740 poor running and stalling

[Beadybc]

Originally Posted by griston64

It's this https://www.skandix.de/en/spare-part...ubber/1012350/

Realised I posted before taking it off and looking up the reference code on it, thanks anyway though Griston.

Turns out there is a thin layer of fuel on the inside above where the top clip is compressed and beneath the lower clip (I've attached photos of it). Going to check for leaks, then put it back on with tighter connections.

[Laird Scooby]

Originally Posted by Beadybc

Yeah the top connection of the sock seems to be getting lower with every run even though the rings are attached tightly.

It has an arrow on it pointing downwards, not sure what it is indicating and I can't find any information on it as I don't know it's official name.

The arrow is an alignment mark that lines up with a point on the fuel distributor, can't quite remember where but by the time you've looked for it to check the alignment you'll be almost as quick looking for it and realigning it.
You'll find the sock (for want of a better word) will fit easiest at that point between the throttle body and fuel distributor.

Might be worth removing the sock and thoroughly inspecting it for perishing, cracks, splits etc, identifying the corresponding mark on the fuel distributor for the arrow and when you refit it, smear a little silicone grease around the inside of each end to help it slip into position properly. Also check the resiliant mounts for the fuel distributor haven't failed and are allowing it to hang on the sock which could be causing problems.

Silly question - have you checked the inlet manifold to head bolts/nuts are all done up properly?

[Beadybc]

Originally Posted by Laird Scooby

The arrow is an alignment mark that lines up with a point on the fuel distributor, can't quite remember where but by the time you've looked for it to check the alignment you'll be almost as quick looking for it and realigning it.
You'll find the sock (for want of a better word) will fit easiest at that point between the throttle body and fuel distributor.

Might be worth removing the sock and thoroughly inspecting it for perishing, cracks, splits etc, identifying the corresponding mark on the fuel distributor for the arrow and when you refit it, smear a little silicone grease around the inside of each end to help it slip into position properly. Also check the resiliant mounts for the fuel distributor haven't failed and are allowing it to hang on the sock which could be causing problems.

Silly question - have you checked the inlet manifold to head bolts/nuts are all done up properly?

Funny you should mention the fuel distributor mounts. As I was placing the sock back on I noticed that whilst it was flush on the bottom, it was not flush at the top, whilst trying to find the reason why I lifted up the fuel distribution unit from underneath and found that there was a lot of play. Turns out the front mount is completely shot and wasn't actually making contact with the unit at all which explains why the top of the sock was lowering after running, the hose that runs to the bottom of the Air Auxiliary Valve was doing the same thing.

I can find replacement mounts but the part of the mount attached to the unit itself looks worn down as well, can I replace that side as well or would I have to get an entirely new unit?

Bolts around the manifold are tight, checked with DW40 whilst it's running and there was no change in rpm.

As usual I've attached photos.

[Laird Scooby]

Originally Posted by Beadybc

Funny you should mention the fuel distributor mounts. As I was placing the sock back on I noticed that whilst it was flush on the bottom, it was not flush at the top, whilst trying to find the reason why I lifted up the fuel distribution unit from underneath and found that there was a lot of play. Turns out the front mount is completely shot and wasn't actually making contact with the unit at all which explains why the top of the sock was lowering after running, the hose that runs to the bottom of the Air Auxiliary Valve was doing the same thing.

I can find replacement mounts but the part of the mount attached to the unit itself looks worn down as well, can I replace that side as well or would I have to get an entirely new unit?

Bolts around the manifold are tight, checked with DW40 whilst it's running and there was no change in rpm.

As usual I've attached photos.

Just renew the mounts, new fuel distributors don't come with them anyway. That might be the whole problem if you're lucky.

[Bob Meadows]

Try some superglue on the rubber bobbins:~ keep then lightly compered whilst they dry.
Polyurethane adhesive/seal also works well.
Bob.

[Laird Scooby]

Originally Posted by Bob Meadows

Try some superglue on the rubber bobbins:~ keep then lightly compered whilst they dry.
Polyurethane adhesive/seal also works well.
Bob.

Has that seriously worked for you Bob?

I've tried it on the condenser mounts on my Rover but recently bought some new resilient mounts instead.
Have also tried it on other resilient mounts in the past to no avail, usually once they split or part company, that's it, they're toast.

