Flush & Fill (or "Coolant 101")

[Stitz Love]

Oh yes, I think a complete change is called for.
z07 says he uses the shop-vac/blower method, which I want to try. I want to make sure I get all fluid out of heater core, too.

That is probably a good idea, to do another complete change out in the fall. Thanks.

[Stitz Love]

As I will be removing the t-stat to use the shop vac method for a complete coolant change, I remember reading in one of the threads here about a 'Fail-Safe' thermostat.
I read up on them, and decided to put one in. According to Autozone info, the 195 degree is the OEM for my truck. There were however, several different temps available, such as 160, 185, 192 (yes 2 degrees above 190) I think there was a 190 also.
I remember my 1969 Chevy pick-up seemed to run about 160 degrees. (but that was around 20 years ago)
So... Does anyone have the scoop on why so many t-stat temps are available for my engine?
I specifically want to know if there is a temp that is better for hauling a 3,800 lb. (+ or -) travel trailer.
As always, Thank you.

[bradrhale]

i would imagine that they make so many different ones for different style climates. being where you are located at, i believe i would stick with stock. dont worry about the trailer. my grandfather has a 96 that hauls a 28ft travel trailer with. with the factory temp t-stat, he says that the temp never goes wild even while going up and down the hills around here.

[Stitz Love]

What did I do wrong here?
I followed the instructions in the Haynes... By taking the t-stat housing off (hose spout?) and remove t-stat, I was able to flush well with water, and use the shop-vac blower technique to rid the stystem of the water. I put in a new "Fail-safe" (195 - oem) t-stat. Then as/per the book, having cleaned the old gasket material off, which by the way was simply made of that form-a-gasket stuff. I coated the clean mating surfaces with a thin layer of RTV, placed the (cardboard-like?) gasket on the mounting surface, over the t-stat... set the 'hose spout' (it's mating surface rtv coated) on the gasket. The book says 'tighten to torque specs'... but I could not located the spec (not with the other torque specs found in the book) so I tightened them to what they felt like when I removed them. (about 20 ft lb)
Filled with coolant... which is another thing, capacity is indicated at 18 quarts, (5.7 with AC).. yet I have put 12 quarts in and it seems to be at capacity... what up with that?
But anyway, I ran the engine, checked for leaks... drove it a couple miles and parked.
Next day, I take a look at it before leaving for work. The light blue gasket somwhat protrudes from under the spout, all the way around it. It had dark blue area... I stuck a kleenex on it and when I came home, checked the kleenex, sure enough, coolant is saturating the gasket. (leeching?)
There is no coolant puddle or liquid, it is just evident that the gasket is wicking coolant. I have never seen this before. My impulse is to remove hose and hose spout, clean the surfaces again and reasemble with out the gasket, just use the rtv silicone sealant... I thought I would check with you guys, see what you think, and if any of you have the torque spec for that housing...
Anyone...? Anyone...? ...Bueller?

[leolkfrm]

if there is a rubber ring around the t-stat go with it, if it needs a gasket, coat it with copper gasket only.
as for temp, go with oem 195 degrees

[bradrhale]

last one i replaced with the rubber ring, i didnt use any rtv. it seals itself. its like using rubber valve cover gaskets. rtv is not needed since you cant crush them like cork.

[Stitz Love]

Thanks guys.
there was no rubber ring that came with it. I just bought the $1.29 gasket the guy pulled up. Low and behold, I have located the copper gasket rtv (around $6.00) and the Rubber Ring by Mr. Gasket (for about $15.00) at the same store via 'internet'. Gee, you'd think the guy would have at least suggested the superior gasket or gasket rtv-copper stuff.
I actually got to drive my truck some tonight (about 10 miles) and everything works fine.. the blue of the (paper? cardboard?) gasket got hot enough to almost dry up that wet spot. So I may table replacing it with the rubber ring, or the copper rtv for some weekend TBA.

But what I'm curious about is the torque on that water spout.
And the coolant system capcity.

I have both Haynes and the Manual supplied with the vehicle, I can find no reference to the torque spec. on that piece.
Meanwhile, though both manuals indicate coolant capacity of 18 quarts (for a 5.7 w/AC) they also both say, "capacity is approximate."
Well, approximate me to means "relatively close" or maybe, "give or take 2 or three quarts"... I have put 12 quarts into it (premix 50/50... it was on sale) I'm thinking SIX quarts is a more generous miss than "approximate" covers... I mean, that's a gallon and a half! I'm sure the boys in the engineering room could've gotten closer than 33% ..? Right?

So what's the consensus, the WOTG (wisdom of the group?) the general feeling out there from you vetran coolant changers?

Thanks again.
and leolkfrm, I did go with the 195 t-stat., thanks.

[leolkfrm]

no not copper gasket rtv, plain copper gasket spray

[z07]

Originally Posted by Stitz Love

But what I'm curious about is the torque on that water spout.

I think you were right at about 20'/lbs. In any event, a PO or the factory may have coated the bolt threads with RTV making removal torque seem much greater than install. If the bolt-holes don't pierce the water jackets then there is no need for RTV on them.

And the coolant system capcity.

I think the listed capacity is for the block, heater core, all hoses and the radiator. Either way, full is full.

Did you "burp" the system as you filled it? By that I mean grab a big handfull of radiator hose and squeeze and release it quickly several times? I can normally get a lot of the air out when the cap is off by doing just that.

If the system uses a rubber like o-ring for the t-stat then I don't put any other type of sealant on at all no leaks.

[Stitz Love]

Yes, I did burp the system. ...and I can live with "full is full". I have been monitoring it each day I have driven it since this coolant swap. The level is consistant in the rad and the overflow tank, no leaks no drips... no need to add any more coolant. (I think I like that shop-vac blower method.)
Regarding the gasket wicking coolant, I tightened the bolts just a tiny bit more. The wet spot on the gasket is noticably smaller than the attached photo so I am going to just keep an eye on it, see if it continues to improve with use.
I believe I will do another coolant change about 1500 miles from now (probably in the fall) so I will replace that paper<?> gasket with a rubber one at that time. (Autozone has it for 14.99)
Thanks again for all the input on... "Coolant, 101."
Hopefully this will help someone.
-SL
ps, leolkfrm, I did find the spray copper as well. Thanks.