Start up/cold weather knock?

[yellowblaze]

Anyone else have a start up knock in cold weather?  We've got just about 4,000 on our 03, and changed the oil to Royal Purple synthetic @3,900.  We were hoping the synthetic would help, but it still does it.   It does it until we drive about a minute down the street (@30 mph), it doesn't seem to matter how long it sits at idle warming up. This is our first Subie, so we're not sure if this is a normal boxer thing, or if she needs to visit the subie dr.

[jaxed]

If it means anything, my '05 does not knock - though I have not had it long.  It was down to -2 the other day, and I had no problems.

[mbaksic]

My 03 makes a funny knock when cold. Its been cold up here in Wisconsin for the last week. It sounds bad, but it goes away when the engine warms up. It sounds like piston slap to me. Its not as bad as my 93 Cherokee was, that thing would have piston slap/knock all the time, and it never used a drop of oil in the 190,000 miles I put on it. As long as its not causing any problems like oil consumption, just let it go and see if it gets worse. If it starts using oil, or the noise gets worse, then I would take it  in and have it looked at. Just make sure its cold when you take it in, or you will get it back and they will tell you that there is nothing wrong with it. I know how this goes working at a Dodge dealership. Its always a pain telling someone that you can not duplicate their problem. They get mad, and look at you funny.

[cyphergirl]

Mine does it as well.  Our BMW motorcycles both do it, so I think it may just be a boxer thing.

[mbaksic]

Yes, the old piston slap. Sounds bad but doesn't hurt anything. I have heard this in GM cars and the Chrysler stuff I work on now. They seem to sound better than they did years ago. Except we had a used Chevy truck, that thing was so noisy, that it sounded like rod knock for the first 5 minutes!!  Mike

[su-be3]

My wife's Outback Wagon makes the same noise when it starts. Let it warm up a bit and it's just fine. I tend to agree, it's piston slap.
So far on my Baja Turbo, I haven't heard it yet.
Keep it under 90, folks!

[Mike Franke]

Mine makes the same basic noise, and it NEVER gets cold in Tampa (ever).

For what it's worth, the loaner Subie's that I've gotten from the dealer when the A/C went freako all did the same thing, from a Forester, to a Legacy, and an WRX wagon.

I've heard piston slap in other engines, and it's similar. The pistons in these engines aren't meant to reach proper clearance until the engine warms up, so it's considered normal. Alldata lists a TSB for this issue.

I've almost reached 30k, all with Mobil 1, and have had the oil analyzed every 10k, with no fault found.

Learn to love the slap...

[Hawk296]

as mentioned, probably piston slap. Subaru engines have a very short piston skirt because they are opposed engines. This causes them to clatter when cold

Did subaru ever change their timing belt belt tensioners? If not it could be that (a cheap design)

[ahyesiam]

My does it also, bugs the crap out of me. I took it to the dealer and they assured me it is due to the short piston skirts and cold weather.

[davecoon13]

Anyone else have a start up knock in cold weather?

I am almost about to hit 35k miles on my 03 (Sport AT). Yesterday, the Baja Dashboard read the outside temperature as 18°F. When I started the car, it shook and sputtered and stalled out. So, I started it again in Park and gunned the engine for about 15 seconds. As soon as I let off the gas pedal, again it sputtered and shook to a stop. Then, as the saying goes, "third time's a charm", I started again and it did not stutter the third time. I let it run for 10 minutes before driving anywhere.

Is this normal for Subaru? I noticed the other day at a stoplight the Baja was idling really rough and shaking slightly.

Thinking that I simply had bad gas, I put a bottle of Slick 50 Fuel Treatment and a tank of High Octane Super/Premium Gas and that seemed to fix the rough idle at stop lights, until yesterday.

Any ideas here? I thought maybe there was condensation in the fuel line given that there was a recent ice storm and the car was covered with ice.


Is this rough idle something that would be covered under my Added Security 6 year / 60K warranty?

-Dave Coon

[mbaksic]

Wow Dave, got me on that one. I have not had this type of problem at all. Oh, it gets a bit weird once and awhile when hot, but nothing like this cold. If you are over 36,000 miles, it prolly won't be covered under warranty. You may have a bad plug or wire that only shows up when damp out. You might like to take a water bottle and mist some water over the plug wires to see if it sparks somewhere. Should show up good, especially if you do it when its dark out. Like I said, I have not had anything like this, and I have 86,000 mile on my Baja right now, with original plug wires. Mike

[davecoon13]

If you are over 36,000 miles, it prolly won't be covered under warranty. You may have a bad plug or wire that only shows up when damp out.e

I have 35,031...I will check out the plug wires myself. Thanks for the tip. Maybe I can use wire dryer spray like we used to do in Louisiana.


The auto parts store had STP Fuel Treatment on sale for $1 per bottle (actually $10 for $10), so I put several bottles of STP in the gas, plus a bottle of the ever trusty Berryman's Chemtool Fuel Treatment. It seems to have cleared up the sputtering for now...and it was 19°F yesterday.

Since you "work on Dodges" it reminds me of a story from my Childhood.
I remember When I was a kid, we had a 1983 Dodge Ram 150 Custom van (the full size van, before Mini-vans). The engine was under a shroud inside the vehicle. What was weird was that the distributor cap was right up underneath the wheel well, a really dumb design--especially in Louisiana. Every deep mud puddle stalled the car out when the distributor got wet. We used plenty of wire dryer on that van back in the day....My dad rigged up an old margarine container to cover the distributor on that van which really helped, but he sprayed 2 cans of wire dryer on the distributor with each rain storm and replaced his homemade cover every few months.

Do the Baja's have an electronic ignition and therefore lack a distributor? I haven't really poked around much under the hood.

[mbaksic]

Not only all electronic, but they only have coils now, instead of the distributer. They are the black colored boxes that the plug wires start out at on top of the engine. All computer controlled, of course. If the gas treatment helped out, maybe it was a bit of moisture in the gas. I have not used that stuff in years, with all the alcohol in the gas, I figure that keeps it pretty well dried out. But with extreme changes in temp, you might have issues with condensation, so if it helped, that was an easy fix. Mike

[Blue Baja]

I have a 06 Baja. I was letting the car warm up and it started out smooth and quiet then for no reason the noise that sounds like a rod knock began, mind you I had less than 10K. Glad to hear that I'm not the only one, but sorry to hear this is considered normal. My other car is an 88 3cylinder Chevy Sprint with over 300K - it burns no oil and doesn't sound anything like my Baja when its warming up.

[bulwnkl]

I have a 06 Baja. I was letting the car warm up and it started out smooth and quiet then for no reason the noise that sounds like a rod knock began, mind you I had less than 10K. Glad to hear that I'm not the only one, but sorry to hear this is considered normal. My other car is an 88 3cylinder Chevy Sprint with over 300K - it burns no oil and doesn't sound anything like my Baja when its warming up.

If yours starts and initially runs smooth and quiet and then starts a horrible clatter, something else is wrong. 'Piston slap' from short-skirt (i.e. high fuel efficiency & low emissions) pistons can't not occur and then suddenly occur unless something else is going on. If that cylinder wasn't firing initially and then it did, I can see it, but you should notice the rough 3-cylinder idle.