Destroyed Cam Bearings!

[6TIME]

Hey guys, I originally posted a topic on some vibration issues with the new stroker motor. I tore it down the other day and found more problems than I was expecting to see.....The cam bearing material oozing out between the cam journal and the Bearing. Looks like #2 and #3 are the worst #1 isn't as bad, and #4 is untouched. The soft babbit is almost peeled away from the shell of the bearing. Motor had 25 hot idle and 40-60 above that. I used LS1 Springs set at relatively low pressures 90lbs seat and 245lbs open. I used the Lunati 63500 cam and the valvetrain was super quiet at 26k with absolutely no binding anywhere. Have a look........
#2 #3 Closeup#2 Closeup#3#1This pic is of #1 Cam journal on a 4.0 I had with a Comp 232-4 it ate up the Cam Bearings too ... after 76k tho.

[SilverXJ]

I don't see a pic of a cam journal. I do see a pic of a bearing though. I don't know if it is a typo or terminology issue. But, the journal is the part of a cam that meets the bearing.

Looking at your pics makes me queasy because they remind me of my own problems. The last attempt I made I had coated came bearings, a windage screen and a solid pin to replace the stock cam pin and spring. That was on top of a HV oil pump and restrictor push rods from previous attempts. All my bearings had failed with very low mileage (like 200 miles) and I saw bearing material pushed out of the bearing as you have seen. On this attempt I had checked the bearings at 600 miles and haven't seen any material pushed out. I not have around 1900 miles on it and will probably check around 3000 miles again, but slide the cam out some to get a better look.

I can't say that one thing fixed mine and I can't say that they are entirely fixed yet. Seanyb505 and Dtcgrant on here have both had cam bearing issues besides myself.

My thread is here: http://www.jeepstrokers.com/forum/viewt ... ?f=8&t=444 as well as this one on Speedtalk: http://speedtalk.com/forum/viewtopic.php?f=1&t=22211

I would recommend
1) having the cam check for straightness
2) having the journals polished while the cam is rotating clock wise from the front of the cam
3) Check the cam bore for straightness
4) inspecting for oil leaks
5) replace the spring and pin with a solid pin with .003"-.008" of end play w/cover and gasket installed,
6) possible coated cam bearings
7) check your oil pump and fitment to the block using the thread I posted which is in the FAQ forum.

Also, did you notice anything that would have caused the bearing failure? Missing front oil galley plug perhaps? Any other bearings show excessive wear? What lifters were you using?

-Chris

[dwg86]

Check for excessive cam end play (cam walk). I would use a solid pin instead of the pin and spring.

[6TIME]

[quote="SilverXJ"]I don't see a pic of a cam journal. I do see a pic of a bearing though. I don't know if it is a typo or terminology issue. But, the journal is the part of a cam that meets the bearing.

Silver, I did not post pics of the cam journals....Must have been grammar mistake! I pulled the pan and then saw the bearing material hanging out next to the camshaft journals, I knew the bearings were toast so I yanked the cam and took pics of the mangled bearings. The cam journals were surprisingly not damaged at all. I talked to my machinist today and he was pretty sure it had to do with the surface Ra of the camshaft journals. He said he's seen this in various types of engines. They micropolish the bearing journals on every camshaft they install. They have a profilometer so we will see how Lunati did on polishing the cam journals. Mahle/Clevite says they want a 10Ra or finer journal suface for reliable service with their bearings. I'm not fully convinced yet! All of the obvious variables that you listed will be checked like: cam runout, tunnel straightness, etc... I've read your saga on another forum that I frequently visit for V-8 resources. I feel your pain having that stroker apart many times. It makes me wanna second guess a once very very reliable engine..........

[SilverXJ]

I doubt the RA is the problem.

