New Chimaera 500
Discussion
I have just bought a Chimaera 500, a few years ago the engine had been rebuilt using forged Pistons. Should I be worried as the engine is noisy when hot, a tapping noise, but a lot worse when the engine is cold. The engine is running an oil pressure of 55psi which seems high ? And I have noticed that the dip stick does not stay pushed all the way down. I have not had the car long enough to tell if it's using oil. Have I bought a pup !!
phazed 11.83 said:
Mine has forged pistons and is quiet.
Yours should be as well. It may well be something like an exhaust manifold gasket.
Don't panic yet.
That's interesting, mine's really noisy on start up, less so when warm but still not quiet... I'm sure RR did tell me the forged pistons are a bit noisier (although I have no idea why), and the CF plenum lets alot more sound through than the standard RR one... Yours should be as well. It may well be something like an exhaust manifold gasket.
Don't panic yet.
She's also smoked a bit under WOT screaming up through the gears, but that's getting worse of late
Might be time for a bit of internal inspection....
OP - hopefully the noise is nothing sinister......
Be worth using a proper mechanical oil press gauge on it - TVR ones are usually way off - it may have the wrong sender on it although the dip stick being forced out sounds odd?
Forged pistons can flap about a bit compared to cast, usually until hot due to larger clearances/different expansion rates.
Forged pistons can flap about a bit compared to cast, usually until hot due to larger clearances/different expansion rates.
shaunmorris said:
Not noticed any smoke from mine. What really concerns me is the high oil pressure, worried I have blow past on the pistons which is pressurising the sump
Shaun, mine runs at 60 from cold in the winter, around 50-55 from cold in the summer... drops to around 30 at idle when hot back up to around 50 over 3k rpm when hot...I have got a fair bit of crankcase pressure, more than I believe it should have, also, not long after this became apparent (after an engine rebuild) we whipped the plenum off and the trumpet base was a bit swamped with oil which had been pushed up from the rocker cover breather... Mine's a 500 with a V8D lump in it running forged pistons, H beam rods, 10.6-1 comp plus lots of other go faster goodies....
Have you thought of getting a leak down test?
Chilli
A leak down test may be the way forward, I am asking myself if the crank breather is blocked, would this potentially cause pressure to build in the engine forcing it to push the dip stick out slightly?
I do not object to the engine being a little noisy, provided that is all it is and it's not a simpton of something more serious.
I do not object to the engine being a little noisy, provided that is all it is and it's not a simpton of something more serious.
ChilliWhizz said:
Shaun, mine runs at 60 from cold in the winter, around 50-55 from cold in the summer... drops to around 30 at idle when hot back up to around 50 over 3k rpm when hot...
I have got a fair bit of crankcase pressure, more than I believe it should have, also, not long after this became apparent (after an engine rebuild) we whipped the plenum off and the trumpet base was a bit swamped with oil which had been pushed up from the rocker cover breather... Mine's a 500 with a V8D lump in it running forged pistons, H beam rods, 10.6-1 comp plus lots of other go faster goodies....
Have you thought of getting a leak down test?
Chilli
You had oil on the trumpet base no doubt due to an unbalanced breather.I have got a fair bit of crankcase pressure, more than I believe it should have, also, not long after this became apparent (after an engine rebuild) we whipped the plenum off and the trumpet base was a bit swamped with oil which had been pushed up from the rocker cover breather... Mine's a 500 with a V8D lump in it running forged pistons, H beam rods, 10.6-1 comp plus lots of other go faster goodies....
Have you thought of getting a leak down test?
Chilli
You had too much vacuum on the induction for the size of a breather pipe fitted.
I don't know where they picked up the breather from on your intake side but they probably corrected that.
As for forged pistons, on my totally rebuilt engine using a new block but with the old pistons and the piston rings carefully sized to fit, the engine is silent.
Regarding the noisy carbon fibre triple plenum. Try placing both hands on the top of it at idle and you'll be surprised how much noise goes away. This confirms how the carbon fibre plenum is just like a thin plastic box exaggerating the valvetrain noise!
Op, if the dipsticks being pushed out then you have crankcase pressure and blowby. Some blowby is inevitable. First off I'd check any flame traps or pcv circuits for blockage. Crankcase fumes should be vented into the plenum but you may have a restriction. Also, inspect the little mushroom that stands on top of the rear of one of the rocker covers. It allows clean air into the engine casing. You should be able to prise off it's filter and blow into the rocker cover if it's not gummed up.
How much air is being pumped out of the oil filler cap at idle and is it smokey?
How much air is being pumped out of the oil filler cap at idle and is it smokey?
Typically there are two common types of forged piston, one has higher silicone content than the other so differing expansion rates. Same as Chilli here bit of slap when cold but goes when warm, nowt wrong with that. This type are probably overkill for the road TBH but,,,,,. Also, there's nothing wrong with your oil pressure, it's good, mine hardly drops below 50 when hot (capillary gauge) and over 55 cold. I think as has been said you have a problem with crankcase ventilation.
Let someone have a listen who 'knows' that type of engine, and then a second opinion.
Let someone have a listen who 'knows' that type of engine, and then a second opinion.
Edited by macdeb on Friday 26th May 09:30
The best thing to do would be drive it to somewhere where other experienced owners are kicking tyre's and suppin an ice cold beer somewhere. Let them have a listen etc.
Hear a few others for yourself too, saves a fortune sometimes.
After removing the excess oil !
Dip sticks popping up has been heard of before and doesn't automatically mean pressure problems so as others have said don't panic yet. It's important to find a trusted Tvr mechanic but it's just as important to listen to owners who have been through all this before.
Find your local meet or monthly gathering of Tvr folk and take your car along.
Ask your questions and you'll hopefully get some honest answers and good advice.
Take it from there.
I find just looking at and hearing other Tvr help me decide if mines a pup too,,
Non of them are with a bit of TLC and a few updates to the systems
If you've just got the car this is really a good place to start, other owners will go straight to the problem areas and describe / offer solutions or warnings for your immediate attention.
Take a pen and pad, your head might be spinning but this will introduce you to the car in a far more personal way and you'll make friends at the same time. Tvr chaps are top notch at this mechanics lark. Valuable info straight off the bat.
Goodluck and enjoy the driving
Hear a few others for yourself too, saves a fortune sometimes.
After removing the excess oil !
Dip sticks popping up has been heard of before and doesn't automatically mean pressure problems so as others have said don't panic yet. It's important to find a trusted Tvr mechanic but it's just as important to listen to owners who have been through all this before.
Find your local meet or monthly gathering of Tvr folk and take your car along.
Ask your questions and you'll hopefully get some honest answers and good advice.
Take it from there.
I find just looking at and hearing other Tvr help me decide if mines a pup too,,
Non of them are with a bit of TLC and a few updates to the systems
If you've just got the car this is really a good place to start, other owners will go straight to the problem areas and describe / offer solutions or warnings for your immediate attention.
Take a pen and pad, your head might be spinning but this will introduce you to the car in a far more personal way and you'll make friends at the same time. Tvr chaps are top notch at this mechanics lark. Valuable info straight off the bat.
Goodluck and enjoy the driving
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