Help! - Chimaera Mystery Engine Noise

[debaron]

Hi everyone.

This one has totally thrown me so I'm offering it up to you lot....It's driving me mad!!!

I just had a call from my mechanic....he was doing the Camshaft, followers and timing chain.

Overcaming is a known issue on the Chimaera what I THOUGHT was causing the knocking/ticking noise that has been with me for the last 1000 miles. Current mileage 69,000 and so I took it to the local TVR shop. They said 'It's the Cam mate' and quoted £1500 - £2000.

Went elsewhere for second opinion in the end (that guy ALSO said , 'yeah, sounds like the Cam' so I booked it in. It's just been fired up after all the work and the noise is STILL THERE!

He knows a fair bit about these cars and says he's fairly sure it isn't:

- The Exhaust Manifold Gasket
- A Noisy Rocker
- The Valves


It sounds EXACTLY like a worn camshaft (medium - high pitched knocking/ticking from right in the chest of the engine) and isn't there immediately on startup but starts to get noticeable after a few minutes and gets quite loud when the engine is hottest...

Something else to note - a HT lead fell off the other day. I didnt notice immediately that I was down on power but I DID notice that the noise was much less noticeable.....

Now to me, since i've just written all this down and started seriously thinking about it...Does sound a lot like a leaky manifold gasket. It would all make sense..


What do you guys think?


Any help and advice VERY gratefully appreciated..

[pk500]

The manifolds crack where the 4 pipes come out mine done that i cut them open and welded them back up . i tryed the gaskets first before realising what it was. also have you checked dizzy caps not arcing .

[tvrbob]

It's not always the gasket. They are renowned for breaking through where the four pipes go into one.

It took me ages to find it on mine because it's too noisy and too hot to find it with the engine running.

Try my method

[dadamsv8]

I had exactly the same noise that you are having and was told all the horror cam stories and price until suddenly noticed when putting the top half of the engine back together after checking all the tappets and making sure they were all lifting correctly thus elimating cam shaft that the exhaust gasket had gone. Replaced and all back together with engine running sweet as...... so take a look at your exhaust manifold I bet its your problem.

I know what you ar ethinking the noise is so metal sounding I thought the same but we live and learn.....and save money every day

You should also get your money back from the garage as the problem was obviously wrongly diagnosed

[Zippee]

Agree with the manifold - the OEM ones often crack and if it's small it may be expanding with the heat hence you not hearing it when cold.

[Meatball]

Both mine have cracked and been welded twice now.

[Timja]

mine is cracked - thought i would have to replace it, but maybe it can be welded.... how much was it to get it welded?

[debaron]

Thanks, guys, much appreciated for all your advice. Gonna go get the manifolds and gaskets checked tomorrow and I hope that'll be then end of it!


Cheers

[tinker-27]

take off the serp belt and try it for a few seconds(no water pump with it off ) i have had two off these that knock and you would swear it was a metal knock but it is the belt its worth a try,sometimes pouring water on it stops it for a bit.

[macca]

tinker-27 said:

take off the serp belt and try it for a few seconds(no water pump with it off ) i have had two off these that knock and you would swear it was a metal knock but it is the belt its worth a try,sometimes pouring water on it stops it for a bit.

Tinker might be right - Thinking back, 4-5 years, to my Chim - had a similar sound. Try a wide blade screwdiver between the grooves on the belt while its running.

[GreenV8S]

macca said:

Tinker might be right - Thinking back, 4-5 years, to my Chim - had a similar sound. Try a wide blade screwdiver between the grooves on the belt while its running.

Isn't that a recipe for getting the screwdriver ripped out of your hands and hurled back at you?

[nikman]

GreenV8S said:

macca said:

Tinker might be right - Thinking back, 4-5 years, to my Chim - had a similar sound. Try a wide blade screwdiver between the grooves on the belt while its running.

Isn't that a recipe for getting the screwdriver ripped out of your hands and hurled back at you?

Yes it is... just before it lands pointy end down on the wing or some other painted surface! And if the screwdriver is short, it's also a receipe for loosing a finger or two!

[macca]

If you lack common sense and can't assess danger then do not attempt this procedure. If you choose to exercise this extremely dangerous practice then apply the blade to the belt running in the downward direction, then if you drop the screwdriver it should fall to the floor (can't guarantee this though). Should the screwdriver fall do not attempt to retrieve it from above unless the ignition is turned off and key removed, otherwise you risk getting your pinkies trapped - Oh, and wait at least 2 hours because the engine might be hot and you could burn yourself.(and never wear loose clothing or jewellery, and get your hair cut as it may get caught in the belt - this rule applies to any work you do in the engine bay while the engine is running). Other rules.... do not carry any sharp objects or tools near your car in case they fall out of your hand and damage the paintwork, or the floor for that matter.... yeh, yeh - nanny state.

I bet you guys would use gloves if you had to strike a match

[spend]

Its probably quicker anyway to slip the belt off on either serp or pre-serp, than the time it takes to ponder the possible risk management of that approach

The Nanny-state is void of common-sense, which it seems that you are advocating?

Dave

[crisp500]

I had the same problem with my belt, a dreadful metalic like ticking noise.After browning my pants thinking of the expensive top end rebuild to come,it turned out to be a tiny stone stuck to the inside of the belt between the grooves.This also happened to a friend of mine,it's worth having a look


Harley

[CHEF_GOLF]

I HAD THE SAME PROBLEM, MINE TURNED OUT TO BE THE EXHAUST MANIFOLD GASKET, BUT WHEN I HAD THEM REPLACED IT KEPT BLOWING THEM, SO I HAD A SET OF UPRATED ONES PUT ON AND HAD THE MANIFOLD BOLTS LOCK WIRED SO THEY DIDNT MOVE, PROBLEM SOLVED

[spend]

CHEF_GOLF said:

I had the same problem, mine turned out to be the exhaust manifold gasket, but when I had them replaced it kept blowing them, so I had a set of uprated ones put on and had the manifold bolts lock wired so they didn't move, problem solved

See what happens when you press that button marked 'CAPS LOCK'

It is considered rude to shout.

Dave

[Automental]

I think mine might also have a leaking manifold causing that tappety sort of sound.
Is turning the stereo up an option or will damage be done or performance affected if it's not fixed? Mine seems to have a bit of a flat spot low down- could that be related?

[debaron]

Ok - Solved!

One complete stripdown (and the discovery of some alarming problems - broken piston, new liner!) later, it WAS actually the cam, but not with wear on the cam itself...It's known as 'End Float' and basically the Cam was actually moving back and forth due to a fault with the bracket at the front end - Giving a 'worn cam' sound but without the worn cam!

Peter @ Roath sorted me with a new bracket and she's purring sweet as now.