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TR2/3/3A TR3 Timing Chain

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jsneddon

jsneddon

Jedi Knight
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So I've finally isolated the annoying rattle at about 1500rpm on my TR3. It's the timing chain. I finally found my stethescope and it is definately under the timing cover where the noise is. Poking around the net I find differing opinions as to my impending doom (on other cars - not TR3 specific). Some say replace it RIGHT NOW and others say it is just annoying.

Obviously I've got to pull the cowl and radiator and take a look at what's happening. I've got great oil pressure and compression is 140 +- 3 across the board. End float is right in the middle of spec. So I'm inclined to leave the engine in for now and just pull off the front cover.

So...

Should I not drive it at all until I get it apart or will the occaisional trip to the store kill me until I get a free day to tackle this?

Does the chain come with a master link or does it come as a single piece that I have to monkey with the gears to get it on? I've read that the tensioner is not exactly the best engineered piece of work on the planet so I'll definately be replacing it at the same time.

Obviously anything can break but do these chains fail catostrophically as a rule?
 
The chain does not have a master link and it should be replaced as a set with the sprockets and a new tensioner.(you have to remove the sprockets to get the chain off anyway)
Putting a new chain on old sprockets drastically reduces it's life, and the sprockets wear out too. The teeth get thin and pointy, just like a motorcycle drive chain.
The tensioner is nothing more than a curved piece of spring steel, and is really simple to replace, the only thing that can really go wrong with it is for the chain to wear through it, or for it to break off the pivot.
As a side note. On your timing cover there should be what looks like a big gob of roofing tar. That's factory sound deadener. If it's not there you will hear the timing chain noise. That may be all that's wrong
 
grrrrr.....

no roofing tar. I've read that but never really looked.... it's as smooth as a baby's politically correct bottom. DPO put a TR4 motor in it and must have scraped it all off.

so what does one consider too much noise? That's the million dollar question I guess.

It's been 15 years since I drove it last. It's always been noisy but I don't remember exactly. A lot of it I attributed to about six zillion things loose and rattling in the front of the car.... everything from the letters and badge, the badge bar, the dzuz fastners when the bonnet is up, the seriously loose hand crank guide. All of these things I've tightened up. It's remarkably quieter now.

So... it very well could have always sounded like this and I'm just picking nits. Or it has finally gotten so bad that it drives me nuts. Tough to say.

Anyone have a magic test to see if it is too loose in there? It pulls really strong and doesn't miss or "drift around" on the timing from what I can tell.

I wonder if I rock the fan back and forth with the plugs out if I can detect some chain slap....
 
Well maybe, but opening or closing valves may give you a false reading.
Really the best thing would be to pull the timing chain cover.
Before you do that, I would research what is an available replacement for the "roofing tar" (it may be just that) and see if that quiets it down. The tensioner rides agenst the inside of that tin timing cover, so ANY noise that chain is making is going to be transmitted into that tin "microphone".
 
Jim, I agree with Banjo about the worn timing gears. Once they get past a certain point even with a new chain there can be to much slop and it will reach a bad harmonic at certain speeds. The first thing I had to change on my 3 when I bought it was to replace the timing cover. It had this small rectangular on the upper side which had been punched through by the tensioner (after it broke of course). If you revved the engine the end of the tensioner would stick thru like a tongue. Pretty funny and I didn't know any better and bought it that way, oil leak and all. As things would have it none of the Triumph dealers had a tensioner in stock and my brother and I were heck bent on driving to Indy for the 500 the next weekend. So we put it back together W/O the tensioner and the car got driven that way for the next five years. Although I'm not recommending it, it certainly runs quiet that way.
 
I'm slowly in the process of tearing down my orphaned TR3 engine that I am convince has about a gazillion miles on it and was still running when it was abandoned (around 1975) and the timing chain/tensioner is still intact. From the looks of the tab holding the cam gear in place, the chain was the original. Of course this is only one example but these things are pretty bulletproof. Still had the roofing tar on the cover. Am a little suspect that the noise is really caused by a problem with the timing chain. (Old American-muscle hotrodders will use all-gear timing gears, the noisier the better.)

Bill
 
Jim -- I've watched your question with interest as the chain on my TR3A seems a bit noisy. I first noticed it about 20 years ago and I often wondered if I should be concerned.

I guess I'm not very concerned.

Neither of my TRs have the goop on the cover -- I strongly suspect this is a case of 'some engines got it and some didn't' -- in particular I'm very confident that the TR4 never had it.

I may try the 'turn the fan/watch the rockers' trick on both engines sometime so at least I have some idea what slop is there.
 
i'd get that cover off in an instant.check it out. my motor tensioner was in pieces when i pulled my motor apart. (got this car from previous owner, not running, didn't even try to start it, just tore it down). what will it cost you? a couple of gaskets and some scraped knuckles. throw the timing light on it and see if the marks jump around. if you do not get even marks, you know what your doing this weekend. rev motor up and down as well, mark will move but you are looking for evenness of the mark.
rob
 
Apron off. Crank dog bolt off. Split the pulley in place by removing the bolts and take the pieces off (as I recall). Put a big bolt in the threaded hole (head inside the flange) and pull the flange. Rest is pretty straightforward. Do not replace fewer than all parts. You will have to mark your new sprockets at the same teeth as the original. Make sure the cam sprocket is facing the right way when you install it. I recall that they are reversible, but it causes a small jog in tooth position.
Bob
 
Floyd -- So far as I know there is only one way, remove the bumper, bonnet, radiator, crank nut, pulley & timing cover.

I had my wife come out to the garage at that point so she could actually replace the tensioner (and say 'she did it').

It's just one of those jobs that is all prep and re-assembly... a lot of wrenching with no short-cuts I know of.
 
Spot on feedback - no shortcuts. If you get into the work I find it easier to pull the fan off with the extension still in place. I put the hub puller on the extension, not the pulley. Keeps everything unbent that way.
 
Another vote for replacing in the very near future. I had a 4A, which made the job much easier. But I had done my first engine rebuild, seat of the pants job no internet forums to help out. I thought all was well, but it started spewing oil from the front of the engine. The chain was loose enough to have worn a hole in the cover. Removed to find the metal tensioner worn through.

In the "kids don't try this at home" department, I didn't know the best way to replace it was to remove the gears, I dissambled the old chain and crudely "created" a master link on the new chain. It probably should have flown apart within the first 10 miles, but lasted at least six more years of my own reship and several more under the next owner until I lost track of it. Maybe still out there working like that today.
 
While we are on replacing tensioners and chains...

The new TR2 rebuild last year incorporated brand new TRF chain, sprockets and tensioner. At the last oil change the oil had fine metal particles, and after running a few checks, I am convinced it is from chain abrasion on the tensioner. Specifically, I assume the new tensioner is not properly hardened and is wearing very fast. Another problem with shoddy repro parts.

Soooo...when you change the tensioner, maybe someone can recommend where to buy a properly hardened tensioner?!? I will also be in the market at some point not to long from now.
 
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