Why so many spun cam bearings
#41
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I may be able to mic the one all the way in the back as that is the only one still intact anymore. I'll also mic the stock cam on that journal and my tick cam that is destroyed. Think that last journal is ok tho. I'll check it out in a little while. I'm assuming this is only happening with aftermarket cams? Wonder y no cam vendors have chimed in on this as this should be concerning them. Unless we all didn't run enough oil in the pan ???
#42
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So I measured the last journal cam bearing in block and cam journal measurements. Block cam bearing measures 2.1450"
Stock cam and tick cam both measure 2.1640"
This is as accurate as I can get. Are these within specs ? Not sure what it should be.
Stock cam and tick cam both measure 2.1640"
This is as accurate as I can get. Are these within specs ? Not sure what it should be.
#43
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Does anyone's 5.3 turbo start harder after there is heat in it ? Car starts great when cold but as I drive it and go to restart after it gets heat in it it seems to crank harder? I have a dei starter heat shield and my dump pipe is wrapped below starter and battery is brand new. Just wanna see if it's common starting harder after its hot ?
#47
9 Second Club
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Centre 3 are the easiest.
I drilled down through the valley, tapped it out M5 ( UK, we're metric here ) then screwed a grub screw into the hole.
I didnt tap right through the bearing, just partly so there would be some degree of interference fit and screwed grub screw in until it stopped cam from rotating, then back 1 full turn. So that leaves about 1mm clearance from the cam.
I loctited these into place
Front and rear are a little more awkward due to access.
I got a Desoutter 90deg drill ( aircraft industry tool, very compact for specific jobs ).
This allowed me to drill through the bearing and into a solid portion of block. Then I cut down a set of taps, welded a nut onto the top of the shortened tap so I can actually screw it in/out, and tapped the blind hole.
After this then again got some m5 grub screws and screwed on for same arrangement. ie approx 1mm below the surface of the cam bearing and loctited into place.
Whole process less than 2 hours.
Pic of grub screw in front bearing
![](http://www.evo-host.co.uk/getimg/32025.jpg)
And type of drill that allows access ( a friend got me mine second hand ). If you dont have one of these or access to one, then the job would be difficult. New these can be expensive.
I drilled down through the valley, tapped it out M5 ( UK, we're metric here ) then screwed a grub screw into the hole.
I didnt tap right through the bearing, just partly so there would be some degree of interference fit and screwed grub screw in until it stopped cam from rotating, then back 1 full turn. So that leaves about 1mm clearance from the cam.
I loctited these into place
Front and rear are a little more awkward due to access.
I got a Desoutter 90deg drill ( aircraft industry tool, very compact for specific jobs ).
This allowed me to drill through the bearing and into a solid portion of block. Then I cut down a set of taps, welded a nut onto the top of the shortened tap so I can actually screw it in/out, and tapped the blind hole.
After this then again got some m5 grub screws and screwed on for same arrangement. ie approx 1mm below the surface of the cam bearing and loctited into place.
Whole process less than 2 hours.
Pic of grub screw in front bearing
![](http://www.evo-host.co.uk/getimg/32025.jpg)
And type of drill that allows access ( a friend got me mine second hand ). If you dont have one of these or access to one, then the job would be difficult. New these can be expensive.
![](https://webshop.cashconverters.com.au/thumbnail/850x520/1533041-desoutter-angle-air-drill-dr300-t3000-t5-90-0.jpg)
#50
9 Second Club
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I wont name names, because I do believe it was a reputable build from a solid builder. I bought the shortblock from a Tech member though, new and unused, not directly from the builder.
I dont know whether the bearings were OEM fitted, or these were replaced, that's a good 5/6 years ago or so
I had no reason to mic the cam, as it resided happily in the previous LS6 blocked engine for a couple of years with no issues.
The LS2 ran for about 2 years before I took it apart to change some stuff and spotted the front bearing had almost walked right out, but as said, I took it apart for other reasons, it was just lucky I caught this at the same time.
Despite the huge hole in the oil system this would have left, oil pressure was still very good.
Next time it happened I've little doubt it was my fault for my DIY attempt at fitting bearings. This only lasted a few hundred miles, different cam though.
After that I decided **** this, got new bearings fitted properly and pinned them too. 2 years on and cam bearings were still perfect....couldnt say same for the mains though, but that's another issue.
Pic is from the more recent build with a brand new LS2 block, and I presume OEM bearings as they dont look aftermarket.
Whether it's needed or not I'm pinning it anyway. It's easy for me to do, costs almost nothing, and means the bearings will never walk. No brainer really.
#53
9 Second Club
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Neither had I until it happened me. Then when you start searching for answers or reasons why....you find it does happen to others.
It shouldnt be a fix, it shouldnt be needed. But pinning cam bearings isnt new and others have done it long before me.
I still dont know what the cause was, or causes can be. I just know that pinning will certainly stop it from happening again
It shouldnt be a fix, it shouldnt be needed. But pinning cam bearings isnt new and others have done it long before me.
I still dont know what the cause was, or causes can be. I just know that pinning will certainly stop it from happening again
#59
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Well add two more second to last bearing failures to the list.
One I heard about and the other one I looked at.
The one I heard about was a gen3 that they had just put a crane n20 cam into...Spun less the 100 miles later.
Welded the bearing to the cam.
The one I seen, was a gen4 5.3 that they had just put a comp cam into.
It spun less than 30 miles later. Same thing as the other one, welded the bearing to the cam.
You can see were the block was discolored from the heat.
Both said that the cams went in with no problems and that they both had good oil pressure until the cam bearings spun.
I will say that I have not heard of any 6.0 that have spun them, only 4.8/5.3 and this was the first gen4 I have seen/heard about.
One I heard about and the other one I looked at.
The one I heard about was a gen3 that they had just put a crane n20 cam into...Spun less the 100 miles later.
Welded the bearing to the cam.
The one I seen, was a gen4 5.3 that they had just put a comp cam into.
It spun less than 30 miles later. Same thing as the other one, welded the bearing to the cam.
You can see were the block was discolored from the heat.
Both said that the cams went in with no problems and that they both had good oil pressure until the cam bearings spun.
I will say that I have not heard of any 6.0 that have spun them, only 4.8/5.3 and this was the first gen4 I have seen/heard about.
#60
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I picked up an LQ9 6.0 today that has a bad cam bearing. It didnt spin it but it was close, it was stuck to the cam. No damage to the block. Engine is dead stock cam and all