Cam gear keeps coming loose

FtoSam · Post by **FtoSam** » Tue May 06, 2008 3:58 pm

Alright...

Just spoke to my tuner...

My freshly built engine is having problems again... On the final tune the front Cam gear (exhaust i think) is having problems. Everytime he hits about 12psi it starts to work the cam gear loose.

Previously we rattlegunned the thing on to make it extra tight... we've put a new one on... we've gone over the whole thing...

We just cant figure out what's doing it... Its always the same cam... it did this before and put a new cam gear on it...

Admittedly, it wasnt loc-tite'd... but he's now put something on it to stop it coming loose... He will see how it goes over the next few days to see if it still happens...

Any suggestions?? Anybody seen this before?

Btw, Engine specs:

6a12 2.0L Quad-Cam V6 24v
6a13tt (2.5L) Cam Gears
Forged (CP) and balanced Internals
Lightweight Fly + Heavy Exceedy Clutch (Customised)
GT-2860r Turbo
Upgraded Injectors and Fuel System
Microtec LT-10x ECU

No idea if any of that affects it at all.. But i've been assured that the dowels on the cams are straight.. No idea what is causing this...

Help??? I want my car back... and my wallet not empty...

Post by **Bennoz** » Tue May 06, 2008 4:02 pm

I was gonna suggest loctite. You can get that in some pretty hardcore formulas.

Question is, why is it coming loose? It would appear that tightening the sh*t out of it is only fixing the end result problem. What's causing it? Are you getting timing belt 'slap?' Does the timing belt tensioner need to be stiffer??

FtoSam · Post by **FtoSam** » Tue May 06, 2008 4:15 pm

Brand new hydraulic tensioner... tested several times since my timing belt kept stripping itself on one side (thanks to a protruding piece of metal)

Dont know if a ARP head and main stud kit affects anything, but its got that too...

Post by **I8A4RE** » Tue May 06, 2008 4:26 pm

Im not sure how is the cam held on? One centre bolt or four little bolts. If its one centre bolt maybe either the bolt or the hole where the bolt goes through have been stretched or damage and are just not holding onto each. It seems weird that only one is doing it, so really it has to be the bolt or where the bolt screws into, i dont know im not a doctor

Post by **Bennoz** » Tue May 06, 2008 4:43 pm

You might be onto something thou... the cams are held in by solid lead lined bearings which are held in by the castings on the head. Where the cams roates in these bearings (cam journal) there are little oil feeder holes which lubricate the bearing, perhaps one of these is blocked due to a bearing shell spun in the journal & causing retardation in that cam...

Still doesnt really explain why the bolt is undoing itself. There's one sure way to lock it in thou, machine a small recess into the cam gear just near the edge of the bolt, then when putting the bolt back in, use an oversize washer. Bash one side of the washer up against a face of the bolt & bash the otherside into the machined out recess. When I say bash, I mean gently manipulate the washer using a brass punch & hammer. Thats how its done on old skool engines.

Post by **I8A4RE** » Tue May 06, 2008 4:49 pm

Bennoz wrote:When I say bash, I mean gently manipulate the washer using a brass punch & hammer.

Why wasnt locktite being used, i thought for that sort of thing it would be mandatory?

FtoSam · Post by **FtoSam** » Tue May 06, 2008 6:07 pm

because we'd taken them off a million times to try and fix the belt stripping itself...

Ben, could you explain a little more what you're saying?? perhaps some CAPS diagrams?