Mains rumble?

Post by **JOWETTJAVELIN** » Sat Sep 15, 2012 9:58 pm

Under moderate/hard acceleration in 1st and 2nd gears there is a sort of grinding/rumbling noise coming from the mechanical nether regions. Oil pressure remains good after a good motorway run. Could the mains be past their best? 1275 engine btw

Post by **MarkyB** » Sun Sep 16, 2012 8:02 am

What has been done to the engine that you know of?
I'd have thought the oil pressure would be low if the mains are worn, what actual numbers do you get from the gauge?

Post by **JOWETTJAVELIN** » Sun Sep 16, 2012 4:23 pm

No idea what had been done to it in the past, but it doesn't smoke, runs well and the figures on the gauge are hot idle 55lbs, cruising at 60 MPH 75lbs.

Post by **les** » Sun Sep 16, 2012 7:08 pm

Do you get the noise when you reach the same revs in third?

Post by **chesney** » Sun Sep 16, 2012 7:53 pm

You don't have much luck with big ends do you JJ??

Post by **mike.perry** » Sun Sep 16, 2012 8:50 pm

Oil pressure on my 1275 is down to about 20 psi on tickover after a motorway run and I know the ends are knackered.

Post by **izzi** » Mon Sep 17, 2012 8:37 am

Hi,

The grinding/rumbling seems odd as you normally get a rumbling from a crankshaft bearing, and a grinding from a gear box. When you say 1st and 2nd does makes you think gear box problem.

When in neutral do you get the noise when you give the engine sudden revs.

Good luck

Roy

Post by **bmcecosse** » Mon Sep 17, 2012 9:34 am

It's not mains rumble with that oil pressure. However - I do believe at one time in the 1275 Marina there was a dizzy fitted with a modified advance curve to eliminate what was perceived as 'mains rumble'........

Post by **liammonty** » Mon Sep 17, 2012 10:43 am

My 1098 rumbled (like main bearing rumble) when ignition was advanced too much- might just be worth retarding the ignition a degree or 2 to see if that quietens it down at all. It's easier than stripping the engine!

Post by **daveyl** » Mon Sep 17, 2012 2:48 pm

Yes about the dissy not having a vacuum advance. As said the early Marinas didn't have it. What running gear do you have with that 1275? I do remember you having some problems with your 803 and I obviously missed your post regarding the 1275 fitment.

Post by **bmcecosse** » Mon Sep 17, 2012 3:58 pm

I could never understand it - because vacuum advance only works on light throttle, and has absolutely no effect on open throttle running - so how it could have any effect on 'mains rumble' has always been beyond me........

Post by **MarkyB** » Mon Sep 17, 2012 8:21 pm

Probably because light throttle is what most of us use most of the time!
If your foot is to the floor, at all times, I'm even less lightly to visit that part of Scotland!

Post by **bmcecosse** » Mon Sep 17, 2012 8:46 pm

Aside from that..... surely 'mains rumble' will only be heard when the engine is working hard - not just cruising along?

Post by **les** » Mon Sep 17, 2012 9:55 pm

Unless you're a 'run it 'till you wreck it' sort of guy, change the gearbox. If you run a 1098 box with a 1275 engine especially if you thrash it, this could well be your problem.

Post by **JOWETTJAVELIN** » Tue Sep 18, 2012 6:20 pm

Thank-you all for the replies. Going off what you all say it does indeed seem to be gears, as when I kept my hand on the stick and this noise occurred the vibrations came up the stick. Also, it doesn't happen in 3rd during spirited driving.

A graunchy gearbox I can live with, thank heavens the mains are OK then!

Morris Minor Owners Club

Mains rumble?

Mains rumble?

Re: Mains rumble?

Re: Mains rumble?

Re: Mains rumble?

Re: Mains rumble?

Re: Mains rumble?

Re: Mains rumble?

Re: Mains rumble?

Re: Mains rumble?

Re: Mains rumble?

Re: Mains rumble?

Re: Mains rumble?

Re: Mains rumble?

Re: Mains rumble?

Re: Mains rumble?