Scrooge Take that pipe of the manifold Suck on it to create a vacuum in the pipe then stick your tongue over the end You should feel it suck onto your tongue and hold it If it doesn’t and you sucking on it just keeps pulling air through Then you have a vacuum leak which will cause your engine to run lean.
Try blocking the pipe to the inlet manifold, the larger diameter bore may be drawing extra air, also it doesn’t look to have sealant on the fitting, check if it has or not.
So I need to suck on the pipe that is going to the top of the oil bath? Are you promising me I won’t get a mouthful of dirty oil?? I’m at work all day, so will give it a go when I get home this evening. I’m going to give everything a good clean so I can see any ‘new’ developments. I’ll also give everything a good check over nut and bolt-wise in case there’s anything loose.
Sealant was definitely mentioned, but I will check. The bore should be the correct size for the oil bath style as it was re-drilled to fit the proper adaptor. Alex is an long established one-man-band only does VWs type outfit, rather like yourself, so I do trust him. He’s just left for 2weeks in California sadly (for me, luckily for him!) so I’ll have to wait til the start of November to ask any questions. Til then I’ll see what I can do myself with the help of you lovely folk on TLB. I’ve got a timing gun, so I should be able to check that myself too. And I’ll spray around a bit of carb cleaner and listen for air leaks around the base of the carb. Thanks everyone x
how about taking the spark plugs out to see what colour they are........... I would take a bet on them being dirty or oily.
because the pipe that's connected to the manifold from the air bath should be connected to the carb..... I think you may find the manifold is sucking all the time drawing oil possibly, causing rough running aswell. don't shoot me but I really think it should be blocked off at the manifold and the pipe re-routed to the carb. it may also need re timing. I know loads of mechanics and even some I would trust to work on my van.....
So now I’m confused. There’s definitely 2 different inlet manifolds as there are 2 different parts numbers: one which I had on the engine from when I bought it, connected to the oil bath with a narrow diameter pipe fitting. The second has a wider diameter pipe connection and is designed for a servo I believe. This is the one that I mistakenly bought from Dunc, and the hole to the manifold had been welded up. @davidoft any thoughts please, you must’ve seen a good few engines like mine with an old style oil bath? I will check the timing, and I will check for air leaks.
Sarah There should be one vacuum feed from the manifold to the vacuum capsule under the air intake flap via a thermoswitch on top of the air cleaner. This as @paradox says is a vacuum feed to the flap actuator. You can NOT suck up oil through this its meant to be sealed. There should another hose from the tank breather t piece above the engine into the oil bath. That one goes into an air space im the cleaner well above the oil just beside the main air inlet. That one sucks fumes from the fuel tank into the air cleaner. Again it cant suck much oil as it is above the oil. If these two are swapped then you get an air leak and permanent cold air feed to the engine as the flap wont work and air will go into the manifold up the vacuum pipe instead of being blocked off at the actuator. As the hot air vacuum pipe is meant to be blocked off by a diaphragm in the actuator .. if no leaks... it really does not matter what diameter it is. Simply drilling out the spigot and stepping down the hose diameter would have done. Look for problems with tightening down the inlet manifold ends onto the heads its easy to overtighten one side and leave a gap through which air hisses at idle. On my setup I used carb cleaner then JB weld to seal a bad joint when I managed to make one of the horizontal bits fall out of my EMPI manifold. Poke around with your ear to the end of a couple of feet of hose and listen for harsh hissing using it like a stethoscope Almost certainly no need to swap out the manifold just get it put in right probably tightening things and checking rubber boots are on properly not pinched or half on round the back ...
There were several variants of the manifolds. As long as they're in good shape and are the ones for a twinport engine, they'll be fine. Some have no pipes on them. Some have the big pipe for the servo (which may not be drilled through). Some have a smaller additional pipe for operating the warm air flap (connection later moved to the back of the carb). Any one will do, as long as you bung up any connections you don't need.
Cheers Mike. This is what I’ve got..... (Took flippin’ ages to do the fancy coloured arrows on the tiny screen of my phone )
Okay, the misty clouds of confusion are beginning to clear; thank you. As long as what I’ve now got is correct, I’m halfway there!
Looks correct For info, the one going from the side of your carb to the dissy is ported vacuum, used to advance the ignition when the engine's sucking hard. The one from the manifold runs up to the temperature vac "switch" on top of the bath, then down to a vacuum actuator (like a flying saucer) on the air filter inlet. This lets in hot air from over the exhaust when the engine's cold, and switches to cooler air from the air filter "snout" when the engine's warmed up. HTH.
Looks Ok here too. Check for hissing. It will be audible above the clatter in the eengine bay. Then check the timing as the distributor may have been removed to fit the manifold with the engine in the bus. Also check your engine against a reference hill - like I know that heading south from Salisbury on the A36 onto the dual carriageway bit just after the corner following park and ride.. it will accelerate gently from 40 to 70 about 2/3 of the way up the hill then drop back to 55-60 at the start of the single carriageway bit. Maybe there is no difference , or it is slight on these warm days we are having. Working heat risers will show up below 10 degrees and make a lot of difference the colder it gets.
So I got home from work and headed to the garage, emerging with spanners, sockets, screwdrivers, degreaser, and a can of carb cleaner. Get me and my well appointed workshop . Cleaned any extraneous oily stuff from anywhere and everywhere, checked all the nuts, bolts and screws I could see (all good), fired Clem up and had a good old spray around joints and hoses to listen for a change in the engine tone. Nothing, nowt, nadda. Disconnected the pipe from the inlet manifold to the air cleaner, as I think this was the one @paradox was referring to when he said give it a good suck to check if there's a vacuum or a leak. There's certainly no vacuum, and it didn't taste very nice! Got the engine nice and warm with lots of revving (having loosened off the accelerator cable a smidge as it wasn't returning properly and the engine was always revving. I have no idea if this was the right thing to do, but at least it returns properly now ) and returned to forage in the garage for my timing gun. This is the bit I don't always feel confident with, as I fear cocking it up and destroying valves etc, but hey ho. Set the gun to 30 and revved the nuts off the engine. A bit of adjustment was required as it was way too advanced. By this time, the narrow driveway between me and the neighbours was filling up nicely with exhaust fumes so I have retired to the relatively fume-free safety of my house for some well earned supper. I shall take Clem to work tomorrow and hopefully all will be miraculously wonderful again. Fingers crossed my friends.
If you removed that pipe from the manifold and couldn’t get it to hold a vacuum by sucking on it Then you have a problem at the air filter housing Either it’s not connected in the correct place or the actuator it’s connected to is leaking This is causing your engine to run lean
^this, possibly. Shut the engine off and suck on the pipe going to the air filter. If you can suck (nice oily) air, you've got an air leak.
