Timing Chain Noise

[Geo Hahn]

I know the adage ‘Don’t ask the question if you don’t want to hear the answer’ but here’s my question anyway:

My 59 TR3A has always had slightly noticeable timing chain noise. It lacks the sound deadening on the cover so that certainly adds to whatever noise is normal for these.

Recently the noise became much more noticeable at hot idle – the extra noise is not apparent at cold idle or at any engine speed above idle.

The obvious suspect is the timing chain tensioner and the obvious fix is to replace it (and whatever else looks like it needs replacing whilst in there).

What’s stopping me is that the paint is pretty nice (albeit 11 years old) and the apron has not been removed in at least 34 years – possibly longer. It has been removed at some point because someone kindly busted off most of the 12 bolts to the caged nuts – the p/s wing has only 2 of those bolts in place, the d/s only one. Goodness knows what is holding things together as the body is quite tight & rattle free.

So my temptation is to drive it this way until something happens (radiator failure, steering box rebuild, front seal leak. Armageddon) that has me removing the apron anyway.

I do drive the car fast and far (but < 500 miles form home) so if the worst case scenario is coming home on the hook I can live with that. I have 200-mile towing which would at least get me to somewhere where I could get home on a borrowed trailer or just pay the man the $$.

I know it is hard to say what is best unless you can hear the noise in person – but opinions invited nonetheless.

 

[tinman58]

If the motor has not been rebuilt in 34 years it is getting close. I would wait and drive it until you have the time and $ to do the nice rebuild. If something breaks that gives you the opprtunity to do it then.

 

[bgbassplyr]

Breaking the timing chain whilst running could cause more damage than you want to have to fix, i.e. valves hitting pistons and the potential damage that would entail to the the valves, pistons, head, etc.

Timing chain fairly easy to replace and, ISTR, can be done w/o removing the apron. Haven't done one since mid 60's, so memory may not match up with reality.

 

[TR3driver]

I think you know which side I'm on ...

BTW, if you've removed the original fan & extension; the tensioner can be changed without removing the front apron. BTDT

Don't forget some new caged nuts. The ones from MMC look easier to install (you could even pop-rivet them in place) than the originals:
https://www.mcmaster.com/#captured-nuts/=ex45jz

 

[TR4nut]

I lived with that noise in blissful ignorance for about 2 years before I bit the bullet and confirmed that I had a broken tensioner. The only casualty that I could see was a small hole on the timing cover, I think from all the flopping around that was going on. Might have been there before me, I don't know.

Yes, you could break a chain, but I'm going to disagree with Jim as bit as I don't think that would kill your engine because in stock configuration the TR engine is not an interference engine.

So, I say fix it, but when it suits you and hopefully in conjunction with some other work you are planning!

 

[Geo Hahn]

BTW, if you've removed the original fan & extension; the tensioner can be changed without removing the front apron...

I can remove the fan -- I put it on with the radiator and engine in place. The unknown is whether I can get the dog-bolt loose and off with the radiator still there (still have the extension). I can certainly get a box wrench on it but am doubtful I can get a socket over it (though I still have the crank hole in the radiator if that helps).

I had seen the pop-rivet idea for replacing the cages on Macy's site and was thinking that could work since any welding on the flange might be bad news for the nearby finish.

Despite the age and mileage on the engine it has great oil pressure, fresh con-rod bearings, winds out smooth to redline and doesn't seem to mind cruising at 70+ with a standard non-OD gearbox. Shoot, the front seal doesn't even leak. And, of course, the TRactor engine is non-interference so a slipped or broken chain isn't a total melt-down.

I think you know which side I'm on ...

Yes, I think I do.

A search of the archives found a very similar post from Tom Sneddon from 5 years ago -- I have PMed him to see what, if anything, he ended up doing and with what result.

I also saw the recent post by Vince, who opened his up to replace the tensioner and showed this pic of what he found:

I guess that's broken (I've never held a new one in my hand) but looks 'mostly harmless'. He also found a buggered oil slinger so that may have been a large part of his excessive noise.

 

[mrv8q]

How many miles on your '3s engine, Geo?

 

[Geo Hahn]

No certain idea but maybe 94,000. I've put about 50,000 on the engine since I got it. Have done the rings once and the bearings twice (including recently), decoked the pistons when I did the head.

Yeah, that sounds like a lot of miles but nothing in its performance or compression suggests to me that it is tired or in need of a rebuild.

 

[TR3driver]

When mine broke, both leaves came entirely off the pivot and were found laying in the bottom of the timing cover. Engine still ran well enough, there was just a strange noise sometimes heard at idle. I'm not even sure the noise was related to the broken tensioner, as I also discovered that the front hub was loose on the crankshaft & had been working back & forth.

Getting the dog bolt out through the hole in the radiator would be tricky at best, IMO. Probably better to just bite the bullet and pull the apron. Just don't do what I did : Stand it on one side and then knock it over!

 

[jimstr4]

My engine had been recond about 20,000 miles ago, when I pulled it apart I found a broken tensioner and chewed out timing chain cogs (amongst other things). A disaster about to happen?

They obviously did not replace the tensioner or chain.

Call me paranoid but I'd vote for replacing the chain, tensioner and even the cogs if they are worn.

