Carb questions - Vac pipes & choke pull-down

[eddbmxdude]

Hi everyone,

Bought our van a long time ago and used to have a thread on here tracking our progress on it. It's been so long our thread got archived. It's here: http://archive.club8090.co.uk/viewtopic ... eddbmxdude" onclick="window.open(this.href);return false;

We've never been in a rush to get it done. Over the last few years we worked on it when we had the time and/or money and finally got it finished early this year. We've fitted a ton of new parts including radiator, clutch master & slave cylinders, all new brake pipes, brake caliper, clutch hoses, remote t-piece for oil pressure switch and pressure gauge. I've got a blog if you're interested in reading about all the work we've done since last posting on here. https://eddbmxdude.wordpress.com/?s=vw+camper" onclick="window.open(this.href);return false;

Anyway, I've been driving it around a little since it passed it's MOT with no real problems until this week. I got in it to go into town and it started fine. However, when I let the clutch up it died. I started it up again, thinking I'd just not given it enough revs and it died as soon as I let the clutch up again. It had absolutely no power. It would start to pull away if I revved the nuts off it and slipped the clutch but it would die again as soon as it had any real load on it. After that it wouldn't even idle properly and when I attempted to rev it, it would die.

Today I took the carb off, suspecting it was blocked with crap. I cleaned it all up externally and gave it a good going over with a can of carb cleaner. I also took out the tiny filter inside the fuel inlet pipe on the carb and cleaned all the rust and crap out of there too. I've fitted it back onto the van and now when I try to start it fuel literally pisses all over the place. Managed to run round to the engine bay before it stalled to see where the fuel is coming from. It's pouring out of the little gauze dome on the top left of the carb if you're standing at the back of the van. Looked in the Haynes and at the exploded diagram on the wiki but neither identifies it. I've checked and double checked I've connected all the hoses in the correct places and I'm confident they are correct.

This was before I took it off.


On inspection there's a few things I'm not sure about. The idle speed control screw isn't touching anything. Is this going to cause any problems? I'm assuming this means it should idle really slowly (as slowly as it can)?


Also, when I suck on the vacuum hose that goes to the secondary throttle diaphram, only the plastic sleeve that goes into the diaphram housing moves, not the rod connected to the linkage. Should it move that mechanism?


Nothing visible happens when I suck on the vacuum pipe to the choke pull-down unit. Should it? I can't suck air through it though. I also don't appear to have the restrictor in the choke pull-down vacuum pipe.

I've got tons of oil in the intake pipes and loads dribbled out the bottom of the carb when I removed it from the inlet manifold. What could be the cause of this and is it going to cause any problems? You can also see that one of the vacuum pipes coming from the air filter housing has been removed and blanked off. Where can I get new vacuum hoses? They seem a bit knackered and I'd prefer to replace them all. The braided bits on the ends are extremely suspect.




Lastly, my breather pipe between the oil breather tower and air box seems to have collapsed in on itself and is full of oil. Is this the possible cause of the oil everywhere? Don't want to have to shell out £30+ for a piece of pipe but if it solves the problem I'm willing to do it.



Sorry for the barrage of questions. I have been searching and reading the wiki but I couldn't find all the information I was after.

Cheers,
Edd

[ghost123uk]

Hi Edd.

Blimey, yes a lot of questions.

Some random replies =

That breather pipe needs sorting. You can get posh ones from Brickwerks but also, in the likes of B&Q they sell some black ribbed plastic pipe, dead cheap (in the plumbing section) and with the aid of a couple of bits chopped off the end of your old pipe it works fine. (The wire in the ribbing stops it collapsing like yours has).

Both vac units should operate with a strong suck.

That blanked off braided vac pipe is fine. It was originally meant to operate the warmed air to filter flap, but in this country these engines don't need that system. Not cold enough to get the carb icing it is used to prevent.

Petrol leaking from the top of the carb is caused by the float valve not closing properly or the float itself is punctured or stuck.

