cct death buzz only when cruising

[turtlemann14]

so let me start off with, I am getting pretty annoyed with this.

back in 2019 I "had" to rebuild my engine due to sheared teeth on the timing belt. engine is stroked and bored. had a different head put on due to a superficial crack between the exhaust ports on cylinder 3.
I am running a fluid damper, ferra super alloy exhaust valves (not sure what valves were used on intake as it was an off the shelf head the shop happened to have), IE's spring and retainer kit with stock cams, new cam chain and cct.

the engine now has about 60k miles on it and is doing pretty well considering I lost oil pressure twice since the build (oil cooler and turbo feed line failed). oil pressure 14psi hot idle.

the major problem is that I have put two new cct on the engine since the build and the one that is currently in it is starting to rattle again.
I had one fail to the point that it could maintain control at idle and started slapping badly. the others have just developed a light load buzz between about 2-4krpm. sounds exactly like a heat shield going into and out of resonance.
all of the wear pads have had cavitation looking wear on them towards both ends of the pads. (I at first thought this to be a casting flaw such as porosity)
the stock unit lasted 282k miles, it amazes me that aftermarket can't make it 20k. surely this can't be common.

dates of replacement.
1/9/2019 ecs assembled
6/24/22 gates
1/30/24 vaico

tonight I got pissed off and decided to dissect the original cct from the build, an ecs assembled kit.
the findings are that it ate a seal and that most everything else looked ok.


gland bore
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piece of seal in port of pushing piston towards the head
20240820_201413.jpg
whats left of a seal in top of housing
20240820_195000.jpg
piston assembly
20240820_195127.jpg
piece of seal that came out of spool valve
20240820_195027.jpg

as you can tell a large chunk of green seal was plugging the port responsible for driving the cct down towards the head. there was a bunch of debris on top of the piston and in the spool valve as well.
I didn't find any debris on the tension side of the unit(check valve behind inlet screen should prevent this), but my theory is that once the seal in the top of the housing bore is gone the spool valve is getting caught on debris in a position that is in between settings and is blowing oil out of the exhaust port. another option looking at this particular one is that the seal is getting jammed in the port and not correctly pressurizing that side of the cylinder. this would allow the spring on the bottom side to pull air into the top half as the bottom vents oil. (cam advanced, no dampening or position control due to air in place of oil)

this seal may only be to buffer the piston to a resting position, as when the top half of the chamber is pressurized there is no seal on that part, just the clearance between the shaft and housing(when the piston is down towards the head).

i think tomorrow I'm going to pull the spool valve out of the one in the car and see if it has debris and if cleaning it will get rid of the buzz.

is there a solution to this?

btw bore on the cam tension part is 16.75mm this would put a max of 25lbs of extra force on the shoes at 73psi oil pressure.

[turtlemann14]

pulled the spool valve out last night, no debris in it. once it was back together I activated the solenoid. in doing so it buzzed/slapped for about 0.125-0.25 seconds as it changed the timing. total timing change took about 0.5-0.75 seconds.
is this just a low oil pressure issue? I found an article from vw now that says minimum is 1.2-1.7bar/17.4-24.65psi. I thought minimum was right about 14 psi at hot idle?
I am running 0-40 fs mobile1 and at cold start 70* day op is north of 60psi idle. hot running 4krpm its bout 60psi. hot 2krpm Im close to 40 psi.

I am also starting to question the temperature (considering what was left of the seal) of the oil but I don't have a good way other than an external probe taped to the cct to check it atm.

[turtlemann14]

It's was about 95 here today and I noticed my oil pressure was a bit low for comfort. by time I got to my garage, found my thermometer and probed the oil temp it was about 225*f Im assuming that since it was that temp after driving 50mph and though a neighborhood for about 15 minutes that oil temps on the interstate and especially while boosting and piston cooling jets are on could be cooking the seal. viton 400*F, hbnr/hsn 302*F both of these seal are green like the one that disintegrated.
if i had to guess the aftermarket units use the HNBR/HSN seal where to stock one uses the viton seal or something else.

so now do I bite the bullet and buy the stock cct? and also I need to sort out my high oil temps.

are these forums dead?

[turtlemann14]

assuming I did the test right, the specific gravity of the bit of seal that I found in the passage ways came out to 1.994.
viton specific gravety is said to be 1.7-1.9
hnbr specifit gravity is said to be 1.2

so this test says that the seal was viton and should handle 400*f

test: weight of seal in air 0.359g, weight of seal in 4*C/40*F water 0.180g