996 hot start noise

So, this litle gremlin still wont go away. youtube I had this issue mentioned allso in the lifter noise topic, but it's now sure that this is something else. Hot engine after aprox. 2h cooldown. When started sooner the noise is a bit louder. No noises when engine is cold. Allso if the engine is turn of after the noise occurs and started right up again, no noises. Like mentioned in the lifter topic, new oilpump new lifters new variocampad's new startermotor new timingchain tensioners tryed with the aux belt off, stil makes the noise. Starting to think that it's flywheel or transmission...

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Well, I'm not at the car so I can only offer some ideas... Are you sure that's a problem? A bit of valve clatter and even a bit of chain noise upon start up is going to happen. Especially if you shut off the engine hot and let it sit a while. The oil is obviously hot and thin (so to speak) and if there's a way out of a lifter or a chain tensioner the oil will find it and leave. Oh, that doesn't sound like anything related to the flywheel or transmission. I've never encountered a noisy flywheel but I've come across some info on how they fail and the dual mass feature fails and the FW can clunk a bit with the engine at idle and warm. Also, if the car's a manual, the engagement of the clutch and the car's take off might be accompanied a clunk. The other source of noise is when the engine/drivetrain is hot and the car is brought to a stop and the tranmission shifted into neutral and the clutch pedal released is the clutch disc car rattle a bit on the splines of the input shaft. This it more a faint clunking noise that is and then is not in time/sync with the engine rpms. The input shaft and its gears can rattle a bit too. What I have found though is depressing the clutch pedal all the way down and then fully releasing the clutch pedal makes this noise go away. Up engine shut down this hardware can rattle a bit and holding down the clutch pedal when the engine is shut off keeps the engine as quiet as a church mouse when it is spinnig down to a stop. If the engine's 'quiet' at idle hot and there are no other noises or symptoms or odd behavior..what you are hearing may not be a sign of anything wrong. Sincerely, Macster.

I'm having trouble hearing anything in the video that sounds abnormal. Can you try to describe the noise a little more? I agree getting it on a lift or at least some high quality jack stands to creep around and identify it's location sounds like a good next step.

Have to agree with logray........can't hear anything wrong.

My car makes the same noise. Porsche North Scottsdale told me it's the drivers side muffler. The previous owner had it replaced twice under warranty and the noise is back. It won't hurt anything.

Thank you all for your replys The camera cut's down the noise. It's much louder in real life. First 2 or 3 sec when the car is started, there is some metallic noise. Trust me, that can't be normal. Everyone that has heard this ratle, ask's that is our car goingto blow up Hope that it is the muffler... I believe that this ain't a big deal, more like a annoying thing. Just want my car to be perfect, like the way it should be

Try removing the muffler and shake it. If you hear the rattling then chances are you've found your problem.

http://www.youtube.com/watch?v=pugKDOd2weA Got better audio in this clip. If this is still normal, then ok.

Logray, I have opened the muflers last winter, nothing was loose. The muflers were cold of course.... Running out of ideas with this one...

Now I hear it, at the 8 second mark. Could it be the starter teeth aren't retracting back in fast enough?

I second Doug's guess... sounds like it might be hitting the flywheel teeth.

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Do not let the mean (and possibly based on envy) comments of everyone asking if the car's going to blow up ruin a good car for you. The noise does sound normal. I wish I could post a video with audio of my 02 Boxster upon startup. There's a bit of valve clatter and some chain noise. Has been there since day one. But cars are different. Be sure you eliminate the possibility of exhaust system rattle, heat shield rattle, or even metal stiffener rattle. I found a couple of nuts that hold the metal stiffener secure to the underside of the suspension at the rear of the car missing once. A stethescope used to locate/pinpoint the source of the noise as coming from inside the engine and from where goes a long way in helping determine if the noise is possibly something worth worrying about or just normal noise. These engines have a lot of cam chain, all with tensioners and guides, and upon engine start until the chain tensioners are pressurized the chains will drag their slack sides on the guide rails and make some noise. Zero lash lifters can bled down a bit and even injectors can make a bit of noise upon startup. Heat shields can loosen up as can exhaust systems, especially in cars used in areas with snow/ice, with or without salted roads. The exhaust system is stainless but the hardware/holders are just plain steel and I've seen pics of cars not too many years old that have serious exhaust fastener/hander corrosion problems. You can clamp vice grips or something similar to the heat shields to see if this affects the noise upon startup. Wrap some chain around the exhaust systems and use a turnbuckle pull the chain tight, not too tight, just tight enough to put some pressure on the system against/or away from the exhaust system hangers/fasteners then see if the noise is still present. Or if the car is in the air just have a helper pull down on the chains as you start the engine. I assume the oil is of the proper grade and type and is reasonably fresh and the engine filled to the proper level? If you want to be sure -- and not rely upon what I post on this -- about all I can recommend then is find an expert in these cars in your area and have him give a listen and then listen to what he has to say. The noise sounds normal to me but I'm not an expert/professional and I'm not at the car. Sincerely, Macster.

