timing chain tensioner noise?

[notbange]

My newly moving 93 149k ATX occasionally makes a rapping noise when running, that seems to go away above 2k rpm. Doesn't make the noise all the time, only when good and hot, and I added half a quart of Lucas to it, and it seemed to have stopped completely for about two weeks. It makes the noise on every cold startup for a second or two. Searching around the forums, it seems like it could be the timing chain tensioner(s) failing. When I had the motor out of the car, I had replaced the valve cover gaskets. Inside was very gunky, as if the previous owner had not changed the oil very often, but the shims and cams were in good shape, no pitting or scarring, so I don't think the noise has anything to do with the shims or cam lobes. The noise doesn't seem to have anything to do with the timing belt, it is good and tight, although I'm replacing that sometime soon.

Anyways.. where do I source the tensioners from, and is there anything I should know before replacing them?

-Sam (the "restoration" is never done!)

 

[fdogg96]

Yes, the timing chain tensioners can make an annoying sound. From what I've been told, its a discontinued item, but you can start off at RockAuto.com If they dont have it, hit the local junkyard and find an ATX. it's kinda a pain in the ass to get to. I watched someone do it.

 

[pccorrig1]

I just went through this on my '94 ATX, 161K. I had convinced myself that the rear cylinder bank was the culprit, so took a chance on a used set of heads on eBay, just to get the tensioners. This cost me $75, plus another $75for shipping. Was unable to find any new parts.

Based solely on what I read here and other SHO forums, I took everything apart, inspected it, and could not find anything worn excessively. My original tensioners only had a shallow groove, measuring .002", no evidence of chain slap anywhere. I could not measure any difference in chain length between my front and read bank chains. The used heads had a .003" groove in the tensioner, and the chains themselves measured the same as my original. I might point out here that the chain tensioners are spring loaded, and also have a opening to the oil pressure feeding the cam journals, etc. They have about 3/4" of travel, and the spring holds the chain about 3/8" at rest, with increasing oil pressure keeping taking up the slack with increased RPMs.

So I put everything back together using the original parts. And not surprisingly, still have what sounds like the chain slapping around on the inside of the cam cover.

Next I did what I should have done in the first place - went out and bought a $15 stethescope, and started probing around. I would recommend everyone get one of these. Probe around, and listen to the various sounds it picks up. What I thought was chain noise on the rear bank near #3 cyl sounds more like a rod knock on the #1 cyl with the stethescope. (The chains are very quite.) I still haven't decided whether to pull the pan or not. At this point, I'm thinking if the rod bearings are worn, I might be loosing oil pressure to the cam tensioners, causing the apparent sound once the oil warms up, thins out, and revs are below 2K.

Searching around the net, I found the V6SHO forum on Yahoo. I was disappointed to find several owners there who had chains and tensioners replaced when parts were still available, but still had the noise. Sic.

FWIW, it is necessary to remove one of the cams on each bank to get the tensioner from under the chain. If you go that route, be careful when retorquing the cam journals, (clean and dry the threads first) as they easily strip out. I had to helicoil 2.

Let us know what you find. And good luck.

 

[notbange]

I drove the car yesterday to work, 25 minutes each way at highway speeds. No noise at all. It bothers me how random it is. How much movement do the tensioners have? Is it possible that it is just sticking in the bore, and I could free it up some how? I was poking at them when I had the valve covers off, but I don't recall their condition. I was too distracted by the sludge. It wouldn't surprise me if the rod bearings were going bad, but the motor is quiet most times. This car also is leaking oil onto the exhaust pretty bad, so my game plan is to do a front 60k with all seals and sensors, and then see if this noise gets more frequent or not before I open the top back up. One thing at a time, I guess.

 

[Rockledge]

You say that when you had the valve covers off "the inside was very gunky". That's not good, especially for the tensioners.

Among other things, the way the tensioners are designed makes a clean oiling system all that much more critical to the SHO.

You should seriously consider an Auto-Rx treatment.

