[Cloud9...68]

When using the cap off method, is it a good idea to overfill the reservoir to account for the amount of coolant that's going to be lost through the bleed screw? Or is the amount of loss generally not enough to worry about?

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[flash]

i would not do it cap off unless you fail to succeed in the normal method - the 19lbs of pressure is a very effective way of ensuring that the system flows fully

to answer the question tough, never overfill the reservoir

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[Johannvb]

Interresting point Flash, learned something new again. [img]style_emoticons/<#EMO_DIR#>/wink.gif[/img]

I love this forum

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[flash]

work on enough cars for long enough, and you learn all sorts of weird things for odd and anomalous situations - i had the benefit of learning from a guy who had been wrenching and tuning race cars for about 30 years when i met him, and that was nearly 30 years ago - i'm sure i don't know even half the little things he knew though

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[blue968]

hi Guys,

I just ran my car with the radiator cap off and didn't see any coolant flow, I revved the motor up and then seen the flow of antifreeze. Is this normal to see almost no flow of antifreeze at an idle??

Thanks

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[Cloud9...68]

Blue968,

Thanks for checking that. The more cars' behavior (with respect to their cooling systems, and everything else) we have information on, the better equipped we all will be to ascertain whether our car's behavior is "normal." I'm so isolated here in Austin, that it's difficult for me to tell how many things may be off kilter with my car. I really envy you guys on the coasts. I didn't think to try rev'ing my engine and checking for coolant flow back into the reservoir - I'll give that a try.

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[blue968]

Hey Cloud,

I'm curious if your car is behaving the same way with the coolant flow. At 1st when I looked in the reservoir I didn't see any movement but you have to look closely but when you rev it up it very clear.

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[Cloud9...68]

Well, I tried this yesterday, and I'm afraid my conclusion is that there really isn't any coolant flow through the tube in the back of the reservoir, into the reservoir, even when I rev the engine. I repeated it several times, and occasionally saw what looked like a ripple in the surface of the coolant as I was looking at it through the cap opening, but I think it was just coming from the vibration of the car as I was revving the engine. For the hundredth time, I wish there was just ONE other 968 here in Austin I could compare notes with [img]style_emoticons/<#EMO_DIR#>/mad.gif[/img] [img]style_emoticons/<#EMO_DIR#>/mad.gif[/img] . If it wasn't for this forum, I'd really feel like Iwas on a desert island with this car, and may even have sold it long ago.

I also tried Flash's method of bleeding the system, and got a solid stream of - wait for it - pure antifreeze spewing from the bleed screw. Not a hint of a bubble as far as I can tell.

But I'm beginning to question my sanity, or at least my ability to remember what was once "normal" for my car's temperature gauge's behavior, and the car, if anything, is running a little cooler (or more accurately, less hot) that it was a few months ago, despite the warming of the weather. So I'm beginning to wonder if I even have a problem, or, like so many other issues I've had with this car, if it has again magically cured itself. Sort of argues against a dying water pump, imho...

Those of you reading this who live in hot places like Texas, Arizona, or Florida: On a really hot day (say 95 degrees+), after your engine is fully warmed up, how high does your temp gauge needle climb if you floor it through the gears (OK, maybe the first three gears only, unless you're DS968 enjoying your usual 150 mph jaunt up Hwy 280 [img]style_emoticons/<#EMO_DIR#>/tongue.gif[/img] )? How about if you repeat this three of four times? Lately, mine goes to about 9:30 - 9:45 (there's definitely still space between the needle and the top line), but dops quickly to about 9:00 after I ease off to a steady cruise. This sounds startlingly normal, as RXTER observed several posts ago...

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[flash]

that is where it should run in ambient temps like those

remember, a properly set cooling system should run 100 degrees over ambient, or 15 degrees above the thermostat, whichever is HIGHER - it should also not swing more than 20 degrees during operation

stability is the key to success here

so, knowing that the second or 10 o'clock like is 212, and the first or 8 o'clock like is 176, at 95 degrees outside, you should be running at about 9 o'clock normally (right in the middle of the 2 lines), and a touch higher under load

altitude, barometric pressure, humidity, and things like that can all affect running temps, but generally speaking, this is where the car should run

lower running temps generally result in wider temp swings under load, which is potentially bad for head gaskets - they also are not as good for combustion or emissions

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[banditsc]

Mine has always run cool, but on hot humid days around 100 with the A/C on it will still keep itself around the first white mark, just crack over it when it's sitting traffic.

