[Subscribe to Daily Digest] |
![]() | [Main General Bulletin Board | BBFAQ |
Prev by Date | Next by Date | Post Followup ]
Member Login / Signup - Members see fewer ads. - Latest Member Gallery Photos
Re: Startup Piston Slap questions Posted by Larry West [Email] ![]() ![]() ![]() In Reply to: Startup Piston Slap questions, nwas, Mon, 18 Jul 2011 18:31:57 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Find someone with an early 90s (or earlier) 4 cylinder, 8 valve, RWD Volvo with high miles. Piston slap is common with those motors. I had a 200k 740 turbo that sounded like a diesel when you started it up from all the slap. I can't say I've ever heard a Saab motor make that same noise, and I've driven them with well over 300k on the motor. I've had rod knock on a Saab, but never piston slap.
And yes, it is the piston skirts hitting the piston walls. It generally is a LOT more annoying than it is damaging to the motor, but a good cylinder honing and new rings would likely cure it.
If you're hearing a noise on a Saab 4 cylinder, it is almost certainly either the hydraulic tappets in a 16v, or "normal valve noise" on an 8 valve.
On the 16v, the tappets that move the valves are pressed on by the cam, and they transfer that motion to the valve, but they are dampened by engine oil under pressure. Often the valves get old and they need to "pump up" in the mornings. Also, if the motor got sludged, they may no longer be getting oil to them. Without the oil pressure, they make a ticking noise.
The 8V doesn't have hydraulic tappets to dampen the noise, so there will always be a small amount of noise evident from the valve tappets. But if the noise is very loud, the valve shims probably need to be checked for proper clearance. This applies to all 99 & Classic 900 8 valve motors.
The best "tool" to diagnose is your ears. It will be evident where the noise is coming from.
_______________________________________ Current: 2002 9-5 Aero Kombi Cosmic Blue 2000 9-5 SE sedan, Imola Red 1990 900S Rose Quartz, Auto Past: 1999 9-5 LPT Combi 1999 9-5 LPT sedan 2002 9-5 Arc 1990 900 5-speed 1986 900 turbo Convertible 1991 9000 turbo 1980 99 GLi 1986 900 turbo 1986 900 S 1991 900 turbo 1984 900 turbo 1976 99 GL
No Site Registration is Required to Post - Site Membership is optional (Member Features List), but helps to keep the site online
for all Saabers. If the site helps you, please consider helping the site by becoming a member.
![]() |
![]() |
![]() |
![]() |
![]() |