gearbox problems

Is it possible to use a diesel clutch pressure plate on a petrol vehicle?

Hang on, in the original post the clue is in the question! There's probably nothing wrong with your drive train, if you've just replaced the dissy you've probably go the timing set wrong - too far advanced. How did you check it?

If its pinking badly slightly it sounds like glass beads being dropped on a glass coffee table, if bad it sounds like dropping big marbles being chucked at your engine...

dominicbeesley said:

Hang on, in the original post the clue is in the question! There's probably nothing wrong with your drive train, if you've just replaced the dissy you've probably go the timing set wrong - too far advanced. How did you check it?

If its pinking badly slightly it sounds like glass beads being dropped on a glass coffee table, if bad it sounds like dropping big marbles being chucked at your engine...

Click to expand...

O poo, gearbox is out and all seems ok apart from the clucth release bearing having some wobble when in gear!, yes it sounds like marbles on a glass table, was set up as per haynes manual, adjusting dizzy until points open, then setting points up well a little more technical then that but that was the gist. I like this theory but Would this marble noise be present when not in gear, and if so why does it only do it in fourth when under load?.

That's doing the points, not the timing you must do both. Easiest way to do timing is to buy a timing gun from Halfords or off the net or you can do it with a simple timing bulb...The gunson thing is worth the extra money - there are cheaper ones on amazon but they all tend to break!

I'd check the timing properly before you go any further with the gearbox! Get a timing light or strobe gun and when we know what type you've got we can direct you how to use it...

D

I thought the noise would be present all the time if its engine?

Dont know about timing petrols, prefer diesel

samc88 said:

I thought the noise would be present all the time if its engine?

Dont know about timing petrols, prefer diesel

Click to expand...

Yes I prefer diesels but the wife fell in love with this series3 so out of my hands lol, I also thought it would be present all the time but the description given of marbles hitting engine is spot on, could it be I'm only hearing it because the engine is under load, i have tried revving engine and no noise present but when in 4th noise comes back, looking through inspection panel on gear box u can see the release bearing wobbling , the nylon bush is still in back of fork but the fork does seem to have a lot of play, is that normal?

The noise you are hearing is the front of the pressure wave caused by the spark igniting the petrol hitting the piston before it's got to the top of its stroke.

The speed at which that wave moves depends on the richness of the fuel which in turn depends on the throttle position. When the engine is under load the carb will richen the mix making it burn faster and so it starts pinking.

The distributor has a set of weights and a vacuum pipe so that it can alter the point at which things go off depending on engine speed (mechanical advance) and engine load (vaccum advance/retard).

The timing position you need to set is an offset to all this - of you've got it wrong (too advanced) then it tends to be the under load / medium revs point where it will start to complain.

Diesel timing is similar but tends to need tinkering less - however getting diesel timing spot on is more important.

Petrol timing unless you're miles out will more or less work. Too far advanced and you get pinking, too far retarded and you loose power especially at higher rpms.

You'll usually hear pinking when in top gear going up hill with your foot down.

phippsey27 said:

Yes I prefer diesels but the wife fell in love with this series3 so out of my hands lol, I also thought it would be present all the time but the description given of marbles hitting engine is spot on, could it be I'm only hearing it because the engine is under load, i have tried revving engine and no noise present but when in 4th noise comes back, looking through inspection panel on gear box u can see the release bearing wobbling , the nylon bush is still in back of fork but the fork does seem to have a lot of play, is that normal?

Click to expand...

Yeah should be ok, the fork isn't held rigid or anything so does have a bit of play in its movement.. As long as the bearing is not noisy should be fine too. Did you say you've taken the box out now? If so, fit a new clutch and bearing whilst it's out and check for oil leaks from the engine. If you have a 5MB then changing the crank oil seal is easy (engine out job for 3MB). Whilst your at it, check the rear mainshaft nut is tight (through inspection plate) and replace your gearbox mounts if shot.

