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3 hours ago, Ian Vincent said:

I’ve tried looking for videos but they are all about modern vehicles. 

I have a dial gauge and magnetic stand so it’s pretty easy to check the lift for each lobe. Is that what you mean?

Rgds Ian

With a extended timing chain or broken tensior

you have an "empty way" turning the crancshaft some degrees back or foreward.

You can feel that very easy, you don't have to open the cover to check this.

There are two other videos on my channel "TR4A Driver", one with a new chain and tensior,

the other one checking it again after some time.

Good luck,

I think the noise in not the timing chain, but it can anyway be extented and worth to change.

Ciao, Marco

 

Edited by Z320
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17 hours ago, iain said:

I hate to say it Ian......that sounds just like the issue I had.......cam followers galling in their bores.

Iain

Ps. I think the various suppliers of these items should be shot, they are absolute rubbish. It took me a day....yes a day to get the last set to spin freely on the bores. The bores were and are unmarked. Total **** springs to mind.

PPs. The last set had not started to make a noise, but on removal, were starting to stick and show clear evidence of non rotation.........they had done 5000 miles with no issue. Like you I  used the recommended cam lube and Penrite 20/60. The bearings were like new so it’s not the oil!

PPS. Did the engine run 3/4 hot before this started? I’m convinced that’s what triggered mine to stick again.

Curious, where these the "standard" type or the uprated versions (tuffrited, drain hole) offered by Revington and others?

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All the failures I have had have been with the upgraded tuftrided variety. I am beginning to think the drain hole is a poor feature allowing the oil to drain out, rather than waterfall over the edge of the full bucket and give better lubrication?

Iain

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FWIW, I have just checked the backlash in the crankshaft (as suggested by Marco) before the camshaft starts to move and it is negligible, which suggests that it’s not the timing chain tensioner. 

Rgds Ian

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1 hour ago, Ian Vincent said:

What would cause piston slap to suddenly start Neil?

Rgds Ian

Normally when items wear it’s the final thou or micron of a thou becoming worn which can lead to an abnormal noise. The previous layers of whatever wears are merely sacrificial, then the further most or ultimate surface matter is eroded and ... noise begins.
However for piston slap it’s normally a cold engine function when in it’s early stages, the piston - bore clearance when cold opens up, and they slap... and then become quieter as heat reduces the clearances back more into required clearances.

In your recorded examples the noise is not in the same cadence as the crankshaft rotation but to my ear at double speed which says camshaft on1 lobe or cam follower. 
 

Mick Richards

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Well I have just spent the best part of an afternoon checking the valve lift on all the valves with no clear result emerging so tomorrow I guess it's off with its head to check the cam followers but I'll start by removing the carbs and the exhaust manifold just to check that it isn't a blow in the exhaust gasket.

I tried putting the stethoscope down on the block ini the region of the camshaft and that does seem to be where it is coming from and it is more prevalent at the front of the engine.

At least I know the quickest way to get the head off, I've had plenty of practice.  And I shouldn't have to worry about stuck studs or anything like that - famous last words.

Rgds Ian

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13 hours ago, ntc said:

Ian

I did reply to your question on page one,I would have put your stethoscope at the sump the sound will travel down there.

It’s ok Neil, it was a technical issue with my phone that caused my query to be posted twice. 

Rgds Ian

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13 hours ago, Lebro said:

Get that head gasket on order first !

Bob.

I think I will probably need more than just a head gasket by the time I’ve finished. I might as well order it all together. (apart from any cam followers). 

Rgds Ian

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When I was studying the Kas Kastner, Competition preparation manual The section on camshafts states:

"When building up your engine or replacing the camshaft, remember to replace the old followers with new ones. DO NOT drill holes in the sides of the followers.

Drain holes were attempted in the bottom of the followers . . . but a rash of broken followers - the foot breaking off, etc, - and the idea was speedily dropped"

Just saying.

Bob.

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Bob, that is a good spot, i had not registered that in my Kastner book........I wonder then if these upgrades are the issue? 

Does anyone make a high quality (OEM) follower?

Iain

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1 hour ago, iain said:

Bob, that is a good spot, i had not registered that in my Kastner book........I wonder then if these upgrades are the issue? 

Does anyone make a high quality (OEM) follower?

Iain

I am using the chilled iron cam followers from Newman, they are undrilled.  I will let you all know their condition later today (Hopefully).

Rgds Ian

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FWIW, before i started stripping the engine, I did a compression test.  Running from front to back of the engine I had 170, 180, 170, 170 psi.  Unlubricated and the pressure came up immediately on virtually the first compression stroke so there doesn't seem to be anything amiss there.

