Ok so my engine at idle has a knock its noticably loud at idle (cant hear it while driving), also accompanied with a kind of loping idle, I am wondering if that sounds like im headed toward engine failure, also my valve train makes alot of noise above 3krpm’s i was wondering are these noises normal for the engine its a 325is 1987, mileage is 164k,
Engine noises
robweenerpi
#3
Lifter Tick??? Oh wait that’s only my car.
If you are still learning the car and can’t isolate it right off the bat. Take a long flat screwdriver and place it up to the valve cover and other areas and listen to it. It lets you hear whats going on in greater detail. Just stick the screw driver up to the valve cover and your ear to the end of the screwdriver.
Just take your tie off first.
Post edited by: robweenerpi, at: 2005/08/16 18:52
Carter
#4
My would hardly idle at all when I bought it. I pulled the idle control valve and cleaned it out with brake clean. It helped some but some of the guys still swear that I put a cam in the car. B)
Chassis dyno at the next race.
Carter
Loping Idle generally is a lean/rich condition caused by the O2 sensor reacting to a vacuum leak. you should look at all the regular places air leaks and fix those first. the big AFM to TB boot generally cracks on the bottom, in the bellows area. The PCV hose hardens and cracks, especially at the valve cover. the vacuum hose that attaches to the fuel pressure regulator is suspect as well.
The press fittings in the side of the throttle body that supply vacuum to the brake booster loosen over time. The throttle body gasket is a leaker sometimes too. Oil filler cap gasket is another place.
The way I find these leaks is with a propane torch with a long piece of tubing on it so I can let the propane flow toward the suspected leaks. if it is a leaker, the mixture will richen up and you will hear it. Just be careful with the propane and DO IT OUTSIDE!
Once the air leaks are fixed, verify or replace the O2 sensor. I have found the best price on that OEM/Bosch from Advanced Auto Parts~~~73.00 or something.
do a valve adjustment on a stone cold engine, if you don’t have the bentley manual, get one because the detail in that book is pretty good. then do it again. you will be surprised how many cylinders will need to be adjusted the second time. you should pull the plugs to make turning over the engine easier so replace them with the proper W8LCR Bosch plugs. These are the best for this engine.
They all make a little valve train noise and they all do not idle 100% smooth at this age.
Carter’s idea of cleaning the IAC is a good one and replacing the fuel injectors or sending them off for cleaning should yield improvements as well.
Lambda Control 1