Clatter & Smoke: Timing Chain?
 

Hello again, Benzmeisters:

So now that my ignition is in good shape and my brakes work, I have a new concern, and I'm getting more concerned about it all the time.

Recently the car has developed a clickety-clattery sound that only appears under certain conditions. It has to be warmed up, and the engine has to be at either a high idle or just above. It doesn't do it all the time...or at least it hasn't been doing it all the time...but it seems to be doing it more just over the past few days or so.

The sound appears to be coming from the front of the valve cover. Using a screwdriver as a stethoscope, I listened around a bit and it really seems like that's from where the clattering emanates.

In addition, I'm seeing more smoke out my tailpipe now...whitish stuff. There's getting to be more of it, especially when I first start the motor, but even when I'm sitting at a light. Not a ton of it, but clearly too much.

I've done a bunch of poking around the archives here, and I'm wondering if this doesn't add up to a timing chain replacement. I have not ever had the valve cover open on this car, so I have no idea what it looks like under there. I was planning on doing a valve adjustment soon...but now maybe I'll have other pressing business under there. Do you think?

If so, how much of a hassle is this? I give my mechanical skills a B- at best. What other parts should I order and replace if I do this job myself? What other problems might it be if not the timing chain?

All your responses are, of course, much appreciated. I'm not keen on ruining my engine just as I'm finally getting it to run well!

I'd check the timing chain for stretch (wear, actually) -- line the mark on the cam thrust washer (a notch, I think) up with the "bump" on the front cam bearing tower, about 2 o'clock. Read the degree wheel on the balancer -- any reading greater than 8 degrees means time for a new chain.

Make sure the chain tensioner is working correctly -- when you first shut off the engine, it should be quite difficult to push the long slide rail on the passenger side back. If it move fairly easily, the tensioner is bad. this usually causes a rattle or clank though, unless it's really shot and you can hear the chain sliding across the valve cover. Unmistakable.

And remember that a '68 gasser will have adjustable tappets -- time for a valve adjust, most likely. You are probably hearing a loose one clattering, and for every loose one there is a tight one...

Peter

There's two kind of "white smoke".

If it's water, from a blown head gasket or cracked something, it will dissipate within a few feet of the car. It may smell sweet like antifreeze.

If it's tranny fluid, it will hang around. And stink.


Michael

So if I do end up swapping out the chain, tensioner and all, what parts should I order? I may actually place an order today, and I'd like to get everything needed at once. Even if it turns out I don't need to do the job right now, I bet I'll need to later, so might as well be prepared, eh?

How many guide rails are in there, and where are they attached? I'm going to see if there's a photo or drawing in the manual I have...I've never messed with a timing chain before.

Thanks again!

The chain may have been changed out not that long ago for all you know. I would tend to check before ordering if it needed one. The valves have to be set or checked every ten thousand with out fail on your model. Good possibility you have too much clearance on one or two of them. The price on these cars for ignoring the valve clearance check is off with your head.:eek:You could order a timing chain and have a bad tensioner instead for example. No sense buying parts you may never need.

Hey, Barry: fair enough. I really should see if I can tell what's the deal before going off half-cocked. It's just that this is my only car, so most of my work has to be done over the weekend, and it takes at least a day or two to get most of the parts...if not longer. Just a strategic concern.

I had another thought, too: Could it be a valve guide? I've seen some mention of that as a noise/smoke issue in the archives. If so, does the head have to come off to deal with that?

You know, I think the smoke and the noise come and go at the same time, by the way.

Please feel free to post your thoughts on this, everybody. I most likely won't be able to crack the valve cover until Saturday, but as soon as I do, I'll post my findings.

Did you change the oil after you found the booster full of brake fluid ????????????????????????

Arthur: No, I haven't changed the oil yet...I was hoping to get that done this weekend. (I bought the stuff to do it last weekend, when I topped off the differential and transmission, but it started raining and I didn't get to it.)

How does the brake fluid in the booster relate to the engine oil?

Please be gentle. I'm always learning.

aircap:

The mention of smoke alarms me. You may have a slipped chain or another problem, so sort this out ASAP. Whatever you do, stop using the engine until you have diagnosed this and know the cause of the noise. It may be serious or something very simple like a cam follower retainer spring having slipped off.

I would check the chain tensioner and also the stretch in the chain. If there is rattling from the front of the cam cover you could be hearing the chain slapping against the head or the cam cover. If the tensioner has failed you run the real risk of serious and costly engine damage if the chain slips. If you need to replace the tensioner you should replace the chain and chain guides at the same time.

If you have 100,000 miles on the old assembly you have reached the end of its reliable service life. The chain may still be OK or it may have been replaced at some time, but the guides and tensioner are suspect unless your records show them being replaced . The single row chains are pretty good, especially on the smaller engines. They are shorter than the chain on the V8s, but even the later model inline engines were upgraded to double row chains for added durability.

edit:

I think Arthur's point is that brake fluid may have found its way into your oil via the booster vacuum line. Maybe, but another thought is that the smoke may be brake fluid related, coming into the manifold and then into the cylinders via the booster line...either way, you need to sort all of this out ASAP and try to avoid running the engine until you have tracked down the noise.

230/8

Fluid in Booster
 

Aircap,

Most power brake systems use engine vaccuum to increase pedal pressure by connecting a vaccuum hose to the brake booster. Rolls-Royce uses an electro-mechanical servo - but never mind that non-sense.

If you've had fluid in the booster, it's very possible that the engine is sucking brake fluid during periods of high engine vaccuum, such as deceleration. The fluid is so thin it will easily vaporize and/or sneak past valve keepers, seals, etc. and be drawn into the combustion chambers/s down the intake valave guides.

Still sounds like you have chain/tensioner/valve finger adjustment issues though...

Tom Webb

I thought that Clatter = piston slap? Ring issue?

Thanks to everybody. I assume it's serious, and will treat it as such. Again, I'll post back when I take off the valve cover.

ONE MORE QUESTION: Does anybody know the size of the fan pulley bolt on my car (1968 220/W115, gas engine M115)? Is it 27mm, as it seems to be on other models listed in the archives?

Fan pulley? If you asking about the harmonic balancer pulley (the bolt which screws into the crankshaft) then the answer is "yes, 27mm".

Thanks, Mike! Yeah, that's what I meant. Sorry for any confusion.

OK, say I'm going to replace the chain, the tensioner and the guide rails. In what order should I replace each item? Special tips/tricks?

I've seen several really excellent tutorials here and elsewhere detailing the replacement of the chain, but none of the tensioner or the guides.

Oh, and one more thing: I've been given contradictory advice on what type of wrench to use to adjust the valves on my car (with the 115 four-cylinder). Is it 17mm or 14mm? I can get away with using a crowfoot, no?

Anybody? (Thanks in advance!)