[6TIME]

I really don't know at this point what the problem is either, Just trying to eliminate variables. It seems that this cam bearing failure is only apparent in motors with aftermarket cams. I dropped the parts off today at the machine shop and had a long talk with the owner. He's still dead set on surface finish of the journals. He said he's seen this type of failure in just about every engine family and that it's a quality control issue with cam makers. I'm open to his idea but skeptical.... The lifters I was using were factory sealed power with the flat spring loaded disc inside. There were no oil passage plugs missing and nothing unusual or abnormally worn otherwise.

[dwg86]

What year block and timing cover did you use?

[6TIME]

I used a 92 block and a timing cover from my Original 93' 4.0

[IH 392]

What brand of bearing are they?

[92tank]

im starting to believe that the spring and pin cam retainer are NOT capable of preventing cam walk. that is probably why chryco went with the new plate style, but cam makers havent made a cam to use them with. so my guess would be use a solid pin with proper end play.


or is the problem with the oil pumps makeing the cam walk?

[wjtom]

my question would be why only 25 lbs of oil pressure with a high volume pump?every jeep i have owned with 100,000 on it has had 40lbs hot.my stroker has 40lbs hot with a stock pump.might be something to look at.is it possibly the oil everyone is using?you must use an oil with the zddp package.getting very tough to find on the shelf.unless you use a specialty oil or add the additive yourself.

[SilverXJ]

25 PSI with a HV pump would be too low, but the OP didn't say he was using a HV pump. With a HV pump you should have around 40 psi at a hot idle. 40 psi hot with a stock pump I would like to investigate, starting at the stock oil sender and testing with a mechanical gauge.

As for ZDDP, it has no issue on bearing surfaces of this type as the cam bearing should not see that much force/friction. Especially considering it is a pressure fed bearing. This is not a cam lobe/lifter failure issue.

[I6FAN]

I'm not totally convinced these failures are due to cam walk. How much can the cam move, and how much does it take to loose the hydraulic wedge? Someone said that the FSB on the cam retention mentions a "bumping" sound, and no mention of cam bearing failure. However, these engines are not using stock cams and timing sets, so something more drastic than "bumping" could happen. If that were the case though, I think we would be reading hundreds or even thousands of cam bearing failure threads.

4.0 I had with a Comp 232-4 it ate up the Cam Bearings too...after 76k tho.

What components did these two engine share?

[6TIME]

Stock Sealed Power oil pump was used. I'm not thinking cam walk is the issue either. It'd have to move pretty far to lose the oil film wedge. The only two things that the 4.0 and my stroker had in common was an aftermarket cam and different springs. Oddly enough, I ran the 4.0 with waay more spring pressure starting out with the 926 Comp springs they recommended. That motor went 3x further than my stroker and the 4.0's Cam bearings were definitely worn but nowhere near as worn as the new stroker's bearings. That 4.0 was pulled at 76k when I lost a lobe on the cam. Everything else looked great. Still scratching my head........

[Cheromaniac]

im starting to believe that the spring and pin cam retainer are NOT capable of preventing cam walk. that is probably why chryco went with the new plate style

I very much doubt it. All the stock 4.0 engines made from '87-'98 had the thrust pin/spring to prevent cam walk and they didn't have any cam issues, so I think we can safely rule out cam walk as the cause of the cam bearing failures.

25 PSI with a HV pump would be too low, but the OP didn't say he was using a HV pump. With a HV pump you should have around 40 psi at a hot idle.

I don't think so. All else being equal, the HV pump will raise the oil pressure by 25% compared to the stock pump so if you're getting 20psi hot idle with a stock pump, you can expect 25psi with the HV version.
My stroker's hot oil pressures are 25psi idle and 50psi above 2000rpm with 10W-40 oil.

The way those cam bearings are being squeezed out at the bottom like toothpaste suggests to me that there are excessively high vertical forces acting upon them from above. The one common factor in all of these cam bearing failures is the aftermarket valve springs so it would be interesting to see if these failures can be prevented by using the softer stock springs.