Excellent stuff, gearbox back in tonight and release bearing seems to be a lot better, the timing was done by checking piston no1 was on its up stroke then turned engine by hand to align the timing mark, then adjusted dizzy till points were open. Is this correct what timing mark should have been used as I used 0 degrees, have I gone wrong with timing??

You'll be lucky to get that right by eye if you are too skint to buy a timing gun a bulb wired across the coil is the next best thing.

You can always get it near enough then keep trying it more advanced until the pinking comes back then reward it a little from that point.

It's worth getting right a few degrees too retarded and you'll lose a lot of torque and power and waste a lot of fuel. To advanced with pinking and you risk blowing holes in your pistons...

dominicbeesley said:

You'll be lucky to get that right by eye if you are too skint to buy a timing gun a bulb wired across the coil is the next best thing.

You can always get it near enough then keep trying it more advanced until the pinking comes back then reward it a little from that point.

It's worth getting right a few degrees too retarded and you'll lose a lot of torque and power and waste a lot of fuel. To advanced with pinking and you risk blowing holes in your pistons...

Click to expand...

I have ordered a timing gun and awaiting it's arrival, as totally agree. Cannot believe it was something so simple thanks to everyone for you kind advise and time

Learn something new everyday

mine is jumping out of 3rd sorry series 2a

series 3 sweet 16 said:

mine is jumping out of 3rd sorry series 2a

Click to expand...

? Detent spring

Timing gun here and yes timing out, I must admit that when timed up it seem to be a little slower on pick up, I have timed it up to first timing mark 6° I believe, as this is what haynes manual says 90-92 octane fuel does anyone know if this is correct?
Unable to say knocking problem is sorted as decided to replace footwear and repair bulkhead at the same time, hopefully be back on the road tomorrow

Unplug vac advance and get her idling about 5/600rpm. On modern fuel you want about 6deg as said but if she's idling above 600rpm you will get centrifugal advance andeven tho no vac advance it still makes a difference.
I found a guide to howmany degrees it advances at a specified rpm somewhere and set it at about 10deg at 800rpm and vac on. It sounded and felt right and no pinking. I couldn't get a smooth 600rpm idle!

All these adjustments are best done with the engine _properly_ warmed up, don't just leave it idling that won't warm it up right. It needs a good hard drive for at least ten minutes then do the adjustments. However, in your case where its out by a lot it might be worth setting it once cold, going for a blast then setting again...

Set idle at 600rpm or if its a newer one (with a three way pipe from breather to intake to carb) set the idle at 800rpm - it will run nicer and cause a bit less pollution.

I've found with it set up right and working correct the vac advance should make no difference when the throttle is shut - so long as the vac advance is taken from the correct place on the carb, however I'd still disconnect it first time to see if it is in the right place. Disconnect it from the carb end.

If your gun is one with an advance knob on the back use that to set the advance that you want then adjust the carb until the mark lines up with the biggest tooth on the timing marks.

I've got mine at about 10 degrees at 800rpm though I tend to put in 98 or 97ron petrol for 95 8 degrees is probably safer for now. Try it at 6-8 and make sure the pinking goes away and then try progressively advancing it (drive it for a few days each time to get the feel) until you get pinking again then back it off.

It's worth the effort to get the extra torque and power and better fuel consumption!

If you haven't set it up yet you can find out where you had it set by using the knob on the back too - just turn it until the big tooth lines up and that is how far advanced you'd set it.

As a final check I'd make sure the vac advance works too - if it doesnt' you'll get driveability problems at low throttle openings (i.e. when cruising - you'll find it hard to hold it at a nice steady speed). The way to test it is to have the vac pipe connected to the dissy and watch the timing while you suck on it, sucking hard should advance the timing by about 10 degrees if I remember right. Make sure its connected to the dissy not the carb - I saw someone do that and he was stoned off his bonce for about 10 minutes by getting a lungful of fuel / air mixture!

D

Well a massive thank you to everyone for all your help and advise, just to let you all know gearbox is back in, and after timing she runs like an absolute dream, funny that it was a timing problem.
I think next time I might ask for advise before I take such drastic actions lol

Many thanks to all who pointed me in the right direction perry