Four days ago I drove to my office, wonderfull drive, parked the car and at lunch time I started, as always, no problems whatsoever, first try, however a big noise coming from the engine. I didn't dare to drive the car and took it to my mechanic with a crane. My mechanic said this is something important and it would be necessary to take the engine out of the car to see what happens.
My car is a v12, convertable, 1991 prefacelift, with only 80000 kms, 50000 miles. everything is in good order, so I am really surprised because of this situation.
Before to take the engine out, could some of you make a suggestion?
Thank yoy very much indeed.
Regards.

 

@santos

The "could be" list is long. Sounds like your mechanic isn't being very helpful. Ask him what he thinks the problem is. Based on that you will get feedback whether the engine needs to come out to fix it or not. Personally I wouldn't let anyone take the engine out of my car (a process which is sure to cost you 000's) just because my mechanic said it's something "important". There are plenty of things that can be checked with the engine in the car to help the diagnosis, ie a compression check. Have you used this mechanic before ? Is he a Jag guy ? Do you trust him ?

How was the temperature on the car recently ? Any issues with overheating ?

"Big noise" doesn't help much either. Big noise, like a single bang ? Big noise like a constant clattering ? Big noise...... what ?

 

Thank you for your answer. My mechanic said it could be a piston or a rod, but he is not quite sure. My mechanic is taking care of my cars from some years ago. He changed the exhaust gaskets and some belts. I trust him in a limited way of course. Could you, please, tell me what can be checked with the engine in place?
The temperatura has always been OK, even one day I was driving very slowly because of a traffic jam and never ever was higher than the "N".
The noise is a continous one, I don't know how to describe it, but it is a continous noise.
Thank you for your help. Best regards.

 

If it was a piston or a rod I believe the engine would not turn at tickover and might well have thrown a bit of metal through the crankcase. Basically, unless you were revving the hell out of it, this is very very unlikely.

It could be that a timing chain tensioner has failed. This makes the car sound dreadful, but it will tick over. If that was it, then it is best done engine out, but can in theory be done engine in, if everything in front of the engine and bonnet is removed. Either way it is not too bad (see K Palm's book on the matter.)

I suggest you try a compression test, just a simple one with a cork or your thumb over the plug hole. That will prove or not the rod/piston theory.

Greg

 

Sounds like a money grab. Try to describe the noise to us.

 

Upload a video of the engine so we can hear the noise.

 

Assuming your mechanic is honest and knows what he's hearing, it could be piston slap or a rod bearing going bad.
Does it sound almost as if someone is under the hood rhythmically hitting the side of the engine with a hammer?

 

I have also had a flex plate crack and then eventually shatter that sounded like a bad rod knock at first.