Would a vacuum leak cause staring problems?

This site contains affiliate links for which LandyZone may be compensated if you make a purchase.
J

Jof

Member
Posts
32
Location
Somerset
Hey All

Fairly new to Landies so be nice!

Since getting my 1973 S3 petrol, I've put on new plugs, leads rotor and cap, changed the points for a 'SimonBBC' electronic set-up along with a new standard coil from same, cleaned up the earths from the negative battery pole and the starter to chassis point, put in a new battery,
and topped up all the fluids.

Unfortunately I did all of this in one hit, and now have an annoying intermittent starting problem!

Typical!

Basically when it happens the symptoms are the same as a dodgy earth - starter turns as if the battery is really low, two or three laboured turns and 'DONK'. Every time it happens I remove the battery, charge it, put it back, check all connections, fiddle with a few bits, and get the same.

Usually after an hour or so of cocking around with the basic stuff it turns over and fires really well and runs perfectly. Starts first time for a day or so as long as it's started regularly. If left for more than a day or two though - same thing - RH RH RH DONK.

Today I got a little ****y with it and took everything to bits again,. put it all togaether and got the same. Then I notices the rigid small bore vacuum pipe from the Webber carb to the diaphragm(sp?) had about 2 inches of flex rubber pipe between the end of the metall pipe wich met the diaphram(sp?). I pulled this off to take a look and it appears this metal pipe hat broken at some point, and a previous keeper had 'mended' it by joining the two ends with rubber pipe.

I 'sealed' both ends with insulation tape and bugger me, it started.

Does this sound like the cause? Or have I lucked out again in the lottery of 'fiddling with stuff 'till it works'?

Grateful for any comments - apologies for the essay!

Jof
 
Last edited:
Does sound like an electrical fault in the starter circuit. Might be worth bypassing the starter solenoid with an old screwdriver to eliminate it from your enquiries but it could be a poor earth (check the strap from the starter motor to the chassis) or worn bushes in the starter motor itself. Are the connectors swaged or soldered to the cables 'cos swaged ones can go intermittent.
Or it could be the battery - what voltage does it show when charged?
 
Sorry - my ignorance is about to shine through here.

Do you mean bridge the solenoid contacts with the screwdriver therefore elimonating it from the circuit?

Have already cleaned up the starter to chassis earth - hopefully eliminating it from the list.

I gurss the main reason I suspected the vac pipe is that I've dome a lot of diddling inh the distributor area and thought I may have loosened something.

I'll try the solenoid thing and report back - though as it's recently started, I'll give it a day or two to rear its head again. Ta for the reply - most helpful.

Just to confirm though, would the vac pipe issue cause this type of behaviour?
 
It could be a sticky solenoid so shorting out the contacts should eliminate it as a problem. Check the solenoid low current circuit as well - a poor earth here would cause these symptoms.
 
If bridging the soleniod doesn't work, From the earth braiding on the engine, take a lead from that to the -ive pole of the battery. Might have a high resistant between the earth braiding on the chassis and the -ive pole of battery.
Just an idea
 
Jof said:
Just to confirm though, would the vac pipe issue cause this type of behaviour?
Click to expand...
not usually.

but in referance to your "- RH RH RH DONK."
when it does its "donk", is it stopping turning over pretty suddenly?

reason i ask, is cos if ignition timing is too far advanced, it sometimes causes this to happen.
however, if turned off and tried again, usually you get the rh rh rh donk again.
with the vac pipe disconnected, the carb wont be pulling a suction at the dizzy, so wont be advancing in this way.

personally, i would be checking the battery voltage while cranking to eliminate a duff battery from the equation. if/when its proven good, would be lookin for bad connections, inc starter brushes, then ignition timing.

how have you set the timing?
 
As I haven't touched the timing since fitting the electronic kit, would it be worth retarding the dizzy by a few degrees to see if that helps?
 
with out reading all the posts on this, yes the vacume pipe does affect starting. the small bore pipe controls the air flow for advance and retard,and a lot of problems occure when working on the distributor. and the main 1 which always seems to get by unoticed is the spring in side the disistributor,which do break have you checked the spring, which is fastened to the plate underneath the points.
 
the springs for the centrifungal advance and wont really matter unless its missing or snapped.
how does the electronic pickup receive its signal?
best thing you could do is buy a strobe light, retard the dizzy so it will start, then adjust the dizzy so the timing mark on the crank pulley matches the pointer.
this can also tell if the centrifugal advance works, and the vacuum advance.

edit
is it the lucas dizzy or ducellier?
 
so it should have the vernier adjustment screw on the vacuum advance.
(should have A-R on casting, advance and retard)
need to know how your electronic timing replaces the points?
 
There's a magnetic ring that goes over the cam, and a module that sits under the dizzy cap which I presume measures the speed of the ring passing by it. Got it from 'SimonBBC' after reading a lot of positive reviews
 
so would I be right in thinking I can retard the timing using the wheel rather than loosening the dizzy and twisting?
 
Sooo - cheeky request time then...

Anyone near Taunton in Somerset fancy a few beers in exchange for an hour under my bonnet with their timing strobe?
 
You must log in or register to reply here.

Similar threads

Hexonxonx
Series 2 RH rear flasher not flashing
Replies
9
Views
873
Hexonxonx
Hexonxonx
Aflyingduckling
Series 3 Fuel Pipe Issue (part 564902)
Replies
1
Views
625
steve2286w
steve2286w
E
Disco 2 Fuel Leak
Replies
1
Views
220
Landmark2
Landmark2
O
Series 2 won’t start! Please help xx
2 3
Replies
47
Views
3K
Shedload
S
G
Diesel fuel pipes ?
Replies
16
Views
861
grewth
G
Back
Top