 

[AREA 91]

I just went through this on my '94 ATX, 161K. I had convinced myself that the rear cylinder bank was the culprit, so took a chance on a used set of heads on eBay, just to get the tensioners. This cost me $75, plus another $75for shipping. Was unable to find any new parts.

Based solely on what I read here and other SHO forums, I took everything apart, inspected it, and could not find anything worn excessively. My original tensioners only had a shallow groove, measuring .002", no evidence of chain slap anywhere. I could not measure any difference in chain length between my front and read bank chains. The used heads had a .003" groove in the tensioner, and the chains themselves measured the same as my original. I might point out here that the chain tensioners are spring loaded, and also have a opening to the oil pressure feeding the cam journals, etc. They have about 3/4" of travel, and the spring holds the chain about 3/8" at rest, with increasing oil pressure keeping taking up the slack with increased RPMs.

So I put everything back together using the original parts. And not surprisingly, still have what sounds like the chain slapping around on the inside of the cam cover.

Next I did what I should have done in the first place - went out and bought a $15 stethescope, and started probing around. I would recommend everyone get one of these. Probe around, and listen to the various sounds it picks up. What I thought was chain noise on the rear bank near #3 cyl sounds more like a rod knock on the #1 cyl with the stethescope. (The chains are very quite.) I still haven't decided whether to pull the pan or not. At this point, I'm thinking if the rod bearings are worn, I might be loosing oil pressure to the cam tensioners, causing the apparent sound once the oil warms up, thins out, and revs are below 2K.

Searching around the net, I found the V6SHO forum on Yahoo. I was disappointed to find several owners there who had chains and tensioners replaced when parts were still available, but still had the noise. Sic.

FWIW, it is necessary to remove one of the cams on each bank to get the tensioner from under the chain. If you go that route, be careful when retorquing the cam journals, (clean and dry the threads first) as they easily strip out. I had to helicoil 2.

Let us know what you find. And good luck.

You should visit me.

Anyway, to answer your question, you only need to remove the tensioner bolts AND the camshaft sprockets. This will allow the tensioner top and bottom to be removed.

 

[pccorrig1]

you are right on both counts.

now if i could only get rid of that code 332 and pass pa emission...

 

[notbange]

You say that when you had the valve covers off "the inside was very gunky". That's not good, especially for the tensioners.

Among other things, the way the tensioners are designed makes a clean oiling system all that much more critical to the SHO.

You should seriously consider an Auto-Rx treatment.

Incredibly gunky, sludgy, whatever you want to call it. My 94 looked brand new inside when I took it's covers off at 120k or so. I changed the oil before I drove it with kendall high-mileage 10w-30 (cheap at work). Ran that for about 200 miles, and now have mobil 1 10w-30 with some lucas in it. The lucas seems to keep it quiet. I have only put about 800 miles on it since I bought it. I got the car with a blown tranny, it had been sitting for more than a year before I got it for 300 bucks. Seemed like a deal at the time ;o). Anyways, where do I get auto-rx? I've heard of others using it before. Will having a clean oil system restore proper function to the tensioners? Can the tensioners be freed up? By "removing camshaft sprockets", I assume that means the chain sprockets, not the belt sprockets? So many questions, so little funds!

I drove the car to work again today, and cruised around on back roads on my way home for almost an hour, enjoying the nice day and my stripper, low option SHO. No noise at all! (no sunroof either!) But the day I made the original post, it was rapping like mad. Odd.

-Sam

 

[Rockledge]

Anyways, where do I get auto-rx? I've heard of others using it before.

You can only get Auto-Rx online: http://www.auto-rx.com/

Will having a clean oil system restore proper function to the tensioners? Can the tensioners be freed up?

I would say that in all likelihood, the answer is yes.

 

[notbange]

I'll auto-rx it in short order, then. I was hoping some mobil one and frequent (for now) oil changes would help somewhat. Maybe it already has. Is there a preferred brand and weight of conventional oil for these motors that I should use during auto-rx treatment? I can get kendall brand oils for cheap through work, but I am not against paying for quality products. Edit: Not implying that kendall is not a quality oil. Never had a bad experience with conoco-phillips products yet,

 

[Rockledge]

Go ahead and use the Kendall oil during the treatment. I think 5W-30 or 10W-30 is fine. Make sure you change the oil filter according to the directions.

