Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5

Tractor noise at startup
#1

I did my best to search for this, but didn't get a lot of traction with 'my car sounds like an airplane when I turn the key.' Anyway, while the starter is running and for the first couple of revolutions under its own power, my new 968 makes a "putt-putt" exhaust-type noise very similar to a tractor or propeller airplane motor starting up. The noise is easiest to hear from the driver's side of the car with the hood closed. It does not seem to be the starter, since it persists briefly after the engine is running.



It's the same hot or cold: about five "putt" noises in a row, after which it idles and runs very smoothly and quietly with no lifter noise. Revving the engine doesn't seem to cause a similar noise.
Partial Post: Please Login or Register to read the full post.
Reply
#2

[quote name='pontifex4' timestamp='1343073407' post='129827']

I did my best to search for this, but didn't get a lot of traction with 'my car sounds like an airplane when I turn the key.' Anyway, while the starter is running and for the first couple of revolutions under its own power, my new 968 makes a "putt-putt" exhaust-type noise very similar to a tractor or propeller airplane motor starting up. The noise is easiest to hear from the driver's side of the car with the hood closed. It does not seem to be the starter, since it persists briefly after the engine is running.



It's the same hot or cold: about five "putt" noises in a row, after which it idles and runs very smoothly and quietly with no lifter noise. Revving the engine doesn't seem to cause a similar noise.

[/quote]



I hope I haven't put this in the wrong forum. It has been suggested that if my timing were off, I could be hearing something like this until the engine is fully running (after which, presumably, I can't hear it over the sound of the engine).



Thoughts?
Partial Post: Please Login or Register to read the full post.
Reply
#3

Not ignoring you, completely mystified....



???



Jay
Partial Post: Please Login or Register to read the full post.
Reply
#4

No clue. My first thought was you're losing fuel pressure and the engine is just turning over and getting a few drops of fuel and "chuffing" until fuel pressure builds back up, but that's a complete WAG.
Partial Post: Please Login or Register to read the full post.
Reply
#5

do a blink test if you can and look for a hall sender code. being a canadian car, you may not be able to, and will need to connect a durametric or hammer
Partial Post: Please Login or Register to read the full post.

94 Midnight Metallic Blue Cab Porsche 968 w/deviating cashmere/black interior and WAY too many mods to list - thanks to eric for creating www.968forums.com



"It isn't nearly as expensive to do it right as it is to do it wrong."
Reply
#6

Look at resonator at both ends to see if there is any telltale deposits from moisture. A cracked exhaust can react funny until exhaust gas temp comes up.
Partial Post: Please Login or Register to read the full post.
Reply
#7

"do a blink test if you can and look for a hall sender code. being a canadian car, you may not be able to, and will need to connect a durametric or hammer"



This is actually a Florida car, but my Canadian 944s all had the diagnostic port. I'll see if I can find my light and try it.



[quote name='RS Barn' timestamp='1343159171' post='129914']

Look at resonator at both ends to see if there is any telltale deposits from moisture. A cracked exhaust can react funny until exhaust gas temp comes up.

[/quote]



This is what seems the most likely to me, since it really sounds as though I can hear one cylinder's exhaust valves opening and closing for that brief period. However, it happens hot or cold.



In any case, I'll finally be able to put it on the lift this weekend and have a proper look around.
Partial Post: Please Login or Register to read the full post.
Reply
#8

cool - i presumed that you had already put the car in the air and looked for leaks. obviously check that first.
Partial Post: Please Login or Register to read the full post.

94 Midnight Metallic Blue Cab Porsche 968 w/deviating cashmere/black interior and WAY too many mods to list - thanks to eric for creating www.968forums.com



"It isn't nearly as expensive to do it right as it is to do it wrong."
Reply
#9

[quote name='flash' timestamp='1343161875' post='129918']

cool - i presumed that you had already put the car in the air and looked for leaks. obviously check that first.

[/quote]



Yeah, it's really killing me that I haven't had time to dig into it yet. The first thing I do may be to change the FPR, since I think it's original (130K miles) and the fuel pump is really whining. I'll update this thread with my startup noise findings, in any case.
Partial Post: Please Login or Register to read the full post.
Reply


Possibly Related Threads…
Thread / Author Replies Views Last Post
Last Post by tamathumper
09-15-2013, 09:37 AM
Last Post by 4matic
10-24-2007, 11:04 AM

Forum Jump:


Users browsing this thread: 1 Guest(s)