new engine tic to knock

[nylewis]

About 3 years ago my 99 996 went bye bye due to the intermediate shaft bearing. I had a new engine from Porsche put in by a Porsche speed shop. After lets say 12K the engine started with a slight tick. Very hard to hear and would come and go once in a while. Over hundreds of miles it slowly got worse. It got more frequent and got louder to more of a very loud knock now. It's directly related to engine RMP and sounds like it's coming from the pass side. Now it's constant and loud. I had the lifters replaced on the pass side, now with 15K miles. No effect. No check engine light ever came on.I took it to the dealer. They said it sounds like it's the pass side top and they would charge me 5K to pull the engine and look at it! :mad: I told them no so they said they will call me back...:confused: I was going to just go pick up the car but I wanted to wait a day or so to see if they have an idea without ripping into the engine.One thing I noticed, the old engine had bad "coffee foam" in the oil. They prob didnt flush the system and all that crap went into the new engine. Is it poss that would clog an oil pass and cause a lifter not to pump up? And would a lifter not pumping up be that loud? When I get the car back I was going to take a video so I can post the sound.If it can be the oil pass, if you pull the cams, could you blow air in the oil pass?Any advise is more then welcome.

[goldenwarrior1]

Don't understand you comment "flush the system"... If you had a new engine installed then the oil is new as well. It is a self contained system and no debris from the old engine could contaminate the new engine. If you are hearing a loud "knock" then I would say its unlikely its in the top end and more likely in the bottom end. Could be a rod bearing, piston slap etc. Sounds like you need to find a different mechanic!

[whall]

lewis,

I have seen posts relating to tics and knocks that were related to a loose sparkplug. In fact, one such report came from a board member whose dealer wanted to replace the otherwise good engine.

Bill

Edited April 29, 2011 by whall

[nylewis]

i was thinking the oil from the cooler and lines were not drained and thus went into the new engine causing a oil passage to clog over time. Of course its also poss some metal or debree from being a new engine clogged the oil passage. I was thinking about it a lot last night and considering it slowly got worse over a few thousand miles, maybe with the lifter not pumping up and hitting against the cam, it slowly worn the lobe down. Then with the new lifters, I still had a worn cam.

I'm getting the car back Saturday. I will try and take a video of the sound and post it. I'm thinking the next step is to use some engine flush, pull the cams, blow the oil passages out with air, and check the cams to make sure they are okay. I remember when the lifters were replaced, looking at the springs and head and everything looked good. No wear marks, springs felt strong.

I'll first look at the plugs to make sure they are not loose.

[nylewis]

I added a video of the knock on youtube

Edited April 30, 2011 by Loren
made video viewable here

[Alfieboy]

I have a similar noise, which is getting more pronounced with time. Car is driving fine. Mine appeared to start 3 or 4 months back after an early 60,000 mile service, which included belt and oil change. Very interested to hear what this might be, sounds just terrible when you are in two lanes of traffic as the noise reverberates off the adjacent vehicle.

Edited April 30, 2011 by Alfieboy

[Alfieboy]

Anybody with experience on 996 engines able to chip in here with some opinion? Is it perhaps running the engine low on oil (I try to keep at least 1/3 full at all times, but around the time it happened I had a check oil level warning come on and had to drop a quart in to top it up.

Edited May 4, 2011 by Alfieboy

[nylewis]

With the way the weather has been, I havent had a chance to pull the cams. But I picked up the engine flush and a caliper to measure the cams.

[TSC85]

Check the spark plugs and make sure they are tight. I have heard that sound before and it was a loose plug, which sounds scary as hell. Hopefully it's that easy. Easy to check should tade about 30-45 minutes.

[TSC85]

Might also check the cats, they make some interesting sounds as well that will make you nervous.

[phillipj]

I have had the loss spark plug "chirp" sound. That was definitely more of a "chirp" than a "knock". You could check the plugs anyway just to be sure..

[Rapewta]

I once had a pin hole leak in an exhaust header gasket that I swore was comming from the tappets. I adjusted the rocker arms two or three times

and still had the "tick-tick-ticking" going on. I finally found it by running my fingers around the headers when the engine was cold and running.

I felt the little puffs of air. Was a couple dollar fix. Your noise can be from many different reasons but I thought I would let you know how one

of those reasons was corrected. Good luck.

[hoacha]

If your cams are wearing to that extent, i think there would be metal debris somewhere in the oil. Whats your oil pressure like ?

[Alfieboy]

My oil pressure guage is skipping up and down, whereas it used to reside at 5 when driving.

[whall]

My oil pressure guage is skipping up and down, whereas it used to reside at 5 when driving.

Anybody with experience on 996 engines able to chip in here with some opinion? Is it perhaps running the engine low on oil (I try to keep at least 1/3 full at all times, but around the time it happened I had a check oil level warning come on and had to drop a quart in to top it up.

