Luis de Prat

On a hot Australian day in stop and go traffic with the A/C on, it doesn't seem unusual for the temperature to go up to 2/3 and down again as the fans cool the engine down.

A sticking fan switch sounds like a possibility, although he did say his fans appear to cycle normally.

As for the radiator being stopped up, it's also possible. Especially if straight tap water has been used in the coolant mix at some point in the car's maintenance history.

The best way to clean out a radiator is having it pressure cleaned by a radiator shop. Unfortunately, the 944 radiators don't hold up very well to this kind of treatment because they have plastic side tanks that are glued to the aluminum radiator and tend to separate. It's usually best to just replace the radiator with a new unit, or they end up leaking.

The coolant you mentioned is good if it's specifically safe for aluminum engines.

wjk_glynn

I think you're worrying about nothing... Hitting the 2/3 mark on a 90F day is okay. The temperature of your block will vary with ambient temperature. Just as an FYI, here are the actual block temperatures that your dash gauge is showing...



Karl.

PS - I do live in Sunnyvale at its in the mid-60's at the moment.

Mark944na86

Karl, thanks for the graphic, very interesting.

So what I'm worried about here is a cooling system temp variance in the order of 20C. Which, as people have been pointing out, is within spec, so I'm really just being a 944 hypochondriac.

But what's interesting is that when I lived in Sunnyvale, I almost never saw the engine temp on my '86 944 NA creep above the 80C mark -- even on the warmest days, with a/c full on. And the a/c always kept up to keep the cabin cool.

Now with my S2 here in Brisbane (no, not the one just south of SF! ;-), I'm seeing it hitting the 100C mark just everytime I drive now, warm weather or not. And it never seems to want to go down to the 80C mark once it's warmed up while I'm driving, although it will if the car's just sitting and idling. While driving, it might go back down to mid-way between the marks, say 90C. And, as I mentioned in the original post, on a 33C (90F) day during freeway driving, the a/c was just simply failing to keep up -- I was hot, and so was the engine. That doesn't happen in my other cars, it never happened in my previous 944, and I hate to think what it would be like on a _really_ hot day.

But let's compare apples and apples: What was your experience driving your S2 in Sunnyvale during the recent summer? How high does your temp sensor get? What mark does the gauge like to sit on?

-Mark

Thom

S2 do not run warmer but in heavy traffic the water temp gauge goes up much quicker than on a NA/Turbo.
Mine used to run at ~79°C before the thermostat was replaced (TB/WP job) and it's been running at a steady 85°C since.
In any case the water temp should increase when the car is already warm and when you are hitting 2nd gear traffic. When warm S2 do heat up quicker than NA/951.

In my experience anyway.

wjk_glynn

On a hot day (say 28C-30C), the temperature cycles between 90C and 100C.

In winter (say 10C-15C), the temperature cycles between 80C and 90C.


Now you mentioned in your last post that its in the 90-100C mark regardless of ambient temperature. To me, that sounds like your cooling system is not operating at 100%, but its also not egregiously broken either. Reasons that it might not be in tip-top condition are:

* Your radiator needs cleaning (make sure there's no crap like leaves on it)
* Your radiator could do with a flushing (that really helped me when my car suddenly started running hot)
* Your water pump is not as efficient as it once was (might be a sign that its going)
* Your thermostat is not fully opening (it happens)

Karl.

Mark944na86

I'm pleased to report some success!

I drained out half my antifreeze, replaced with 4litres of distilled water, bringing my glycol/water ratio down to about 25/75. Added 8oz (half a bottle) of Redline Water Wetter. Now running noticeably cooler -- about 10C, on average, according to Karl's graphic. A/C now running noticeably cooler as well.

So I'm much happier :-)

Thanks all for your advice.

-Mark

But the "conservation of things being broken" principle has kicked in, of course, to now have me trying to figure out what's (intermittently) drawing 7A of power of my battery when the car's sitting parked! But there's no fighting thermodynamics...

Danno

Don't forget to burp the radiator hose...

Mark944na86

I used the method as detailed by Dal Heger in previous posts... simplest method I've tried, and works very well (a bit messy perhaps -- I spill about 1litre coolant total in burping). Thanks Dal.

-Mark