Thank's again for your reply's. The starterbendix has come to my mind allso, just cant remember that was this problem on the car before I changed the startermotor. The "new" starter was remanufactured. I'm goingto take the car to lift and have my friend start the car. Macster, I just changed the oils, oilpump and lifters. I have drove 60 miles on these. Oil is 5w40 Castrol Syntec. I have tested Mobil 5w50, no affects on the noise. Diagnosing this problems is slow process, after start up, I must wait aprox 15mins to get the noise back. And for the ruining this car for me No, nothing can do that.

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Well, if the starter was replaced recently then the post by another person (I can't remember the name or I'd give him credit) suspecting the starter gear might be dragging becomes a more likely possibility. The noise doesn't sound like that to me but I could be wrong. But the last thing touched is always (well, almost always) the first thing suspect. But I have to point out that I think having to wait some time before the noise reappears sort of eliminates the starter. It suggests a possible bleeding down problem of a chain tensioner, but I could be wrong and I would not want to have you tear into the engine on my WAGs. So, it becomes even more critical then to try to pinpoint the source of the noise. Have you removed the oil filter housing and checked the oil in the housing and the filter for any signs of debris? I'm not necessarily thinking IMS bearing but perhaps a chain guide/tensioner guide covering (made of hard composite plastic) might have come at least partially apart. Sincerely, Macster.

I'm pretty sure it's going tobturn out to be the drivers died muffler.

Ok, so next step, try the car with out the mufflers. That will eliminate those. Car has new chaintensioners and variocam pads, only pad that I haven't check is the IMS chain one. The IMS chainpad looked ok, thru the chaintensioner hole. I have allso installed LNE ims bearing last winter. All the parts that have something to do with the oilpressure, are new. Only the oil scavengepumps are old. Will check the starter and the mufflers next, hope that the problem is in one of those. Thank's again

Cam tensioner pads are shot. how many miles. Im sorry if I missed that in the above talks

Shark Attack, do you mean those long guides for ims to ex-cam chain? Car has about 60k miles (95k km's)

no, Im talking the pads under the chain that connects the 2 cams under the cam covers. But at 60K I doubt it. But it sounds EXACTLY like that.

At 50K my cam tensioner pad were shot.

He just had his cam covers off and replaced lifters, I'm guessing he did his variocam ramps/pads too since they are so inexpensive compared to all that other stuff? He probably didn't replace the long chain ramps for the drive chains.

Yep, I changed the variocam pad's last winter. So I have all ready taken the engine apart twise. Could the variocam actuator cause this, how tight the compression bolt should be? I mean that, the bolt you use when the actuators are pushed together when changing the vario pad's? Mine was quite loose, and the actuator did compress easily. I quote myself from first post: "Like mentioned in the lifter topic, new oilpump new lifters new variocampad's new startermotor new timingchain tensioners" So, part's that are old: scavenge pumps (those in the cyl.head) variocam actuators long chain ramps for drive chains (inspected, had only slight wear) IMS chain ramp (no idea of the condition) I just don't think that this could be something related to the bottom end. Meaning the rod- and crankshaftbearings. This morning the noise was there allso when the engine was cold, so I think that the position where the engine stops, has something to do with it.

Still, As soon I have the time, I will remove the exhaust system and check the starter first. Then make the desision what to do with the engine, if necesary.

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I say drive the bitch! It sounds like a lot of us have the noise.

Shark Attack, I think that, thats the right thing to do

'99 996 CAB 6-speed here, I have the EXACT same noise on start up. I've been assuming it was a fan motor as the sound has a kind of plasticky clatter to it. I can definitely rule out starter solenoid not retracting. I just can't imagine that it is chain clatter ... but ... maybe? LV

Certainly check all of the pulley bearings if it hasn't been mentioned... one way is to start the car and run it for a few seconds without the accessory/serpentine belt. Another way is once the belt is removed hold onto them with your hands and try to move them around, if there is any play that could be it. If you remove the starter you can have it tested at most parts stores for free (at least in the USA). If you remove the mufflers it is going to be LOUD, might be hard to hear the noise. If you had an actuator making that noise but it was still working then I would be surprised.

