The same 528e that now has trouble starting in the cold also takes a VERY long time to warm up, both as indicated in the water temperature gauge and by the temperature of the aire coming out of the heater. My '88 535i, on the other hand, warms up very quickly. What is likely to be the problem and is it sometihng I can fix (medium aptitude) or is it best left to a qualified mechanic?
You can test your thermostat, or just replace it. Does the car run too cool even after warming up? How long does it take to warm up? Does it only have heat during in-town driving? There's more you need to tell us so we can help. The E28 has an electromagnetic heater valve that can cause lack of heat at higher speed but your slow-to-warm-up symptom sounds more like a thermostat issue. They normally fail in the open (cool) position.
It takes about 10 minutes of in-town or hwy driving before the water temperature gauge registers 1/3 off the left hand side. Not sure what you mean by "running cool" even after it warms up. When it warms up....it get's warmer. The car runs fine while still cool; you just don't get any heat inside.
What he is asking is, where does it run on the gauge when it is warmed up completely. Does it get to the middle? If not, you need a t-stat. If so, does it then drop back down once you get moving? if it does drop back down, you need a t-stat. BMWCCA1 = Phil?
Thanks for the explanation. I took it out yesterday for 20 minutes of spirited in-town and then another 20 of hwy driving and the temperature gauge never got past about 1/4 inch off the left hand edge.
Either the gauge is faulty, or the thermostat is sticking open. My vote is for the second one since you say you have no/weak heat.
