240 General: Low-Pitched Whine At Slow Speeds

[TheHungriestBadger]

Interesting Bob, and thanks for the photos, they've all been really good

I noticed mine had excess thread on each end as well, and that when refitting the cross-member, the mount was the limiting factor, even when it had essentially maximum play... I may have to crawl under again and reinvestigate, making sure that the mount is actually sitting flush against the bracket and cross-member, although visibility is pretty poor in that area.

I may have already put this, but I know that both mounts were the same width/diameter and thickness, yet the cross member was always a few mm out from being square (probably 10mm or 1/2"). I tested numerous times bolting each side in first. It didn't matter which side I bolted in first, it was always super easy (could tighten both bolts into the chassis ~80% by hand if not more. But always when trying to bolt up the other side, the cross-member was always that 1/2" from being square. Again, this was forced into place using a screwdriver as a lever and then starting the threads on the other bolt.

Does that further point to engine shiftage at all (assuming the mount is flush on both faces of course)? The exact reassembly process was:

1) Locate mount thread into trans bracket and tighten nut ~1/4 of the way.
2) Thread cross-member over exhaust and locate other mount thread into hole on cross-member, again tightening nut ~1/4 of the way (tons of play in mount).
3) Bolt cross-member on one side (both bolts, finger tight, with spacer plate).
4) Jam cross-member back square with screwdriver (required a helper in my case, likely because I'm weak) and then thread in other bolt a few threads to hold.
5) Remove screwdriver, thread in final bolt, tightening both bolts and with spacer plate - these two bolts required a socket wrench the whole way to tighten.

Finally, I was able to tighten the nut on the cross-member-side thread of the mount without needing a u-joint on the socket wrench - just a 15mm deep socket and 3/8" short extension. I was pretty sure I needed a u-joint in the removal process, but to be fair, I didn't actually check if I could get away without... Maybe this points more to the mount not being seated correctly?

Maybe I'll try redoing the trans mount myself (with the correct part, and more knowledge on the process) as a first port of call given that'll be the cheapest option, and surely can't make the problem any worse as long as due care is observed?

[BicycleBoy]

Plenty of room: aw70 and a febi after market mount



Bob, you're missing a blind grommet that covers the hole in the crossmember. Stops it rusting out from the inside.

[TheHungriestBadger]

Bicycle Boy, looks like you've also got the square mount in there (with the offset threads?)? Any advantage to attaching the mount to cross-member before bracket?

Also, agreed, there should be a rubber grommet covering that hole in the cross-member, I have yet to refit mine given it's barely going anywhere.

[BicycleBoy]

Originally Posted by TheHungriestBadger

Bicycle Boy, looks like you've also got the square mount in there (with the offset threads?)?

Yup, that't the one for the aw70, two metal teeth on it to grip the bracket.

Any advantage to attaching the mount to cross-member before bracket?

Remove the two bolts holding the bracket to the gearbox, and the four bolts and spacers holding the crossmember to the car body, then with the whole doodah on the bench start dicking about changing the rubber mount.

Plenty of opportunity to get fresh with the wire brush and paint when everything is off. Did mine three months ago and look at the muck already.

[Bob 1967]

Originally Posted by BicycleBoy

Plenty of opportunity to get fresh with the wire brush and paint when everything is off. Did mine three months ago and look at the muck already.

Before

After

[Othen]

Originally Posted by TheHungriestBadger

No, the motor mounts are still in one piece so far as I can tell - certainly, the car still drives as smoothly as it did (which was fairly smooth, except for a rumble on deceleration which I lived with since no extra noises over 6k miles).

My only suspicion that I may have done, is that I needed to jack it up quite far (i.e. more than just 1", but probably not more than 3") to force the cross-member back. It seems pretty obvious that something shifted more towards the rear of the car in the process, otherwise it would've all just lined back up again pretty nicely.

My curiosity comes from seeing lots of people say "don't do it or else big damage" but don't state along what kind of lines that big damage is. 'tis all

The only way the motor could move backwards is is one (or both) of the front engine months has let go. This is certainly possible (this one is from my previous 244):



... and isn't necessarily obvious because the motor is pretty heavy. If that has happened it would certainly explain why you suddenly have a new noise. You could put a jack under the sump and see if the motor lifts without the car, or just see if you can move it around a bit with a pry bar. If this is a concern then get the engine mounts changed without delay.

Good fortune,

Abe

[Clifford Pope]

I'd suggest that the misalignment at the gearbox end is easily explained by ageing engine mounts. I've always found these difficult to fit. They sag and distort with age, especially the one on the right underneath the oil filter. It is very difficult to avoid oil dripping on it when changing the filter.
Eventually the block comes apart from the plates, but even then it is hard to distinguish a slight sagging from total disconnection because the engine is so heavy. Once the engine has shifted position it requires a lot of heaving and leverage to move it, especially if both mountings have gone. Moving the gearbox end to replace its mount shifts the engine out of place.

In the end I found it easier to unbolt the entire mounting brackets and then fit the new rubber on the bench. Bolt the mounting to the engine block first, then lower the engine a little and guide the bolts into the crossmember.

[Othen]

Originally Posted by Othen

The only way the motor could move backwards is is one (or both) of the front engine months has let go. This is certainly possible (this one is from my previous 244):



... and isn't necessarily obvious because the motor is pretty heavy. If that has happened it would certainly explain why you suddenly have a new noise. You could put a jack under the sump and see if the motor lifts without the car, or just see if you can move it around a bit with a pry bar. If this is a concern then get the engine mounts changed without delay.

Good fortune,

Abe

Originally Posted by Clifford Pope

I'd suggest that the misalignment at the gearbox end is easily explained by ageing engine mounts. I've always found these difficult to fit. They sag and distort with age, especially the one on the right underneath the oil filter. It is very difficult to avoid oil dripping on it when changing the filter.
Eventually the block comes apart from the plates, but even then it is hard to distinguish a slight sagging from total disconnection because the engine is so heavy. Once the engine has shifted position it requires a lot of heaving and leverage to move it, especially if both mountings have gone. Moving the gearbox end to replace its mount shifts the engine out of place.

In the end I found it easier to unbolt the entire mounting brackets and then fit the new rubber on the bench. Bolt the mounting to the engine block first, then lower the engine a little and guide the bolts into the crossmember.

... without having seen the engine, I'm tending to think that Clifford is right and it has shifted on its mounts (probably because one of them has sheared through).

Clifford is right that the easiest was is to undo the 3 nuts at the bottom of one of the mounts from the cross member and lift the engine up with a hoist:



... this was to remove the sump, but the principle is the same. Then remove the aluminium casting you can see here from the motor:



Remove the whole assembly and change the rubber mount on the bench and replace. Then do the other side (don't undo both at the same time, that engine is really heavy!).

It really isn't as difficult as it sounds.

Abe

[TheHungriestBadger]

Just took some pictures of the engine (looks like it's sagging slightly to me), and the engine mounts on both sides, would be grateful for your wise opinions.

Alternative Links:
https://drive.google.com/file/d/1Mqg...usp=share_link
https://drive.google.com/file/d/143C...usp=share_link
https://drive.google.com/file/d/1fij...usp=share_link

[Bob 1967]

This is where the drivers side bracket is attached to the crossmember.
3 12mm nuts.


Newly installed mount on pass side.

Just to give an idea of how it compares to your old ones.

Just did a visual inspection, they are still the same shape.(haven't quashed or settled.) They were done 3 years ago.