55 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHVideo. Identify that engine start rattle.
Reported or suspected cause
failed diaphragm in the aos
Reported cause
No successful repair reported for this finding.
1
Identified cause
0
Suspected cause
0
Reported fixes
Read evidence and context
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Discussions that report identifying a cause
1
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Reported cause · Original poster
So, we haven't identified the engine rattle source yet but the CEL was due to a failed diaphragm in the AOS.
Leading evidence: 'failed diaphragm in the aos' (1 discussions report identifying this cause; no attributable repair resolution). Across 1 matching discussions, the most frequently mentioned possible cause is 'failed diaphragm in the aos' (1 discussions; 1 report identifying it and 0 suggest it). The most frequently discussed action is 'Adjust fuel mixture' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Performed · outcome unconfirmed
I replaced my 1-3 and IMS tensioners and also went with 5W-40 Motul X-cess oil two weeks ago.
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Performed · outcome unconfirmed
I only locked the engine at TDC and replaced only one at a time using a new crush washer.
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Performed · outcome unconfirmed · Original poster
So, they ran the diagnostic for the CEL and came up with a vacuum line leak.
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Suggestion
or composite plastic, pale green rubber like material) then the noise takes on a more sinister characteristic and the engine should be left off and checked by a very knowledgeable tech.
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Suggestion
Throw a manometer on it and check for crankcase vacuum values, then look at TRA, FRA or RKAT fuel trim values and start comparing the numbers to the manometer numbers.
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Rennlist: 1 discussions
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Hard to say. Sounds like a heat shield rattling. Need to get the code(s) read for sure.
Does it rattle if you give it some gas or it just does it at engine start?
I can't listen to the sound at work (streaming media block) but for a week or so before my water pump died I noticed a rattle at startup that I couldn't pinpoint.
You could eliminate that possibility by checking the bearing at the pulley - pull off the belt if you need to. It's better to do this before the impeller disintegrates and sheds plastic bits all through your engine and cooling system. (bummer)
Just a suggestion...
Post the codes when you get them.
I've listened several times and the noise doesn't sound sinister, unless the engine sounds that way upon every start.
The first start after the engine has sat a while -- long enough to cool completely down or when started and then shut off before getting fully up to temperature left off as long as would be required to cool completely down -- my Boxster sounds similar to your's but subsequent starts are quieter as the oil has not had time to drain away from the various surfaces/areas.
However, because the noise might the sign of a pending serious problem do not run the engine on my account.
You can if you want to get your hands dirty remove the oil filter housing and carefully dump the contents into a *clean* drain pan and examine the oil and filter element. If you find a scary quantity of metal particles -- ferrous is the worst -- or a good quantity of other material (alum. or composite plastic, pale green rubber like material) then the noise takes on a more sinister characteristic and the engine should be left off and checked by a very knowledgeable tech.
I note the engine quiets down and idles nicely after startup. The noise could be due to as another poster mentioned heat shields.
I would add perhaps a noisy converter, which might account for the CEL. But of course the codes are needed.
Sounds a lot like chain slap due to a weak chain tensioner? They are pressuruized by oil and leak down after sittiing aloowing some noise at startup - common problem. One way to narrow that down is to pull the fuel pump fuse on a cold engine (Position C4, 25A on mine), turn her over for 10-12 seconds, push the fuse back in, and then try it. Mine cranks quietly after doing this but rattles for 1 sec @ crankup like yours after sitting 4-6 hours otherwise - I don't have any thrown codes though. I am replacing my IMS and 1-3 tensioner as well as swapping to 5w-40 Motul Xcess this weekend to see if I can make things any better.
Pleae post the codes when you find out more.
Agree on the chain slap. Install new 2001> updated chain tensioner with the preload spring should minimize the noise until it to becomes clogged with dirty engine oil.
I have the exact same noise on my car. Comes only when hot, and started after 20min sitting.
Been listening it for 3 years now.
I fully rebuilt my engine after rodbearing failure about 2 years ago, but this noise never stopped or changed.
When my engine was going back to car, I noticed that my flywheel had slight slack on the springs.
My best guess is that the noise is coming from the flywheel.
Ummn, you need chain tensioners. I have diagnosed this one correctly from 1/2 a world away via telephone. Replace all 3.
And I bet the engine uses M1 oil.
Change the characteristics of your oil. The tensioners are pressure fed and friction modifiers in different oils impact them greatly.
If the noises don't respond to these changes the chains are stretching or the chain rails have worn, or both.
Nothing is worse for chain wear than a tensioner issue that leads to these mechanically challenged components at start up.
So, they ran the diagnostic for the CEL and came up with a vacuum line leak. That was Monday. This is Tuesday night and my Indy can't find the source of the leak. Tomorrow they are going to go at it again to see if they can figure it out. Still no feedback on the engine rattle sound on startup. 24 hrs and counting my baby is down. Luckily I can walk to work from my house. Unluckily, it has been raining in northern Louisiana for the last three days.
So.. Throw a manometer on it and check for crankcase vacuum values, then look at TRA, FRA or RKAT fuel trim values and start comparing the numbers to the manometer numbers.
Its not hard.
It wouldn't seem to be that hard. Thanks Jake. I believe he just isn't prioritizing my car. Everyone here raves about this Indy. I believe he is competent but overwhelmed. The nearest Indy is 4 hours away. When I went to his shop it looked every P-car in a 200 mile radius was is the parking lot and garage. He left a message this evening saying they weren't able to get to it today. Apparently we have enough Porsche owners for more independent garages but no one stepping up. Any chance of you franchising two states to the West?
