QuestionI just bought a 1997 bmw 528I. It needs some work. The main things it needs is the valve cover gasket fixed. It will begin to throw some oil on the sparkplugs soon. I need a temperature sensor. The one that controls the onboard display. Without this sensor the AC won't come on. I plan to get a tune-up. Also, the back vents are not hot. Does that mean a big problem or can I just turn them off?
AnswerHello Edith,
The replacement of the valve cover gasket is an easy repair
(both for a mechanic or a do-it-yourselfer) provided the parts and usual tools are available. You do not even need detailed instructions here. Just take off the top engine covers, remove the connections to the sparkplugs, detach the sparkplug cables from the valve cover, and take off the various bolts holding the valve cover. Replace the valve cover seals and small bolts' seals, then re-install everything.
Now the temp sensor responsible for the temp display---
this one is either on the front left or right bottom end of the car, the area behind the front bumper that regularly scrapes at parking barriers. It simply slips/clips into the plastic cover we call the splashshield. It has two wires.
If the temp sensor is missing along with the wires and connector, all of them can be bought from a BMW dealer for replacement.
But your comment that without this sensor the AC won't come on is intriguing. For even without it the AC should come on
although its proper operation is a little compromised (and would also show something like a negative 40 degrees reading).Perhaps you have an additional problem here. Fix the temp sensor problem and if the AC still does not turn on, tell me about it.
Getting a tune up is always nice. But an engine tune-up is most usually just a matter of replacing the plugs, maybe
adding an injector cleaner to your fuel tank, and replacing your air filter. Tune-ups for BMW is not a complex affair.
The problem of the back vents not getting hot (front ones are working I assume) can be due to a number of possibilities. Usually, the stepper motors inside the evaporator/blower assembly does not switch open the vents
concerned with rear heating. Or the switching itself is faulty. It is not a big problem but neither is it an easy one for an inexperienced mechanic. The switch if it is faulty is part of the AC/Heater control module.
And because of the AC not turning on, you may also need an
AC final stage.
Dealer repair or neighborhood mechanic repair or DIY?
It is your decision.
Tino
