I'm just over 100,000 miles with no internal engine problems until yesterday. I started the car to move it out of the garage and the engine was making a noise that I've never heard before. The best I can describe it is a few ticks followed by a louder clunk, or bang. This cycle took a few seconds then started over again, and again, and again. The engine started and ran pretty much as normal but I only drove the car 50 feet. I'm concerned that something needs attention. Does anyone recognize this? Am I about to get into timing chain tensioners? Thanks for all replies.

 

If it only occurs every few seconds, I wouldn't suspect chains and tensioner per se.

 

But they are overdue even if they aren't the source of the noise.

 

I'd not be overly worried by ticks, but clunks & bangs - yes.
Recommend you don't run the motor again until you have a better handle on the source.

Wild guess, as it's cyclic it could be the serpentine belt running out of line and then snapping back into place? Try removing it and spin all the pulleys in the accessory train to check for roughness. The idler pulleys can make any manner of noises when they're failing.

If there's nothing obvious, I'd be tempted to lift the cam covers. As the others have said, it doesn't sound like normal tensioner problems, but...

 

on a different engine a set of sounds which could have been described similarly were dropped valve seats.

flatbed the car to someone qualified to figure this out. i have someone close to NJ if you need a referral. Parks Auto Group 718-442-5151

 

This sounds like a valvetrain problem, as was said, dropped valve seat, broken valve spring or it could be VVT failure. Pull a valve cover and have a look. The VVT will not be a visible problem but the others will be evident. The only thing is that valve seats and springs would cause a bad misfire, so it may be the VVT unit has a broken spring. By the way, if this car has not had the tensioners replaced, it needs it now.

 

OK, I'm going to at least do a compression check and take it from there. I'm going to tackle the timing chain tensioners too. February seems like as good a month as any for this project.

 

Call me Mr. Overcautious, but I really wouldn't spin the motor again until you are clearer on what's going on in there.

 

disconnect the battery. use a bore scope to inspect the combustion chamber. if you see any debris, do not reconnect the battery until the heads have been removed.

 

Problem identified and it's an easy fix. I started the engine and followed the noise to the front of the engine. I could see the serpentine belt tensioner moving while it's making squeaking, squealing and other mechanical noises, then it snaps back into position with a clunk.

 

OK, so I've got a serpentine belt tensioner that isn't moving freely. It's just a pulley on a spring, right? And things that don't move freely need lubrication so I gave the tensioner a bath in motor oil. I haven't reinstalled it yet, it's draining. Having a little free time, I was looking in the manual which said not to oil the pulley ( I get that), or the tensioner. What the hell? What is the logic? If I can't lubricate a sticking tensioner, it's trash so what harm could I do? Will oil affect its ability to provide spring tension? If so, they way over engineered this. All they needed was a pulley on a spring.

 

not just a pulley on a spring. There's a bearing in there. Sounds like the bearing has a flaw and is trying to seize at a certain spot on each revolution. Not something I would drive with until changed out. Seems like I read on the forum that there is a replacement part common to other makes.

Z

 

I'm sure there is a bearing in there, and what bearing doesn't like lubrication, like oil? I still don't understand why it would be a bad idea to introduce the tensioner to some oil. I'll replace it if I must but first I'm going to see if I must.

 

here's my take based on 50 years of replacing bad bearings of all types.

Yes bearings like oil. But based on the description of the noise, you have a badly damaged sealed bearing. Likely the seal has become ineffective due to age and heat and the lubricant inside has drained out. Soaking it in oil is not going to repair the bad spots. And the oil you introduce is going to run out of the ineffective seal just like the original lubricant did. That oil is going to drip on your serpentine belt which won't do it any good either.

Eventually the bearing will refuse to spin at all. When that happens you are very likely to lose the belt. How far away from home will you be when that happens. Walking distance I hope.

Everyone has their own ideas of what is the correct maintenance for their own vehicles. Certainly you can fool around with the oil soaking concept, but it's not going to fix the issue with the bearing, And you run an unwarranted risk of additional damage by putting off a relatively low cost repair.

Z.

 

Dayco 89016 works for both tensioner & idler pulleys.

<$20 at Amazon:

 

Yes bearings like oil. But based on the description of the noise, you have a badly damaged sealed bearing. Likely the seal has become ineffective due to age and heat and the lubricant inside has drained out. Soaking it in oil is not going to repair the bad spots. And the oil you introduce is going to run out of the ineffective seal just like the original lubricant did. That oil is going to drip on your serpentine belt which won't do it any good either.

I cannot dispute any of the above. Sure, changing the tensioner is an absolute solution.

I spent 35 years maintaining commercial aircraft, mostly Boeing products, a little A300, some DC8 and MD11 and I can confidently say that airplanes love grease. Sure, lubrication won't reverse damage. However, if the damage is mild, some lubricant will get things going for a while, and in reality, all we really do when we lube anything is to buy time. Time until we need to lubricate again. Eventually, wear wins in the end and replacement is necessary. This is why any time I change universals in a driveshaft, I only install the ones with grease fittings so that I can lubricate them (and extend their life). Sealed bearings just don't seem to be as sealed as we'd like to think, at least after a while. Again, the time factor.

So here's what I did. I soaked the tensioner, not the pulley, for 24 hours in some 10W40 oil that I have no other use for. I let it drain for 24 hours. I reinstalled the tensioner and started the car in the garage. I tickled the throttle a little bit and I could see the tensioner smoothly responding to differences in belt tension as I did. No noise. I believe that what I did provides at least a temporary solution.

I will probably change the tensioner before long, but I want to see what effect my experiment had. Let's just say that the tensioner is on a suicide watch for now.