Timing chains, age or mileage ?

[Mrs hoskins]

I know that my chains haven't been changed since at least 1989, but have only covered 4000 miles in that time .
Should I get them changed ?

[LAMBRETTLAD]

Hi are they making a noise? If not why change? Just keep changing the oil every 3k ?

[flying farmer]

They don't deteriorate with age like a rubber timing belt so mileage is the important factor.

If you shine a light through the oil filler hole it is possible to see one of the chain tensioners. The more of the plunger that can be seen where it goes into the tensioner body, the more worn the chains are.

The maximum travel of the plunger is about 2 cm, I have generally changed my Rolon chains after 30,000 miles and the tensioner is about 1 cm out by this point.

Neil

[Mrs hoskins]

Presumably , if I remove the cam cover ( got to change the gasket anyway) I will get a clear view of the tensioner,plunger , chains etc ?

[LAMBRETTLAD]

Mrs Hoskins

I would love to watch / help you do that as I've never worked on a stag engine ,every other triumph engine,and I'm keen to learn

Cheers Alex

[Mrs hoskins]

Haha, you mistake me for someone who knows what they are doing !! I'm only intending to remove the cam cover to have a look.......any spanner work will be done by a consultant surgeon with at least 150 yrs experience . I will let you know when the pre-med happens .

[LAMBRETTLAD]

Ta

[tonyh]

The life of timing chains depends on various factors, how often you change the oil, BL recommended every 3,000 miles, distance travelled and hours of engine running. I had customers that only used there Stags for short journeys and customers that were up and down motorways almost every day, in a short journey across London and back would be about two hours, if you’re lucky, with constant stops and starts, covering about 30 miles, the motorway driver in the same time could cover 140 mile, engine running at a constant RPM, I found the short journey Stags timing chains could last as little as 10,000 miles and long distance drivers chains would last well over 50,000 miles. So it’s not how many miles before changing it’s more how many hours running time and type of driving, maybe we should fit hour meters like they have on boats and aircraft engines.

At least with the standard chains as they stretch they will start to rattle on cold start up to warn you, unfortunately the more expensive foreign chains don’t stretch giving you a warning, they just snap with no warning, unfortunately nobody has done any tests on these chains so whilst the do last longer nobody knows how much longer before they need changing.

Tony.

[flying farmer]

Interesting how the length of journey affects chain life. I know short journeys are never good for any engine but I never considered the effect on the chains. Just glad I don't do many short runs in my Triumphs!
Neil

[davidf]

Interesting how the length of journey affects chain life. I know short journeys are never good for any engine but I never considered the effect on the chains. Just glad I don't do many short runs in my Triumphs!
Neil

I have always had a theory on this, but never seen anything to confirm it. My theory is this:-
If you turn the cam on a Stag head (off the engine), the load varies enormously because at some points, 3 valves are opening together, at other points, 3 are closing together. By contrast a conventional 4 cylinder 8 valve engine is quite well balanced.
This leads to chain load snatching between directions. However, as the rpm rises, two other factors come into play.
Friction to turn the cam will increase, so that, instead of the load changing between directions, it will become consistently in one direction, although of varying tension.
The rotational inertia of the camshaft and sprocket will smooth the load.
So, I guessed that low rev hours were more damaging than high rev hours. By how much, and at what revs, I have no idea.
Anyway, that's my excuse for my speed, officer!!

[redstag]

Interesting discussion as I am currently in the middle of changing my chains right now. This is the third time I have changed them on my car, the first time was just after I had bought it and found the chains were rattling on start up.
The second time was 40,000+ miles later when I restored the car and was done as a matter of course not necessity as there was not much wear. I actually reused the tensioners as they had very little wear (and I wasn't overly impressed with the Rolon aftermarket ones), just replacing the chains and guides.
Another 60,000 miles later I decided it would be prudent to change them again simply because of the mileage they had covered. I must admit to being a bit surprised at the lack of wear and would not have been particularly concerned about reusing all the parts (including the 100,000 mile tensioners) with the exception of the chains. Picture shows the extension of the tensioners which I would say is not a lot for 60,000 miles.
I am currently replacing everything (all OEM parts) so hopefully I will get a decent mileage out of them this time. Can only agree with Tony's comments, using the car works for me.

