85 740t burns oil below 1500rpm and at idle
#1
85 740t burns oil below 1500rpm and at idle
hello everyone, new here on the forums and was wondering if anyone could give me and idea. today I proceeded to cut the exhaust off before the cat and straight pipe it. when the job was complete and the car warmed up it blew steady blueish white smoke from the exhaust. (didn't happen on warm up but while car is idling when warm) smells like really burnt oil and rubber. car runs good not boost lost, still pulls strong with 235k.
I have a few ideas from some other threads but no of the situations were exactly like mine.. i appreciate any and all advice.
I have a few ideas from some other threads but no of the situations were exactly like mine.. i appreciate any and all advice.
#6
iirc, smoking at idle is a sign of worn valve guides more than rings/cylinders. a definative test woudl be if it smokes a lot going down a hill at speed with your foot off the throttle and downshiftedd so you're getting significant engine braking.
oh, if this is a turbo, there's another possibility, the turbo itself could be leaking oil into the exhaust out its bearings.
oh, if this is a turbo, there's another possibility, the turbo itself could be leaking oil into the exhaust out its bearings.
#7
Yeah, w/ your mileage, it's a crap shoot whether it is the motor or the turbo allowing oil into the combustion chamber. A compression test is in order. I asked about the oil because when turbos get worn seals, they can spew oil. Along with with worn seals, passages can get coked with old oil residue. Often, experimenting with different viscosity oils can make a big difference. I had a worn T3 on my 84 760 that smoked in a similar fashion after my first oil change. I had switched to 20W-30 Castrol GTX, an oil I've run for decades in 4 cylinder motors w/ success. Switched back to 10W-30 and the smoking all but stopped. Worth a shot...
#8
#11
doesn't it? you said it blows blue smoke when warmed up at idle. only way to know if its smoking on the road is to follow behind it and even then, a small stream of smoke might not be that obvious.
#13
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