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TR6 hammering sound from engine...


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Hi All,

 

After 6 months off the road fitting EFI amongst other things, I took the car out for a test drive /shake down today ahead of its rolling road next week. The standard tr6 map that was installed worked ok to get fired up but the timing was definitely a little out.

 

 

After 10-15mins i put my foot down and got a tapping/rattle at 4000 revs onwards getting quite shrill at above 5000 rpm as soon as I backed off it eased but I decided to limp home and over the next 10 miles it got progressively worse. It now sounds like i have an angry dwarf with a hammer in the engine above 3000 revs and a fairly loud clear tapping noise on tick over.

 

Something has clearly gone quite wrong in the engine but i wanted some help to try and establish whether its head or bottom end.

 

I have checked compression which was +/- 5psi 170PSI on 1,3,4,5,6 and 140psi on 2. all spark plugs where light brown and similar.

 

Regards

Steve

 

 

 

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Fuel is fresh, its run fine in the garage on the ramps it misfired a little due to the set up not being perfect but it was only today 20mins into its first road test that the issue really started.

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Long screwdriver, wooden handle works well, and use it as a stethoscope - pointy end on the engine, handle against your ear . . . . .

 

Alternatively a long stiff tube . . . .

 

That should enable you to ascertain the approximate location of the noise.

 

Cheers

 

Alec

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Always worth lifting the rocker cover. Could be a Broken rocker or something dislodged and bouncing around.

Tim

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Hi Steve.

I'd have a look inside the bores, to make sure nothing has fallen in while you had the inlet manifold off.

I know it sounds like a long shot but it happened to me when I rebuilt a Lotus engine years ago. I still have no idea how it happened.

Good luck, I'd be interested to know how the mapping goes. Mark.

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Hello Steve, it does indeed sound like 'pinking'. Pinking us pre-detonation, usually caused by over-advanced timing, too-weak a mixture or low octane fuel. Or any combination. It usually leads to holed pistons. Unlikely to cause a hammering noise, unless it has damaged the big-end bearings. I guess that's possible, but I understand these can be changed with engine in situ (though I've never done it myself).

Let us know how you get on.

Austin

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It is almost impossible to get an an engine to pink at tickover. The tapping getting worse above 4000rpm also does not seem to me to be detonation.

As is is worse above 3000rpm, the point of max disy advance, I wonder if it is a c/f advance weight spring at fault, allowing the weight to hit the housing.That's where I'd put the screwdriver stethoscope first.

Peter

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stethoscope test definitely, hope its something simple like Peter's suggestion, but from the Angry Dwarf description etc. sound just like my total BE failure at Shelsley in 2015.

 

Six months standing with odd bit of manual turning over, and no forced pre oiling before start up could have meant a very dry bearing on start up. Hope not though.

 

Alan

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Could be head gasket between cylinders. Happened to me couple of months ago driving home from work in the Hurricane (Spit 1300 engine). Started off just like pinking and within 3 miles considerably louder and well down on power. Number 2 down on compression could be your clue. In my case, fixed with a new head gasket.

Jerry.

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. It now sounds like i have an angry dwarf with a hammer in the engine above 3000 revs and a fairly loud clear tapping noise on tick over.

 

 

Steve

 

 

 

Hi Steve,

 

Maybe because you haven't seen him is it possible you have misidentified the dwarf and actually he's a midget as reported to the Quantas engineers by one of their

pilots on their snagging list ?

 

And perhaps, the best Qantas joke...

Qantas Pilot: Noise coming from under instrument panel. Sounds like a midget pounding on something with a hammer.

Engineers: Took hammer away from midget.

 

Hope you can find the little fella and treat in a similar manner.

 

Mick Richards

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Loads of great advice thanks all,

 

i just had it ticking over with the rocker covers off and its best described as a loud tapping @ 600rpm which turns into a proper hammering noise at anything above 1500rpm. i had hoped it was just a head gasket as suggested but the noise is too severe and metalic me thinks for it not to be the bottom end.

 

I guess the best plan of attack is to get the sump opened up and hope nothing horrible falls out!

 

regards

Steve

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Do the easy things first. Check out what Graeme suggested first before you rip it apart ????

Oh and BTW yes you can change big end bearings from the sump. I did it once in the street. (I was young and skint)????

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Hi Steve,

 

Nobodies asked, is the knocking synchronised in time with crankshaft revolution or much faster (likely camshaft ).

 

Micky

Edited by Motorsport Mickey
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Had a tappet adjuster ball pierce the top of a pushrod once which picked the pushrod up and made a similar hammering noise.

Stuart.

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1, yer rocker gaskets compressed, lett,n rockers hit the cover

any tell tale mark ont inside

 

2, slack tappet, , esp if they worn, as will be set to wrong figs

 

3,cam follower gon already, this,ll show uo as a loose tappet too

 

4, a spark plug has got loose between the housing an procelane

Butt, they still fire, !!!

 

5, ye had valve inserts fitted, is one coming loose, wont be a first with that !!

 

 

M

Edited by GT6M
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