I know you already explained the codes, but I am gonna tell you what I tell everyone.
Get an OBDII reader! They are $30, and worth every penny.
Even if you don't work on your own car, at least you will know what the CEL is from. It gives you a starting point for repairs, and prevents unscrupulous mechanics from trying to screw you over.
As a woman, this has saved me many times. Some mechanics think women are ignorant when it comes to cars and I have had a few of them try to rip me off
7 workdays in the shop. Car was still not ready today. I'm hoping for tomorrow. The owner of the shop says they are way behind. From the line of cars at his shop, I don't doubt it.
The twist to the plot today is that his mechanic has heard the rattle on at least three occasions and now suspects that it is a failing....I'm cringing even mentioning it before people start throwing things at me...he thinks it could be the death throws of the IMS
. Now, that said, I have an aftermarket power train warranty that doesn't expire until June 2015. I don't think warranty claims can be filed until absolute failure of a part, not suspected failure. I mean, can this really be detected from a sound? Further, and maybe Jake Raby can chime in, should I just let it fail and let the power train warranty replace the engine? I'm certainly not going to pay to pull the clutch and trans off for a peek when I have a warranty. Thoughts?
If the warranty will pry without running you through a gauntlet. The only aftermarket warranty I have seen that actually pays is from LaSalle... Those guys impress me a lot. We do all their claim work.
That said, is this noise that's suspicious occurring at start up only?
My car makes that same exact sound when it has been sitting for more then three or four days
; however, once I've started the car it no longer makes that rattling sound unless it sits for several more days without starting it
I don't get any errors messages
I replaced my 1-3 and IMS tensioners and also went with 5W-40 Motul X-cess oil two weeks ago. The car is so much quieter on startup now. In fact I hear the starter whining now (next project)… but mine will still rattle slightly after a few days of sitting. If I cranked every day I probably would notice it. How normal is this for a 01 with 68K miles? How hard to get to the 3-4 tensioner? Looks like the A/C compressor is in the way?
UPDATE:
After having the Air-Oil Separator and Brake Vac Line changed on 24 Oct ($1,206), the car drives better than ever and it cleared the CEL. I'm not sure what difference it made other than the vac leaks having some impact on the fuel mixture, thus better throttle response or maybe my power to weight ratio went up now that I have a lighter wallet.
Just today I got another CEL with a P1123 code. Now I'm wondering if the punctured AOS diaphragm caused some issues with something else Any thoughts. Now, occasionally at start up my engine idles up and down from 800 to 900 RPMs as if it is trying to adjust the fuel mixture. It eventually settles to a constant RPM. I still have the noise at start up featured in the OP video. Now the noise is at every cold start up. My mechanic noted in my last invoice that he thought the noise was originating from the IMS bearing
.
Does it do it on the 2nd start? In other words crank it let it idle a minute, shut it off and immediately restart it. How does it sound? Mine makes noise on the first crank but starts perfectly quiet on the 2nd crank.
DMW,
Yeah, its always on the first crank then ok when warm. Hey, I'm driving it to Rogers, Arkansas tomorrow, then from there to near your neck of the woods in Southern Birmingham for Thanksgiving.
I would at least lock the crank at TDC, maybe even the cams to be safe. I know you can up date two of the tensioners but opinions vary on the IMS one. I can get some pics later if you need them. 1-3 side and IMS are easy to reach. The other (4-6 side) will require you to remove PS reservoir and AC compressor and PS line bracket.
Without re-reading your post, I dont remember if you pulled the easy ones to take a look? Reminder:
LOCK THE ENGINE FIRST! (and cams if it were me).
When I finish dropping my engine this week, I will be giving mine another look too. Our weather went to heck this week. Here is a link with pics of all 3 tensioners. I think these are the updated ones. Scroll Down on linked page.
http://www.autoatlanta.com/results.p...ar=996 1999-05
Here is a pic with explaination (courtesy of Pelican). Its a boxster (yes, I know the engines different) but I think their the same tensioners now:
Not a hard job at all on 2 of them. Mine is a 2001 3.4L and I used the latest tensioners recommended from someone at Pelican on 1-3 and IMS during my last oil change. I only locked the engine at TDC and replaced only one at a time using a new crush washer. I did not do the 4-6 due to the extra effort. Mine is somewhat better but still rattles after sitting overnight. Should I go ahead and do the last one? Maybe it's the one causing the noise.
I was hoping for a DIY from someone or news from you TexAg911 to see if maybe all 3 fixed yours.
And Happy Thanksgiving from Alabama! I bet I'm within 10 miles of you right now.
Please keep me updated.
When you say AC compressor has to come off, do you mean moved out of the way with the sytem still pressurized? I replaced my starter last month. How much harder do you think this will be?
You dont have to disconnect the lines. Just remove the three bolts and work it out the front. Let it rest on your fender cover or something on the back. You will be able to see the 4-6 tensioner but you will have to remove a PS line bracket to get it out. I will post a pic tonight. This is all so much easier with the engine out. I say drop the engine for everything!
Thanks! They don't call you the KrazyK for nuttin'! KrazyK motto - "When in doubt, drop it out"
Seriously, I would love to have your mad skillz and do this some day.
Hey for what it's worth I ordered a bank 2 (4-6) tensioner today. I hope to put it on during some downtime over the holidays. If anybody's interested I'll post an update?
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