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Engine tick / rattle when cold only

Rob001
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Rob001 Member

Rob001

Posted
Posted

Reading about engine ticks, knocks and ratles and hoping this not happen to me it is now my turn to listen to the jingle bells..

I got a MY99 C2 manual. When cold (overnight) starting the engine, I hear a tick/ rattle after a few seconds which then will last for approx. 1 minute if I keep it idle. It seems to be irraguar as well.

When reving slightly up during this minute the tick is gone too. When engine is warm or after 2-3 minutes no tick at all. Starting after a few hours no tick either so it is only when totally cooled down.

Oil is recently changed (5W40) Engine is not using oil or is smoking. Water and oil level is ok and no intermix signs.

I recorded the tick from a cold start on the file attached and it seems to come from the underside of the engine.

What could it be? Valve tappets, chain tentioner, chains, piston slap or something totally different?

I know it is hard to judge from a recorded file but I do not want to tear the whole engine apart looking for it. So any suggestions are welcome here.

Memo.mp3

Rob

Beninki Member

Beninki

Posted
Posted

That sounds serious. I would not drive the car or start it. Not to be alarmist, but it definitely could be the IMS bearing going. I would check for bits of the rubber parts of the bearing in the oil and flatbed it to an independent, who is familiar with this issue, to have it evaluated. Seriously, do not start or drive the car until you get a good diagnosis- the cost could be a new engine.

Post over on Rennlist and see if you can get a comment from Jake Raby- he is the IMS upgrade guru...

The good news is that you caught it early, whatever it is. Good luck to you.

Best,

Tom

Dharn55 Member

Dharn55

Posted
Posted (edited)

An IMS noise is usually not going to go away with revs or when the engine warms up. Sounds more like a tappet or a chain tensioner to me. Have you tried listening with a screw driver pressed against the engine and your cheek bone near your ear to try to locate the noise? I had a sticking lifter that made a clicking noise before I replaced all of them. And now I have a tapping that is a sticking tensioner that needs to be replaced. It akes a while to pump up on first starting the car but goes away when it warns up a bit or with RPMs. Planning on doing that this spring, probably with the IMS upgrade.

If it is the IMS bearing then the noise should be coming from the trans end of the engine. There is a lot of paranoia on the IMS, and if it fails the results are disastrous. But there are many many sources of tapping or clicking noises unrelated to the IMS.

Edited by Dharn55
Rob001 Member

Rob001

Posted
  • Author
Posted

An IMS noise is usually not going to go away with revs or when the engine warms up. Sounds more like a tappet or a chain tensioner to me. Have you tried listening with a screw driver pressed against the engine and your cheek bone near your ear to try to locate the noise? I had a sticking lifter that made a clicking noise before I replaced all of them. And now I have a tapping that is a sticking tensioner that needs to be replaced. It akes a while to pump up on first starting the car but goes away when it warns up a bit or with RPMs. Planning on doing that this spring, probably with the IMS upgrade.

If it is the IMS bearing then the noise should be coming from the trans end of the engine. There is a lot of paranoia on the IMS, and if it fails the results are disastrous. But there are many many sources of tapping or clicking noises unrelated to the IMS.

Agreed that not every tick has to be an IMS issue and I'm for sure that this is not the case here .

I still drive it daily and not trying to be carefull being affraid something will give, this is not the car for it. (however I sometimes wish it did as a good excuse for a major engine upgrade..)

judgejon Member

judgejon

Posted
Posted

An IMS noise is usually not going to go away with revs or when the engine warms up. Sounds more like a tappet or a chain tensioner to me. Have you tried listening with a screw driver pressed against the engine and your cheek bone near your ear to try to locate the noise? I had a sticking lifter that made a clicking noise before I replaced all of them. And now I have a tapping that is a sticking tensioner that needs to be replaced. It akes a while to pump up on first starting the car but goes away when it warns up a bit or with RPMs. Planning on doing that this spring, probably with the IMS upgrade.

If it is the IMS bearing then the noise should be coming from the trans end of the engine. There is a lot of paranoia on the IMS, and if it fails the results are disastrous. But there are many many sources of tapping or clicking noises unrelated to the IMS.

Agreed that not every tick has to be an IMS issue and I'm for sure that this is not the case here .

I still drive it daily and not trying to be carefull being affraid something will give, this is not the car for it. (however I sometimes wish it did as a good excuse for a major engine upgrade..)

I had a similar sound with a 3.0 engine in my 911sc. of course, all sounds were were really obvious with the air-cooled, lots of "clicks and clacks" all the time, but always smooth sounding. hard to describe.

then I heard a mysterious, disturbing sound only at about 3-4k, that had a raspy nature to it. checked it out, got some good opinions, decided to bite the bullet and get into it. and sure enough a main bearing on the crank had cracked. this was at about 160k on the engine. rebuilt the engine, new pistons and jackets, and then drove the car every day, really, until I sold it at about 325k. engine was really strong.

moral of the story is to listen carefully, hope for the best, plan for the worst. good luck.

  • 4 years later...
Jamesx19 Member

Jamesx19

Posted
Posted

Hello Rob,

 

May I bring this topic back to life..?

