Cam bearing surface slightly rough?

[Torchred96]

After taking out the cams on the driver's side (left the sprockets on) I noticed about 4 of the lifters on the intake cam seem to have bled down and are soft. Recall I'm working on a ticking lifter noise.. This after sitting for about a month in my garage. None of the exhaust lifters exhibit this softness..or sponginess..

I ordered the complete set of lifters for that bank (16) and am awaiting their arrival. And since I have time on my hands, my mind was thinking...perhaps overthinking as I tend to do....but,Im thinking that perhaps an oiling issue to the intake cam may have caused the lifters to collapse? Then, I went to look at the head and noticed that the bearing surface where the oil galley that feeds the cam appears to be rougher than the rest. How rough is too rough and should I try to polish it somehow?

Also..How can I check to see if oil is indeed flowing through this galley?

[Hib Halverson]

Originally Posted by Torchred96

After taking out the cams on the driver's side (left the sprockets on) I noticed about 4 of the lifters on the intake cam seem to have bled down and are soft. Recall I'm working on a ticking lifter noise.. This after sitting for about a month in my garage. None of the exhaust lifters exhibit this softness..or sponginess..

I ordered the complete set of lifters for that bank (16) and am awaiting their arrival. And since I have time on my hands, my mind was thinking...perhaps overthinking as I tend to do....but,Im thinking that perhaps an oiling issue to the intake cam may have caused the lifters to collapse? Then, I went to look at the head and noticed that the bearing surface where the oil galley that feeds the cam appears to be rougher than the rest. How rough is too rough and should I try to polish it somehow?

Also..How can I check to see if oil is indeed flowing through this galley?

I tend to think you don't need to worry about that.
Why?
Well...let's consider what would happen if there was no oil flow in that oil passage. There's be no oll to the cam bearing and the camshaft would have long ago seized up. Clearly, you don't have any camshafts which are seized so oil must be flowing to the cam bearing surfaces.

As pointed our earlier, the majority of the cam bearing wear occurs in the cam cover because load wants to push the cams outwards. If that cam bearing surface on the head seems more rough it may be because it's not worn.

Lastly, I would consider carefully using any abrasive to change that surface.

[Torchred96]

Thanks Dynomite and Hib. Well, hope these pics don't change your mind. Keep in mind the car has been sitting so the oil u see is not the circulating oil, it's just old oil i dribbled on it keep moisture/rust at bay. Btw the 2 pics are of the same bearing surface.

[Paul Workman]

I just happen to have a head sitting next to me (doesn't everybody?) and I see something on some of the bearing surfaces that looks like light scoring, similar to yours, but perhaps a little lighter.

There is some similar scoring on the cam cover bearing surfaces - perhaps slightly deeper (but still pretty superficial).

the head came off at approx 45000 miles to be ported. Up to then, it ran fine w/o any oil issues. Both heads had some of the same type of superficial scoring on some of the bearing surfaces, but deemed insignificant by me (and later by Pete).

For unrelated reasons, one head was damaged and I replaced it with a head off of a 92(?) LT5 that Marc was parting out. My motor now has 55k on it and there has been no problems with either head before or since.

All this to say you're probably OK. But, timing the cams is something best done with the motor out of the car anyway. So, sending the head off to one of the gurus for inspection and expert opinion and measuring is a consideration. (Can't really tell from the pictures...)

BTW...What kind of oil are you using?? I hope it isn't API rated "SN" or the like.

P.

[Torchred96]

Thanks Paul, Hib and Dynomite.. It's not going back together anytime soon I don't think. I still want to look at a couple of the bearings in the bottom end. I wasn't comfortabe with the noise it was making with a stethescope on the plenum..sounded like metal to metal rubbing somewhere...along with the ticking. I've never heard that before on my lt motors. I've haven't put that many miles on the car since I've had it in a year..maybe 3k if that. I changed the oil shortly after buying the car, again after the porting process and added only one quart since, all mobil 1 10/30 synthetic. Of course that was before reading recommendations.

The Cam surface on cam cover opposite this oil bearing doesn't look bad at all. Scuffed but not gouged. The cam itself is shiny and does not appear to have any aluminum transferred to it, nor is it scored like the head. All the other bearing surfaces look fine, in head and cam cover.

