Reply With QuoteTim - did you inspect the cam lobes for scoring? If you have cam damage, you'll be able to see it. Otherwise, you may just need to adjust the valves.
Jeff
Banjo bolt backed itself out, front end ticks now... how bad is that??
So I've been hearing some noise from the engine lately, so I decided to do a valve adjustment, hoping it was just a noisy valve... Pull the cover off, and I see a banjo bolt just lying there... dammit! The frontmost bolt had worked its way out and off the rail, and was just lying there in a valley. Luckily, I had Don's new bolts in hand, so I replaced them and adjusted the valves to .013, replaced the cap and rotor (Bosch), new igntion wires (Bremi), and a set of new plugs (NGK V-power, .30 gap). Put everything back together, and fire it up... still hear the damn metallic tapping from the front of the engine. So... how bad is it? Does this just mean I'm going to have a noisy engine (I can live with that), or is something damaged and going to fail in the future? I also snapped the stupid bolt that bolts the valve cover down (the front one, only bolt on there as opposed to nuts everywhere else), half of it's hanging out in the head somewhere... whatever!
Anyhow... anybody know what that noise means, and is it going to get worse or will something break?
-Tim
total casualties: 1 snapped valve cover bolt, one banjo bolt (AWOL), 1 twisted allen key (from trying to loosen the rotor), and 4 skinned knuckles (gotta love spark plug #6!!)
Grand Master
Tim - did you inspect the cam lobes for scoring? If you have cam damage, you'll be able to see it. Otherwise, you may just need to adjust the valves.
Jeff
Bellevue WA
90 535iM - not much stock remains. 3.7 liters, ported head, cammed, 3.73 diffy, M5 brakes, MAFed, yadda yadda yadda
86 Porsche 951 - Track Toy
Adjusted all the valves to .013, looked at the cam lobes, but they didn't seem to be "grooved" or anything where the rocker contacts them?Originally Posted by Jeff N.
Major Contributor
Valve ticking
If you can isolate which cylinder(s) it is with a stick held up to your ear, take the cover off again, take a close look at the tip of the valve stem & maybe take the eccentric off & make sure the stem isn't cupped or the eccentric has any flat spots. Next time I adjust mine, I'm going to replace all the eccentrics and pinch bolts. It might be a bit of overkill but they've been adjusted so many times I'm afraid one of these days I'm going to snap off one of the pinch bolts when tightening it & I did remove a couple eccentrics last time & examined them under magnification & could see that there was a slight sharp corner at the end of the worn patch & the virgin portion just beyond where it rubs, & could be responsible for some ticking when swivelled to a new position when adjusting them. Not much you can do for a cupped or pitted valve stem short of a valve job. Also could be a noisy injector, try the stick trick with them too.
Also, even tho .013" is better for smoother idle, right now I have mine set at a tight .012 & next time I'm going to set them at .011, it seems to have a bit more power & smoother at upper rpm's with a tighter setting & I'm willing to sacrifice idle for that. Rarely do we hear of an m30 with a burned valve so I'm not worried about running them tight.
gale
92 735i 5-spd, turbo project finally underway!
Grand Master
yup.
Loose valve settings effectively retards the cam timing a small amount. Setting to the factory spec should help upper RPM timing. Loose settings also minimizes any overlap which accounts for the smoother idle.
Everything you say makes sense Gale.
Personally, I find I prefer my valves set on the tighter side than looser side of spec.
PS - package arrived!
Bellevue WA
90 535iM - not much stock remains. 3.7 liters, ported head, cammed, 3.73 diffy, M5 brakes, MAFed, yadda yadda yadda
86 Porsche 951 - Track Toy
Grand Master
Agree with what Don wrote as well Jeff. As with Bill R...hard to find a time when we didn't agree about these cars :-) I have mine set to a slip .013" and have considered setting them to .012" as well for the reasons stated. I like .013" for idle quality however and my engine still revs like a drill at higher RPM...pulls hard for a big car with a modest power to weight...so am enjoying the decent idle. Agree that the modest overlap and lift increase of setting the valves fractionally tighter would make it pull even harder.
I love the big six and enjoy talking about it with you guys. I too should consider changing my eccentrics. I haven't looked at them under magnification but if I did, would probably find the same condition as what Don mentioned since our engines have about the same mileage. One last comment about valve adjustment...I find that it is pretty easy to strip a pinch bolt here and there. The threads are not very deep or big or robust. Easy to over torque the pinch bolt with a small 10mm box end wrench. I torque these by feel and generally do not like to ever over torque anything. My biggest concern however is one coming loose and causing disaster so I generally try to get a good sense that I am getting adequate torque on those pinch bolts and that the threads are not stripping.
George....by your package Jeff...I presume it is from Don for safety wire and banjo bolts. Hats off to Don for offering this service to the board....wonderful contribution to this community of bimmerheads.
Super Moderator
Don, valve lash caps could be used to repair a damaged
stem provided you can back the eccentric off far enough for them to fit.
And keep in mind as your tightening the valve clearance that the cams aren't pressure fed.. that you're depending on drip and it needs clearance between the cam and rocker in order for oil to get in there for lubrication for the 2 surfaces... a couple of other things to mention are valve stem rotation for cleaning the valve seating surfaces and heat transfer..
You don't hear about too many burnt valves but you do hear about dropped exhaust valves, I don't know if reduced heat transfer is related to the fatigue issue that occurs on the valve tulip and stem area resulting in dropped valves or not but just thought it might be a good idea to bring up these points. I personally would rather err on the side of looseness rather than tight...BYMMV
Grand Master
all excellent points...why I too run mine on the loose side....the cam in effect ends up doing slightly less work with the valves set a tad loose or on the high side...as the valve is picked up a little higher on the lobe and gets off a bit sooner...much of the valve train benefits including the springs, lobes etc...
George
So, a ticking noise, caused by oil starvation off the spray bar... the general consensus is... dangerous, or no?
Come on guys... I haven't driven this thing in 2 weeks, I want to take it to work!!!
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