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Internet connection's flaky today. Anyhow, I checked my Boxster today after having driven it in for a 30+ mile commute. After a few hours of sitting the engine was quiet upon restart. That your car's engine is noisy (as in the clip) after just a few minutes of sitting has me thinking there is a problem. Now going by what info I have (factory manuals for my Boxster's engine but I think the info is applicable in some way to the 911 engine) as best I can tell there is a difference between the 2 actuators (and solenoids). For cylinder bank 1 (cylinders 1-3) the solenoid (top where the electrical cable enters the device) is black and the actuator is marked 'zyl 1-3'. For cylinder bank 2 (cylinders 4-6) the solenoid is grey and the actuator is marked 'zyl 4-6'. It is important (I bet) that these not be mixed up. Next as best I can tell there is *no* compression or adjustment bolt at the actuator. There is a 'tension screw' (Porsche special tool 9632) that is not to be removed until the actuator is installed. Let me quote: "4: Complete unit is pre-assembled and ready for installation. Do not remove the tension screw, special tool 9632, until the bearing saddles and the chain tensioner have been fastened on the cylinder head. If the allocation is correct, the groove or lug of the camshaft position sensor housing faces upward [emphasis added on 'facing upward]." If you PM me with your email address I can make PDF copies of several pages from my Boxster factory manual that covers the solenoid/actuator and will send them to you. Then you can read them and combined with your recent experience at the engine determine if the info has any value or not. Sincerely, Macster.

The solenoids and actuators for each side are very different, in particular the actuators. The actuator of 1-3 actually moves in the opposite direction as the actuator for 4-6. Mix these up and you have big problems. They are clearly marked both with the part numbers and 1-3 and 4-6 markings. Not so clear with the solenoids but there are different Porsche parts numbers and have idfferent part numbers from the manufacturer on them.

I tried installing the solenoids on the opposite side actuator for kicks and it doesn't fit. The screw holes don't line up. Why they didn't use one solenoid is beyond me.

Have someone else start the car. You should be able to put your ear by the "variocam" lettering on each side of the engine cam cover (chain box) during this start problem/noise and see if it is coming from there... which might indicate an actuator issue. You can also take a long screwdriver and hold it against the engine in certain spots while cupping the other end in your ear. You'll be able to hear chains and ticks and things you can't hear with the naked ear. When you have it on a lift that might be useful. BE sure to wear eye protection!!!

Thank you all again! Macster, I have had only one head open at a time, and cyl 1-3 had the black solenoid. And, I did remember to remove the bolt that I used to compress the actuators. The time that the car needs to cool down is about 30mins to 4h, during this period the engine is noisy. If I start the car after 10min's no noises what so ever, and engine purr's like a kitten. If the engine is completely cooled down, there is (allmost) no abnormal noises. Car was dynoed 4 months ago, 255hp at wheels, so I don't think that there is nothing wrong with the variocam system. This noise is more like the annoying thing (crazy frog) This morning I listened the engine when I started it, and I think that startermotor did make some metallic noise. As the starter is easy to remove, I will check that one first. Well at least next week, work and other hobbies take too much of my time...

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Ok, then I think the starter becomes the more likely source of the noise. Sincerely, Macster.

Finally had the time to do something else than driving the car (and working) I got used "scavenge" oilpump for 1-3 cyl head from e-bay. Changed it and the problem is still there. While the car was on lift, I had my friend to start the car. It seems that the noise is coming from, starter, flywheel or gearbox. Soon I have used parts to build a nother engine :P

Could it be throwout bearing or something related to clutch?

First startup noise, now the engine developed new symptoms. These noises cause me to do this Like a marbles in a can Took the gearbox out first and started, still making noises. Took the aux belt off, sama thing. Took the IMS bearing off, it was ok. I had all ready installed LNE ims bearing. ims-chaintensioner was very soft. I mean that there was litle or no preload in it when i removed it. Should the ims-chaintensioner be like the camchaintensioner??? I will take the heads apart tomorrow and check whats lurking in there.... Just hate this, I love driving this car but the engine so, new engine, buid new engine, put some other engine, or???

Ok, problem found. Connectingrodbearing on cyl. 5..... Engine on stand, cyl.head 1-3 removed Small scraches in cyl 5 and cyl 4 you can hardly feel those with finger, goingto use the blocks anyways. Block 1-3 is like new. Engine with the 4-6 block off So end results, need a new or good used crankshaft and one connectingrod. If enyone has these parts, please send me private message.....

wow, grats on solving the problem. Did replacing the rod bearing fix just the "can of marbles" problem or the original clatter problem as well? I would have sworn that was the chain tensioner sound I heard. LV

Hi LV Engine is still in pieces, hunting the parts to put it back to gether. But I'm quite sure that this was the cause of these noises. If enyone will come up with an idea, that what could have caused this?? All the other bearings were in good shape.