One thing that still gets me is that several of the intake lifters can be depressed with finger pressure approx 1/8" or so. ON the exhaust side, none of them are soft at all. Just wondering if that may be an oiling issure which is really why I started this whole thread.

[Hib Halverson]

Is there more than one cam bearing surface in the heads that looks like that?

What did the cam journal that was running on that bearing look like?

By chance, had you been doing periodic oil analysis? If so, can you post the last print out from the lab?

[Pete]

How many miles on the motor?
Has it been apart before?
Is it all factory assembly?
How do the cams look like?

From the looks of it they look like normal wear but without having it in front of me to feel how deep the grooves are can't really say for sure/100%.

Use some Scotch bright on one cam bearing surface and see if it polishes smooth then it's ok,you will not hurt anything.

It is very hard to find one ticking lifter if you know which bank it is i would change all the lifters on that bank.

Had this same issue with a friends low mileage Z (20k) we just changed all the lifters and no more ticking.

Melling JB-2236

Pete

[Hog]

Any issue with putting a new lifter surface on a lobe surface that was broken in against a different lifter?
This a no-no on any other non-roller cam engine. The cam lobe and lifter burnish together as the lobe slides on the lifter which causes the lifter to rotate evidenced by the round burnished areas.


Be careful with Scotchbrite, its reminents are murder on bearings if it is circulated in oil. Be sure to wash all possibly exposed areas well.
I would say that you could do damage with a Scotchbrite cookie on a rotary, but a handheld pad would mitigate any risk. I'm sure that was what Pete was referring to.

GM wont pay engine warranty work to dealerships if there is evidence of Scotchbrite use.

peace
Hog

[Torchred96]

Ok Guys. Thank for your input. I am, as Dynomite said having basically a dual post from the other forum, not for any particular reason other than I know that others might be interested in what I found and what you guys say. I'm trying to remain a-political and stick to the facts. I certainly appreciate all of your help.

Pete: The car and engine have approx 140k miles. I've had it a year and put on about 3k. Much of that was pre-new injector/porting etc, when it was running very poorly. After that, the car ran unbelieveably well, far exceeding my expectations..as well as my old hotcammed lt4 I assumed the heads have never been off. At least it did not appear to me to have been. However, inside the left cam cover appears to be painted the letters FU2. I don't know what that means, maybe someone had this head redone at one time. I can't tell. I bought the car without knowing any history except what carfax told me and the dealer who sold it to me.

Appears to be a factory assembly. All I did to this motor is port intake, IH and remove secondary port throttle plates and shafts, and coolant bypass etc..Also changed oil 2 times in 3k miles because of the above work that I did and not knowing the history when I bought it.

Basically The cams look excellent to me...no obvious wear either on the lobes or the bearing surfaces, and especially surprised that none (scratches) is where the scratched bearing surface are that I posted pics of. Honestly The pics are the only thing in the head that caught my attention OTHER than the 4 or 5 intake lifters that are soft. And again, NONE of the exhaust lifters on that bank are soft.

If you look closely at Dynomites photos, you can see little specs that look like pits in the aluminum. In mine, they are similar, pin hole small. That's basically what the rest of them look like.

I think I will carefully try the scotchbrite idea and report back my results.

Hog thanks for the tips. I won't be using anything so aggressive. I've heard that about lifters and cams too, but what is the alternative when you have bad lifters. Unless you're implying that it's time to upgrade my cam...while im in there?

[Torchred96]

Is there more than one cam bearing surface in the heads that looks like that?

What did the cam journal that was running on that bearing look like?

By chance, had you been doing periodic oil analysis? If so, can you post the last print out from the lab?
__________________
Hib Halverson
Technical Writer
95 VIN140

Hib. No That's the only one that concerns me. The cam journal looks fine. No metal appears to have transferred to it from the head, and it is not scored..You can tell where it was riding, but it's only discolored as far as I can tell.
No oil analysis. Honestly I wouldn't even know where to get that done. Only changed the oil 2x so far in the circa 3k miles i've owed it.

Thanks for your responses.