993RS

There have been a number of threads on this topic, but not really similar to what my car does.

I currently have close to 100,000 miles on it. When I had 70,000 miles, I had an engine rebuild to address the oil leakage. Ever since, when the car is really cold, or has been left standing for a number of days without being driven, I hear the tapping sound of the lifters until it has warmed up. Afterwards, during the day I don't hear it anymore.

My mechanic had me switch to Castrol 10W 60. It improved the situation, but now that it is winter, I sporadically hear it again, but it has never worsened.

Anybody else experience something similar? Any ideas?

geolab

Hello, the oil you are using is great. It must always be the TWS (10 weight Sixty) or Castrol EDGE 10W60 and never put the castrol edge sport 10W60 or the castrol edge RS 10W60
THe API on the back of the bottle must say API-SJ and never put the API-SM/SL which is the same bottle.

I use the same oil in summer since 8 years, and it is totally normal to hear a slight tap when engine has not turned in more than 10 days.

I want to try the new Mobil 1 newlife 0W-40 here in europe, which has a zddp level of 1100ppm just to see if there will be tap sound after a long time not turning the engine.

Mike J

Standard story - one or more lifters are having a hard time pressurizing. Typically its not the actual lifter that fails, its the O ring that disintegrates which seals the lifter into the rocker.

You can oil up the system by pulling the DME relay, cranking the engine over to get oil pressure, put back the relay and fire it up - that might reduce the time to pressurization. Its a bit of pain to do though.

Other than that, you will need to replace the lifters. No one has manage to source the O rings (yet).

Cheers,

Mike

993RS

A mechanic told me that it might not be a lifter problem: could be caused by an oil shortage in the canal from the pump to the hydraulic lifter. The oil flows downward, causing air to build up in the canals. Start the engine and it takes a certain amount of time until the oil arrives and the lifters are filled up again. He also said that everytime the motor is stopped, one or more intake valves are in an open position, exerting pressure on the lifter, so that slowly oil flows out. If the engine is used daily, the oil in the canal is never completely empty, and the hydraulic lifters fill up with immediately, which is not the case if the car has been left standing for a relatively long time. So maybe this accentuated by the O ring usage?

Aussie Alan 993

Mine sometimes makes the same noise but only if I haven't started if for months, and not every time.

BTW - I use Mobil 1, 5W50.

Cheers
Alan

jhg41977

I had a similar issue last year. Now I am replacing the cams and a few rockers while rebuilding the engine. Dont ignore the issue. That knock or tap you are hearing is the rocker slapping the lobe of the cam.

Mike J

I guess the way to test this is to pre-crank the engine like I noted above every time, and see if the issue goes away.

Cheers,

Mike

Steve Weiner-Rennsport Systems

Hi Phil,

My money is on the same thing as Mike's; failing lifter seals.

Given the car's age & mileage, this is the root cause of lifter noises usually turn out to be and changing oil viscosities does not appreciably alter the outcome.

This has become sufficiently common now that we usually replace lifters when the engine is rebuilt.

993RS

Hi Steve,
Actually I had an engine rebuild with 70,000 miles and my garage said it was not necessary to replace the lifters. The strange thing is that it seldom occurs and has not gotten any worse. So, am still not sure what to do. If I drive the car daily, I seldom have an issue. If I leave it for a couple of days, then I have the noise. If I replace the lifters, I just might have solid lifters installed.(yes, I know they have to be calibrated periodically, and it is not cheap...) but they are more precise. What do you think of solid lifters, Steve?
Regards

Ponchobroke

I think this is the correct answer to your situation and can't think of a better outcome to the problem. I would NOT switch to solids, I believe it is more that just a lifter swap... it probably includes rockers and possibly the entire valve line. If you are thinking about that why not just put a new set of hydraulics in instead and get another 70K on the road?

Steve Weiner-Rennsport Systems

Hi Phil,

Lifter seals fail over time due to heat and age so its not simply mileage that does them in. Typically, they begin the process by not holding oil after the engine is shut down and the noise occurs on startup. It doesn't improve (like a fine wine),..

I'm no fan of mechanical rockers on these cars due to the difficulty (cost) of valve adjustments every 10K. Unless the engine will see continuous operation over 7K RPM, I don't think they are necessary as the hydraulic versions are very durable. Replacing lifters every 17 years seems reasonable to me, given the cost of a valve adjustment on these cars.

JMHO, naturally,

993RS

Thanks John and Steve.

geolab

Hello Steve, Since the OP got his answer, I was persuaded to have seen the same exact thread with the same people and questions, until I found it here:

https://rennlist.com/forums/993-foru...ve-weiner.html

In the 'esprit' of debate, I am persuaded it will take me less time to adjust valves on solid lifters on a 993 than change the hydraulic lifters.
I have not seen a driven 993 making it for 5-6 years without lifter change.
A 16-17 year 993 driven normally should have over 100000 miles.
The people who have the original lifters with this mileage are "hearing-impaired".
A 993 with original hydraulic lifters today must have less than 35k miles original.
I would like to know here on rennlist how many first owners have more than 40k miles and never changed their lifters.
regards

993RS

Ooops... Thanks.... Must be getting old....

geolab