 

[rubydist]

My experience is that the Mobil 1 will help it, but at a much slower rate than something like AutoRX. And change the M1 fairly often - not more than 5000 miles until you get it cleaned up - M1 is particularly good at keeping sludge from forming or helping to get rid of it. If you are using Mobil, I'd stick w/ Mobil conventional during the AutoRX treatment. And, I'd run the AutoRX for a few hundred miles before draining it, not just a few minutes like some guys do.

If that doesn't do it, there is still a good chance that you can save the tensioners by disassembly and cleaning. btw, I'd expect the timing belt tensioner to be gooped up too, if the timing chain tensioners are.

Here's another thing I've found - these engines don't like to stand idle for long periods of time - the rings are very low tension and they get stuck very easily if the engine stands for a while. If the rings are stuck, the pistons will rock and slap a little. This typically is more noticable when the engine is cold, but depending on which rings may be stuck and how badly, it could be when warm too. The piston noise is generally more noticeable at certain rpms, depending on how much movement the piston has. This is very likely to be the case in your engine, since you describe the valve covers as being full of gunk. The AutoRX / M1 may make that better, or it may need to be taken apart and cleaned to restore proper ring function.

Have you done the cylinder balance test portion of the koer diagnostic? That will tell you if some cylinders are worse than others. If you pull the dipstick out while the engine is running, does it blow out the dipstick tube? Does it burn more oil than it should? All of those are indications of sticky rings.

 

[notbange]

My experience is that the Mobil 1 will help it, but at a much slower rate than something like AutoRX. And change the M1 fairly often - not more than 5000 miles until you get it cleaned up - M1 is particularly good at keeping sludge from forming or helping to get rid of it. If you are using Mobil, I'd stick w/ Mobil conventional during the AutoRX treatment. And, I'd run the AutoRX for a few hundred miles before draining it, not just a few minutes like some guys do.

If that doesn't do it, there is still a good chance that you can save the tensioners by disassembly and cleaning. btw, I'd expect the timing belt tensioner to be gooped up too, if the timing chain tensioners are.

Here's another thing I've found - these engines don't like to stand idle for long periods of time - the rings are very low tension and they get stuck very easily if the engine stands for a while. If the rings are stuck, the pistons will rock and slap a little. This typically is more noticable when the engine is cold, but depending on which rings may be stuck and how badly, it could be when warm too. The piston noise is generally more noticeable at certain rpms, depending on how much movement the piston has. This is very likely to be the case in your engine, since you describe the valve covers as being full of gunk. The AutoRX / M1 may make that better, or it may need to be taken apart and cleaned to restore proper ring function.

Have you done the cylinder balance test portion of the koer diagnostic? That will tell you if some cylinders are worse than others. If you pull the dipstick out while the engine is running, does it blow out the dipstick tube? Does it burn more oil than it should? All of those are indications of sticky rings.

Well, right now it's *leaking* oil from the front onto the exhaust, most likely the rear most cam seal and crank seal, so I plan to redo all that. It may be burning a little too; I've stood in our work parking lot when my buddy was driving it, and when he floored it a puff came out of the exhaust, but that was right after we got it rolling a month ago, and it has a code for O2 sensors, so maybe (hopefully) it was some fuel.

Now that you mention it, it has a slight knock when cold. We have a quarter mile long, slightly downhill gravel driveway that I pretty much idle down, and I can hear it lightly tapping the whole time, but this sound doesn't increase with the gas. Possibly stuck rings? Would that go away when warmed up? Either way, I'm going to do the front 60k first here in a week or two, because the oil leak sucks, and then examine the tensioner further. So many projects.

-Sam (why did I want this?)

 

[rubydist]

My experience is that the piston slap from sticky rings tends to go away (or reduce significantly) when warm, due to the pistons (aluminum) expanding more than the block (iron) and tightening up the gaps.