Cam gear walking off?

fatty

fatty

VE
Over this past winter I pulled my engine for a reseal as it was leaking pretty bad. I decided it would be a good idea to put in a cam and new lifters at that time. I did that and followed the manufacturer's instructions for break in exactly. Lots of Royal Purple assembly lube and cranked without starting it until oil pressure was built up and let it run at 1500-2k for 15 minutes.

Then I started losing valve lash on at least #5 exhaust and maybe #6 too. It's been almost 4 months since I've driven it so I'm not positive. I also started getting a big oil leak from the back of the engine which makes me think the cam gear may be walking off, but I don't know that it would lose lash like that.

Now I'm almost positive I saw a thread once that had a way to check if the gear was coming off without pulling the cover. I can't find it now though. Does any of you guys know if that's possible or am I barking up the wrong tree altogether?
 
Anyone got anything for me? It's been about 200 miles since I lasted adjusted the valves and last time I drove it was starting to make valve noise again. I was told it may be a bent pushrod so I'll be checking that tomorrow.
 
Who's cam and lifters? Sounds to me like its eating a lobe. A walking cam gear wouldn't make you loose lash I wouldn't think.

I'd check the push rods first. If they look ok I would dail indicate number 5 and compare it to one you haven't had to readjust. Also check out your rocker make sure threads are good and hardface looks OK.

Hope this helps
 
Cam gear walking won't change lash. Anything wearing down would cause lash to increase as well. Only way I can think of to lose lash would be head gasket crush, or the adjuster is turning.
 
My bad, I meant to say lash is increasing. I set it at .010 and .020 and it was at .026 on the exhaust.

It's a Hamilton cam and Cummins lifters I got from Mumau. Now I guess I need to cut open a filter and see what's inside there.
 
^^^ agree. I was thinking maybe the adjusted was cross threaded and thinking it was tight but wasn't touching the rocker arm.

Best of luck.
 
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I'm pretty sure I ordered 12v tappets. Also I should clarify the cam is a Hamilton but I got it used supposedly never ran.
 
Send in an oil sample! Sounds like your wearing a lobe down. Do the dial indicator as said above for a definite ruling! Did you add zinc?
 
The lobes could be wearing into the block. It usually happens to the last 3 cylinders since they're the last to get oil.
 
Jon, could be I just don't know how to install a rear main seal correctly.

If the cam is wearing the block down, is there any fix or is it new block time?
 
I got the filter off today and I'll hopefully figure some way to cut it open neatly.

Also I just remembered that the last time I drove on a WOT run I was up to 50 psi where before the cam it would hit 46-47. Also egt was up about 1-200 degrees to 1900f.
 
Did you degree the cam when you installed?

The front cover doesn't take much time to remove.

I use a cheap large pipe cutter at work to cut filers open. PVC pipe cutter work as long as you go slow and sub 20$ for a decent one.

What did you set valve lash at? Did you do the quick set per the manual or did you do the long and annoying setup that's much more accurate? Did you actually torque the lash adjuster nuts?
 
Did not degree the cam. I set the valves at .010 and .020 using the companion cylinder method. I've done it that way tons of times and lash has never changed like this. I'm talking it gained at least .005 in 150-200 miles.

Pretty busy at work so I don't know when I'll be able to look at it more.
 
- When was the last time you inspected the rocker-arm bearing surfaces?
I bought my truck new back in '93. At about 260 some thousand miles, I had similar issues and found a couple that were heavily scored on the bottom (load side) of the rocker-arm shaft.

- When was the last time you closely inspected the surface of the rocker-arm valve face (that surface that makes contact with the valve-stem)?
With use/time, the valve-stem will wear a broad groove in the face of the rocker-arm. **If you use the standard flat steel blade type feeler-guage, said blade will span said groove and you'll end up with a loose clearance. Assuming there's a little normal wear, use the wire-type feeler-guage instead and ensure you measure the clearance directly over the valve-stem.
 
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Smokin it's a 188/220 Hamilton. I basically just pulled out the stock cam and put this one in.

David I have my ever checked that stuff. Hopefully I can get to it this weekend sometime. Thanks for the ideas.
 
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