Looks like you have a nice shop to work in. I'm wondering if you are using a used shaft if you are going to have it turned and balanced with the rods and pistons on since you seem to know and be into engine performance. I'm not sure if porsche cranks can be turned (advice from porsche maker shadows) but as far as I know it’s generally the best thing to do with a crank that has been broken in with different rods and pistons to at least turn the crank. Some guys have just repolished the bearings areas which keeps from hunting new thicker bearings to make up for what's been turned off the crank. Could be best to check the tolerances of the block bearing areas for uniformity and get a good idea of the size bearings that might be needed to keep the problem area from coming back by possibly going with non standard bearing thickness’s. Regretfully it isn’t always going back to off the shelf part numbers. Whatever the case have fun and enjoy.

Glad to hear you found the problem. If I were in your shoes I would either look for a rebuilt engine. OR if you want to salvage what you have: Send block to autofarm.uk for 3.7 rebore and new pistons Perhaps new connecting rods if required example: http://www.lnengineering.com/rods.html Send crankshaft to reputable source to have it balanced if possible??? (or if money is not an object source a new one example: http://www.flat6innovations.com/shop/home.php?cat=301 ) Valve job since you have the heads off. Replace other serviceable items such as chains, ramps, aos, pumps, seals, gaskets, orings, washers, hardware, oil cooler, main and rod bearings, thrust washers, circlips, hoses, etc, etc etc. Keep us updated!

Pac, I thougth that there is no oversize bearings for these engines? I have traced a good used connectingrod from England, only the crakshaft is still a mystery. I try to make this engine work, and spend money little as possible. Reason for doing this, I was planning to build better engine next summer. And I don't have the fund's to do it properly now. And for the money, I'm now at about 1600usd and only missing the crank. So I hope to rebulid this engine for 2-2.5 k usd But, does enyone have an idea, what would have caused this? No over revs in ecu counter. Rodbolts were tight Everything else inthe engine is in good condition, including all the other rodbearings. I hate to put this back to gether, if I dont know the cause.

So, the rod bearing did not fix this noise.... I have been testing and finding the conditions that this noise occurs. And this is what I have found. When starting the engine, idle valve lets the engine rev to 2200rpm when this noise occurs. If the revs stays about 1300 or less, there is no noises. Could the idleairvalve be the cause?? If it lets the revs too high in the startup? My car starts fast, it takes about one rev from the engine to get going, and when the IAV lets the engine run to 2200rpm, the noise will be there until the oilpressure is over 3bar... Could some one check how high the IAV let's rev's go, when the engine starts?

Doubt it's the IACV. I think I read somewhere crank position sender might cause this overrev on startup. Or maybe throttle position sensor. Perhaps clicking is due to not enough oil in some areas because of startup high rev? Just ideas...

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I've kind of lost the context of this thread, being on the road and all. Have you used a mechanic's stethescope to try to pinpoint the location of the source of the noise? Knowing where the noise comes from can help with a diagnosis. Idle racing from cold start is not unknown. I can't recall what rpms level is hit upon startup with my cars but it is over 1K and possibly closer to 1.5K. The tach in your car may not be reading the right level at startup so you need to hook up an OBD reader/data logger and capture the actual rpms that is obtained at engine start. The ticking might be due to a noisy (even leaking) fuel injector. If it is leaking not only can it be noisy it can add too much fuel and the engine can race. Long and short fuel trims can provide a clue. Also, check the intake air temp and coolant temp at engine start. If these are wrong -- due to sensor/sendor problems -- the engine controller can add too much fuel which can result in an abnormal engine rpm level during engine start. Sincerely, Macster.

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I have seen a car with the wrong actuator assy on the wrong side...running (though poorly) took a while for the tech's to figure out that a replace part was the wrong bank actuator and installed on the wrong side (someone ordered the wrong side part) SO yes, it does fit now back to your regularly scheduled rebuild

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LOL, yea I could see that the actuator could fit on the opposite side. However the solenoid on the actuator does not fit on the opposite side's actuator. The flange on the solenoid and the holes drilled for the screws only allow it to be installed one way. As for my rebuild, I'm still waiting to sell a few remaining things before I can dive in. I'm hopeful I can start teardown in a couple weeks. And then the long agonizing 4-6 week wait LNE publishes for Nickies. It might be December by the time I'm finished if I'm lucky. :;

when I first wrote that I went back and re-read what you said (solenoid) and had to change my words

Macster, tra and fra values are 1 and -0,06 on both sides. I had my friend start the car, and the noise is coming from the flywheel area. All the engine internals are now checked and worn parts are replaced. When the IACV was stuck and it took about 3-4 times of starting before the engine stayd in idle, there was no noises and the revs stayed below 1k rpm. So, the reason that causes the noise is the high revs in the start up. Now I need to find out the the what is causing this. logray, I was thinking the same. That the oil pressure might have something to do with this. I read that Porsche had some issues with these early models on IMS chain ratle on starting. I do have new IMS-chain tensioner.

