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Merian
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PostPosted: Mon Oct 12, 2015 3:23 pm    Post subject: Vacuum Leaks Reply with quote

Oddly, there is no topic in Vanagon Essentials ~ The FAQ Guide that tells DIYers where to check for vacuum leaks in the engine.

Can we start one?

Here is my minor contribution:

Vacuum Hoses on 2.1L Vanagon

Vacuum hose that runs from ?? on the engine to the brake power booster runs under the Van

One hose to vapor emissions charcoal canister from top of air filter housing was deleted by VW and it is normal to see a plugged fitting there.
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Merian
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PostPosted: Mon Oct 12, 2015 3:38 pm    Post subject: Reply with quote

check valve is under the FPR - does not need to be checked at that point tho

http://www.thesamba.com/vw/forum/viewtopic.php?t=552515
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Merian
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PostPosted: Mon Oct 12, 2015 3:40 pm    Post subject: Reply with quote

from another thread:

deprivation wrote:
I feel your pain. And the Bentley doesn't have a paragraph entitled "VACUUM LINES" Worse, if you have running issues people say "check all your vacuum connections" Great. Which ones? Where are they?

I can't speak directly to your question because I have a 2.1L '86 and I don't know how different that is from your ride. But I can tell you that it won't take but a foot or two - if you cut and measure carefully a foot will probably cover you but get more incase you screw up like I did.

On the 2.1, I found the following REPLACEABLE (non-plastic) vacuum lines:
1: between the intake plenum and fuel pressure regulator
2: between the throttle body and the line going to the evap valve
3: between the evap valve and the hard line (purple)
4: Plenum to brake booster check valve (this is not the 3.5mm - it's much bigger)

The only problem I had in replacing my 3.5 vacuum line was the connection between the plenum and the fuel press reg. The connectors are of different diameters. So I had to get a bit of slightly bigger hose for the pressure regulator and the usual 3.5 for the plenum. I bridged the the two different sizes of hose with a one-inch segment of aluminum tubing and silicone ATV. I don't know if you'll have the same problem or not.

Other vacuum-related connections to look at are the four intake sleeve between the plenum and the intake manifolds. I was doing a major engine clean-up and I soaked my rubber sleeves in Armor-All for a few days.

There is a possible source of leaks between the idle air control valve and the valve itself. There is a vacuum tube between the oil breather tower and the intake boot.

And there is the big intake boot itself. It has two big connections at the throttle body and the air box. I've read that the boots on the 1.9L engines are getting old and crappy. Some can be repaired with ATV and silicone tape. They are not making new ones so repair is the only option for most.

The injector seals can leak, too. Just to be safe I installed new seals and I coated the outside of the seals with a smear of hi-temp ATV just to be sure that I had a good seal.

The brake vacuum line is a mystery to me in terms of what can be replaced. Like I said, there is a replaceable bit of hose in the engine compartment and I honestly canít say for sure if there is any other rubber along the way to the front of the van. I traced the line (youíll have to remove the spare tire to do this) on up to the front floor and the peeked down into the dashboard and didnít see any other rubber connections.

Does any of this help? Iím VERY new to Vanagons, but I am happy to share what little I know.
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mrcool
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PostPosted: Fri Mar 04, 2016 3:14 pm    Post subject: Re: Vacuum Leaks Reply with quote

If you get a good fit to the nipple where vacuum hose goes, does it matter if it is 3.5mm vs 5mm? Or do you just need to make sure its air tight?



Why this question came up:
I am running a 2.0L Aircooled CV engine.

According to Parts base, the vaccum hose I need is 3.5mm... But the air intake nipple it goes on is bigger! I haven't measured it yet but 5mm hose fits ok.

Part #18 in this diagram.
http://www.partsbase.org/vw/vanagon-va-us-1983-27-overrun-air-system/
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djkeev
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PostPosted: Fri Mar 04, 2016 11:22 pm    Post subject: Re: Vacuum Leaks Reply with quote

Vacuum leaks are far more heineous than old rotten Rubber hoses.

The intake plenum rusts badly (in the NE at least)

The intake plenum's rubber hoses to each cylinders intake pipe

The intake pipe to cylinder head gasket

Fuel injector seals

Fuel Pressure regulator diaphram rupture (introduces unmetered fuel to intake)

Charcoal cannister control valve

Brake booster rupture

Brake booster hose

Brake booster check valve

Crankcase ventilation system... Oil tower, hose to intake boot, inline heater

Some vacuum lines have restricted metering orfices that are often thrown away with the factory vacuum hose.

Throttle Body wear or rotten shaft seals

Throttle body to air filter boot dry, cracked or poorly installed.

Dave
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Zeitgeist 13
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PostPosted: Sat Mar 05, 2016 10:27 am    Post subject: Re: Vacuum Leaks Reply with quote

A list of point sources is fine for visual inspections, but these types of leaks often occur as tiny openings in junctions etc. Far more preferable would be to smoke them out or (safety nannies avert yer eyes) strategic blasts with starter/brake cleaner fluid. That way you can narrow it down to specific areas on the list
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Mellow Yellow 74
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PostPosted: Tue Mar 08, 2016 1:19 am    Post subject: Re: Vacuum Leaks Reply with quote

I would say the 3mm fabric covered hoses that join the plastic vacuum lines in the engine bay are a likely source of vacuum leaks. I replaced these with new original style hose a while ago and the hoses all cracked at the ends and became loose or came off altogether in a fairly short period. I have now replaced these with silicone hoses which will hopefully last better.
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mrcool
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PostPosted: Tue Mar 08, 2016 10:16 am    Post subject: Re: Vacuum Leaks Reply with quote

I'm with you on that one Mellow.

My aircooled van was stalling all the time on startup. It isn't perfect yet but as I replace more and more of those 3.5mm vacuum hoses it gets better. I have a vacuum kit from german supply but the kit is so vague I don't know if it will have the hoses I really need like the aux air reg hoses. I also have some worn out rubber hoses on the way and the 4 air intake hoses.

Pretty much anything that is rubber is shot.
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xflyer
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PostPosted: Mon Jun 11, 2018 1:37 pm    Post subject: Re: Vacuum Leaks Reply with quote

The hose connecting the fuel pressure regulator to the intake plenum is a different size than all the other 'small' hoses in the engine area. It was 4.5mm IIRC and had red fabric on the outside to make it visually distinct from all the black hoses. Probably all the OEM hoses are gone by now.
I don't know if you can get that hose anymore. I think there is a American (inch) dimension hose that is the right size to fit, seal and not fall off or crack and split right away. See your FLAPS.
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