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I had several intake valves that were slightly out of spec (tight) at my 60K inspection.yechave said:I am looking to see how often you have found it necessary to adjust the valves between 6k and 60k miles, and were they any that were more than 1 or 2 thousandths out? Is there a point where it is not that likely they need further adjustment? Thanks!
Beleive me, if you get as far as checking the valves, you are almost there. I have done it, and I am no grease monkey. All you then need to calculate is what size buckets you have in there, what you need in there and put the new ones in. Very little expense compared to what you will be spending if it all goes pear shaped.yechave said:I did not want to take it apart to check the valves to find it then needed to go to the dealer anyway to adjust them. Don't need the expense and did not want to deal with the long wait to get an appointment. I
Tight valve clearance is only a couple thousandths, so has no bearing whatsoever on valve to piston clearance. Tight exhaust valves however, can cause premature burning of the valve/seat, which when started will cause valve work to be needed far ahead of normal, which is probably well in access of 250,000 miles if kept adjusted properly.LAF said:When I talked to my Service Manager on this topic and expense at 12,000 he said do not worry about it. At 12,000 we will go over it and listen with a stethoscope and if it sounds fine go to the 18,000 and do it then.
This is why I like this Dealer because he also feels the BMW maintenance schedule is aggressive, and believes that listening, checking the fluids well when drained, visual inspection, and how I feel the bike is running a better gage of maintenance. He told me flat out he will do what he feels in his opinion needs done, and if breaks in warranty, he will fix it, period.
I would think the biggest issue, that I was not aware of until someone on this Forum posted is the LT valves wear tight.
Now a loose valve you can hear pretty well.
I am not totally sure of what symptom (s) of a tight valve would be?
What, combustion wise, would a tight valve create?
I assume that a tight valve is one that is dropping farther into the cylinder, thus getting closer to being able to strike a piston?
I want to get the first one out at the dealer, but from then on I would like to do it. As others have said 12,000 is pretty quick and I sure can live with 18-24,000 checks if it seems safe to do so.
I guess on a used bike you have to do it once to see where you are as a point of referance anyway.
dshealey said:Tight valve clearance is only a couple thousandths, so has no bearing whatsoever on valve to piston clearance. Tight exhaust valves however, can cause premature burning of the valve/seat, which when started will cause valve work to be needed far ahead of normal, which is probably well in access of 250,000 miles if kept adjusted properly.
The reason is that all solid lifter cams are ground with "clearance ramps" which take up the normal clearance fairly slowly until all the clearance is out, then rapidly open the valve. That is to reduce both impact damage and noise. If the valves are allowed to run below normal clearance range, the valve starts to open slowly (relative) on the clearance ramp before being opened on the fast opening ramp. This slow opening causes hot exhaust gasses to blast through the tiny gap at ultransonic speed for much longer than in normal valve opening, and that starts to erode the seating surfaces. Those very tiny, microscopic size erosion pits then fairly rapidly enlarge until you have a noticeable valve leak, which progresses quickly to badly burned valves and seats requiring a valve job.
The valves and seats in the LT engine must be pretty darned robust though, becausee for the several years I have been on this site, I don't recall anyone requiring a valve job! Maybe because we usually preach "don't let your valves run tight!", and most heed the warnings.
Loose valves are not as much of a problem, but on the LT engine (or any cam over valve design) the normal pattern is for them to wear tight, not loose.
You still are a bit Lee. The valve seat is what wears on the LT not the bucket. As the seat wears the valve stem is now "approaching" the bucket and if close enough it will not fully seat - thus burn more valve seat away. That is why the valves wear tight rather than loose.LAF said:Thank you VERY much on that explanation.
I was assbackwards.
I understand now that it is the valve not opening enough. And because of the overhead cam on the buckets wearing on the buckets not opening the valve to it's full throw. Which how far is that in one of these? I mean how far doest the valve open into the cylinder?
Got it................jzeiler said:You still are a bit Lee. The valve seat is what wears on the LT not the bucket. As the seat wears the valve stem is now "approaching" the bucket and if close enough it will not fully seat - thus burn more valve seat away. That is why the valves wear tight rather than loose.
Think of it as the valve is not closing enough. Hope this clears it up.
Have you owned it since new?rab1967 said:Had my 99 LT checked at 50,000 miles and still good. No adjustment needed