Excessive wear on exhaust cam lobes

[puddy]

Hey guys I pulled my valve covers to do a valve adjustment tonight on my 3.3.

This is cam lobe on #2 exhaust lobe, #5 is identical.


This how all the othe lobes look.


So am I screwed, is it rebuild time? I don't want to track the car hard this spring and spin a couple bearings and do major engine damage.

Thanks.

[puddy]

Here are some lightened pictures so you can see the good vs bad easier.

[VFR750]

Before you commit to a teardown, remove the rocker and check the pad. You may find your answer there. Most likely the bearing surface has failed.

How many miles did this build have?
Which oil?

[Flat6pac]

Check the holes in the oil tube. Probably have junk in the oiling hole.
Bruce

[puddy]

Thanks guys, The previous owner rebuilt this motor and has about 20,000 kms on it, or 12,500 miles, however this was around 15 years ago or more and the car hasn't been driven alot in the last 10 years.

I've been using Brad Penn oil.

I'm not sure what the oil tube is, do you mean the tube that runs on the under side of the motor from the valve cover to the case? I'll check that tonight.

So if the bearing surface on the rocker has failed that means a new rocker and cam right?

[Flat6pac]

Each pair of rockers has 3 cam and rocker squatters for lubrication. If you look on the intake side you will see a tube running and visually you can see one squirted hole. There is 2 more out of easy visual sight. They all have to be free of plugging up materials.
Bruce

[JFairman]

The cams and rockers need to be removed and then the cams need to be repaired or replaced. The rocker arm pads need to be resurfaced or replaced at the same time.

The single cam spray bar in each cam tower has 3 sets of small oil holes per cylinder. Two spray oil directly at the rocker arms and valves and one sprays oil straight up towards the upper rocker cover where it splashes off and splatters all over the rest of the valve train. The small oil holes in the cam spray bar can become clogged with oil coke/carbon particals from the turbo. This is the reason synthetic oil with is so much better in a turbo motor. It can handle the extreme temperatures in the turbo bearing housing before it burns and turns into carbon.

That wear on your cams looks like lack of lubricating oil and is only going to get worse quickly. The rocker arm pads will be worn the same way on those cam lobes. You don't need to remove the cam towers or the heads and it can be done with the motor in the car but most people and shops remove the motor if they have an engine stand and a way to get the motor up and on it.

The rocker arms, chain tensioners, cam sprockets, and the turbo oil scavenge pump have to be removed and then the cams will slide out of the cam towers. Web cam or Elgin can repair the cams. Cgarr who posts on the engine forum is very good at refurbishing the rocker arms.
Good luck with it.

[puddy]

Thanks alot for that info JFairman. Maybe this would be a good time to switch to SC cams from current 964?

Maybe I should drop the motor, i've wanted to do it for a while to address some oil leaks in the triangle of death, but just not 6 weeks before my first track event :/

[afterburn 549]

I am going to say "feel" it
If ruff I could see buffing it out . (with jewelers rouge and polishing compounds.)
You might have to pull the cam.
Check the timing B4 you do and record it.
I have done it with pads in the past .
Like said - pull your tubes, clean them, then tap the holes and put in pipe plugs . (makes it much more EZ next time)

[puddy]

I pulled the two rockers, the inside of the one was very worn on half of the bearing surface. I sense a very slippery expensive slope ahead...

[JFairman]

That's lack of oil.. cam spray bar oil hole(s) probably clogged. You caught it before it got real bad. The rocker arms and cam can be repaired so it doesn't have to be real expensive to fix this unless you do more upgrades too.

[puddy]

I went to my local Porsche expert last night after posting these pics and he showed me the oil tubes that need to be cleaned and how I can clean them out. He also showed me other rockers that were damaged due to lack of oil that were much further along in the destructive path. I'm really happy I decided to adjust the valves or I would not have caught this. I might have found this problem out the hardway at the track. So i'll pull the motor and start with cleaning the oil tubes. Then hopefully the cam can be reground and thats all I need to do.

At the same time I will check and clean my injectors, i'm trying to figure out why cylinders 2, 3 & 5 are running lean. I can also address the leaky triangle of death. I'm sure theres many other things to do while the motor and trans are out...

[jason2guy]

how are you going to clean those tubes?

[kenikh]

Brad Penn has a bad rep for coking on turbos. The spray bars are alkost assuredly gunked up.

[tharbert]

The tube is held in place with two pressed-in plug. You can pull the plug out with an appropriate sized bolt/nut or drill it out with a 5mm bit. The bar can then be removed (with your fingers, it's not super tight) for thorough cleaning. I pulled mine and there were two partially clogged with silicone sealant. Here's a pic of removal from this thread:



Here's the bar coming out:



When reinstalling, you have to be very careful about the bar's orientation. Here's the page describing r/r:

[puddy]

Thanks for the tube removal info.

What I was shown for cleaning was simply spraying brake cleaner into the oil fitting on the one end and spraying it in, then we did the same with oil and added compressed air to watch the oil stream out of all the small holes. then we used brake cleaner again and compressed air. I was going to try that to avoid removing the tube but perhaps i'll try removing the tube first?

[Steve@Rennsport]

Originally Posted by kenikh

Brad Penn has a bad rep for coking on turbos.

Uhhh,..not really.

That sorta thing falls under the classification of Pilot Error,....Human Factors.

Its too long of a story to write, but a phone call can explain in detail if its important to you.

[trond]

I checked the spray pattern from the spray tube by hooking up this device http://www.clasohlson.com/no/Cocraft-7-l-trykksprøyte-/40-7917
to the oil supply line. Very easy and conclusive check. You should have similar spray pattern from each hole along the spray bar
Just cut off the nozzle and stick a hose on then connect to the oil line somehow. I used an old brake line banjo I think

[kenikh]

Originally Posted by Steve@Rennsport

Uhhh,..not really.

That sorta thing falls under the classification of Pilot Error,....Human Factors.

Its too long of a story to write, but a phone call can explain in detail if its important to you.

The joy of hearsay. Thanks, Steve!

[KTL]

I would at minimum remove the end plugs like tharbert shows. That will allow you to look thru the tube and see any blockages at the pin holes or at the cam bearing holes.

Try to clean the tubes in-situ instead of tugging them out of the cam housing. Reason I say leave them in place is because they're a tight fit. When you remove them the tight fit is lessened and upon reinstallation you can have some oil sneak past the cam bearing orifices.

Cam and rocker oil tubes

Plus leaving them in place avoids the opportunity to install them improperly. There is an orientation to installing them. If you install them backwards you can starve the cam bearings of oil

Soda blasting engine case