Post and Courier
July 11, 2014

Car Talk - Broken sprocket could have unhinged VW's nearly new timing belt

Posted: 01/25/2014 12:01 a.m.

Q. I recently had to have a new water pump put in my 2005 VW Bug. At the same time, they replaced the timing belt. Twenty-three days later, I was stranded because the timing belt broke. After they examined it, they found that the crankshaft pulley


RAY: They might have. I'd have to say it's extremely unlikely that a broken crankshaft pulley would break the timing belt, though. It's possible ... if it broke in a jagged way and tore through the plastic timing belt housing that sits behind it. Possible, but not very likely.

TOM: So let me put a more-likely scenario on the table. Perhaps what really broke was the timing belt sprocket. It sits directly behind the crankshaft pulley.

RAY: To investigate, the first thing you need to do is check your receipt to see if they replaced something called the "front engine seal."

TOM: Normally, that seal gets replaced when you do a timing belt. Not always, but if you want to do a thorough job, you replace the front engine seal and the water pump whenever you do a timing belt job.

RAY: Why? Because both of those parts are relatively inexpensive, and they're easy to access once the timing belt is off. And if either one fails, say, three weeks later, you have to do the timing belt all over again.

TOM: Which, as we've found out, makes our customers extremely grouchy. So we never change a timing belt without also changing the water pump and the front engine seal.

RAY: But in order to get to the front engine seal, both the timing belt sprocket and the crankshaft pulley have to be removed. And that's not always easy, especially on VWs.

TOM: So if they had to use force to pull off the sprocket, they could have put a small crack in it. Or if they used heat to loosen the bolts that run through the pulley and the sprocket, and accidentally overheated them, they could have weakened the sprocket's metal and caused it to fail a few weeks later.

RAY: So look at your receipt. If it's illegible or indecipherable, ask some other mechanic to help you read it (if you want to find an honest mechanic, try the customer-generated listings at www.mechanicsfiles.com).

TOM: If your shop charged you to replace the front engine seal, then I think you have a right to be suspicious. And since what you need now is major surgery, I think a second opinion is called for.

RAY: I'd search the Mechanics Files for a trustworthy mechanic in your area, and have the car towed there. Tell him what the other shop told you, and ask him to look at the car and see if their story checks out.

TOM: The second guy may tell you there's no way to know exactly what happened. Or he may confirm our theory. Or he may have a theory of his own that either exonerates or convicts these other guys. Ask him to write up his professional opinion for you. You'll have to pay him for his time, but I think it's worth it, in this case.

RAY: Armed with that information - and expert witness testimony, should you need it - you can go back to the original guys, if warranted, and suggest, a little more persuasively, that they do the right thing for you and fix the car.

TOM: All reputable shops carry Garage Keeper's Liability insurance (what we call "Bonehead Insurance") to cover serious mistakes they make on customers' cars. So they probably have the means to repair this if they need to.

RAY: And if they continue to tell you to go sit in your hat, you'll have to decide whether it's worth taking them to small-claims court over this. But at least you'll be better prepared to win. I hope it doesn't come to that. Good luck.

Q. Is it safe to add a few capfuls of denatured alcohol to the crankcase of my two older vehicles to remove oil sludge before I change the oil?


RAY: Is it safe? Well, I don't think it's ever a good idea to dilute your oil. But you can put a couple of capfuls of almost anything in five quarts of oil without doing a whole lot of damage. I mean, you can add a couple of capfuls of cat urine to your crankcase and still drive the car for a long time. The question is, Why would you want to?

TOM: The same question should be asked of denatured alcohol. I don't see a good reason to do it.

RAY: First of all, while denatured alcohol is a solvent, we have no idea whether it does anything to remove engine sludge.

TOM: Second, we don't even know if you HAVE excessive engine sludge. Did your mechanic tell you that your oil is not draining down quickly enough from the top of the engine? Or do you just have S.A.D.: sludge anxiety disorder?

RAY: Unfortunately, even if you're sure your engine is sludged up, it's unlikely that any oil additive is going to fix it.

TOM: We work on Volvos that develop sludge problems sometimes. What happens is that the crankcase ventilation system gets plugged up and doesn't allow oil fumes to be purged from the engine. So those fumes get trapped and solidify, forming sludge and gunking up the top of the engine.

RAY: At that point, the only way to remove the sludge is to remove the valve cover and actually scrape off the stuff.

TOM: If you're wanting to add the denatured alcohol simply as a preventative measure - if you're worried about getting sludge in the future - then the single best thing you can do is change the oil regularly instead, and make sure your crankcase ventilation system is working properly.

RAY: Save the denatured alcohol for cleaning your windows. And on those nights when you toss and turn, restlessly worrying that sludge is somehow building up inside your valve train, get up and change the oil, then go back to bed.

Got a question about cars? Write to Click and Clack in care of this newspaper, or email them by visiting the Car Talk website at www.cartalk.com.