Knocking sound

[chrisperry05]

Hi Jonners,

The one's here look to be the part? About a quarter down the page.

http://www.rob-beere-racing.co.uk/newproducts.html

[Jon Tilson]

Indeed....

Fair old price though, I'm going to pay Moss a visit....

Let you know.

Jonners

[Jon Tilson]

From some more grubbing about....

"part # EAC3629 and has no dowel and small oil pressure hole. Moss lists this part # for the 3000 (Healy and MGC?) engine."

Jonners

[mahony]

I'm gonna order one of those as a spare, £42 or a damaged engine/head with a cheap alternative is a no brainer !!

[Howiesprint]

Sorry for hijacking this thread but I'm getting slightly concerned about the rattle/knock coming from the top end in my Sprints engine and it seems I might have the same tensioner problem. Can I just confirm where tension in the chain should be. I removed my crankcase cover and there is 5-10mm movement in the chain in the long run against the straight fixed guide. Is this ok or should it be tight here? It seems to be pretty tight up against the curved adjustable guide on the tensioner side although this is harder to check because of the limited access. I've done about 2000 miles since this engine was rebuilt although the rebuilding was not done during my ownership and probably done in late nineties early noughties by Rimmers I was told. The noise is not a rhythmic tapping but more sporadic tap/light knock at idle and then seems to be immersed into the engine noise as the revs increase.

Thanks
And sorry for the Hijack.

Howard

[Mad Mart]

There should be no slack on the straight run between crank & cam (right hand side in photo).

[Howiesprint]

OK Thanks Mart. Bugger!

Next Question! Why would I have slack in the chain there and how do I get rid of it? Does it sound like I have tensioner problems? I can't get my head round how the tensioner could take up the slack there as it sits the other side of the bottom sprocket??? Would it be that the chain needs to be re-fitted keeping that side taught in the process The car seems to be running fine. Only after a spirited run can you hear the light knocking/tapping.

Thanks

Howard

[trackerjack]

Right ho
The tensioner is hydraulic and works on a ratchet system.
When the tensioner is first installed a 1 mm spacer should be placed between the tension pad and its holder and the straight run of the cam chain should be straight from the sprocket as Marts photo clearly shows a correct install.
the curved guide is now pushed into place and the bolts done up.
Now remove the spacer that was mentioned earlier.
When the engine is started oil is forced into a small hole behind the tensioner which then pushes the tensioner into the chain as well as a small hole in the tensioner sprays oil on the chain.
As the guides wear there is a ratchet that stops the tensioner from going back when the oil pressure is absent. (this ratchet wore out on my Stag and caused the tensioner to return to start every time engine stopped, so on start up a rattle was heard until oil pressure forced tensioner into chain).
There should be no slack chain to rattle in a healthy engine.

[Howiesprint]

Ok thanks Trackerjack.

Seems I have a tensioner problem. Either rubber slipper missing or tensioner returning to start position. Time to pull it to pieces then. Never done this before and weirdly quite excited about getting the spanners out and getting stuck in. I will report back.

Cheers

Howard

[Jon Tilson]

There are a few threads on how to do this so have a look at the rich back catalogue, including
lots of debate on whether or not the tensioner is hydrauilc. I think we concluded that it should be
as TJ says.

My tip for the day is that the pulley bolt is a bit tight but succombs to a braced socket and tommy bar braced
against the chassis rail and a quick burp on the starter.

Jonners

[Mad Mart]

No, we concluded it was semi-hydraulic.

[xvivalve]

I am checking manufacturer at the moment, but I may have found a cheaper source for the Reynolds' item. There are many suppliers listing EAC3629 but on enquiry they transpire to be the Rolon product!

[mahony]

I will wait to get a spare then Alun to see if you locate them cheaper

[Howiesprint]

OK I'm back after much dismantling!

Right then, I have a Rolon tensioner fitted. The rubber slipper was in place and seems to be well stuck. In situ there was about 2mm gap between slipper body and main tensioner housing. When I tried pushing on the chain so as to push the slipper back into the housing, it pushed back in! I then used a flat screw driver to gently lever the slipper out of the housing against the chain and it obviously caught on a ratchet groove and remained tight up against the chain without moving back to start position. So I'm guessing that the tensioner has not been functioning effectively enough to push hard against the chain and reach the first ratchet groove to keep it tight. Or maybe in wasn't installed correctly in the first place. Do they normally need a little helping hand to reach the first ratchet groove?

I did remove the tensioner to clean and check it and it all looked ok. All very new looking as expected of a rebuilt engine with low miles. The very small oil hole was not blocked.
What to do now though?? Do I put it all back together in the hope that it will keep working the way it should now and risk having to dismantle it again once the chain becomes loose enough to warrant another manually assisted click up the ratchet or do I try and source one of the Reynold tensioners?

No other damage seems to have occurred.

Any advice appreciated.
Thanks

Howard

[Jon Tilson]

Tough call but given the damage that can be done by these Rolons if the pad comes off...

I'd wait a week or so and see what Alun comes up with.

Jonners