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MG Midget and Sprite Technical - 1500 Timing chain rattle ??

Hi,

Just a thought.... thinking the rattle IM expereinceing could maybe be timing chain ?.... whats the best way of pin pointing this ? ie how can i be sure that it is the timing chain ?....

Also can the tensioner be replaced with the engine in the car ?...

any advice please

Thanks


Darbs.
Darby Allen

You could try using a mechanics stethoscope to confirm if it is the timing chain that is rattling. Either buy one - cheap ones often sold at market stalls - or listen to the end of a metal bar as you hold it against different likely sources of the noise.

Temporarily removing the fan belt and running without alternator, fan and water pump during the test will also eliminate a lot of noise and make it easier to pin-point. A lot of people ignore this trick but I think it is a really easy way of narrowing down where noises are coming from.

If it is the timing chain, then on the 1500 the tensioner is a very simple affair on the inside of the timing cover. This can be removed "in situ" but is a bit fiddly. You will need to remove radiator to get access, and remove the main crank pulley which can be very tight to undo. You may need to remove the water pump and fan. I think you also need to undo the front engine mounts and the exhaust to manifold joint to enable you to jack up the front of the engine a bit to get the pulley off. When you replace the timing chain cover fit a new oil seal and remember to centre it properly before tightening it up or the new seal will wear out and leak very quickly.

The tensioner is so basic there is not much that can go wrong with it unless it is actually broken. So if noisy, it may well be the timing chain that needs to be replaced, and not just the tensioner. You could end up chasing your tail!

Guy

Guy Weller

The tensioner on the 1500 is held in place in the timing cover by a pin retained in double shear in a small bracket that is riveted into the timing cover.

The pin is retained with two small shims and two small split pins. Disassembly is relatively easy, reassembly a wee bit more fiddly and requires some fine needle nosed pliers (and a certain amount of dexterity).

http://www.rimmerbros.co.uk/spitfire/images/19a.gif

As Guy says, getting the timing cover off in situ is a bit of a pain in a midget - you can get away with leaving the water pump in place but removing it does give greater freedom of access.

I'm afraid I have to disagree with Guy about "The tensioner is so basic there is not much that can go wrong with it unless it is actually broken."

Tensioners on the Triumph engine DO wear, but such wear is usually indicative of wear or (more commonly) stretch in the timing chain (a known problem with the Triumph 4 pot). You can check the degree of stretch in the chain by placing a straight edge against it on the tensioner side between the cam and crank sprockets and assessing the amount of possible deflection of the chain from the straight edge (acceptable figures are in the workshop manual).

If you change the timing chain you should also change the tensioner. Currently Rimmer Brothers are selling these at £4.40 for the chain and £10.29 for the tensioner kit (inclusive of VAT).

However, the chain will eventually stretch again and I am not certain of the quality of a lot of aftermarket parts since they seem to come from a common source - somewhere from the east.

A better bet would be to fit the duplex chain set up from the big brother to the 1500 (ie the 2.5L TR6 engine) since this is a direct replacement and will abrogate the problem of chain stretch. I do this for any 4 pot Triumph motor I build.


I'd have a word with Mark Field at Jigsaw Racing

http://www.jigsawracingservices.co.uk

since he may be able to source you good second hand sprockets (usually about £35.00) along with a new duplex chain at £7.60 and tensioner at £4.50.

Alternatively he does a complete kit new at £95.00 - if you wanted to go the whole hog you can get a vernier set up from him for £135.00

I source most of my components through Mark and have never had issues about the quality of his stuff.
Deborah Evans

What I meant was that the tensioner is basic, and non-adjustable. If it isn't working, then the only thing to do is replace it, in which case the chain will also almost certainly need replacing as well.
The chasing your tail comment was that if the chain and tensioner are worn, then there may well be other wear elsewhere that also needs attention
Guy Weller

Did you skim the head?

When tuning motorbikes I often find that skimming the head (for power tuning, not just taking the warp out) caused the chain being effectively too long and beyond the capabilities of the tensioner.

Replacing the followers might solve it but when they wear (even within normal parameters) you're stuck again. Modifying the tensioner is the way to go, a lot of suppliers of tuning parts sell adjustable tensioners too.

Just a thought, if your head is standard this will not apply...

Guy's remark about the stethoscope is a good one too, this will tell you for sure if it's the chain!

Cheers,

Eddy
Eddy Veuger

Eddy,
I think that skimming the head would only effect the timing chain length on an OHC engine.

Guy
Guy Weller

crap, u'r right.....new to MG's....hahaha
Eddy Veuger

Hi All,

Thanks for your helpful advice.... will try as reccomended without fan belt, as this makes very ggod sense to me and will help eliminate ambiant noise somewhat.

Some one I spoke to suggested it could be the water pump bearing... ???.

Maybe Im convincing myself already without listening but it does sound a bit like the sort of rattle i would immaine a chain to make against the casing...

The Engine has only done 69k (I believe this to be genuine from the comprehensive history and the fact I have nearly all the cars MOT certs).

would it be reasonable to suspect the tensioner to fail or the timing chain to have stretched significantly on such a milage fugure ?.

Thanks again

Darbs
Darby Allen

Darbs,
Have you tried turning the tickover up a bit? If it is rattling on tickover the solution could be as simple as that!

Guy
Guy Weller

This thread was discussed between 22/02/2009 and 23/02/2009

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