Please excuse my lack of understanding, but what do you mean by: "I try to keep at least 1/3 full at all times..."?

Bill

[Dharn55]

Try the screwdriver trick to isolate where the noise is coming from. Take a long screwdriver or other ling metal rod and touch it to various places on the engine are other components while touching the other end to the bone in front of your ear. A stethoscope will also work if you have one. If it is a mechanical knocking you should be better locate where it is coming from. Once you have done that post on here so we can be of more help.

[Alfieboy]

I try to keep my oil level between 1/3rd to 2/3rds at all time, in terms of the oil level check you can run when the car is not running. I check mine around 30 mins after running the car, ensuring it's level parked.

[Alfieboy]

I hate to write this, given the way oil threads go, but having just read one and given that the ticking started after my 60,000 service, and they used 0w40 oil in the oil change, and I prefer a thicker blend, could this thinner oil and abundant yellowish "coffee foam" on the cap and upper oil fill tube be the cause of the ticking? Could it just need topping up with something thicker in order to get the ticking to settle down. It sounds like a diesel engined london taxi cab as I move around town between 25-35 mph. Drives like a dream, despite the awful sound from the engine.

Tried to detect the source of the noise, per suggestions, but I am way too novice and so just poked my head around in the engine compartment and underneath with a screwdriver next to my ear bone feeling less than adequate for a good hour this afternoon! Gave the wife a laugh, at least.

[fpb111]

Assuming that the other end of the screwdriver was pressed hard against the area of the engine where you wanted to isolate/amplify the sound?

Edited May 12, 2011 by fpb111

[Alfieboy]

I am not sure how hard one should press, but I was leaning my head into it as well. Being a novice really didn't help me out in this regard. I could hear the noise without doing this and it seems to be coming from within the engine itself.

[fpb111]

"could this thinner oil and abundant yellowish "coffee foam" on the cap and upper oil fill tube be the cause of the ticking?"

How much coffee foam? !/2 oz, 1 cup? What does the coolant look like? Pretty Pink/green or dark and muddy? What does the oil on the dipstick look like clear or coffee?

Oil pressure skips up and down while driving? Like engine at steady 3K rpm oil pressure skips?

Edited May 14, 2011 by fpb111

[violaGT3]

Hi, From the video, I hear a couple of things.

I immediately think stuck/bent valve. I would make a personal recommendation to properly put Marvelous Mystery oil into your crank case and run it a little. Again that is a personal recommendation, I am not a certified mechanic. Just a guy who's played with motors for the past 25 years. But with that being said it could be a loose injector being popped into the retainer and sucked back in, or it could be that you torqued your ratchet on a pully nut and forgot it and now it is smacking the ***** out of your rear end.

You can do a missfire run to check for stumbles in the RPM and diagnose a valve issue.

JIC FYI: Misfire Run= running the RPM's up 300 at a go and hold there for 3-5 seconds to look for stumble's.

Also I think I read that the Oil PSi was varying. I would check the pulley that drives the pump.

[RFM]

Have you already checked the cylinder walls with a borescope, some engines suffer with cylinder wall damage. The knocking noise produced by this issue is the same as a faulty lifter. I would do that before stripping the engine or replacing parts.

[fpb111]

Stuck/collapsed lifter

Look at post #6 on this Rennlist thread.

http://forums.rennlist.com/rennforums/996-forum/623466-lifter-noise.html

[gusmagoo]

Few issues here I feel I have to comment on.

Firstly, the yellow mayo stuff at the top of your oil filler pipe is a red herring. They all do that, caused usually by a build up of condensation at the top of the pipe during cold/humid weather or when the car is only used for short journeys. It will probably be less evident during the summer months in a dry climate. Check your water, if there's any oil in that, start to worry. Water in your engine will most likely be identified by plumes of steam exiting your exhaust pipes!

Secondly, oil pressure gauges fluctuate, they all do it. Mine is at 4 or 5 when motoring and 2 to 3 when stood still. Don't worry about it. Unless it reads 0 and you have warning lights lit!

Thirdly, remember that when measuring your oil level on the dash, you HAVE to have the car on perfectly LEVEL ground. Even the slightest gradient will show too little or too much. I measure mine in my (level) garage before use and (about 15 mins) after use. Additionally I've been advised to always keep my engine oil FULL. Each bar represents about 200 ml so filling up is easy to work out.

These are all things I've picked up from various sources and have accepted and adopted as my opinion so if you disagree with any of it don't shoot me, if there's any doubt about a symptom you have get it to a decent independent (or the OPC if you're desperate) ASAP.

The suggestion of a borescope inspection of the cylinders is a good one, this could be piston slap due to scored cylinder liners and the borescope will find that. For what it's worth, If my car had that loud a knock, I wouldn't run it, it would be being recovered to the repairers right now.

When you find the cause, please let us all know! Good luck!

Edited May 20, 2011 by gusmagoo