art911

Hello,

my 928 GTS sounds like it has some very noisy lifters. I can hear them rattling alot.
I am using Mobil 1 15W/50.
I am considering to open the cam covers and change them.

I have read about blanked oil check or oil control valve. What is this ?
Should I change all lifters if I open the cam covers ?
How do I recognize a worn lifter ?
What else should be done "while you're at there ?"

I would really appreciate your response and help

Mike Frye

I would recommend a search for noisy lifters (or tappets). There is stuff called Rislone here in the states (don't know if it's available over there) that you can put in your oil to free up the gunk that might be in there. I used it when I got mine and it quieted them right down.


Has the car been sitting for a long time?

2ndof2

I tried a million different additives and in the end the lifters were toast. If the rislone approach doesn't work I'd probably bite the bullet and replace the lifters. The symptoms of mine was that it would be quiet shortly after start up and then got very noisy after it was running for a while. Mine was a much older 1980 motor.

TheoJ

art911: can you be more precise? Do you hear them when cold, hot or always? Does the clicking go away when revving up to 2000 rpm? What's the oil pressure at cold and hot?

Sure it is the tappets you hear? Use a stethoscope (or similar) to inspect above the intake and outlet valves and try to compare them to others. Make sure it's not the injectors you hear.

There's a check valve in the head that prevents the oil from returning into the engine when the engine is off. This keeps oil in the tappets and prevents them getting oil starved when you start again. If this valve leaks you have a typical rattle at startup until the oil enters the tappets and then it's ok. It can be cleaned.

regards,

jpitman2

Go to a THINNER oil and see if that helps - heavier grades cant get into the lifters....FWIW I run Delvac 5w40 in my 16V (temperate clime), and in her Miata. Whats the history - has the noise slowly increased, always been there since you have had the car, or suddenly started? What is your pressure reading? Try using a mechanics stethoscope - long screwdriver with end against your ear, tip on engine part you suspect of producing the noise. Sometimes injectors can make a lot of noise.
jp 83 Euro S AT 50k

jaybuni

I had a similar issue not too long ago and used 2 bottles of Wynns Hydraulic Lifter and took the S4 for a good blast of 30miles etc. redlining most of the time and noise cured itself.

HTH

Regards

Sy

art911

Hello guys,

thanks for your response. The noise is been there since I bought the car 2 months ago. It doesn't get any worse. Sequence of rattling rises with revs. I use 15W 50 instead of 0W40 Mobil 1.

Sometimes its quieter, but NOT QUIET. It does not seem to be related with hot or cold engine.
I doubt that its the injectors, but how can I check them ?

Today i am opening the valve covers to inspect. I have read about this oil check valve, but I don't know where/what it is. Please post a picture or part number if possible.

Could it be the chains knocking ? How do i inspect the chain tensioner for correct operation (considering I take the cams out) ?


Your help is very valuable. Thanks

RngTrtl

When I 1st got my 1985 US 928 I thought my lifters were kind of loud, after closed inspection it was my injectors. They are not super loud, louder than I thought injectors would be.

hacker-pschorr

They make a few products, which one did you try:
http://www.barsproducts.com/rislone_products.htm
FWIW going from 15w-50 to 5w-40 Delvac caused my lifters to start ticking. Noise went away when I switched back to 15w-50.

TheoJ

here's a direct link to my website. It shows the oil check valve in the head:
http://jenniskens.livedsl.nl/Technic...3/MyTip368.htm
Also check the plugs closing the oil passages at the end of the cam.
regards,