Pete

Tensioners.jpg

[Lingen]

Tony. You say that BL recommended an oil change every 3000 miles. Where? All the references I can find state 6000!
I have always changed my oil and filter once a year, 5000 miles on average, and it is still reasonably clean by then. Doing that, my engine still lasted 117,000 miles before I had to rebuild it. I suspect that changing it every 3000 miles, particularly as oils are so much improved since the seventies, may be rather wasteful. I do also have a decent sized filter which almost certainly helps to keep it clean.
As for those chains, both types get longer, (or "Stretch" as you put it), as the links and pins wear, and then start to give a warning rattle. The expensive ones merely take longer to do it, and are no more prone to snapping than the standard ones. Why should they be? I have rebuilt many engines with the "German" type, and have them in my own car, and I can confirm that they do last far longer. I am told that the reason for this is that they have a minute extra tolerance between the pins and rollers, which allows better lubrication in that area of wear. When replacing the head gaskets on my Stag last year, 50,000 miles after a full engine rebuild, they were showing virtually no "Stretch" at all, and so there was no noticeable wear on the sprockets either. Timing chain life will always vary enormously depending on the way the car is driven and maintained, but I believe that however it is used, the more expensive (better!) chains are always worth fitting. They more than pay for themselves.
Mike.

[jleyton]

. I suspect that changing it every 3000 miles, particularly as oils are so much improved since the seventies, may be rather wasteful. Mike.

Hi Mike,

Like you, I change my oil once a year.

However my point is that it seems almost bizarre that the Club, on it's website under the 'What to look for' section of 'The Car', continues to state "Change engine oil and oil filter every three months or 3,000 miles, whichever occurs first"

This seems crazy to me as, with many cars only doing 1 or 2 thousand miles a year, it means that owners would be having to change oil every 250 or 500 miles . Now that would be wasteful

Cheers

Julian

[dasadrew]

Tony. You say that BL recommended an oil change every 3000 miles. Where? All the references I can find state 6000!
I have always changed my oil and filter once a year, 5000 miles on average, and it is still reasonably clean by then. Doing that, my engine still lasted 117,000 miles before I had to rebuild it. I suspect that changing it every 3000 miles, particularly as oils are so much improved since the seventies, may be rather wasteful. I do also have a decent sized filter which almost certainly helps to keep it clean.
As for those chains, both types get longer, (or "Stretch" as you put it), as the links and pins wear, and then start to give a warning rattle. The expensive ones merely take longer to do it, and are no more prone to snapping than the standard ones. Why should they be? I have rebuilt many engines with the "German" type, and have them in my own car, and I can confirm that they do last far longer. I am told that the reason for this is that they have a minute extra tolerance between the pins and rollers, which allows better lubrication in that area of wear. When replacing the head gaskets on my Stag last year, 50,000 miles after a full engine rebuild, they were showing virtually no "Stretch" at all, and so there was no noticeable wear on the sprockets either. Timing chain life will always vary enormously depending on the way the car is driven and maintained, but I believe that however it is used, the more expensive (better!) chains are always worth fitting. They more than pay for themselves.
Mike.

Thanks for that Mike, I thought I was going to have to revisit my view of reality after a few of the above posts!

The 1973 UK Workshop manual puts the oil change at 1000mls, 3000mls, 6000mls, 12000mls. Interesting that it doesn't say "thereafter every 6000 mls or 12000mls. (Was the car only expected to go 12000mls?)

The 1970 German driver's handbook puts an oil change at 10000km, 20000km, 60000km. (~ 6000mls, 12000mls, 36000mls).

Was BL getting increasingly desperate to stop the engine failures that they kept reducing the oil change intervals?

Regarding those foreign chains which snap without warning but no-one knowing when that is, wouldn't there be more posts about that here if it were a known and regular occurrence? Does my memory deceive me or didn't we have this question on the forum a couple years ago? Were we inundated with accounts of sudden snapping without any other factor causing an engine to seize?

BTW, what is the opposite of expensive foreign chains? Cheap British chains?

Drew

[redstag]

The 1973 version of the ROM I am looking at says to change the oil every 6000 and the filter every 12000 miles.

Personally when I was doing 5-6000 miles every year I changed the oil and filter twice, the last few years I have done a lot fewer miles and change the oil and filter once a year. Both more than adequate in my opinion but good for peace of mind.

Pete

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