Odd sound--any guesses?

artgirl774 · Post by **artgirl774** » 19 Aug 2011, 22:26

Hey guys, yes, I'm back about my lemon, aka the money pit. My previous issue with my 1994 960 (2.9L 6 cylinder, 182,000 miles) seems to be back on the right track (oil leakage and starter replacement). But over the last month I have noticed a strange ticking "tat-tat-tat" sound (sounds almost a baseball card placed between the spokes of a bicycle wheel). It started out as a once in a while sound, but has now progressed to almost all the time. It doesn't seem to have rhyme or reason (it happens if the engine is cold, or hot), it sometimes goes away, but sometimes gets louder. It will speed up when I hit the gas, and it will slow down when I am sitting at an idle speed, but again, at points, it makes no noise at all. I've looked some information up, and initially thought it was the timing belt or timing belt assembly (I have no idea when the timing belt or serpentine belt was changed last as I bought it in October 2010), based on other user's postings of similar sounds. Well, my husband took off the camshaft cover, and now we're not sure at all where the sound is coming from. He is still going to change out the serpentine belt (and possibly the timing belt). The pulleys all seem to to move fine, and there doesn't appear to be any leaking from the tensioner. I did notice when he took the cover off the timing marks on the camshaft gears were lined up (someone had obviously changed out the timing belt at some point, and marked them with Whiteout, but after he started it and ran it, the marks do not line up. Will this affect the timing, thus causing the noise? Pardon my ignorance on any of my questions--this car continues to confound me!
I've included a video (of course, the odd tat-tat-tat sound is very muted) here:

Here are some photos (we didn't notice any odd leaking, metal shavings,etc.--a lot of dust--this is the first time we've removed the cover, and we've had 3 sandstorms in Phoenix in the last 30 days)

Any ideas? I know this is pretty vague, and could pretty much be anything--Engine runs cold, no loss of power, and other than this very annoying ( and disturbing sound), it seems to run normally.

Post by **precopster** » 20 Aug 2011, 04:44

If it's engine speed related it could be a number of things, including torque converter or a slapping bearing.

Mark the crank pulley with white-out (anywhere will do) Start and run the engine and see if the noise happens at the same interval as the belt mark coming around the bottom of the crank. If so it's an internal engine noise such as a bearing. If the interval doesn't match it may be alternator, power steering pump, a/c, serpentine tensioner or idler pulleys.

Remove the serpentine belt and start the engine (don't worry the water pump will still cool the engine, but you won't have power steering, a/c or battery charge) Is the noise still there??

If not it was in the serpentine area. If the noise disappears with the serpentine off turn the alternator by hand and listen for noise, then turn the tensioner and the pulley by hand. Any noise? Post back when you find out some more.

danr960 · Post by **danr960** » 20 Aug 2011, 08:51

You can remove the serpentine belt and then idle the engine, that will separate the source, if it stops then it is on the serpentine drive system or if it continues then it is the timing belt train.

My money is on the serpentine belt tensioner or the serpentine idler.

If he has the cover off, then when he checks the pulleys, he wants there to be no noise or grind feel, but there should be resistance to turning, if he can spin it and it spins more that a single revolution, the the bearing are worn. That goes for any of the pulleys on the timing or serpentine drive systems.

You have a car with 182k miles, off course you are going to have to put money into it, I'll bet though, any other car in similar condition you would also be spending money repairs. All components on a vehicle are going to need be replaced eventually. In my opinion, it is a whole lot cheaper than a monthly car payments to get a car that you will not have to repair for maybe the first three years of ownership.

Your guy sounds like he is very capable.

Good luck,

DanR '94 964 358,000 miles (124,000 on the new engine)

Edited to improve the grammar.

artgirl774 · Post by **artgirl774** » 20 Aug 2011, 12:27

Thanks guys, you always seem to give me good advice and trails to follow--I appreciate it. Dan--you sound like my husband! He tells me the same thing all the time. I just get frustrated because it seems that since January of this past year, every 2 weeks, something goes wrong with this car. I know that Volvo makes good cars, it's just that money is tight(for everyone, isn't it?),the parts are pricey, this is our only vehicle, and riding the bus in Phoenix heat is less than desirable. That being said, I would never buy a new car, because I don't like having a car payment, and I know that used cars are always cheaper. I think I'll go now to eat some cheese with my whine--lol. We'll be investigating this weekend, and will post updates--thanks again guys!