Rgds Ian

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No, I haven't got the head off yet because I have been givning lessons on canals & bridges via Zoom to two sets of grandchildren.  But I have got the car up on the hydraulic ramps ready to take the head off and anything else that needs as my investigation progresses but the one thing I noticed is that when I started the car initially it was absolutely quiet - so much so that I thought it had fixed itself and then as the engine warmed up the noise reappeared at its full volume.  Does that suggest a cam follower that is sticking? - by why suddenly when it hasn't happened for that last fwe thousand miles?

Rgds Ian

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21 minutes ago, Ian Vincent said:

No, I haven't got the head off yet because I have been givning lessons on canals & bridges via Zoom to two sets of grandchildren.  But I have got the car up on the hydraulic ramps ready to take the head off and anything else that needs as my investigation progresses but the one thing

I noticed is that when I started the car initially it was absolutely quiet - so much so that I thought it had fixed itself  It was cold so the clearances had opened up and the area causing interference (cam follower sticking in bore ? now had clearance and spun)

and then as the engine warmed up the noise reappeared at its full volume.   It then warmed up reducing the clearance into an interference fit and the cam follower again started to pick up...tapping .

Does that suggest a cam follower that is sticking? ….Yes a strong indication that the follower is sticking or the cam lobe is causing a problem on it's top...probably a bit of both 

by why suddenly when it hasn't happened for that last fwe thousand miles?...because the wear on the components remained within it's limits until it exceeded them ...and then it started picking up....as per the example I posted 11 posts ago.
 

Please bear in mind this is from a scratchy recording of a noise in your garage, ...it's a guess, but a reasonable hypothesis. Mick Richards

Rgds Ian

 

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On 6/10/2020 at 8:27 PM, Rob Salisbury said:

Hi Ian, I had a noise very similar to that,  was convinced it was a follower or stuck valve guide, started to take the engine to bits and discovered a blown exhaust/inlet manifold gasket, i have a 4 branch like you and it was No. 4  exh. that had gone.

Cheers Rob

Unfortunately it's not the exhaust gasket Rob.  I started the strip down an hour ago and have removed the carbs and disconnected the exhaust manifold.  The gaskets came out as clean as whistle without a hint of a blow anywhere on them.

Rgds ian

Edited by Ian Vincent
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Hi Ian,  shame that, would have been an easy fix, still it's always fun taking off the head and seeing what lurks down there!!  ... you mention the chilled iron followers from Newman, it's just that they state that only the road cam should use the chilled iron, any of their other cams should use the EN40B ones, ... I don't know which cam you have so it may or may not be an issue.

Hope whatever it is is an easy fix.

Cheers Rob

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Hi Ian,

As an option for a very small amount of extra work BEFORE removing the front cowl rad etc... drop the sump. You should be able to inspect the bottom of the camshaft to view the lobes and even get views onto the followers foot (to a degree). If you see a failure point there on either components at least you won't feel as if you are wasting time removing cowl/rad/ timing cover etc.

Mick Richards

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7 minutes ago, Motorsport Mickey said:

Hi Ian,

As an option for a very small amount of extra work BEFORE removing the front cowl rad etc... drop the sump. You should be able to inspect the bottom of the camshaft to view the lobes and even get views onto the followers foot (to a degree). If you see a failure point there on either components at least you won't feel as if you are wasting time removing cowl/rad/ timing cover etc.

Mick Richards

Thanks Mick,

That’s why I put the car onto the hydraulic ramps before I started but thks for the suggestion. 

Rgds Ian

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The head is now off and unfortunately there is zero evidence that any  of the followers have been sticking in their bores.  They are all showing a nice circular wear pattern so it would appear that the followers have all been rotating.  When I say wear it is not a measurable amount it just shows the interface between the cam and the follower.

I also tried checking the camshaft for wear by putting a depth mic down onto the lobes from the top surface of the block at max and min lift and deducting one from the other.  Strangely the results showed a variation across all the valves from 0.277" to 0.295"  which is much more than I would have expected and in any event even the minimum figure is greater than the specified lift for the cam (Newman PH1) of 0.270".

I guess the next step is to remove the front shroud and radiator to take a look at the timing chain.

Rgds Ian

PS looking down on the cam from the top there is no eveidence of any wear.

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Curiouser and Curiouser.

Ian, despite all your hard work so far I hope it’s something obvious, easy and cheap to sort out.
H

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