bureau13

As you can see from the picture below, I'm missing the motorized flap assembly. I'm not sure how much I should worry about that, other than that if you get down that low it looks odd. Obviously, I'll replace it at some point, but I'm wondering if the lack of anything there to direct air might be a problem?

I'm wondering it a little more now, because I took it for a slightly extended drive, getting a bit more aggressive on the throttle and getting on the highway for a bit, since it's running so much better after the distributor change. The first time I started venting white steam from under the hood...my bad, I had the radiator hose pop off. Never got any overheat warning (temp gauge isn't working, fyi...next on my list). Fixed the hose, topped off the coolant, did it again. This time, after exiting the highway, I started getting a flicker of the overheat warning in the gauge (apparently that part works...different sensor?). It was on pretty solid when I pulled into my driveway...I shut it down, but there was nothing indicative of the car overheating...no steam, nothing really. I need to figure out the REAL temp in that situation (ordered an IR gun) but could having no flaps there at all to direct air be an issue? No idea if that condenser fan is working, btw...my AC certainly does not...no belt on the compressor at all.





Something missing here :-)

The Forgotten On

Only 87 had the air flaps. In your 86.5 you would just have a standard 3 fin grill. Of which the bottom fin holds the spoiler.

Mrmerlin

FWIW the 928 cooling system is self bleeding.

To fill it ,
open the heater control temperature controller full hot,

add about 4 gallons of coolant this may take a while as the system will bleed off the air. (note engine off)

Once your at close to 4 gallons installed start the engine.
Let the system come up to temperature coolant cap off.

Once the fans come on or if no elex fan after the thermostat opens, install the cap.
NOTE coolant bottle should be filled just over halfway.

take the car for a drive about 5 miles, this will fill and purge the air from the heater core.
park the car shut off the engine let the car cool off .

Once the car is cool then remove the cap and top up as necessary,
coolant level cold should be just over the seam in the bottle



https://rennlist.com/forums/928-foru...t=bleed+system

bureau13

Thanks for the info. I may have had an air bubble in there, although it wasn't a complete drain-n-fill. I do need to do that though...

17prospective buyer

The usual suspects to check, is there plenty of heat from the heater core, does thermostat open at prescribed temp, does the resevoir/expansion tank cap open when it should (at defined pressure), is there residue on the cap from previously? Follow what Merlin said then work through it.

bureau13

I'm reasonably sure now that I do NOT have an overheating problem. Especially since I read in another thread that the same sensor drives the analog gauge and the warning light at the hot part of the gauge. Drove it around some more, warning light started going off, but it's flickering, it's on, then it's off...very much like an electrical glitch. Pulled over anyway, popped the hood...all quiet, seemed normal. I was worried still though, because I never saw the light come on until I had been driving a bit. However, I ate dinner, then got in after maybe an hour, and the light started flickering on and then going off, etc pretty soon after starting. This is really feeling like an electrical thing. Next up, I'll try to test that sensor. The wires leading to it seemed kinda loose in the connectors, so if the sensor checks out I'll do something about them.

Mrmerlin

replace the connectors,
you will need two different sized female plugs, radio shack has them ,
and clean off the male pins on the sensor,
use deoxit on the connection and heat shrink

bureau13

Will do, thanks. I actually bought some Deoxit based on this forum before the car had even arrived, so I'm prepared for this

GlennD

If the car appears to run hot, did you check your clutch fan? If it just spins free with little resistance when hot (or even cool), it probably is not doing any good.

If the engine temp is good on the open road but quickly climbs up in stop and go, then your clutch fan may also be low on (or missing) the silicon fill fluid.

There are some threads on refilling it using the 10,000 cst to 30,000 cst silicon oil from Toyota. The part numbers are in the old threads.

The other useful change out is replacing the old school clutch fan with electrical fans from approx 1999+ vintage ford cars. Again, lots of threads on this conversion.

Of course, bleeding the cooling system is first and foremost.

Cheers

Tony

Im not sure of the pre87 cars but perhaps make sure there aren't any parts missing behind that front fender. On the 87+ cars the cooling flaps and the housing help keep the air directed to the front of the radiator ...not letting it go out the sides or around it?

bureau13

I've actually got a box of goodies (front grill stuff) on the way from 928 International. I don't THINK that's causing my issue, but it can't hurt to get that stuff put back together properly.

bureau13

OK, for what it's worth, I did some experiments. Started the car up, unplugged the temp sensor and connected the leads via a very low value resistor...gauge still reads 0. Shorted them...still 0. Got out the DMM, infinite across the sensor contacts. Drove the car around for a bit, came back and took it's temperature (IR gun arrived in mail today, yah). I was getting around 190 on the upper radiator hose, 160-170 on the lower as it approaches the motor. Seems reasonable I think? Measured the sensor with the DMM again, this time I was getting some glitchy readings, it would flicker around from infinite to wildly varying values in the M-ohm range. Does this seem like a bad sensor? That's my working theory right now. But...shorting the wires should have affected the gauge as well, so there may be something going on in that part of the circuit too. However as someone suggested earlier, I need to change those connectors. I haven't done that yet, but I will before I start assuming I have a bad gauge or something. Connectors are easy :-)