 

I am the newish owner of a 1998 UK registered 996 C2, manual..... and a even newer member of this excellent forum.

 

The mp3 sound file you downloaded sounds exactly like my car on cold start as well. Its currently being looked at, but would dearly love to know what the result was for you? Did you get the car looked at or inspected. Did you discover what the fault was?

 

Many thanks,

 

Jim

  • 4 months later...
Jamesx19 Member

Jamesx19

Posted
Posted

Hi grown,

 

I took the car to a Porsche specialists. They were inconclusive about the noise, but felt that it wasn't something to be to worried about, on a 18 year old engine. 

 

The consensus was that it was probably the hydraulic lifters taking time to fill with oil. I reckon the noise on start up was slightly worse when I swapped to 10w50 millers nanotec oil. I imagine this is because the oil is slightly thicker at cold start up than the oil before it. 

 

The fault is not the oil, but the engine will inevitably be worn. So it could be the chain tensioners, or vairocam hydraulics, or hydraulic lifters (tappets). None of those things are great, but not engine life ending either I'd hazard. Just symptoms of an engine that will be getting on a bit.

 

Hope this helps,

 

James 

Ahsai Member

Ahsai

Posted
Posted

If your noise is exactly the same as the mp3, I doubt it's the lifters. It sounds more like water pump, altenator, or idle pulley.

Just remove the sepertine belt and see if the noise goes away. Also hand spin all the pulleys and accesories to feel if any is gritty or noisy. Last, use a mechanics stethoscope to check for noise.

10w50 is not the proper oil. Its too thick. Try 5w-40 motul xcess.

grown Member

grown

Posted
Posted

My car makes a noise very similar to what was documented in the first post. It's also a 99 c2 with about 135k km. It will only happen at first cold start of the day (A/C off) and doesn't kick in for ~ 5 seconds after engine on. I'd describe it as a rattle or a knock -- and agree with Ahasi that it doesn't sound like lifter tick. It doesn't increase with rpm and will disappear slowly over the first minute of running. I've always let the car build up a little heat in the oil before backing it off the driveway. Outside temperature doesn't seem to affect things either.

​

After stumbling across this thread I spent a little time trying to hunt the source of the noise. I removed the belt and started the car cold, the noise was much reduced. I'm not sure if it was just my heightened senses in the moment but I thought I still heard a faint knocking. My water pump was replaced within the last year and was tight and free spinning. The idler pulleys are all tight and medium-to-free spinning. The alternator, P/S and A/C seemed fine too.

​

​Car will be on the lift in a couple months for a clutch/etc and may delve deeper into this issue at that point.

​

​I might try the driveway experiment again in a couple weeks but really need to get a new trunk strut first. Stupid struts.

grown Member

grown

Posted
Posted

I'm going with bore scoring.

 

​

:rolleyes: Thanks. IMS bearing too cliche? Or maybe you could explain your 'going' a little more.

White987S Member

White987S

Posted
Posted

 

I'm going with bore scoring.

 

​

:rolleyes: Thanks. IMS bearing too cliche? Or maybe you could explain your 'going' a little more.

 

Research "bore scoring" on Rennlist and pay close attention to posts by Jake Raby of Flat Six Innovations.

 

Idling your car, on the driveway, "to build up a little heat in the oil", is one of the very WORST things you can be doing to your 996.

grown Member

grown

Posted
Posted

Getting back on topic... what makes you think the noise in post #1 is bore scoring? I'm not ruling out the possibility but I've read the same threads you have and I haven't been able to make the connection.

Ahsai Member

Ahsai

Posted
Posted

It's very simple. Just put the car on a lift with the serpertine belt remved and do a cold start and check around. Also use a mechanics stethoscope.

Guest porschesal

Guest porschesal

Posted
Posted

cd18d74601b1c70216bf2295f2c4aad3.jpg

this is from a cayman with a very bad engine tick

grown Member

grown

Posted
Posted

this is from a cayman with a very bad engine tick

 

But this doesn't help -- did you listen to the sound clip? Do you realize you're posting in a 996 forum? The Cayman doesn't even use the same engine.

 

Not only are you (and White987s) not contributing to the topic but you're sabotaging those who are. So thanks but no thanks.

Jamesx19 Member

Jamesx19

Posted
Posted (edited)

The original post is talking about, and describing a very specific noise at a specific point when the engine is switched on from cold.

There are of course many documented problems for this engine, simple speculating / guessing / regurgitating things from other posts on other engine topics is probably not helpful or constructive to the original poster. 

Edited by Jamesx19
  • Admin
Loren Member

Loren

Posted
  • Admin
Posted

@grown and @Jamesx19: Please focus your questions and comments on the issue rather than the posters (per this site's Guideline/Rules).

 

@grown: The Cayman, Boxster, and 996 all use the same basic M96 engine.

 

@Jamesx19: There are diagnostic procedures can help identify the source of your problem. Those will likely include a compression test and borescope examination.

If those prove negative then you are likely looking at a transmission removal to inspect the IMS bearing.

Guest porschesal

Guest porschesal

Posted
Posted

grown you are an ******* !

Guest porschesal

Guest porschesal

Posted
Posted

I just put it up so you would know what it will look like when you use a bore scope

Guest
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