Loose Intake Valves-Tight Exhaust Valves

[athflying79]

Ok..got married and back to real life....or as many have told me, the end of my life....but anyway.


Got back to the car today. I had ordered some new eccentrics and planned on putting them in during this valve adjustment (I decided since everything looked ok, to hold off on the eccentrics). Pulled the cover off and started checking the current clearances. Seemed all my intake valves got looser and all my exhaust valves were tigher. This is after maybe 5 hours of running since last valve adjustment. I took a really close look at all my cam lobes and they all seem nice and smooth. Everything seems to look good, no unusual wear from any one set of valves. Re-adjusted everything and cranked several times to check the oil spray bar. Good pressure coming out of all the holes.

The problem is, when I then rechecked the valves after cranking several times without starting....again my intake valves were loose and exhaust valves were tight. What would be causing this. I'm tightening the eccentric bolts pretty tight and I do re-check the valves after tightening....everything seems fine at that point. Could worn eccentrics be causing this?? I didn't think so cause it seems so uniform across all the valves...I chalk it up to something I'm doing wrong. I'm going to try and finish on Sunday, so any advice is appreciated.

[Jeff N.]

How much change are you seeing? Are we talking slight changes in the thousands of an inch range or more significant changes? Are the gap changes consistent across all intake and exhaust valves or different?

Sounds a bit like a cam positioning issue...but...I'm not really sure until you share more.

thx

[Martin in Bellevue]

I replaced the eccentrics on my m30 a while back. The old eccentrics wore a slight ridge, keeping the tip of the valve stem in the same spot instead of where the adjustment was intended.

[athflying79]

How much change are you seeing? Are we talking slight changes in the thousands of an inch range or more significant changes? Are the gap changes consistent across all intake and exhaust valves or different?

Sounds a bit like a cam positioning issue...but...I'm not really sure until you share more.

thx

I haven't had a chance to check the change in every single one since the re-adjustment. But when I did the re-adjustment 10 out of 12 valves were out of spec (going by Bentley's Spec of .012 cold). They all seemed to follow the same trend...intake loose, exhaust tight but I didn't actually check at that point how far off, though I should of.

I just ran out there and I was able to slide a .015 underneath the first intake valve. Have to go eat dinner out and will try and check all of them again and see how far each one is off.

[Jeff N.]

When I do mine, I do the first iteration and adjust each valve to the spec I want. Then, I roll the engine over and recheck each one to ensure that I have it correct. I usually find several that are off and have to adjust again (and recheck them again via another rollover).

I've found that by doing this, I've been much better at getting an accurate adjustment.

I'm also wondering if when you're tightening the ecentric nut if you're not somehow changing the setting. You say you recheck after you tighten right? A problem with procedure here might also cause this issue.



I haven't had a chance to check the change in every single one since the re-adjustment. But when I did the re-adjustment 10 out of 12 valves were out of spec (going by Bentley's Spec of .012 cold). They all seemed to follow the same trend...intake loose, exhaust tight but I didn't actually check at that point how far off, though I should of.

I just ran out there and I was able to slide a .015 underneath the first intake valve. Have to go eat dinner out and will try and check all of them again and see how far each one is off.

[Jeff N.]

...but wouldn't it still measure the same each time? That is, you'll measure the ridge to the stem each time but get the worn section to stem clearance. I would think it would be consistant(ly wrong).

Maybe not?



I replaced the eccentrics on my m30 a while back. The old eccentrics wore a slight ridge, keeping the tip of the valve stem in the same spot instead of where the adjustment was intended.

[athflying79]

When I do mine, I do the first iteration and adjust each valve to the spec I want. Then, I roll the engine over and recheck each one to ensure that I have it correct. I usually find several that are off and have to adjust again (and recheck them again via another rollover).

I've found that by doing this, I've been much better at getting an accurate adjustment.

I'm also wondering if when you're tightening the ecentric nut if you're not somehow changing the setting. You say you recheck after you tighten right? A problem with procedure here might also cause this issue.

This is my procedure. I roll the engine over till the intake and exhaust cam lobes are as close to down as possible on the cylinder I'm adjusting. Then loosen the eccentric and slip my .012 gauge in. I use a piece of wire to hold a bit of pressure on the eccentric to the feeler. Then proceed to tighten up the the eccentric nut. Before tightening to much, I will move the feeler around a bit to make sure I have the right clearance. If it feels good I tighten it down pretty good. Once I have done that I check again with the .012 feeler. Sometimes I'll try slipping in the .013 and the .011 just to be sure. At this point I have checked the clearance twice. I then move on to the next cylinder. Now once all are done, I can roll the engine over several times and it seems all my clearances go out of whack. Like I said, intakes loosen up, exhaust tightens up. It is pretty much uniform across all the valves. I am going to get up early on Sunday and swap all the eccentrics, just so I know I'm eliminating one possible cause. Then going to readjust all the valves again. Hopefully third time I get it. Then I will proceed to swapping the water pump out and getting to bleed the cooling system yet again. Any ideas on the valves are appreciated.