Re oil in the inlet tract and carb. After you have sorted other issues out, fit a new air filter and after a decent drive have a look at the filter. If it has got any appreciable amount of oil on it you may have piston / ring / liner wear.

[ghost123uk]

Oh, and the idle speed stop screw, Kev will be along soon to talk about that mess of cams, levers and stuff

[eddbmxdude]

That's a load of my questions answered, thanks!
I've got a rebuild kit on the way, so I'll pull the carb apart when that arrives. I shall have a look at hose and get that breather sorted too. Cheers!

[MidLifeCrisis]

Also, when I suck on the vacuum hose that goes to the secondary throttle diaphram, only the plastic sleeve that goes into the diaphram housing moves, not the rod connected to the linkage. Should it move that mechanism?

The secondary throttle linkage rod will only move if the 'primary' throttle is pretty much fully open - so try opening the primary throttle then suck on the vac hose and you should see the connecting rod move.

[eddbmxdude]

Thanks for all the help guys



No going back now

I've taken out the jets and blown them through with carb cleaner, replaced the accelerator pump components, part load enrichment valve, float needle valve and given the insides a thorough cleaning. There are a load of O-rings and gaskets in the kit that I can't work out though. I haven't seen a single O-ring on disassembly, only the one on the part load enrichment valve, and that one was pre-installed on the collar in the new kit. I haven't taken the choke pull-down unit or secondary throttle diaphragm off though; are there O-rings on those?

I took the choke mechanism off and had a look at the components. The element looks intact, although I didn't test it.

Also tried sucking on the vacuum pipe to the secondary throttle diaphragm while holding the primary throttle open and the secondary throttle opened, so I'm assuming that means that it's working correctly?

Is there anything else I should do while I've got it this far apart? I haven't seen any obvious reason for it not working properly so far.

[CJH]

I've fitted service kits to a couple of these carbs now, and I've always had a load of O-rings left over too. Glad I'm not the only one!

I'm guessing that the general clean-up will have fixed your original problem - I once had a sudden onset problem where I had to rev the engine hard to get any power at low speeds, but on the open road with a wide open throttle it was fine. It turned out to be a blocked jet - or at least I assume that was the problem since a blow through all the jets with WD40 fixed it.

[itchyfeet]

Lastly, my breather pipe between the oil breather tower and air box seems to have collapsed in on itself and is full of oil. Is this the possible cause of the oil everywhere? Don't want to have to shell out £30+ for a piece of pipe but if it solves the problem I'm willing to do it.

Check theair filter, if it's blocked with oil it won't run well and may be the reason for collapsed pipe, coupled with a float valve that doesn't seal may have just been over rich.

too much oil in sump is often the reason for oil in filter.

[eddbmxdude]

I've fitted service kits to a couple of these carbs now, and I've always had a load of O-rings left over too. Glad I'm not the only one!

That makes me feel much better. I'll put it back together and throw it back on the van then!

Check theair filter, if it's blocked with oil it won't run well and may be the reason for collapsed pipe, coupled with a float valve that doesn't seal may have just been over rich.

too much oil in sump is often the reason for oil in filter.

We've had the van 8 years and have driven it 200 miles (stop laughing!). The filter that was on it when we bought the van was full of oil but we replaced it long before we got the engine running. We've changed the oil since too, but I'll check the level. Thanks!

[itchyfeet]

We've had the van 8 years and have driven it 200 miles (stop laughing!). 

1 mile every 2 weeks, Cheaper to tow it

[eddbmxdude]

Well, I rebuilt the carb and put it back on the van. It took a while to fire up as you would expect after a carb rebuild. It wouldn't start without a bit of throttle though and it would die if I took my foot off the pedal.

Then I remembered to plug the vac hoses in and it fired up first try with no throttle at all and ran lovely

Thanks for all the help and advice guys. Just got to sort hat breather pipe and replace the vac hoses now. Oh, I checked the oil level too and it's bang in the middle between the high and low marks on the dipstick.