Aquiesce · Jun 21, 2012

I have been messing with this disco for a week now just getting things fixed as i find them as it was a non runner, I now found out that the vacuum advance wasnt working so i swapped it out for one that seemed to be functioning when I sucked on it, the arm moves in and out, the old one when i sucked on the pipe I was just sucking air so i presumed its knackered. Anyway it seems that I dont actually have any vacuum from the engine?
Im wondering is this a blocked breather somewhere maybe or is it a problem at the plenum chamber?

I happened ti have noticed a brand new plenum chamber for sale on eBay last week with all the internal butterflys etc, brand new im guessing these would cost a fortune so I bid on it and won it for £1.20 and £18 delivery so if that helps then it should be here anytime soon.
Im wanting to set the timing exactly but it needs to be done with vac off so could do with sorting it, any ideas?
Cheers

Diesel Do · Jun 21, 2012

Trace the vac pipe back to the manifold and check it for splits or blockages first. The only reason I can think changing the manifold would fix it is cos somethings blocked! Much easier to unblock it

you could also try a vacuum gauge to see what it's doing at idle,

discool · Jun 21, 2012

It's not a big deal in tracing the vacuum pipe.

Aquiesce · Jun 21, 2012

Haha I know where the vacuum pipe is, but like I say there is no vacuum from the plenum chamber itself, nor the pipe obviously.

Diesel Do.......when you say trace it back to the manifold did you mean to the plenum or do you mean something else?
Cheers

discool · Jun 21, 2012

Aquiesce said:
Haha I know where the vacuum pipe is, but like I say there is no vacuum from the plenum chamber itself, nor the pipe obviously.

Diesel Do.......when you say trace it back to the manifold did you mean to the plenum or do you mean something else?
Cheers

I hope u do

it was in responce to the trace it back bit, there's nothing to trace, u can see it at a glance, also u have nothing going to your manifold.
I would say that maybe you have a leak either the plenum seal it's self or from the six or so items that are screwed into it.

I believe the trick is spray WD40 over the suspected areas and if the idle speed increases that's the spot, i've never had to try it but that method has been posted befor.

Aquiesce · Jun 21, 2012

discool said:
I hope u do it was in responce to the trace it back bit, there's nothing to trace, u can see it at a glance, also u have nothing going to your manifold.
I would say that maybe you have a leak either the plenum seal it's self or from the six or so items that are screwed into it.

I believe the trick is spray WD40 over the suspected areas and if the idle speed increases that's the spot, i've never had to try it but that method has been posted befor.

OK thanks I will check everything, already tried the easy start trick, dont think WD40 works does it as its not very combustable, I usually use Brake cleaner or easy start.
Cheers

discool · Jun 21, 2012

Aquiesce said:
OK thanks I will check everything, already tried the easy start trick, dont think WD40 works does it as its not very combustable, I usually use Brake cleaner or easy start.
Cheers

Ok it may the other stuff, as I've never had any problems this type of info goes straight over the top of me.

Diesel Do · Jun 21, 2012

It would need to be a huge air leak to have no vacuum at all? Disconnect the pipe at the manifold and poke something thru the drilling to make sure it's not blocked, plus blow thru the pipe. Wd40 is fine for finding leaks, spray around pipes, gaskets etc if the revs rise you have an air leak! Vacuum at idle should be quite high cos the engine is sucking against a closed butterfly. It drops as you open the throttle. It's possible the vac pipes been fitted to the wrong union. Make sure it's connected after the butterfly!

Diesel Do · Jun 21, 2012

Do not use easy start on a petrol! You can blow bits of it to pieces, it's way to volatile, I've seen air boxes blown to bits

HenryD · Jun 21, 2012

Diesel Do said:
Do not use easy start on a petrol! You can blow bits of it to pieces, it's way to volatile, I've seen air boxes blown to bits

+ 1 stick with the WD40

Aquiesce · Jun 23, 2012

Yeah I know about the explosions easy start can give, lpg's tend not to run air boxes as a backfire can blow them to bits too! I've seen it happen!

As for my problem where on the manifold am I checking for blockages? I've already had the crankcase breather and associated pipes off and cleaned out. No difference though and they weren't blocked.

Aquiesce · Jun 30, 2012

Anybody got any more ideas? Does the cruise control also work via vacuum? As just so you know tha doesn't operate either. Im about to remove the whole plenum chamber now as I have a brand new one that I won on eBay for £1.20!!

jamesmartin · Jun 30, 2012

cruise control does work off vacuum system ,if engine hasnt run a while tappets may not be opening valves fully but there should be some vacuum ,is butterfly shut ,plenum been off ,connector blocked etc

discool · Jun 30, 2012

"Does the cruise control also work via vacuum" yes it does but it has it's own vac pump.

Aquiesce · Jul 2, 2012

well I have now fitted the new plenum and had everything off and cleaned it all up, its now lovely and shiny in there, and there is definately a better response from the engine and the idle is a lot smoother, however I didnt find and split or leaking hoses and I still have no vacuum which is annoying!

One other thing which has bothered me a little is that when I put the TPS back on the plenum, if I tighten the 2 screws properly it affects the butterfly closing fully its kind of notch when you pull the throttle cable, if I loosen the screws off to hand tight then its OK. I have 2 TPS's and have tried both with the same results. I thought maybe I have assembled the linkages incorrectly but I dont think I have as its the only way they will go together really. Any ideas on this anyone??? BTW it still runs fine. I just wish I could get some vacuum to check if the vacuum advance unit is operating correctly and to time it correctly with vac disconnected.

Aquiesce · Jul 5, 2012

Do the brake servos work via the same vacuum? Still not got any vacuum at vac hose(as in when its pulled off there is no change in engine note/revs) Im gonna also pull the dizzy apart this weekend and check all the bobweights and springs etc.

discool · Jul 5, 2012

Your brake servo does work from the engine vacuum via a pipe on the left of the plenum chamber the rear one of the two..

Aquiesce · Jul 6, 2012

OK thanks mate, so I am getting vacuum then as the brakes are working fine, just that there is no difference when I pull off the vacuum hose so its got to be a leak somewhere then right??

discool · Jul 6, 2012

Aquiesce said:
OK thanks mate, so I am getting vacuum then as the brakes are working fine, just that there is no difference when I pull off the vacuum hose so its got to be a leak somewhere then right??

I must pull off my dizzy vac hose and see what is what when the engine is running, that will be a first.

Aquiesce · Jul 6, 2012

yeah, engine timing should retard shouldnt it?

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