Low rumblings

[12jslater]

After buying a seven and wanting a proper seven since I was eight I have drained the sump and dropped it to clean it of its oil and water mix, filled it back up with fresh 30 weight and the engine is far from perfect, it iran smoothly at first but now it idles smoothly however when moving along it sounds as if there is a diesiel generator and a teaspoon attempting to escape the crankcase, I don't want advice as I am tackling it myself however I would be interest to hear opinions on what it could be, just a test I suppose to see how accurate you older seveners are haha.

[Nick Salmon]

I'd wager that there is a teaspoon in the crankcase...It can't be a diesel generator cos that would not fit.

[Tony Press]

After buying a seven and wanting a proper seven since I was eight I have drained the sump and dropped it to clean it of its oil and water mix, filled it back up with fresh 30 weight and the engine is far from perfect, it iran smoothly at first but now it idles smoothly however when moving along it sounds as if there is a diesiel generator and a teaspoon attempting to escape the crankcase, I don't want advice as I am tackling it myself however I would be interest to hear opinions on what it could be, just a test I suppose to see how accurate you older seveners are haha.

If you don't know the history of the car I think running it before a complete strip down could lead to more serious problems- just my thoughts !

[Dave Wortley]

It could be so many things but the most common culprit is rear main bearing rumble. They lose the interference fit between the crank journal and inner race bore or the rolling elements in the rear main have gone rusty due to crankcase condensation, creating an ideal mess for rapid wear. A clue might be as you say the oil/water mix in the sump.
You may need to remove the engine for closer investigation. The teaspoon-like noise could be the clutch thrust race. You will find all this out when engine is removed.

[Tony Betts]

it sound like you want to be able to say at the end of everyones good intensions. ha ha, im cleverer than you old people.
  
the truth of your problem is, if the engine has been left a long time. it could be a number of things  how clever am i 

[Alan]

Right on, Tony.

[12jslater]

Not at all, I trust old blokes with experience in these things more than any of the so called "proffesionals" half the time, fifty years experience beats a uni education any day! I have never had a modern car (the newest being a 1954 ford 103e) and if it wasn't for the old blokes with experience I wouldn't be where I am today with my understanding of vintage mechanics, I was just interested in seeing who's guess was closest as it is a very unsual noise from an engine, unlike anything I have heard before.

[David Stepney]

Jake, It is almost certain to be the rear main bearing. I had a similar problem with my own car some time ago ( see my thread entitled 'Rear main Bearings' from April 2019)

Incidentally you don't say what species of Seven you have.

[Chris KC]

If you have (had) water in the sump then more than likely the head gasket has failed and the cylinder head may well be warped. If it has been running in that state for any length of time the crank bearings will have suffered. Before doing much else I would check the ignition timing as over-advance is perhaps the easiest way to make an A7 engine noisy. If running straight oil in your engine make sure it gets a warm-up before setting off, especially at this time of year.