 

[HerronScott]

Yes, you could break a chain, but I'm going to disagree with Jim as bit as I don't think that would kill your engine because in stock configuration the TR engine is not an interference engine.

Correct, it won't kill a TR 3/4 engine. I had the timing chain "break" on me not long after I rebuilt my engine (first ever) while going 45 with no damage at all.

My broken timing chain was due to using a timing chain that came with the car with a master link and installing it with the keeper facing the wrong way.

Scott

 

[mallard]

I'm not 100% sure on this but can't you tell if the tensioner is broke by slowly turning the engine one way and then back. Then watching the valve to see how long it takes for one to open.

 

[Geo Hahn]

I did an experiment on this using the distributor rather than valves as I thought I could measure that more accurately.

I used the usual test light (actually a buzzer in my case) to find the exact moment when the points opened as the engine turned... then backed the engine up to the exact moment the points close. The difference should be the amount of play in the works.

The difference was 3 degrees (crank). I was able to measure this fairly accurately as I had the timing mark & pointer near one another and have a pretty good sense of how much is 3-4-5 degrees on the pulley edge.

I then repeated the test on my TR4 which demonstrates no noticeable chain noise and got [drum roll]... 3 degrees.

Of course a failed chain tensioner isn't the only thing that can add slop to the movement -- chain wear, sprocket wear and (in this case) distributor gear wear can all add a little.

It would be interesting to know how much play there is in a fresh engine and to see sometime how much difference a tensioner makes in the chain as an engine is rotated backwards.

 

[TR4nut]

Geo-

Not definitive, but your tensioner may be right where it was before it broke, and I suspect it may still be working somewhat. On mine, only half was broken, the other half still effectively pivoted as before.

Randy

 

[sp53]

Heck Geo you have your 4 to drive. My experience has been when I pull the apron off, I end up doing a bunch of stuff that needs to be done. Fix an oil leak from somewhere, paint something maybe fix a leaf spring who knows, but once I get started, I am glad, I did those little things.
Steve

 

[Don Elliott]

I changed the tensioner about 4 times during the 53 years that I've owned my 1958 TR3A. That's 189,000 miles from new. So I assume the time bewteen failure is about 45,000 miles. But in my case, it was not a "failure" - my tensioners never broke apart or got grooved through. They became grooved (2) by the chain links. This would cause a "rattling" sound as I took my foot off the gas and slipped it into neutral At this point there is no tension on either side of the chain and the loose part flops back and forth making the rattling sound. It did not rattle while accelerating, driving hard or while I was slowing down on hard compression. Each time I changed the tensioner, the rattle disappeared. I'm still using the original sprockets, bolts. timing chain, cam. pushods and rockers.

I restored my TR from 1987 to 1990 and I removed all the sound absorbing goo from the timing chain cover. I did not replace it. I can hear the tell-tale rattle better witout it. So it is an indicator for me that tells me if it need to be changed again. I used captive nuts made specially from stainless steel. All the bolts for the apron, fenders etc. are also stainless. It takes me a hour to have the bumber and apron off. I only ever changed the tensioner when I had other major stuff to do at the same time.

 

[tinman58]

I am with Don. I don't see what all the apprehension is about taking off the apron. It takes about an hour more or less depending on the bolts being rusted on. I have removed my apron a few times and have never scratched the paint or had any problems doing it by myself. A good idea is to "pop rivet" the beading to the wings so they don't flop around.

 

[TR3driver]

It takes about an hour more or less depending on the bolts being rusted on.

Heh heh. An hour he says. First time I took one off, it took me closer to an hour per bolt. These days I'm a little quicker to whip out the angle grinder; but back then all I had was a OA torch which I was reluctant to use because it ruined the paint so badly. I spent what seemed like forever trying to find a way to clamp the vise grips onto each caged nut, then work each bolt back and forth, back and forth, a tiny fraction of a turn farther each time, until they finally came out. Then of course, the very last bolt, I could not find any way to clamp onto the caged nut and wound up using the torch anyway. It not only ruined the paint, but caused a large section of Bondo to fall off ...

Living in CA, we just don't see the kind of rust that was so very common on any car driven in a midwest winter. I understand they've reduced the amount of salt used on the roads, so perhaps it's not as bad now, but it used to be that anything over 4 or 5 years old had significant rust problems already; and a 20 year old car (then) would have already been repaired multiple times.

 

[Geo Hahn]

Re: Timing Chain Noise - Follow-up

Despite a landslide victory for the 'Drive it and see what happens' ticket -- a 100 mile cruise convinced me that this noise and I were not going to have a happy future together.

The task was actually made easier by 9 of the 12 wing bolts being missing or broken -- knowing I would be replacing most or all of the caged nuts freed me from the kinder gentler approach and had me reaching for the angle grinder.

Only issue so far is that the dog bolt has rounded corners -- nice for sliding the fan into place but not much meat for a 12-point socket. Tomorrow I'll have a 6-pt and hopefully get loose.

Thanks for all the input -- now we'll see if I can stay focused on the task and not get too caught up in 'as long as I'm in there' stuff.

 

[Darrell_Walker]

Re: Timing Chain Noise - Follow-up

Nice shot of the front.

Being a 4A owner, I don't get to experience the joys of dealing with the apron, but once you get it off, you really have clear access!