[Rustam]

Ok..got married and back to real life....or as many have told me, the end of my life....but anyway.


Got back to the car today. I had ordered some new eccentrics and planned on putting them in during this valve adjustment (I decided since everything looked ok, to hold off on the eccentrics). Pulled the cover off and started checking the current clearances. Seemed all my intake valves got looser and all my exhaust valves were tigher. This is after maybe 5 hours of running since last valve adjustment. I took a really close look at all my cam lobes and they all seem nice and smooth. Everything seems to look good, no unusual wear from any one set of valves. Re-adjusted everything and cranked several times to check the oil spray bar. Good pressure coming out of all the holes.

The problem is, when I then rechecked the valves after cranking several times without starting....again my intake valves were loose and exhaust valves were tight. What would be causing this. I'm tightening the eccentric bolts pretty tight and I do re-check the valves after tightening....everything seems fine at that point. Could worn eccentrics be causing this?? I didn't think so cause it seems so uniform across all the valves...I chalk it up to something I'm doing wrong. I'm going to try and finish on Sunday, so any advice is appreciated.

When you tighten the nuts pay attention to the direction in which you are pushing the wrench and the position of the valve. The force is sufficient enough to start compressing the valve springs. For that matter place the wrench is such way that you pull on it - so that it travels up away from the engine. This way the rocker reclines against the camshaft eliminating movement.

Tightening while pushing the wrench down results in movement of the rocker while compressing the spring - making final clearance smaller...

[Jeff N.]

From memory...

To reduce the clearance of:

The intake valve, roll the ecentric away from the cam.
The exhaust valve, roll the ecentric away from the cam.

To tighten the intake ecentric, the nut turns toward the cam.
To tighten the exhaust ecentric, the nut turns away from the cam.

Somehow, when you are tightening up the intake nut, you are rolling the ecentric. See how the tightening turns the ecentric towards the 'looser' postion?

Conversely, when you are tightening up the exhaust ecentric nut, you are rolling the ecentric tighter.

This is the only 'technique' explanation I can come up with. I'm going to guess you're tightening up the nut too much. Only takes a light touch, just a few foot lbs of torque. Personally, I've seen this when I've put a bit too much twist on one nut but never for all of them like you've described.




This is my procedure. I roll the engine over till the intake and exhaust cam lobes are as close to down as possible on the cylinder I'm adjusting. Then loosen the eccentric and slip my .012 gauge in. I use a piece of wire to hold a bit of pressure on the eccentric to the feeler. Then proceed to tighten up the the eccentric nut. Before tightening to much, I will move the feeler around a bit to make sure I have the right clearance. If it feels good I tighten it down pretty good. Once I have done that I check again with the .012 feeler. Sometimes I'll try slipping in the .013 and the .011 just to be sure. At this point I have checked the clearance twice. I then move on to the next cylinder. Now once all are done, I can roll the engine over several times and it seems all my clearances go out of whack. Like I said, intakes loosen up, exhaust tightens up. It is pretty much uniform across all the valves. I am going to get up early on Sunday and swap all the eccentrics, just so I know I'm eliminating one possible cause. Then going to readjust all the valves again. Hopefully third time I get it. Then I will proceed to swapping the water pump out and getting to bleed the cooling system yet again. Any ideas on the valves are appreciated.

[athflying79]

Well, the only reason that doesn't make sense to me is because after the final tightening, I recheck the gap and it is right. What I'll do is re-do a few using less force and roll her over to see what happens. I'm going to do the eccentrics as well.

What is the torque setting for the eccentric nut?? I don't have a Bently nearby. I usually tighten the nuts pretty good just because the first time I adjusted them, they needed quite a bit of torque to loosen. My concern was after several heating cycles they would loosen up, but guess not.

