Thermostat...?

[Etienne]

looks I posted twice in a row in here...

Do the ti's in general have a problem with heat? My heat works, but it doesn't get really hot... I was thinking thermostat perhaps, but thought maybe it just doesn't get very hot...? It keeps the car comfortable but the girlfriend is from FL. and it drives her crazy... lol.

I won't need heat again until next year, but I hate working on the car in the cold (no heated garage... ) so thought I would look into it as the weather has gotten warmer now.

Thanks for any insight.

[2ndBimmer]

No not a problem with heat, for the 2 years ive had my car.

last year a valve (or something in there) broke and it wouldnt put out anything more than lukewarm, but after it was fixed the heat was back to normal, which after about 50 minutes of PA to MD driving gets me sweating if i have it cranked.

[1996 328ti]

There is a bypass valve that could go bad. It's located on the firewall. I think with the heat on both hoses should be warm.
Another problem is sometimes the cable to the temp control pops off. You need to gain access to it by removing the glove box and knee bolster.
You might also want to bleed the radiator. Remove the plastic bleed screw and run the engine until water starts to come out.

I don't think it's a thermostat problem.
My money is on the bypass valve.

[J!m]

I'm with Steve- Heater control valve or air.

If it's air, there could be a small leak that needs to be located...

[Etienne]

any more info on the heater cotrol valve? I put off doing this all summer and now the weather is getting chilly again.

I really appreciate the assistance.

[1996 328ti]

Just replace it, then bleed the system.

[J!m]

Bleeding is a bit tricky, so be dilligent and heat-cycle the motor at least twice to be sure the air is out.

[Compact Missile]

Check if inlet and outlet hoses to bypass are both hot. They should be roughly the same temperature. If not, I bet the system is not correctly bled. With engine off, key on ignition position and rad topped up to the very edge of the filler neck, set heater to hot, and switch on the blower to full speed (to open up the valve) then open the rad cap and loosen to top hose to the bypass valve. remove hose gently and let all air come out! Reconnect when water pours out. Then top up coolant again and bleed from rad bleed valve as normal. Hope this helps. It sorted out my heating problem

[Jeff Spooner]

BMW says to turn heat on wide open and rev engine up and down from 3500-4500 rpm for 4 to 5 minutes. Sounds a little rough on motor but it works.

[Constant]

I replaced my thermostat after I noticed the heat wasn't very warm. The water temp gauge was also never moving past 1/3 on the cold side. Worked like a charm, and only took 30 mins. Downside is that the thermostat was rather expensive because it is integrated as an assembly.

Constant

[mrnine]

Best deal I've seen on thermostat & housing is $17.85 from Pelican for the M44 w/o gasket. Just $13.50 for the M42. As opposed to $42 for M44 from Bavauto. Ouch!

[Constant]

Wait, the M44 thermostat is only $17.85 from Pelican? I think I paid dealer price for it ($60?), since I had a credit at the parts dept. Damn!

Constant

[aceyx]

i'm not sure if i need to bleed the coolant system or swap the thermostat on my car. my engine temp gauge will generally reach operating temp around town. if i turn up the heat, or get on the highway (~70mph cruise) the engine temp drops fairly quickly. however, it isn't a constant change with heater/speed. sometimes it's fine, sometimes it dips.

i'm thinking i need to bleed, because it seems like there's an air bubble moving around. anybody have insight?

[KIRASIR]

Bleeding only helps if you are overheating. In your case it's 99.9% the thermostat.

SL

Originally Posted by aceyx

i'm not sure if i need to bleed the coolant system or swap the thermostat on my car. my engine temp gauge will generally reach operating temp around town. if i turn up the heat, or get on the highway (~70mph cruise) the engine temp drops fairly quickly. however, it isn't a constant change with heater/speed. sometimes it's fine, sometimes it dips.

i'm thinking i need to bleed, because it seems like there's an air bubble moving around. anybody have insight?

[mrnine]

KIRASIR is right...that's not a bleeding issue. Based on my limited knowledge, if you're overheating but can cool it down on the highway, it's almost certainly a thermostat or a fan clutch.

Of course I guess if you're changing the thermostat, you'll get to bleed the coolant anyway.

I just helped someone troubleshoot an overheating issue on an e34 and they gave this (somewhat lame) advice to determine whether your thermostat is working:

How to check the thermostat:
A slow working thermostat is hard to diagnose. When the engine is warming up and the temperature needle is near center, touch the top radiator hose. If hot, the thermostat is working (could still be a slow one). If there is cold area in the hose or radiator, check the thermostat.