Hi there Folks,

Have a SS Commodore here in Aus with LS1. Purchased car with 93,000km and motor was nice and quiet with only mods being cold air intake and cat back exhaust (2.5").

Last week car went in for cam, push rods, valve springs, double row timing chain, mafless tune, full exhaust and diff gear swap. Once I took delivery I babied it home as traffic was heavy but noticed an intermittent top end tick/clack appear for about 2 minutes or so and then blend back into the normal valve train noise.

I know this topic has been covered many times here and with the limited access to testing I've had since getting the car back (Easter holidays here at the moment) I think I've narrowed it down to an oil pressure issue or foaming issue. What I'm hoping to do is list what I've noticed and get some opinions so I am armed with some info before I take it back and get them to rectify.

I know increased valve train noise is a given with non standard ramp rates / lift cams but this intermittent noise (which I believe is a lifter not maintaining pressure due to foaming or supply pressure) creates a noise way outside the normal ls1 valve train clatter). - Here is what I've been able to duplicate and what I've noticed.

Noise only occurs with oil at operating temperature.

Noise increases in frequency with engine rpm - it's not a rotational noise but a high frequency percussive noise.

Motor taken to anything over 4000rpm then back to idle / coast - clacking noise will appear for a minute or two and then blend back in.

Motor driven under moderate throttle with rpm always under 2500 - no clacking noise.

When 0w - 30 or 5w - 30 grade oil used, clacking under the above conditions is able to be replicated each time the car is driven.

With 10w - 60 oil is used, the clacking is far less able to be replicated under the above conditions BUT the check oil warning alarm appears when the car is let sit and then started again at operating temperature. The warning only appears at start, never when it's running.

While the clacking noise is occuring, there are bubbles around the oil film on the dip stick.

This morning when I went out to the car a few drops of what appear to be coolant (red) were directly underneath the oil filter of the car. I got under it and tried to trace the origin and it appears to be coming from the timing case cover at the seal between it and the sump pan. I ran the car to operating temperature on the jack stands and noticed what appears to be some crank case blow by escaping from the same leak point.

Do you guys think I'd be on the money by guessing that unless there is a pressure drop because of a cam bearing, retainer plate or other bearing issue, that either the pump or a pinched o-ring (both replaced during cam swap) might be sucking air into the oil feed? - With this noticable leak issue I spotted today do you think this could also be contributing to a foaming issue with oil if the pickup o-ring is damaged? - Are crank cases negatively pressurised while the motor is running? - I'm thinking that an o-ring issue coupled with the crank case vent to atmosphere through this gasket issue may be compounding the problem.

Anyway, sorry for the long rant, just trying to get some ideas. I also don't have a definitive oil pressure reading yet either as I've been unable to get the required equipment until the parts shops are open on Wesnesday.

Cheers from across the pond

 

How does the oil look, is there a chance there may be coolant in it? That will certainly reduce lubrication qualities. A bad o-ring could also cause issues, especially at higher RPM. Not sure I would push it too hard until sorted out to prevent more issues down the road.

 

what cam did you install and how long are the push rods?mite not have enough lifter preload.should consider new lifters .consider installing some comp cam trunnion bearing,the stock ones mite be a little worn .

 

The oil looks good, I cannot see any traces of coolant in there. I'm starting to think the o-ring may be the issue. - Thanks for the response.

 

Comp Cam Part Number: 54-416-11 (Cam Grind Number: XR273HR)
GEN III/LS1/LS6 350 Xtreme RPM Cam (1600 - 6600 rpm)

Adv Duration: 273 (In) / 277 (Ex)
Dur @ 050: 220 (In) / 224 (Ex)
Valve Lift: .530 (In) / .534 (Ex)
Lobe Sep: 112.0 degrees

Push rod length is 7.40

Rockers and trunnion bearings are stock.

 

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I would guess that cam would have a base circle close to stock. And with stock (non-LS7) lifters and heads those pushrods should work. The o-ring would be a good bet. What springs did you install?

 

Hows your oil pressure what pump do you have?

 

what he said, is your pump still workin?