[Bill R.]

leave the adjusting tool on the eccentric and hold it right where the correct setting is while you tighten the eccentric..I always rotate my adjusting tool down with the feeler gauge in place, then just before i tighten it down i move the adjusting tool in the opposite direction, not enough to change the eccentric setting, just enough to provide a push against the eccentric while it tighten it down to keep it from moving while its tightened... Bmw doesn't have much of a problem with this happening its just an old habit left over from 30 years of vw's and porsches valve adjusts.
Also i always push the rocker face back down against the cam lobe after its tight with my thumb and check the gap at the valve stem one more time with the feeler gauge to see if it changed before i go on to the next one.






Well, the only reason that doesn't make sense to me is because after the final tightening, I recheck the gap and it is right. What I'll do is re-do a few using less force and roll her over to see what happens. I'm going to do the eccentrics as well.

What is the torque setting for the eccentric nut?? I don't have a Bently nearby. I usually tighten the nuts pretty good just because the first time I adjusted them, they needed quite a bit of torque to loosen. My concern was after several heating cycles they would loosen up, but guess not.

[athflying79]

leave the adjusting tool on the eccentric and hold it right where the correct setting is while you tighten the eccentric..I always rotate my adjusting tool down with the feeler gauge in place, then just before i tighten it down i move the adjusting tool in the opposite direction, not enough to change the eccentric setting, just enough to provide a push against the eccentric while it tighten it down to keep it from moving while its tightened... Bmw doesn't have much of a problem with this happening its just an old habit left over from 30 years of vw's and porsches valve adjusts.
Also i always push the rocker face back down against the cam lobe after its tight with my thumb and check the gap at the valve stem one more time with the feeler gauge to see if it changed before i go on to the next one.

Bill as always thanks for the advice. What I do is take the .011, .012, and .013 out of the feeler set. I loosen the eccentric, slide the .012 under there and then rotate the eccentric to tighten it against the feeler with my tool. I slide the .012 around a bit to get just enough drag and then keeping pressure on the eccentric with my tool, let go of the feeler gauge and use that hand to tighten the nut. After tightening I will jiggle the rocker arm a bit and then push down to pull the rocker arm from the valve which would give me the most clearance. At that point all seems good. Then I move to the next valve.

The problem comes when I turn the motor over, it seems all my specs go out the window as described. I thought maybe I wasn't tightening the eccentric enough, but maybe I'm overtightening.

[Jeff N.]

Angled gauges help quite a bit.


Bill as always thanks for the advice. What I do is take the .011, .012, and .013 out of the feeler set. I loosen the eccentric, slide the .012 under there and then rotate the eccentric to tighten it against the feeler with my tool. I slide the .012 around a bit to get just enough drag and then keeping pressure on the eccentric with my tool, let go of the feeler gauge and use that hand to tighten the nut. After tightening I will jiggle the rocker arm a bit and then push down to pull the rocker arm from the valve which would give me the most clearance. At that point all seems good. Then I move to the next valve.

The problem comes when I turn the motor over, it seems all my specs go out the window as described. I thought maybe I wasn't tightening the eccentric enough, but maybe I'm overtightening.

[joshua43214]

Lots of good advice on adjusting here. I would only add 2 things. One is to make absolutely sure the feeler gauge is not bowing over some obstruction, bend the gauge as needed to ensure it lays flat. The other thing that is frequently overlooked oil film has a thickness. I always overtighten enough to squeeze out any oil, then adjust properly. You will wear out the gauges over time, but small scaring on the gauge is no problem provided it still slides smoothly. I get maybe 100 valve adjustment per gauge before I break it from repeated bending or its too scared to trust. I also check the adjustment by cranking the engine with a remote starter as I slide the guage under the tappets rather than running back up the line 1 at a time, Its faster and more accurate once you have the feel for it.

[Rustam]

Well, the only reason that doesn't make sense to me is because after the final tightening, I recheck the gap and it is right. What I'll do is re-do a few using less force and roll her over to see what happens. I'm going to do the eccentrics as well.

What is the torque setting for the eccentric nut?? I don't have a Bently nearby. I usually tighten the nuts pretty good just because the first time I adjusted them, they needed quite a bit of torque to loosen. My concern was after several heating cycles they would loosen up, but guess not.

The setting for the torque is 10 +/- 1Nm or 7 +/- 1/2ftlb...

I never used this setting in fact this figure is new to me. There is a reason why you don't see a 10mm wrench of length 30 centimeters (1 foot) - it has to be short enough not to strip the thread that it is intended to be used for.

[athflying79]

I was using a Gear Wrench ratchet that had kind of an egg shaped end. As I would tighten, it was pushing against the valve spring which in turn was screwing everything up. Used the open end and everything works as it should.

My eccentrics didn't look worn and I didn't see what some refered to as ridges, but after replacing them, it was much easier to get the right adjustment.