1987 325E Overheating Question

[Pro1914]

Hey folks!

So recently, I've been taking my 1987 325E out for quick 15 minute drives around town, and I'm starting to notice it's overheating. If I sit in traffic or stop at a drive-thru, the temp gauge will slowly flicker up to just short of the 3/4ths mark, but when I'm moving it keeps perfectly in the middle. Turning on the heat kind of helps to keep the temp down.

I've just recently done the timing belt and while I was in there I replaced the water pump, radiator fan clutch, thermostat, coolant, and coolant hoses. All of my hoses get hot, and the rad feels warm to the touch. I did notice however, it feels as if the hoses fill with air after I shut the car off, but the system has been bled multiple times. The coolant isn't boiling when I check it, and there is no milky stuff in the oil, nor is the coolant any different from when I put it in. I haven't lost any of the two fluids either.

I did also notice that when I take the coolant cap off, there is no pressure behind it. Like usually, when you take the cap off a hot car, you have to do it slowly and it will hiss as the pressure is released, but mine doesn't hiss. The cap just comes off freely. I also noticed that when I squeeze a hose with the car off, and the cap on, I hear squeaking coming from the cap as if there's a small opening in it. I figured I'd mention it since I have no clue if this is normal behavior from the reservoir or not.

Thanks so much for any info!

Also, here's a video of what the temp gauge is doing when it starts to overheat.
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[It's Soda Not Pop]

More than likely you need to bleed the system again. Raise the front of the car up. With it running and the heat on full blast. Crack open the bleed screw until it's a steady stream of coolant. You may also have to add coolant as well.
First time I replace my water pump I had an issue with it overheating. You have to really bleed all the air out.

[jeffw]

Make sure you’re fan is working correctly. Sounds like there isn’t enough air flow. That’s why it over heats at a stop but cools down when moving.

[tomstin]

Replace the radiator fan clutch. Look up the newspaper test.

[digger]

Also sounds like Cap seems busted as should be pressure in there

[ADEN]

I guess your gauge is going crazy when idle caused by lower voltage and corrosion in gauge ground. To prove my guessing rev the engine above 1.5k steady less then 10 seconds the gauge will go back to 12 o'clock or try to give a couple of knocks to the cluster you will see the gauge go back to the middle.

If it is actually overheating you will lose coolant (cap will release access pressure throught pipe under driver door) and the hoses will get hardly unsqueezeable.