Engine flutter noise



Hi. I just replaced the engine in my 1986 Jaguar xj6 and picked up the car today. I hear a flutter sound now coming from this “new” engine. I had a broken ring in the other engine that made a knocking noise, however, I never heard this type of a flutter sound from the old engine.

As I’ve never heard my new-to-me 20-year-old car without the knocking noise, I am not sure what a good running engine is suppose to sound like.

Is this flutter okay, part of the normal noise of this engine?

Or is this something that needs further investigation?

It is not an annoying noise like someone who drives by with squeeky brakes…and you want to tell them to get their car fixed. I am just a concerned owner that would like to have a named source for strange sounds, even if they are good sounds.

The sound is a kin to trying to make a flutter sound with your mouth/tongue. It can be heard with the windows up or down.

Any ideas?

I appreciate your feedback.

Thank you.


Maybe your former knocking noise was masking the flutter noise you hear now. Does it vary at all with the speed of the A/C blower? That would be my first guess. If not, does it vary with engine speed? If you don’t get a satisfactory answer here, go to http://www.british-cars.co.uk/ and join the best UK car site on the plannet. It’s free.


Hi. The a/c is an interesting comment. Actually, the noise does not vary with a/c blower speed. I drove without the a/c. However, when they replaced the engine, they replaced the following items on the a/c:

low press. switch
two hoses: cac6657 & 4019
hose clamp -04: m4hc
hose bypass c41356

Do you think it has something to do with the a/c?

The a/c was intermittantly working prior to the engine replacement. Then it burst the long skinny hose coming from the evaporator…on the driver’s side of the car. Probably too much info. But I included it in the event that it might help.

thanks for the link too.


No, it’s just that an A/C fan that has picked up a piece of debris or plastic bag (my most recent find on a Taurus) is likely to make the sort of noise you describe. I once had a Peugeot that would suck papers from the glove box into the blower. After the first time, it got to be routine. Jaguars are notoriously expensive to maintain. I’m sure you’re discovering that. They are certainly not within my area of expertise. I thougt I had one once, and vowed never to let another one have ME. If I want to drive Brit iron, I’ll chose one of my MGs.


I drove the car again this morning and have a different idea about the noise. I wonder if it could be an exhaust leak. ??

In a way it sounds more like a kid making the engine sound by pushing air through the lips and making the lips vibrate. Does that make sense? Like the pretend engine and changing gears sounds we made with our mouths as kids.

It is louder with acceleration and idle, at coasting speed, it is no existent.

Could this be an exhaust sound coming from the front of the car?


You should have the exahust checked for blockage; also, have the convert(s)checked.


Could this be an exhaust sound coming from the front of the car?

Sure, it could be an exhaust pipe leak, a manifold leak, or a manifold gasket leak. Can you locate the noise when the car is stopped?



Thank you to each of you for your responses.

I took the car to a muffler shop, thinking they might have the best-tuned ears that could detect exhaust leaks.

Sure enough, the manifold is leaking. They are not sure exactly where the leak is at this moment. Whether the sound is coming from the manifold/cat seal or the manifold/head gasket.

My friend and I both commented on the fact that the noise is definitely much louder in the driver’s seat. This makes me think (worry) that the leak might be the gasket one. HOpefully, it is not in both locations.

Next question.

As I had a new-to-me (70k) engine installed to replace the one with the broken ring, is this gasket or o-ring/seal something that would have been in tact when the new engine was installed? The noise/problem is clearly something inherent to the new engine as the old one did not do this. More specifically, is the bad part in an area that the mechanics would not have touched when they replaced the old engine?

Ultimately, the question boils down to money. Is this a bad ring that the shop transfered over unbeknownst to them. Or, did the bad part come from the shop and inadvertently get used during the installation?

I don’t know what gets transfered over during an engine replacement. I’ve just started using this mechaninc and just want to be sure that everything is good.

Thanks again.