Northstar Engines and System Technical Discussion Discussion, Lifter starting to tap and needs replacing, in Cadillac Engine Technical Discussion; this is a continuation from another thread that I started "grinding noise" which was another problem although this problem started ...
this is a continuation from another thread that I started "grinding noise" which was another problem although this problem started while I had the other thread going.
I started to get a tick in my engine but it would only tick about 2-3 seconds at idle and then it would go away for about 6 seconds. This pattern was repeated over and over where the engine would be quiet at idle for about 6 seconds and then tick for about 2-3 seconds. This went on for about a week, maybe 10-15 miles of driving and then it started to tick all the time once the engine was warm. When First started there is no noise but when it warms up, the ticking starts. I changed the oil twice and the second time I used fleet oil like Submariner mentioned and it made no difference. I see nothing in the oil or filter, clean as a whistle.
I now removed the cam cover on the front bank suspecting that a lifter if bad would be the #8 exhaust. All of the lifters look like mirrors, not a scratch or any imperfection that I can see. The timing chains that I can see look good along with the tensioner. I can't see under the cam lobes but I doubt there is anything therefrom what I can see now. Can I loosen the cam caps and lift the cams just a bit s I can see underneath? Does anyoine knoe the torque spec's for the cam caps? I know I need to keep the cam timing unchanged so I would mark the position of each in the event something moved.
I tried to attach a picture last night but somehow lost my post so I'm not going to try that again for now.
Any suggestions on where I go from here other than remove the cover on the rear bank.
A local Cadillac mechanic who has worked on cadillacs for years said they have never changed a lifter on a N*. From reading here, it seems like there are a lot of lifters being worn out and changed.
Another important note, the tick had turned into more of a tap when I decided to remove the cover, it's no longer a light tick rather a pretty good tap, it seems like something would show on a lifter or cam lobe!
Lifter-wise, nothing to add to my previous posts. Eyeball each pair of cam lobes (2 intake and 2 exhaust lobes) for each cylinder. Are they all matched for tip height, i.e. one lobe of a pair doesn't seem more "rounded off" ??
While you're in there, pull the plugs and see what they look like. All in one piece, no pieces of electrode missing ? Tips light gray to brownish gray ???
Submariner, do you know if the two lobes per cylinder are timed the same, for example do both of the exhaust lobes for Cylinder 8 open and close at the same time, they appear like they do but there could be soem overlap. The only thing I noticed is that the very last lifter, when the valve is fully opened, looks like it's down in the bore about 1/32" from the top of the lifter boss. The other lifter from the other lobe appears to be flush with the lifter boss just like all of the lifters from the other cylinders.
It could be the way the head is mchined and means nothing but it is down below the top of the lifter boss if that means anything. I guess these lifters can collapse and of course not running and sitting, it could've went down that little bit. The lobe for that lifter looks good as does the lifter. I didn't drive it very much, maybe not even 10 miles so there may not be any visual signs.
Submariner, If all of the lifters were good, that is the surface that's good but one of them for one reason or another is collapsing enough to make the tapping noise, do you think that with about 20-30 minutes of run time there would be evidence of which lifter it may be.
I'm thinking that I haven't driven it enough for any physical damage to show up yet and how would you know which lifter is collapsed?
I know I'm getting ahead of myself because I still have the back bank to look at but, in a way, I'm discouraged thast I didn't find something on that front bank.
Does anyone know if the back cam cover is harder to get off than the front cover or is about the same amount of work. That front cover wasn't that bad but it wasn't that easy either. I guess what I want to know is will I have to loosen a motor mount to remove the back cam cover? I'm getting older and it's hard staying bent over these cars for a significant amount of time!
These are the two best pictures I could come up with, no matter how I turned them the light would reflect back into the camera lens. I tried two different cameras and still these are terrible pictures.
This is the last exhaust lifter from cylinder #8. There is a groove in the middle the width of the cam lobe, disregard the grainey surface, that's the camera. It's obvious this lifter quit turning in it's bore therefore the groove in the middle where the cam lobe rides. There is an indentation maybe five thousands of an inch, not much but it's really the only sign of a problem.
In the prior post, the picture with the car in the background shows the indentation the best.
This is what I decided to do before taking the back cover off, remove the cams in the front so I could get a better look at the lifters. In doing so, I see that exhaust lifter is aproblem, may not be the one that started tapping but then again it could be. I'm going to replace that lifter and out the cover back on, start the engine and see if the tap is still present, if it's gone, great, it as that lifter. If not, then I remove the rear cover and go from there.
I'm almost convinced that the lifter with the indentation is the problem. It appears that it quit turning and maybe could've pumped down which in turn caused the indentation from the tap I was hearing. I took a wrench and tapped this lifter on the bottom with a cloth around the wrench, of course I tapped on a non contact surface area and it sounds just like the tap I was hearing.
Any suggestions or contradictions to what I'm thinking, I don't want to do this again and hope to get it right the first time around!
This is a little off topic but I found this interesting. In the last thread I started, I had mentioned I didn't notice any difference in the performance of the engine and that it still would idle like a top, how could I have a bad cam lobe, lifter etc. etc.
I was getting ready to go to bed one night thinking about my problem with the car and I kept repeating to myself, double the valves and double the fun which 97EldoCoupe puts at the end of his posts. That's when I realized or it dawned on me that the N* has 4 valves per cylinder. Even if a cam lobe is ground down to nothing you still have another valve that's operating like it should and that cylinder will still fire pretty decent.
I remember commenting that if an exhaust valve or lobe was gone the engine would backfire through the intake but that's not true with an engine that has 4 valves per cylinder. Sure you would probably hear a loud tap or knock with a lobe ground down or a lifter that's ground down to nothing but the engine will still run pretty darn good and still make pretty good power.
It was that comment from 97 EldoCoupe that got me to thinking about that. I'm old school and the first thing I do is listen to the idle if I have a problem. With an N* you can just about throw the idle procedure out the window if your looking for a valve train problem.
rodman, Go ahead and replace that follower (lifter) pair. Be sure to use CompCams, Engle, or Edelbrock cam breakin lube. Better yet, lube ALL the lobes and follower faces before you bolt down the cams.
I thought it was best to replace the cam anytime a new lifter (set) goes in, and new lifters when a new cam goes in (or replace with a used cam with the lifters that were broken in on it). Is that just belt and suspenders thinking?