Smoking after timing belt change? - Subaru Outback - Subaru Outback Forums
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post #1 of 6 (permalink) Old 11-03-2011, 11:57 PM Thread Starter
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Smoking after timing belt change?

Hey everyone-
I've got a 60k 06 2.5i, took it to the mechanic this week to have the valve cover seals replaced. They also noticed that the timing belt tensioner had failed and replaced that along with the belts.

I got the car back from the mechanic yesterday and finally drove it for about 20-30 mins today around town. About a block from home, I noticed at a stop that the car had started smoking

I got home, popped the hood and low and behold, there's a fair amount of white smoke swirling around the front of the car. Needless to say, not too happy.

I let the car cool down and went back to make sure the problem was reproducible (and not just some stray oil). I let the car sit in the driveway running for 15 mins, and there's no smoke. However, I drove it around the neighborhood a few times after warming up and suddenly, the smoke is back!

Looking at the smoke with a flashlight, the odd part is that it doesn't seem to be coming from the engine- it's swirling around on both sides of the radiator (without the fans running)

Any ideas? I noticed that on the shop receipt they added some coolant, and when the car is warm, the coolant level is about 2-3in above the Full line. I haven't lost any oil, don't have any drips on the driveway (but with the undercover, who really knows). Also, I don't see any evidence of oil on the exhaust manifold or the engine/radiator.

Any ideas? thanks!

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post #2 of 6 (permalink) Old 11-04-2011, 08:14 AM
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Factory fill of the coolant reservoir is often at or above the Full mark. (Look for a yellow mark on the reservoir.) On my 07, the level rises about an inch over the cold level when the engine is fully warmed up. So if the cold level is an inch above the Full mark (as the yellow line is on mine), then the coolant will be a couple of inches above Full when hot. The thing to check is the level when the engine has fully cooled (e.g., overnight).

I believe white smoke is more indicative of coolant (i.e. steam) than oil, but I might be wrong. Coolant also usually has a distinctive "sweet" smell.

It's possible some coolant was spilled down on the radiator and AC condensor, and is just being boiled off when the radiator gets good and hot. (I've had this happen after going through a "brushless" car wash, where the front of the car is directly sprayed. However, in this case, the steaming is short-lived because it's only water; coolant has a higher temperature boiling point and will take longer to evaporate.)

Was it the timing belt (TB) tensioner or the accessory belt (AC) tensioner that was bad? If the former, I wonder how they determined that -- was it noisy? If it was the TB tensioner, and if the TB itself was also changed at the same time, then it's possible that the radiator was removed to get clearance to the timing belt area. That would explain the added coolant. But it could also suggest that perhaps a radiator hose clamp wasn't re-tightened properly, or the rad cap wasn't seated fully -- both could lead to coolant in the radiator/engine area and steaming.

And if the coolant reservoir was significantly overfilled when cold, this too could lead to coolant overflowing out of the container when the engine is hot, at least for the first few drives.

This doesn't discount the possibility that the smoke is, in fact, oil, which would suggest perhaps a problem with the TB tensioner replacement, or some other source of leakage, directly or indirectly related to the work that was done.

The cover underneath does make it difficult to check for leaks. If you can't get a good look, take the car back (if it's not too far) or to a nearby garage and have them check it out on a lift (easier to see above the cover).

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post #3 of 6 (permalink) Old 11-04-2011, 09:44 AM
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valve covers leak oil when pulled.
some folks remove radiator hoses when doing a timing belt job.

so you've got the possibility of leaked out fluid burning off (oil or coolant). in which case it'll go away shortly.

or a valve cover gasket or coolant hose isn't properly seated - that needs to be fixed immediately.

H6 OBW VDC, H6 OB Sedan, Tribeca, Lifted XT6
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post #4 of 6 (permalink) Old 11-04-2011, 11:03 AM
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Yes...replacing a timing belt can be stressful and warrant a smoke or 2 after completion.

Seriously...take it back to the shop. I'm sure they will not charge you to identify and rectify the issue.
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post #5 of 6 (permalink) Old 11-04-2011, 11:26 AM
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If your timing belt tensioner had failed you would have lost your belt and blown some valves. I wouldn't trust this mechanic. Those tensioners easily last 150k+, although I would personally replace at 105k along with the timing belt.
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post #6 of 6 (permalink) Old 11-04-2011, 08:12 PM
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Originally Posted by Glennda5id View Post
If your timing belt tensioner had failed you would have lost your belt and blown some valves. I wouldn't trust this mechanic. Those tensioners easily last 150k+, although I would personally replace at 105k along with the timing belt.
Perhaps the OP, or mechanic service writer made an error in noting timing tensioner rather than accessory belt tensioner? You don't just "notice" that the timing tensioner has gone out, but the tensioner pulley bearing for the accessory belt is a common failure and easy to swap out. Swapped it out in my wife's 2005 Outback in about 15 minutes.

If you hear a noise that you suspect might be a bad pulley bearing/tenioner, then you disconnect the alternator belt and AC belt to rule them out (you can run the car without alternator for a few minutes). If the nosie is still there then pull the timing covers and inspect further.

If timing belt was done, then all the pulleys and tensioners should have been inspected/replaced along with the belt. Not just one that had failed. This is the only way you should do the timing belt:

Also, check the hoses and valves for the windshield wiper fluid reservoir too. Maybe they buggered that up.
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