Just bought the car, overheating problems.

[agent4573]

Hey guys, was hoping you could help me out with a little issue. Just bought an 82 320i with 132k on the odometer. On the way home the needle slowly crept from the mid point to almost in the red in about 25 miles. The faster I go, the higher the temp needle goes. When I slow down or sit at a traffic light, the temp drops back to about the midpoint. Temp outside is ~65F. I'm worried about the upcoming summer with temps upto 120F and a/c on. I flushed the radiator out and put in new coolant, tried to bleed the system but after 20 minutes of idling in the driveway, the temp wasn't past the 1/4 point on the gauge so I gave up. Fan belt is tight and isn't squeeling like its slipping. Should I just start replacing things like thermostat and water pump? What about a clogged exhaust? I can do a compression test if I need to check out the head gasket, but it runs dam near perfect and I didn't see anything signs of water in the old oil, so I don't think its head gasket related. Thanks in advance.

[e21-Mark]

Thermostat & water pump would be a good start. Problems are usually the other way round as over 30mph the thru draft should be enough to cool the rad/engine without the fan. It doesn't sound like a headgasket if you're not losing any coolant? A new temp' gauge sender might be worth getting too? Keep us posted.

[agent4573]

Would you suggest 180 for the thermostat? Hotter? Colder?

[creedon]

Don't know if you already know this but if you rock the wheel (the top one which the fan belt goes on, between the fan and the water pump) towards the engine and back and if there's some play on it then it's the water pump bearing. I had an overheating problem very recently too. The tightening up of pipes and changing the water pump sems to have sorted it.

[quinn_656]

if the temperature raising and then dropping suddenly then that sounds like ur thermostat

[e21mad]

is your car manual or auto? autos can over heat at speed if there is trouble in the trans and cool at low speed if the engine is ok

[agent4573]

Just replaced the thermostat, didn't help. Now it over heats at IDLE too. Its an auto that needs at least some adjustment. It shifts into 3rd by 20 mph and even at WOT, shifts out at a max of 4500 RPMs. There used to be a miss at startup for about 15 seconds so I put in new plugs and now it misses everywhere. I'm gonna start with the clogged exhaust first, hopefully its just a muffler, but I might be welding in a new CAT, then I'll deal with the overheating issue again, because I think a fully clogged exhaust could be playing a hand in the overheating and even the miss. Its cooling off now and I'm gonna pull the muffler to see if thats clogged. I'll let you guys know how it all goes.

[agent4573]

Things I did today:
1. Replace t-stat
2. Replace plugs
3. Adjust timing
4. Adjust mixture screw

It runs a lot better now. It runs at a rock solid 3/4 hot mark on the temp gauge, which I'm not happy with, but it doesn't seem to go above that so I guess its good for now. The miss seems to be gone after the idle/mixture adjustment. I couldn't get the O2 sensor to read .47, but I got it as close as I could. It started at about .8 and I have it set now at .7. If i turn it 1/32 turn more, it drops to .25, so I figure thats as close as I'm going to get it. It's idling at 1100 rpm, so I need to adjust that just a tiny bit more, but its a lot better. Now to find a universal CAT to put in it, cuz I think mine is totally clogged. There's a 50 degree temp drop across the cat, and only a 7 degree temp drop across the muffler, so I'm assuming its the cat thats clogged.