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[Cloud9...68]

Thanks for the replies, as usual. The thing that got me worried is that I so clearly remember it NEVER getting above the lower line the first couple of years I owned the car, so it just seemed that its recent behavior was unusual. Now I'm beginning to wonder if it really is my gauge acting a tad "differently" than it did before. It definitely wasn't my imagination a few weeks ago that it hit the bottom of the 10 oclock line after just one trip to the redline, but this is something I haven't been able to repeat. OK, I'll just keep an eye on it. Since I'm temporarily not tracking it, and I drive like a little old lady on the street anyway, I think I'll be fine. When I pull the head prior to installing the supercharger (in batch 2 or 3), I'll take a good look at the water pump to see if the impeller is loose at all. Sorry, it seems like I've wasted a lot of you guys' time... [img]style_emoticons/<#EMO_DIR#>/dry.gif[/img]

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[Johannvb]

I had fun none the less [img]style_emoticons/<#EMO_DIR#>/wink.gif[/img]

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[flash]

always a good exercise

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[blue968]

NOT A WASTE OF TIME AT ALL.

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[Cloud9...68]

Thinking about Flash's post #49, it seems that something's still amiss, as my car isn't behaving that way AT ALL. Flash says the coolant temperature should track about 100 degrees above ambient (which makes sense), but in my car's case, it doesn't matter much if it's 30 degrees outside, or 95 - once warmed up, the temp gauge settles at the 9:00 oclock position, or 194 degrees. Again, it's not overheating, it's just behaving very strangely. It NEVER stays below the 8:00 oclock line, but so far at least, it hasn't hit 10:00, either, although summer is setting in. Like I said, I'll take a good look at the pump when I eventually pull the head.

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[raydog]

The ambient temp will affect your temp at the radiator, but the thermostat controls your internal engine temp regardless of what is going on outside. Therefore what you see on the dash gauge should remain somewhat constant, in relation to what temp tstat you are running. Being here in New England, I am always in the 9-10:00 area when the weather warms up. I run the factory tstat... around 185F I think. But I know there is nothing wrong with the cooling in my car. That is the way it is supposed to run. My 944 is the same way.

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[Cloud9...68]

"The ambient temp will affect your temp at the radiator, but the thermostat controls your internal engine temp regardless of what is going on outside. Therefore what you see on the dash gauge should remain somewhat constant, in relation to what temp tstat you are running. Being here in New England, I am always in the 9-10:00 area when the weather warms up. I run the factory tstat... around 185F I think. But I know there is nothing wrong with the cooling in my car. That is the way it is supposed to run. My 944 is the same way."

Thanks for the input. As I said, maybe I'm imagining this whole thing, but I like to think I have reasonably good awareness when something that's been behaving a certain way suddenly changes, and I swear I don't remember seeing my temp gauge ever get above the 8 oclock line, but who knows? Maybe with the particular thermostat I'm running at the moment, with the particular fan switch, this is normal behavior. My only concern is that it not overheat when I start tracking it again, hopefully sometime early next year.

Anybody else care to describe how their temp gauge behaves, particularly when driven hard, in warm weather? Thanks.

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[raydog]

When I bought my 944, the temp gauge was always, and I mean always at the 8:00 mark. I did the usual maintenance, changed tstat, antifreeze, etc. When I took the car for a drive, the temps registered a little higher, more like 9-10:00. It has now been 6-8 years since, and the car is fine. Who knows what temp tstat was in there before. Also I am not a believer in lower temp tstats. Engines need to run hotter for better efficiency and lubrication. All I am getting at is that when you changed the tstat, I would allow for a little fluctuation in what you were used to. As long as you are constant, in other words the fans still kick in when they should, no hot smelling odors or anything way off base, drive it and go from there. Sounds like you are OK to me

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[flash]

reread what i said

it should run 100 degrees above ambient or 15 degrees above the thermostat point, whichever is <b>HIGHER</b>

it should NEVER run below 8 o'clock after warm up

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[Cloud9...68]

OK, one more wipe, yes, that should do it; I think I have all the egg off my face now. On a cold day, 15 degrees above the thermostat opening point should put me at about 195 - 197 degrees, or right between the two lines, which is exacty what it is doing. Check. And on a hot day, say the 95 degrees we're forecast to see tomorrow, it should read, wait, let me grab my slide rule, oh, about 195 degrees, or exactly what it sees on a cold day. Check. As the weather warms up to the low hundreds that's forecast for later in the week, I should expect to see it creep a little higher, which I'm suddenly confident it will do without overheating. So, I think it's time I find something else to worry about, because my cooling system appears to be operating exactly as it should.

And it never actually ran below the 8 oclock line when warmed up; I just don't remember it ever getting much above this line. But I no longer trust my memory of this, and it isn't really relevant anyway.

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