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I have a 1985 GSL-SE, 193,000 miles, runs almost like new (to me anyway). Ten years ago (and 60 or 70,000 miles ago) after buying the car I installed a new Champion brand thick aluminum radiator. It had been running hot with the original unit and the new radiator fixed that. I'm in the Arizona desert so it's normal here to get to 105-110 degrees out sometimes so cooling is critical. A couple of months ago I noticed the temp. gauge reading seemed to be reading higher than I remember. I flushed out the cooling system, and I'm now running about a 60% anti-freeze/40% distilled water mix (with a bottle of Redline water wetter added) but the gauge reading is still higher than I like it.
It was 100 degrees out when I checked things today, idling at 1050-1100 RPM for about 30 minutes, air conditioning on, auxiliary electric fan I installed running in front of the a/c condenser (stock fan running behind the radiator). In the morning in cooler weather with the AC off at idle the gauge usually sits a bit to the left of the halfway point of the gauge (about 1/3 of the way over). In today's hot weather, with the AC on at idle and all above being equal, the gauge needle goes to the red mark just to the right of the halfway point. I'm thinking in past years the needle would be more to the left.
I got an infrared temperature reader today an here's what I found, assuming it reads correctly)...The top radiator hose, where it goes into the radiator, read 205 degrees. Aiming it at the top of the thermostat housing, it read about 210-212 degrees, but that may be picking up engine heat too. Aiming it at the radiator fins, it was around 200-210 degrees. The car runs, idles and pulls great with these readings.
I wonder if the temp sensor on the block near the rear top spark plug is not reading correctly, or maybe the gauge is off, although I think the gauge read lower in past years. Am I correct that this sensor is the one that goes to the gauge?
Questions: Could that sensor be bad (I have a new one I can swap in), could that be OK but the gauge isn't reading right, do I need a new radiator, or for it being 100+ out, could the gauge readings be correct, and should I stop worrying about all of this and the readings are normal for very hot weather?
I will appreciate any opinions and ideas. Thanks in advance as usual.
according to the FSM, the thermostat should start to open at 180, and should be fully open at 203. with the system doing it's job (heat removal), what you saw at the radiator could be normal (i don't know that for sure).
if you're concerned with temps and actually want to get data, i would recommend that you get an actual temperature gauge.
Thanks. This is great help to me. Now I'm not as worried about the heat issue.Now I'm wondering if my recent poor running is in fact an ignition problem and not from overheating. The car still starts instantly cold or hot but it's missing sometimes, gives an occasional pop out the exhaust, then idles pretty well for a short time, misses a bit and RPMs drop to around 500 until I give it some gas, then it idles higher again, but still a bit rough. Also, since this started happening recently, the car is down on power quite a bit.One thing is when I turn on my AC, the idle holds higher and a bit steadier for a bit longer,which is a function of the ACV (air control valve), but after a few minutes the same issue happens again,and it's still down on power.
Trying to figure this out tonight I got a new (made in Japan!) distributor rotor and will be picking up a new distributor cap (also Japan origin) tomorrow. About 6 months ago I installed new NGK plugs and wires but not a new cap and rotor, although (see pics below, then my post finishes below the two pictures)....
it ran great until recently. Pulling off the old cap and rotor tonight I notice that by turning the rotor a bit to the right, it would stick in that position sometimes. Inside the round post that the rotor presses onto it looks like there's some dried up goop, or maybe some material that needs to be lubricated. I've not done that in the 10 years I've had the car. Is that supposed to be lubricated and, if so, what with? Also, one of the parts on the distributor plate with all the electronics (the distributor pickup coil plate?) is cracked. There are two wires going through it that are intact and connected beyond that, but I wonder if that could be an issue. It's on the far right of both the pictures here and you'll notice there's a bigger gap on that piece than the identical part on the left of the photo; You can wiggle that part on the right at that crack, although the wires through it still seem intact. So my main question is I wonder if the distributor is sticking and I need to put some lube of some type into that post that holds the rotor.
Finally, if the above doesn't fix things I'm taking the car to a guy who has a rotary compression tester on Tuesday, hoping my compressdion isn't suddenly down.
If you've read this far I am grateful as always for your suggestions.
Regards.
08-07-22, 08:42 PM
