Rocker arms: one side varnished, one clean

[HawkeyeScott]

Buddy's 2005 Chrysler 300 3.5L with 174k miles...He put new rocker arm assemblies in today, thinking he had an oil supply issue that had created some engine problems/sounds that made him nervous. (Said it wasn't lifter tick but was more of a diesel-like knock.)

Anyway, when he got in there, he found the passenger side rocker arms varnished up. It wasn't terrible but was a little heavier on the rear of the engine near the firewall. The other side looked really, really clean. He was baffled.

We did some research and think it may have been PCV related. The PCV replacement schedule on this car, he says, is 30k miles. He changed out the original today. The PCV hose runs into the side that ended up being varnished. Also, based on what he saw, it doesn't look like he had the oil supply issue he'd expected.

Was the unusual varnishing (only on one side) related to PCV age? Could it have also contributed to the noise he was hearing?

 

[OPR4H]

If that head takes more time to cool off than the cleaner one, that may contribute to varnish. Rear banks can have a worst scenary in that regard.

This or a restricted lubrication by blockage (specially silicon on galleys) getting less cooling effect from the oil.

 

[Brybo86]

Pictures are worth more than words....

 

[Shannow]

Where you find varnish isn't typically where it is formed.

It will be formed in areas of high temperature, high oxidative stress (like around ring belts), and transported to somewhere that is relatively cooler, and not as active in terms of mixing and oil flows.

PCV could certainly have a part in that, and one rocker cover to the other is quite reasonable to expect to find.

 

[Lubener]

Different temperature distribution. The varnish is harmless and not worth worrying over.

 

[kschachn]

Originally Posted By: OPR4H
If that head takes more time to cool off than the cleaner one, that may contribute to varnish. Rear banks can have a worst scenary in that regard.

This or a restricted lubrication by blockage (specially silicon on galleys) getting less cooling effect from the oil.


Silicon accumulates on galleys? How does that happen? Where is the silicon coming from?

 

[440Magnum]

Originally Posted By: OPR4H
If that head takes more time to cool off than the cleaner one, that may contribute to varnish. Rear banks can have a worst scenary in that regard.

This or a restricted lubrication by blockage (specially silicon on galleys) getting less cooling effect from the oil.


There is no "rear" bank on a 3.5 in a Chrysler 300. Its a rear-drive with the engine mounted the correct way in the car.

IMO, the give-away is the fact that the "dirty" bank is the one with the PCV intake. As the PCV clogged up from neglect, the flow got slower and slower and the nasty crud had more time to settle out on the bank that it was drawing from. The other bank gets the fresh make-up air, so its slower to varnish.

 

[OPR4H]

Originally Posted By: kschachn
Originally Posted By: OPR4H
If that head takes more time to cool off than the cleaner one, that may contribute to varnish. Rear banks can have a worst scenary in that regard.

This or a restricted lubrication by blockage (specially silicon on galleys) getting less cooling effect from the oil.


Silicon accumulates on galleys? How does that happen? Where is the silicon coming from?


Evidently silicon as gasket material, if the excess dislodges, obviously goes to galleys.

 

[artificialist]

The valve cover with the fresh air inlet is exposed to less blow-by gasses than the one with the PCV valve on V-type engines. That is why one side has more varnish.