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Tappet Noise or is it a cam follower issue?


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I spent last night searching the forum for possible answers to this conundrum.

 

The background is is as follows.

 

Engine completely rebuilt, machining all by a company with decades of TR experience.

New Cam/ cam bearings and followers fitted with Cam lube and run as advised on here and by the machine shop.

 

Engine has now done 750 miles. the last 350 of which have been accompanied by a fairly loud tappet (individual) noise at tick over "when hot". Clearances have been checked and rechecked and they are spot on at 16" and 18".(Fast Road Cam). This issue is not present when cold. So heat has some impact. However the tappet clearance should close when HOT, not open and logically the tappets would be noisier cold ......?

 

So far I have tried the following

 

Stethoscope to rocker box....no sign that the noise is in the valve gear.

Stethoscope to the cam chest area of the block...... yup there's the knocking, but only when hot. Most noise comes from around push rod 3 area, so fairly close to the tacho/oil pump drive. Cam and Distributor gear teeth all in good condition with no signs of poor meshing or wear.

(Oil pump is fully refurbished. End float on distributor drive is within tolerance, distributor is a DDoctor rebuilt unit with no play in the bearings or the thrust washer.)

 

Slightest touch on the throttle via linkage and the noise goes...

 

Had the sump off to fix an oil leak, check the cam lobes from underneath no sign of wear (relief ;) )

 

So before I do some damage, is this likely to be caused by dodgy cam followers? I did not think to mic them up before fitting and now reading reports that in the past they have been less than brilliant, is this likely to be the cause. Perhaps a follower sticking and therefore being slapped by the cam if it is not returning down its bore correctly?

 

Cheers

 

Iain

 

 

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If the noise is from a sticking tappet, the relevant valve won't be closing as quickly as it should. Try a compression test (engine hot). If the compression on that cylinder is down, it's further evidence supporting the sticky follower theory. If the compression is good, almost certainly the fault lies elsewhere.

 

Were the little ends re-bushed as part of the rebuild? A worn little end can make a tapping noise and would be worse when hot.

 

 

Nigel

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Hi Nigel

 

No the little ends where not replaced as they were deemed good to go. I did suspect a little end but the noise does not stop when a plug lead is pulled from any of the plugs, I would have thought this would remove that source?

 

Cheers

 

Iain

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Had a similar noise in mine after a head rebuild where a valve guide was reamed incorrectly and caused the valve to stick when hot (was ok a little tight perhaps, when cold)

Compression check when hot paying attention to how many rotations the engine takes to reach compression should show this up.

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Worn distributor / oil pump drive shaft ?

 

James

James I ran this by Neil R and his opinion was it was fine.

 

 

Had a similar noise in mine after a head rebuild where a valve guide was reamed incorrectly and caused the valve to stick when hot (was ok a little tight perhaps, when cold)

Compression check when hot paying attention to how many rotations the engine takes to reach compression should show this up.

Andrew not run a compression test will do and report back.

 

Iain

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new engine ye say,

new pistons, name begins wid a C ,!!! = a nok wen cold or idling

 

as for rocker gaps,

new rockers,or re faced olde,ns, !!

 

if not, then yer gaps could be twice size yer actually set,n em too.

slacken off adjuster /s, turn upside doon, an inspect,

 

then re set, minus the indent depth, + a few thou moer for wear,n tear

 

M

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Hi Iain,

 

This may not help but who knows:

 

I had a knock at hot idle with my TR4 in 1974 ( sounded like a diesel idling ). Valve clearances were all correct. I was forced to drive it with the noise until one day the engine died just as I pulled into my parking space at the apartment complex. Less competent then than I am now, I had it towed to a repair shop to be fixed. The cam sprocket bolts had sheared. While the mechanic was reassembling the engine he noticed the rocker shaft was very worn. I got a replacement from a junkyard for $10. It solved the knock.

 

Cheers,

Tom

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Valve guide loose in the head, or valve partially sticking in it, gets warm and it closes up the clearance between head and valve or valve and guide and the noise gets worse.

Mick Richards

Edited by Motorsport Mickey
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Valve guide loose in the head, or valve partially sticking in it, gets warm and it closes up the clearance between head and valve and the noise goes.

 

Mick Richards

Not sure I understand this Mick, the noise is worse when hot.

Cheers

Iain

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Not sure I understand this Mick, the noise is worse when hot.

Cheers

Iain

Sorry Ian, brain beat my fingers and typed incorrectly.

Hotter increases the interference between guide and valve stem and the guide moves more. Try running the engine without the rocker cover (mask up where you don't want oil ! and wear goggles) see if you can spot a guide moving or other irregularity that discloses a sticking cam follower also, the guide will only be moving a small amount but you may get a better idea without the rocker cover.

 

Mick Richards

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Hi Iain,

I have a very similar problem. However mine is at cold and hot and at only one position.

