Jump to content
Ultimate Subaru Message Board
Sign in to follow this  
outback_97

Poor starting -> acute piston slap ?

Recommended Posts

Summary: Car required way more cranking to start, had quite loud tapping sound which eventually went away.

 

Hello, just wanted to run this past the folks here. My '97 Legacy OB (4EAT) didn't want to start this morning, crank crank crank crank crank crank... nothing. Tried that again, nothing. Third try with all accessories shut off.. crank crank.. finally turned over and sputtered to life, running very rough at first, I gave it some gas, and eventually the idle smoothed out after warming up a bit.

 

What was weird was that after it finally started, there was a pronounced knocking or loud ticking sound, much louder than I've ever heard. It's always had a slight tick when cold, primarily under load, that I assume is "piston slap", which disappears as it warms up. But this was a lot louder, my wife even heard it inside the house (through an open window) 'cause she noticed I was having trouble starting the car.

 

Once car was warmed up, it drove fine, idled fine, etc. Started it a few hours later, and it started right up as it always has.

 

Any reason why the hard start would cause an acute severe case of the piston slap? I'm assuming the hard start may indicate a problem with the starter or solenoid, we'll keep an eye on that.

 

No CEL's. Car had sat for 4 days, nothing unusual. New battery. No previous problem resembling this, seems to work fine now, moderate temperatures (low 50's), normal humidity, no other odd things I can think of to comment on.

 

Steve

Share this post


Link to post
Share on other sites

Loud ticking could have been a sticky valve lifter. Which might cause hard starting, if the valve isn't opening right.

 

Chalk it up as a fluke.

Share this post


Link to post
Share on other sites

How low was your gas level when you parked it; and what was the outside temp/humidity?

 

Sure sounds like you gulped a big slug of water in the fuel from condensation. 'Specially after being parked for several days. Best reason in the world to always drive off the TOP half of your tank.

 

Nothin to do with the noise, tho'. I might be temped to throw in a can of Seafoam, and change the oil after a couple hundred miles.

Share this post


Link to post
Share on other sites

Mtsmiths:

 

My gas gauge is not accurate (reads too low always), but my trip odo always gets reset... and it says I have over 3/4 tank. Agreed on the top 1/2 of the tank idea. Grew up in rural northern MN... you don't want to run out of gas there in the winter... probably like Whitefish, MT :) But I suppose it wouldn't hurt to run some Isopropanol through the tank, although I stick to good quality gas as a rule.

 

The SeaFoam intrigues me, I've read about that here, might be worth a try. Just had the oil changed very recently.

 

The only other thing I can think of is: The last time the car had been started before this incident, it was only run very briefly to move it in the driveway (by my wife) and wouldn't have gotten warmed up at all. Still don't see how that would have caused it, as although I try to avoid doing this (starting the car just to move it 20 yards) we've had to do it before as we have a single lane driveway.

 

Steve

Share this post


Link to post
Share on other sites
Mtsmiths:

 

The only other thing I can think of is: The last time the car had been started before this incident, it was only run very briefly to move it in the driveway (by my wife) and wouldn't have gotten warmed up at all. Still don't see how that would have caused it, as although I try to avoid doing this (starting the car just to move it 20 yards) we've had to do it before as we have a single lane driveway.

 

Steve

 

My hypotheses:

1) the car was hard to start cause excess fuel (present at startup: choke effect) was still present in the cylinder (mild flooded condition) because of the brief time the engine had been running previously.

2) the slapping noise was due to part of this excess fuel running down the cylinder walls and removing the oil that usually sticks there until next startup.

Share this post


Link to post
Share on other sites

I've experienced the same hard starting a couple of times before, seemed to me it was always when the car was never allowed to warm up and on for short periods of time. I just assumed the engine was flooded due to the high idle and rich running at start-up.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

×