Took my 85 245ti on the freeway today and it ran hot...But around town temp is fine right in the middle of the gauge....After my trip idling was rough but I saw no liquid from the radiator....New thermostat to boot.....Any hints....

I agree with Ken C. It's most likely the rad. And as runwld2 mentions, corrosion of the fins can be a problem (mine crumbled when touched).

However, as long as the temp doesn't go too high, you've got some time to check out the PickNPulls in your area for a new rad. I think most 740s also take the same rad (check FCP or IPD rad listings).
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1980 245 Canadian B21A with SU carb and M46 trans in Brampton, Ont.

you may be experiencing electrical issues... the gauges can act a little like voltmeters. the cooling systems are very robust on these cars especially compared to the electrical systems. it might be overcharging at higher rpms. Real overheating is rare, and would be unlikely to happen on the highway unless you lose coolant or fan. check to see if the gas gauge is also reading a little high under the same conditions. it isn't impossible that there is a radiator issue, but electrical stuff is more common; it's an expensive shame to replace ok metal because of an electrical situation.
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Stef (scotia blue 81 245 B21A SU M46 3.91 350000km)

First, don't let anyone suggest a Temperature Compensation Boards. That's practically a "reflex response" from some folks who don't read your car's model year -- the C.B. is a real possibility, but only for cars '86-on! Your '85 doesn't have it.

But as for your problem, "...on the freeway today and it ran hot...But around town temp is fine..."
Clearly, when your car is generating lots of heat (running at higher speed where it is putting out more horsepower and therefore heat byproduct), the cooling system can't handle the extra burden. While, when the engine is loafing, and therefore not generating as much heat, the cooling system can cope.

The first possibility I'd consider is your radiator. If it hasn't been changed, or it hasn't been changed in a long time (and your car is 21 years old), even though it isn't leaking there is a real possibility that it is, inside, so clogged or thickly coated with mineral deposit that heat cannot easily be conducted from the liquid coolant to the outside air. It can dissipate a little heat (in-town), but it can't dissipate a lot of heat (on the highway).

And while you're at it, consider the belt driving your water pump -- if it slips at higher rpm (the belt is glazed, for example), it won't circulate coolant as it should.

Of course, your ignition timing and other adjustments can also effect heat production in the engine -- make sure everything is at specs.

Good luck.

What if I try a radiator flush first? then go from there...

I had a car which exibited same symptoms. When I removed the radiator and brought it in for a flush, the guy turned the hose on it, and many of the fins between the tubes flew out. The corrosion along the tubes can make the fins very inefficient, so even with no leaks once the radiator gets corroded, in and out, it's efficiency drops.
If you have a metal tanked radiator, you may be able to find some one to replace the core. It may be cheaper, but those places are disappearing. I went to Maine to get the last one done (and only because it was on the way to my daughter's college).
I recently pulled a 3 row rad from the Junkyard, we'll see how it works out in the Turbo..........
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744 & 745 16v 4+OD, 245 SE auto, 242Ti 4+OD, 745 8v auto

Assuming you've acknowledged (from my speculation in the previous message) that you have an old (possibly original?) radiator, there's little that you can really do to revive it -- it has a finite lifespan of 6 to 8 years (maybe 10-12 or so in the best of circumstances such as best quality antifreeze that's only ever been mixed with distilled water, never tap water). Your car is approx. 2 to 3 times that age, and (particularly if your radiator is original) you've certainly got more than your money's worth out of the radiator.

If it's really clogged up with deposit, I'm doubtful that the scale would be dissolved by a mere flush -- and, if the radiator is really old, it may have some weak seams that are just held together or blocked by such deposits, so if you do break down the deposit the radiator may begin to leak ... you're damned if you do, and damned if you don't. The one positive thing the flush may do is remove some scale from inside the engine's passages, though. A really good flush protocol involves a step with citric acid, followed by a good flushing with fresh water -- if it doesn't involve this, it may not be at all effective.

To check the radiator even though you can't look into it, try removing it (very, very easy -- remove two bolts for holders on top and disconnect the hoses and ATF lines) and then pour water into its inflow opening (while holding in a positions so it doesn't spill out the other outflow opening right away. See how much water you can get it by then spilling it's contents into a bucket. I think a new standard (2-row) radiator should hold about 2 quarts -- but you may have passages fully clogged, and therefore it may hold much less. Draw your own conclusion from that result.

All in all, a radiator is more an expendable item like tires -- lasts many years, but eventually has to be replaced. And don't use a used radiator from a p.n.p., as you may get one worse than your own.

A step up for radiators is, of course, the Nissen's 3-row (all metal) from IPD (compared to the OEM 2-row), which has 50% more cooling capacity than standard.
IPD is www.ipdusa.com

In any case, good luck.