[Bob Meadows]

Yes:~
Used the superglue on the same bobbins for a '88 240- it works well on rubber items to include "O" rings I use these as outer seals on classic lamps- not for engineering applications though.

The Polyurethane has also been used on the large rubber bump stops for the same car-broken away from the chassis fixing bracket, submitted a brief write up some time back.
If the surface looks contaminated I normally clean it with panel degreaser first.

I've seen these bobbins for sale somewhere or very similar- Rimmer Bros from memory?
Regards Bob.

[Laird Scooby]

Originally Posted by Bob Meadows

Yes:~
Used the superglue on the same bobbins for a '88 240- it works well on rubber items to include "O" rings I use these as outer seals on classic lamps- not for engineering applications though.

The Polyurethane has also been used on the large rubber bump stops for the same car-broken away from the chassis fixing bracket, submitted a brief write up some time back.
If the surface looks contaminated I normally clean it with panel degreaser first.

I've seen these bobbins for sale somewhere or very similar- Rimmer Bros from memory?
Regards Bob.

Be careful with the ones from Rimmers, chances are they're for the classic Mini and similar and will be 5/16UNF instead of (if memort serves) M8 threads. They can easily be found on fleabay very cheaply.

You need to know the original body diameter and depth and thread size but once you do, it's easy enough to find them on fleabay.

https://www.ebay.co.uk/sch/i.html?_n...bin+m8&_sop=15

Just to give an idea ^^^^^

For some unknown reason they are now coming up as exhaust bobbins (the most common use i suppose) rather than resilient mounts.

Maybe i've been unlucky with my efforts to repair them, that said i've done nothing different to you so not sure why there was a problem on mine but not yours. Superglue is a bona fide way of joining "O" ring cord to make custom "O" rings, even for engineering use.

PS - which polyurethane adhesive/sealant do you use?

[Beadybc]

Originally Posted by Laird Scooby

Be careful with the ones from Rimmers, chances are they're for the classic Mini and similar and will be 5/16UNF instead of (if memort serves) M8 threads. They can easily be found on fleabay very cheaply.

You need to know the original body diameter and depth and thread size but once you do, it's easy enough to find them on fleabay.

https://www.ebay.co.uk/sch/i.html?_n...bin+m8&_sop=15

Just to give an idea ^^^^^

For some unknown reason they are now coming up as exhaust bobbins (the most common use i suppose) rather than resilient mounts.

Maybe i've been unlucky with my efforts to repair them, that said i've done nothing different to you so not sure why there was a problem on mine but not yours. Superglue is a bona fide way of joining "O" ring cord to make custom "O" rings, even for engineering use.

PS - which polyurethane adhesive/sealant do you use?

How do they actually work because the ones that I have don't have the threaded part on both sides as you can see in the photos. Do you just cut them in the middle to get two or do the metal parts slide out of the rubber?

[Laird Scooby]

Originally Posted by Beadybc

How do they actually work because the ones that I have don't have the threaded part on both sides as you can see in the photos. Do you just cut them in the middle to get two or do the metal parts slide out of the rubber?

None of the above!

If you look at your pics, you'll see in one of them there is the metal end still in the bracket and you can see where the rubber has come away and it's basically a flat disc. Imagine a couple of normal bolts but with the heads replaced with similar flat discs. Have a jig so these bolts could be held securely with a gap in between and this gap is fill with rubber, polyurethane or nitrile compound and allowed to set.

It bonds to the flat discs so the two threaded parts are now held apart (and together!) by the rubber/PU/nitrile in the middle.
Because the compound in between the two threaded parts is fairly strong it will support various weights but more importantly, dampen vibration from one end to the other of the mounts while returning to it's original shape when the vibration stops. This makes them resilient, hence the name of resilient mounts.

They are used a lot in NVH engineering (Noise, Vibration and Harmonics) to prevent noise being transmitted, vibrations which may eventually cause mechanical damage or other problems. Perfect exhaust mount for a classic Mini or the noise and vibration from the exhaust would transfer to the floorpan creating a sounding chamber better known as the passenger compartment.

As you can probably guess, you wouldn't really want vibration from the engine upsetting the mixture in the fuel distributor (easily done as it's controlled by an air-flap on a spring, lifted by incoming air to the engine) which is why the fuel distributor is mounted on them.