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Timing chain replacement


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I am planning to replace the timing chain on my TR4A that I believe is the source of a rattle from the front of the engine, I would appreciate any hints and tips. Note I am still running a wide fan belt set up.

 

  • I am planning on taking out the rad and perhaps removing the bonnet, anything else needed?
  • Any problems getting the crankshaft pulley bolt out?
  • Obviously the chain, gaskets etc will be replaced, should I also consider the tensioner and sprockets?
  • Where are the best quality parts available?
  • I am wondering about switching to a narrow belt set up, is this worth doing? I have already taken off the mechanical fan and rely on a Kenlowe.
  • While I am working in the area with the coolant drained down I will check the water pump, anything to look for there, any useful upgrades?
  • Any other snags I should know about

Thanks in advance for any advice

 

Mints53

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I find it so much easier to remove the Bonnet then Radiator. Use the pre stretched German chain (from Moss). I also fitted their tensioner which some have said it is not good quality. Seems to work for me.

Good luck and ask your better half to assist removing the bonnet although I can do this myself it is so much better to have an extra pair of hands.

Regards Harry.

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Replace the tensioning spring.

If the chain is noisy due to stretch it has most likely started to eat the spring.

Sprockets you can check when you remove the cover.

 

If the water pump does not leak, you do not have cooling issues (ie water is circulating ok so fins on impellor are intact) and bearing is quiet when you spin and you feel no play it it is usually best to stay with what you have rather than replacing with remanufactured.

Narrow belt is a matter of choice. Main advantage is it's easier to replace the belt but there are well known tricks to make an emergency change easier.

 

Steve

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I would almost certainly remove the radiator. One slip with the wrong tool or tapping with a hammer and you could puncture the rad.

 

You might time the engine before removing the pulleys and chain as it can be difficult to turn the crank with the pulleys and bolt off. Then you won't be far off, if not spot on when you fit the new chain.

 

I changed my water pump this morning with a replica of original from Moss, and it does look pretty good, though the impeller blades are slightly smaller, but still metal. Look at the bottom of the pump for any leakage and down the timing chain cover for water staining.

 

Kevin

Edited by boxofbits
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If you leave your rad and bonnet on, tape some thick cardboard across the rear face of the rad to prevent the aforesaid risk of damage when messing with the front of the engine...Oh and you'll likely find the "dog bolt" that holds the pulley extension onto the crankshaft is tightened to about 120lb ft torque (mine is) which may need an impact gun applied to remove it.

If no gun available put the car in gear and get the missus and/ or friend to stand on the brakes whist you apply lots of force through breaker bar onto the dog bolt, and remember it needs 120lb ft going onto it when being retightened.

 

Mick Richards

Edited by Motorsport Mickey
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Cross tube needs to come off. If you take the weight with a jack in the centre of the front x member this allows the chassis flex making the removal and refitting a lot easier.

Alan.

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Thanks for all the advice, I will start on the job tomorrow. Just one question Alan, why do I need to take off the cross tube? it looks like I can get access with it in place.

 

Cheers

 

Andy

 

So much easier access wise and I also remove the radiator. Why risk it damaging it.

Alan.

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  • 1 month later...

Hi all

 

I have finally got round to getting stuck into this job. But I haven’t been idle, before starting I thought I’d just check if the rocker shaft was the source of the annoying rattle - hurrah I thought when I discovered significant wear – some rockers had a couple of mm of lateral play, an easy fix. So I have replaced the complete assembly, this made a significant improvement in the general mechanical noise from the engine and at least meant I could set the clearance correctly. But there was still something not right, a serious rattle from the front especially when the engine was hot, so I opened up the timing chain cover to have a look. Out fell ½ of the tensioner, the rear portion had snapped off meaning there was no tensioning effect at all. More worryingly a bolt also fell out and I can’t find where it came from. It is a ¼ inch unf by one and three eighths long has anyone got any ideas?

 

The chain and sprockets seem ok - I’ve measured the stretch, according to my manual slack of 10 mm is the max allowable, I’ve got 7 mm so I’m not inclined to change it especially given the issues with modern replacement parts. Any comments on this?

 

Finally regarding the oil thrower, when I took it of the crank sprocket the convex side was towards the sprocket my manual (Haynes) states in the text that the concave side should be towards the sprocket. But the photo shows the convex side towards the sprocket, which is right?

 

Thanks in advance for your help with this

 

Andy

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Camshaft sprocket bolt? Oil thrower is fitted concave (dished) face facing forward allowing oil to be thrown off convex rear face onto chain.

Alan.

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Hi Andy,

you have done well. Finding broken bits is half way to resolving the rattles.

 

The quality German chains are good but if your is within tolerance keep it.

Change the cranks shaft lip seal #10http://www.moss-europe.co.uk/shop-by-model/triumph/tr2-4a/engine/engines-components/internal-engine-components.html

Check the hub #75

for wear - it is cheaper to replace than to repair. You want no wear what so ever where the seal runs.

 

Roger

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Finally regarding the oil thrower, when I took it of the crank sprocket the convex side was towards the sprocket

And that is the correct orientation for it, not as Alan says above.

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Hi John,

I think that is what Alan has stated - convex (facing rearwards) towards the sprocket, Concave (facing forwards) over the seal throwing oil away.

 

Or was it the other way!! :wacko:

 

Roger

Thanks Roger, that's what I said :wacko:

Alan

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I've finished this job now - magic, the engine runs sweetly and quietly, no oil leaks yet apparent. I wonder now how many other niggling issues could be down to this. For example I seemed to be forever having to muck around with the ignition timing, I would think I had got it spot on and then a few days later find that it seemed to be different. I guess this would have a knock on effect to the general running and especially the idling which now is much smoother, I have been searching for air leaks on the induction side and and looking at carb adjustments to improve this aspect for ages.

 

Thanks for all the advice

 

Andy

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