artgirl774 · Post by **artgirl774** » 23 Aug 2011, 14:18

***UPDATE**
Ok, I took it into my mechanic this morning and he called to tell me that the belts and belt assemblies look okay, including surrounding areas. He said the oil, oil level and oil pressure looked fine. He basically said that from what they can determine, it seems to be coming from inside the engine in the front lower area, and sounds like a Rod knock. He said that it wouldn't be worth it to repair based on the age and worth of the vehicle, and that I should just make sure I keep up with oil changes, and perhaps add an 'anti-knock' additive (ala 'Lucas" brand), and basically just drive it as is until it dies (or throws a rod, and is worthless). How labor intensive is it to repair a rod, and how much should the repair cost--ballpark? I paid $1600 cash for it last October, and since then, have put about $2500 in repairs (parts/labor/tows/diagnostic testings/etc) into it. Knowing that it could run for another 2 days, 2 months or 2 years, with no guarantees, I'm trying to figure out if I should pursue a "proper repair" or cut my losses and get rid of it.
Thanks!

***P.S.--I should clarify that he "thinks" it's a Rod knock. Could it be anything else? As I stated in my earlier post, it is a ticking sound (it truly sounds like a baseball card in the spokes of a bicycle), with no rhyme or reason. It is sometimes not there at all, sometimes loud, sometimes soft. It sometimes it increases in speed or sound with an increase of RPM's, but then again, sometimes on an increase of RPM's it goes away completely. It will start if the engine is cold (or hot)--I can't find a pattern to it. I am leaking oil (though he didn't seem too concerned about the oil loss--it's had small oil leaks since I bought it). No Check Engine lights or any other, though, now that I think about it, when I start it up the oil light stays on for perhaps 1/2 second longer than the other lights before it goes out (am I grasping at straws?) He said there is no way to know for certain without cracking open the engine block. He's been in business for a long time, and has a good reputation, but, well, ya never know--ya know?

D_V_ENT850R · Post by **D_V_ENT850R** » 23 Aug 2011, 18:25

Could just be rod bearings! Pull engine and replace! Or find a used one and replace? Still cheaper than payments!

You can also take the old engine and rebuild it while you're driving with a used engine!!!! Just a thought!!!!!!

artgirl774 · Post by **artgirl774** » 23 Aug 2011, 18:55

Rebuilding an engine is definitely beyond my personal scope--it would have to be something a mechanic would do for me, and frankly, money wise, I just don't have several hundred dollars to do that right now (one income, and this is my only car). I've been doing some looking around online, and noticed some posts about "Lifter tick" or valve lifters ticking. I almost wonder if this is what it is (combined with my oil leaking under the car). The noise started intermittently about 4-6 weeks ago right after I had the oil changed in June (my mechanic did another oil change today). It started out as a once in a while thing that would go away, and then, after my mechanic replaced my starter and knocked my dipstick tube loose at the point where it connects to the engine (see thread "Bleeding Oil"), and I lost quite a bit of oil, it got much worse. The sound comes and goes--if it was a rod knock, would it be constant? I spoke with my mechanic again, and mentioned the valve lifters and he said he couldn't be sure it was a rod knock, just that the sound seemed like it was coming from the lower part of the engine (it sounded to me like it was coming from the top). He also said it wasn't that bad, and to just keep an eye on the oil (I've never heard anyone describe a possible rod knock as "not that bad"--I'm no mechanic, but even I know those are BAD)--time for a second opinion??

D_V_ENT850R · Post by **D_V_ENT850R** » 24 Aug 2011, 17:42

Get a new mechanic!!! My opinion!!! Haha!

danr960 · Post by **danr960** » 25 Aug 2011, 10:19

If it is a rod knock, which I do not think it is, a rod knock is not sudden, it is a gradual increase in sound, it takes time to get to that point. Time as in many, many miles.

There is a simple test, while the engine is hot and idling, remove one spark plug coil at a time, listen for changes in the sound, the engine will rock a bit, but once you get to the cylinder that has a rod knock, the knock will change sounds.

I think, since the timing cover was off, something is interfering with something. The cover is rubbing somewhere, or a bolt is hitting something.

DanR

Post by **precopster** » 25 Aug 2011, 17:02

I'm going to go with DanR on this one. The bottom ends on these are pretty solid. Since the starter was removed the engine plate could be knocking the new starter due to poor clearance. I don't think the oil leaks your mechanic created would affect rod bearings as long as it had at least a couple of quarts left and the oil light didn't come on.