Abnormal cam wear question
 

I have seen too much cam and rocker arm wear in my 3.0 sc. The engine has been apart twice in about 5 years and both times I replaced cams and rockers. First time I installed new ground cams and refurbished rockers. I also checked cam spray bars without finding any plugged holes. 3 years and 10k miles later the cams were worn and pitted and most of the rockers too. I installed new stock cams and replaced only the dodgy rockers. Two years later again both of the stock cams are still OK but I had to replace 5 rockers. This time I split the case and found two stuck open piston squirters that appeared to flow significantly more than the others but find it hard to believe this can have much impact on oil supply elsewhere as long as oil pressure is good. And oil pressure has always been good according to the gauge with 1 bar/1000 rpm when hot.

I have always been very careful with warming up the engine and used mostly brad Penn 20w-50 or swepco 306 15w-40.

Living in a cold climate and using the car all year I am starting to think poor oil supply through cam spray bars after cold startups may be the issue, especially with 20w-50 mineral oil. So much wear in in very few miles must be lubrication related and I can see no issues with oil types or how I have been operating the engine, except possibly heavy viscosity mineral oils may not be the best for winter use (compared to most of US we have winter temperatures all year).

I am still on 10w-40 break in oil and plan to go to full synthetic motul 300v 15w-50. Or should I go thinner?

Any viewpoints on my theory on oil starvation at coldstarts ? Am I on the wrong track here?

Might want to consider a 5W-40 synthetic for the winter months? How are you warming it up?

Warm up consists in drive off on startup, and limiting rpms until temp gauge has moved up slightly. I also limit RPMS to keep below where psv starts opening

Oh, and since I make rebuildable piston squirters and I have somewhere near the area of a gagillion hours in studying them, I wonder how you came to determine that two of your squirters were stuck open.

I determined they were stuck open after splitting engine and applying air pressure to the oilways. 4 opened around 3 bar while 2 were always open. Ok?

I’m interested headquartered I live in a somewhat cold climate. Do you park in a heated garage or are the cold starts in temps below say -10C?

Are you using the cam oil line restrictors?

No restrictors, and usually temps above freezing point. Garage is not heated

trond ,do you get enough oil on the rockers from the camshaft squirt tubes?Have you checked that?

Ivan

I don't think I get enough oil on the rockers but don't understand why, or even how to quantify

if you think that ,that is correct.It should have rung the bell , when you did 2 times the rockers and cams.
You have to clean out the tubes......and mainly find out why is it happening .

Ivan

Where were the rockers sourced?

Original Porsche. Refurbished set from DC. Both failed equally

Took out the tubes both times. Never found anything. Also checked spray pattern when installed. Looked as expected. Problem is I can't find any explanation for the wear except maybe I have more cold starts than most. Could it be the problem has been caused by to thick oil and oil starvation. I am leaning towards that and will go full synthetic. Looked at the Mobil 1 racing 0w-50 but unable to find out why people say it should not be used on street cars. I don't have cats so not concerned with high zddp concentration damaging cats. Does the oil break down to quick. Meanwhile I have 300v 15-50 but maybe this is on the thick side so will look for a 5w-40 synthetic or 10w-40. Gibbs has one..

Are tubes oriented correctly? (Just trying to cover all the bases)

hmm ,i got it how is the oil pressure .Did you check your oil pump while doing rebuild?
You have never found anything in the oil? So on rebuild all bearing were ok just the cams and rockers?
i do not think it is the oil it self problem..at least i have never heard of it.

There is something blocking the oil going to the cams....

Ivan

My cars have 20/50 Brad penn. I only start or run them in warm months. Starting a car and running 20/50 in cold freezing weather I would think is not a great idea...

Even Porsche I believe specs 10/40 or 10/30 in very cold weather...

My garage is attached to the house so maybe 50F degree cold starts. Been using 15w40 but recently switched to Porsche Classic 20w50 because I get it cheap at work. I will have to check my rockers. Starts down in the teens and I’m sure going to find something lower viscosity.

Have full oil pressure according to gauge, a little more than 1 bar/ 1000 rpm when warm. When cold I can hardly make 50 mph in fifth before the oil pressure hits max on the gauge. Based on that my oil has been maybe too thick. There was no other damage to bearings anywhere and all was clean. No debris found anywhere. Only damage have been cam lobes and rockers. Rod bearings as new with 120kmiles on the clock

What is your temperature when you are at 50MPH in 5th and what RPM's?

You see, as temps get closer to operating levels, oil will thin out the and pressures levels will normalize.

I have been using DELO 10w40 Conventional ever since my rebuild and love how cool & quiet she runs. My levels are high when cold then as she gets warmer, the pressure levels off to where it should be almost a bar per 1K RPMs

I replaced all my squirters, and used standard bearings

I think it a good idea for your temps to go with thinner or thinner to PAG specs at a minimum.

the oil should be at the highest point when cold, your is not...that is strange..right there....and it does not matter which oil or temperature.
Of course in cold you do not want to use 20w50..ask me why.Got stuck in Texas going cross-country from LA to Florida and my oil cooler exploded.
that is just a story for another day....

Ivan