only water be a bad idea? Any particular kind of coolant used? I'm partial to the green prestone, not a fan of the long life stuff since I tend to change it out within a couple years of the last flush, anyways.

Any reasons why I should just let the dealer do it?

Any special tools I'll need? I have basic hand tools, sockets, etc, but since I plan on doing this every year or two, I would not be opposed to spending a few bucks if I need any specialized tools.

My car is a 95 SC Auto, 96,5xx miles on it. Maintenance records tend to indicate the head gaskets were replaced within the last 35k or so, but that probably doesn't mean anything. I bought it off a dealer's lot earlier this year where it had sat for almost 2 years.

Thanks!

--john
 
Well, here's what I do:

1. Undue bottom radiator hose, undue pitcock if you want to be clean. I usually don't care if I get a little on the driveway. I do drain it into some kind of container though.

2. Screw hose back on and fill with water and flush of your choice, make sure it is good for aluminum, I also leave cap off so I can drain quickly.

3. Run until it is up to operating tempertaure and let run for 5 minutes or so.

4. Drain again.

5. Fill up with 50/50 coolant of your choice and distilled water. When filling make sure you unbolt the screw on top of the engine to allow for air to get.

6. Fire it up and make a blast down your favorite street.
 
Isn't there a drain plug on the side of the engine block that you must also open to make sure all the old coolant is drained?
 
Not that I know of and I have taken my engine out three times. I think the flush gets most of it out but if you want to make sure to get it out you could always take out the thermostat and stick a hose in there. Most of it will come out from gravity though. The lower radiator hose is the lowest spot on the system so it will all flow out unless it is caught in a pocket somewhere. That amount left would be negligable.
 
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I just flushed and filled mine a couple days ago. The only block drain I am aware of is the knock sensor. It's too much of a pain to remove to ensure every last bit is drained out.

If you have an air compressor, you might want to try using a blow gun down that vent tube (with the bolt you need to remove before filling) I got a bit more coolant out of the block that way.

I ended up putting about 2 1/2 gallons back in. I think the system holds just over 3 gallons, so I know I wasn't draining it completely, but if you replace the coolant as much as you say that shouldn't be a problem, just try to account for the 1/2 gallon or so of water left in the system after the flush (add a bit more coolant than a 50/50 mix).

I also fill the system back up once with plain water after the flush to make sure that is mostly out before adding the coolant. flush out the overflow too.
 
There are block drains on both cylinder banks, just behind the engine mounts. Unfortunately they have like 1/4" square heads on the plugs and are very hard to get to. What I do is remove the stat. and, then use the Prestone flush kit (dumping the old coolant from the upper rad. hose into buckets - via their plastic sleeve and, at the same time feed fresh water from a hose into the upper rad opening - via their plastic hopper. I then drain the rad. & add the correct amount of full strength coolant, so it mixes with the water left in the block. I'd prefer to fill pre-mixed distilled water & coolant into an empty system (like I do on my other cars), but I have a bad feeling that I'd break those block drain plugs if I tried to remove them.
Jim.
 
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