 

I took it all apart and found after 8000 miles two or three followers were quite worn (cracked surface) the followers were new 8000 miles prior.

 

I replaced the oil pump for a new one at this time.

The cam looked perfect.

I replaced the cam followers and the noise was still there - perhaps a little less so.

 

I closed the gap on the effected follower down to 0.006" and this quietened it remarkably.

 

The follower was no looser or stiffer in its hole as the others. It is not sticking.

 

If a valve was sticking then there could possibly a 'tap' when it releases and catches up - but I don;t think it is that.

 

Roger

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Sorry Ian, brain beat my fingers and typed incorrectly.

Hotter increases the interference between guide and valve stem and the guide moves more. Try running the engine without the rocker cover (mask up where you don't want oil ! and wear goggles) see if you can spot a guide moving or other irregularity that discloses a sticking cam follower also, the guide will only be moving a small amount but you may get a better idea without the rocker cover.

 

Mick Richards

Got it!

Hi Iain,

I have a very similar problem. However mine is at cold and hot and at only one position.

 

I took it all apart and found after 8000 miles two or three followers were quite worn (cracked surface) the followers were new 8000 miles prior.

 

I replaced the oil pump for a new one at this time.

The cam looked perfect.

I replaced the cam followers and the noise was still there - perhaps a little less so.

 

I closed the gap on the effected follower down to 0.006" and this quietened it remarkably.

 

The follower was no looser or stiffer in its hole as the others. It is not sticking.

 

If a valve was sticking then there could possibly a 'tap' when it releases and catches up - but I don;t think it is that.

 

Roger

Ok so the followers were not hardened properly?

 

Cheers

Iain

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Umh not liking the sound of this.....

 

Is this the problem our Hoges had with cam followers?

 

 

So why I'd I put new followers in. The old ones were unmarked! Apart from having nice radial lines:-)

Why do we put up with this ****!

Iain

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Tappets have to be flat. They should stick together bottom to bottom with the slightest smear of oil; otherwise they're crowned and will fail in a TR engine. I had pitting several years ago in some crowned ones supplied by Racetorations after 150 miles - these engines really hate them!

 

Cheers,

Tom

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Evening All,

had similar noise after full engine rebuild. Head rebuilt new guides, valves, springs and seats. New camshaft, followers, oil pump and crank reground. Baffled driver visited regular MoT man for comment. Noise definitely in mid height of engine but MoT man also baffled. Only unknown was little ends not rebushed. Off to machine shop to get rebushed. Machine shop asked why! Noise described. " Little end not you trouble mate, there`s nothing wrong with them." detail inspection of all parts before reassembly again. Found a fat spot on the cam followers. Light weight shorter followers with the oil drain hole had been bought and the diameter at the drain hole was fatter than the main barrel. Hence they were sticking off the cam at tickover when the engine was cold. Went away when warmed up. Honing the sides of the followers with valve paste till free cured it

Best of luck

John.

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Your'e just being paranoid :ph34r::ph34r::ph34r::ph34r::ph34r::ph34r::ph34r::ph34r::ph34r:

Maybe!

Evening All,

had similar noise after full engine rebuild. Head rebuilt new guides, valves, springs and seats. New camshaft, followers, oil pump and crank reground. Baffled driver visited regular MoT man for comment. Noise definitely in mid height of engine but MoT man also baffled. Only unknown was little ends not rebushed. Off to machine shop to get rebushed. Machine shop asked why! Noise described. " Little end not you trouble mate, there`s nothing wrong with them." detail inspection of all parts before reassembly again. Found a fat spot on the cam followers. Light weight shorter followers with the oil drain hole had been bought and the diameter at the drain hole was fatter than the main barrel. Hence they were sticking off the cam at tickover when the engine was cold. Went away when warmed up. Honing the sides of the followers with valve paste till free cured it

Best of luck

John.

What a coincidence!

Cheers

Iain

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My money is on bad cam followers. I had pitted followers after a few hundred miles on a Spit 1500 a few years ago. I note the fast road cam requiring (much) larger valve clearances. Triumphs like to be tight don't they? Got to be worth nipping them up and seeing what happens. Are the valve springs uprated? That would put more stress through the tappets.

 

Good luck with it. A noise like that would utterly ruin my enjoyment and confidence in the car.

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My money is on bad cam followers. I had pitted followers after a few hundred miles on a Spit 1500 a few years ago. I note the fast road cam requiring (much) larger valve clearances. Triumphs like to be tight don't they? Got to be worth nipping them up and seeing what happens. Are the valve springs uprated? That would put more stress through the tappets.

 

Good luck with it. A noise like that would utterly ruin my enjoyment and confidence in the car.

Steve theprings are standard

 

Looks like I need to warm it up, remove the rocker cover, mask off everything and run to see if anything looks out of the normal. Close clearances one to by to remove the noise.If this ids the problem then off with the head and inspect the follower?

 

Iain

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