BaysideC4

For the last month or two my car has had a rattle when starting. It’s not consistent (sometimes goes a day or two without a rattle) but I fear it may be the DMF. The sound is coming from the engine compartment but could be lower. It has a distinct rattle then fades away with in 5 seconds or so. No rattle at all when shutting the car off.

Does this sound like a Dual Mass Flywheel problem?

Thanks,
Brad

joey bagadonuts

I hear this, too! Usually after I let my car sit for at least 3 or 4 days. If I'm running it daily, then there's no noise. Does this sound familiar?

I have no idea what's causing this, but I don't think it's DMF failure--mine's been replaced. Like you mentioned, Brad, the sound is coming from the engine compartment and is gone within seconds.

Anyone?

Adrian

Dear Brad,
As it wasn't there before and now it is I suggest you need to al least have a look from underneath. When the engine is started it twists on its mounts. You need to pull the rear cover off and check to see if anything is loose.
The quick DMF check has already been posted. If you can move the 964 in 1st gear, engine off (hand brake off) this says one mass of the DMF is moving against the other which is the failure.
Rattles are very hard to diagnose because anything loose rattles. Again my first bet is the engine mounts. These things have a life and seeing as the years are rolling by I think more and more will be found failed.
Ciao,
Adrian
964C4

Fred, Long Island

Chains can rattle at start up until tensioner pumps up. Should only last a second and occur once or twice in months. Shouldn't be a common occurrence. Anyone out there had any experience or reason to replace the 964 tensioners?

joey bagadonuts

Excellent, Fred! I think you're right on the money. As you mentioned, the noise lasts only a second or two.

BaysideC4

The sounds is sort of like a "clap" then a "rattle" that fades out. The whole thing is over in seconds. Yesterday it didnt happen at all. Today it happened on the first startup.

Trader220

Could it be the dreaded bottom motor cover? Then as it heats up it expands ever so slightly eliminating the lose fit and the rattle. Keep in mind this is only a guess.

Adrian

Dear Fred,
I know two people who have had to replace chains and covers. Both threw their chains. However before anyone panics these were race prepared engines. I know of one road car that had a chain case replaced (internal damage discovered during overhaul) but the chains were correctly adjusted and did not appear damaged so wer enot replaced. The chains should be tensioned correctly and not rattle. Remember the 964 was not the first with chain driven cams.
Ciao,
Adrian
964C4

bj

Hi All

I have the same symptons as Joey described. Started doing this within the last couple of months. I was suspecting the catalytic converter. Could it be the ceramic which is loose and when the exhaust and heat hit it, it goes back into place?

Just a thought
90C2
Bill

Andy Roe

I too have had a rattle that's lasted about 1 or 2 seconds & does change as then engine revs come up. It's done it once in the last 3 or 4 months since I had my failed LUK flywheel changed and it did it before too. I'd be interested to know what's causing it, but, sadly, these things are very hard to trace - especially when the happen very rarely & never in the presence or your mechanic!

Surf Twang

Well, just this morning my RSA just started making a noise on startup. Sounds like a rattle. I went on the BAR drive Sunday morning and drove the car very hard but no harder than I had driven on the previous two BAR drives. I didn't drive the car again until today (Wednesday) and that's when I heard the noise. It went away after about 30-45 seconds. The clutch pedal has been feeling a bit different, too. Could they be related? I'm anxious to see if I get the noise the next time I start it.

Chris Martin

Found this old thread and wanted to see if there is any new advice on this topic. I have heard what I think is a chain 'rattle' on startup 3-4 times over the past few month in my car. I have the chain housing covers off and there is no apparent wear on the ramps. However, the left tensioner has a little, a few mm's, more play than the right side. The sound seemed to be coming from the left side of the engine, when it did occur.

Is there a way to test the chain tensioner? I dont want to buy a new one just to try, but also dont want to grenade the engine just to save a few hundred $$.

Any help is much appreciated!

Chris

JAMES J

bj...... My DMF would rattle when shutting engine off...replaced with LWF etc. Now I have rattle that occur's when I start up with cold engine....goes away after thing's heat up....positive it is the catalytic converter (ceramic). Need's to be replaced. My P-car has 104,000 mi.
JimJ

Chris Martin

Thanks for the suggestions. The engine is in an SC, so it has a lightweight flywheel and no cats, good ideas though.

Is there a way to test the chain tensioner?