Chain tensioner or else ?

[Aurel]

Hello All,

I own a 911 SC Targa 78, with 97K miles on it. I got the clutch changed recently. Everyhing was fine, and the car was pulling strong. Now, the engine has lost most of its torque, and does not have the same frank explosive sound at high rpm, rather a softer sound. Also, there is a rattling noise when the engine is on charge and torque is needed (high gear, low rpm), but this noise does not occur at higher rpm, or when idling. My assuption is that the timing is off, because of worn chain tensioner (they were not upgraded yet). Has anyone experienced the same and could confirm ? I hope it could be simpler, like an ignition timing problem, but fear it could be worse than just chain tensioners too. For now, I am not driving it anymore, and praying that my baby get better soon...Thanks for your insights...

[rstoll]

Does the 78 have a catalytic converter???? Hmmmm?

[stormcrow]

I'd look at the cat converter also. When I did a rebuild on my 78 SC the cat converter was in pieces blocking the exhaust causing the engine to lose power

Steve

[Aurel]

Thanks for the catalytic converter suggestion
Did you hear that rattling noise with a bad catalytic converter, or just lost power ? And do you think that an exces of oil going through the exhaust could have shot the catalytic converter ? I had a huge smoke problem just before all the trouble started, because the mechanic had put too much oil after replacing the clutch...I`d work on the car myself if I had a garage...

[rstoll]

Sounds like it may be time for a test pipe and a bottle of techron.http://www.pelicanparts.com/catalog/shopcart/911M/por_911M_exhaus_main.htm

[wckrause]

If you had a lot of excess oil getting sucked into the intake, then you may have also gunked up a lot of things, like the throttle body, CIS sensor plate, vacuum connections to WUR, and to distributor.

If the mechanic overfilled the oil, then they should be more than willing to clean up the mess in the intake.

Make sure the vacuum lines between the throttle body and the distributor (and WUR)are clear.

------------------
Bill Krause
'79 911SC Euro
MY PELICAN GALLERY

[Roland Kunz]

Hello

A failed chain tensioner normaly doesn´t affect the poweroutput ( Only if the chain snaps and the pistion hits the valve )

The oil overfill could have starting to gloog the catalyc. Nomally they burn free after a while.

A visuall check will show.

Grüsse

[Superman]

If you see chunks of dark grey honeycomb stuff rattling around in the CAT, there is a way to convert that CAT into a test pipe. Hehehe. A broom handle works well. If chunks got in the muffler then shake them out.

------------------
'83 SC

[rstoll]

Hey Super, I have been thinking about a test pipe. Converting the converter sounds good too. Broomstick eh?? I have heard that you get the converter to operating temp and then spray cold water on it and the temp shock will shatter the catalyst. Seems if this worked to loosen up the catalyst so would a big rain puddle in the road. Broomstick sounds good. Thanks.

[Aurel]

Thanks for all the suggestions guys. I will use my week-end to find out where the trouble is. But I am worried not only by the loss of power but also this bad rattling metallic noise the engine does at low rpm. It sound like a dead bearing in the transmission. But if it was, power should still be there...I dont think just a clogged catalytic converter would cause that noise. I`ll keep you posted when I solve the mystery anyway...

[ronin993]

yep, had the same ratteling prob. thought somthing was seriously wrong with the engine. then i had a friend play with the gas peddal while i inspected the exhust system. turned out the rattling was from the cat, was i ever happy it wasnt anything serious. so i grabed the end of the broom and cleaned her out, chucks of honey omb came out, and pushed it all out by whaling on the peddal. and presto it all came out and gaind a few more ponys.

[L Sjoberg]

man am I glad I stumbled on this post today. I've had a rattle that's been scaring me forever - I have the updated tensioners, have checked for a lean problem; etc. I guess this means a weekend of checking the cat, and maybe finally making the move to the test pipe and sport exhaust : )

Lee
'83 SC

[Aurel]

Well, I guess I will dismantle the exhaust this WE, just to see...and this is the first step to acces the chain tensioner cover anyway, so it will not be lost time...and if I don`t find out, I will tape record the noise and post it, so that you can hear what I`m talking about! By the way, here is a pic of the car.

Cheers
Aurelien

[emcon5]

Give the cat a whack with a rubber mallet. If the core is cracked, you will hear it rattle around inside.

Tom

[rstoll]

I think I'll whack my cat this weekend.

[jjrowe]

I have the exact same noise on a 76 911 S that has backdated exhaust (no thermos). Rattling noise at low rpm that disappears as the rpms speed up. Can't figure out what it is...

Jesse

[rstoll]

May have a broken chain ramp. Chain to stud is noisey as hell.

[Aurel]

As far as I am concerned, and after 1 and a half year that I posted that thread, I found out that this was a transmission noise, not an engine noise.
Probably the differential.
The noise is still there, but the engine now has 102K miles and still runs very well, besides a few broken head studs...
I will do a compression test soon.

Aurel

78 SC Targa