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Check out this thread and TSB concerning startup noise and the correct IMS tensioner to use: http://www.renntech.org/forums/topic...-1999-996-m96/ TSB 1551 http://www.renntech.org/forums/index...ttach_id=23703

So should I be using 996-105-180-56 or the older style that I have now in the engine? My PET7 is saying to use -55 that has superseded to -56. So could this really be the cause??

I think your car is a 98 or 99 correct? Then 996-105-180-56, or 55 are NOT the right parts for your car. 996-105-180-54 or 996-105-180-57 can be used on your car. But not OK to use 55 or 56, those require more changes inside the engine (details in TSB 1551). If your IMS tensioner looks like the one on the left, that could be part of the problem: In order to use the 55 or 56 P/N's (springy looking one), that TSB 1551 details all the changes that need to be made inside the engine (chain design goes to tooth instead of roller, differeent rail design, etc.)

Ok, I have the one on the right.

Then that is the correct one...

Yep, I was just confused becouse the pet says to use -56 ending part. I think that I have missread it some how..

Yes it is a long read and gets a little confusing.

Speed rII-you asked for someone to start their car cold....... 1999 C2 -outside air temperature 72 F-Idle at cold start 1,000 rpm -oil pressure instantly 5 .

dcdrechsel Thank you! My oilpressure is allso "instantly" 5bar, but the engine rews over 2k rpm and idle setles somewhere around 1k rpm. Could you confirm that the rew's won't go past 1500rpm on the startup??

Does not go past 1500 rpm -in fact seems to not go past 1000.You didn't ask but these are the things I would check .I am assuming that car didn't do this before rebuild .Throttle cable is tricky slight misrouting can do strange things.Chain tensioners in the right positions and working properly -simple test to pull each one and pump up in can with oil .Possible that gasket sealant partially plugging hole . Cam driven oil pumps aligned correctly .IACV -I kow you cleaned it but may still have some binding .Intake manifold boots for cracks . My guess is that it's something to do with the tensioners which is throwing everything off .

Thank you dcdrechsel These symptoms were on the car long before the rodbearing failed. My idle smooths out fast to 1k rpm. When engine is started the rew's jump fast to 2-2.2k rpm for about 2sec. and drops to normal. Infact I have begin to think that this could be the cause that made the mainbearing fail. Like starting the car with throtlepedal pressed. Like Pac996 mentioned in the rodbearing topic.

Just thought of this -my car is US model and I believe you have an ROW model .They are probably programmed differently .For example the US model has secondary air injection for emissions and I don't think the ROW does .The point being that my results may not apply to your car .

I spent some time with search on this high startup rev problem. The primary causes found were throttle cable routing and dirty or bad IACV. Check that the throttle cable is not too short due to improper cable routing. When it is routed correctly the throttle body butterfly should be resting against the stop and the cable have a very small amount of slack in it. Also I think I remember reading if you unplug the IACV the DME will go to a "default" idle control behavior, might be worth trying, even if this doesn't work.

Thank you logray, I have checked the throttle cable. Cable is "loose" and the butterfly is fully closed. BTW. should the butterfly be completely closed, or shoild there be small gap? Mine's fully closed, and all idle air will flow thru IACV. I think that I will take the IACV apart and see if I can put more preload on the spring that keep's it closed. Will see if that helps.

Ok, I took the IACV apart and cleaned it. There is no springload, operated by magneticfield only. Valve was amaizingly easy to take apart, just pull the locking pin off and twist. thats it. I turned the coilpart litlebit so the valve is closed. For now it fixed the problem, let's see what happens when(if) the ecu adapts to the changes.

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A very small gap is normal.

Thanks Topaz330ci, the gap was about 3mm. I might adjust it to be litle open, if it gives me some trouble. The new one is over 300usd, yiks....

More info-Just got a chance to try my car again-this time temperature was 50 degrees f and cold start it jumped to 2000 rpm for a split second then back to 1000.

Thank's dcdrechsel Just tested the car after I adjusted the IACV, revs jump to 1600 and just faint tick for sec or two. So, I think that this one is solved. Thanks everyone that helped