Itinerant Air-Cooled

Hey there folks. I have a 1978 2.0 FI bus. It smells like it is running pretty rich, doesn't idle great, sometimes dies, seems like there is a vacuum leak (as it idles inconsistently). What is the best way to test for a vacuum leak? I read people used Gumout to determine a leak, but also read 'bus on fire', so I don't want to just go in blazin' or go out out blazin'! I am due for a valve adjustment, my driver side push rods and my valves on same side are leaking. UGG. I could go on probably. I did replace my rear shocks and replace the copper ring in the passenger side exhaust manifold (that sucked), but successful, so I got that going for me. I realize this is all over the map, but I am a little overwhelmed and figured I would reach out to the IAC family! Thanks in advance. Kris

You can use gumout or WD-40. I think some people use an unlit propane torch. Have a fire extinguisher ready.

Have you replaced your Temp II sensor? I believe you can test it per the Bentley or replace it for about $20.

Colin's Rich/Lean test:

Here is a quicky check anytime.
At a stop, lightly pump the brake pedal quicklyquickly.
If idle drops dramatically - too lean
If idle goes up ridiculously - too rich
If idle drops mildly and recovers when you stop pumping the brake pedal lightly and quicklyquickly - just right

Vacuum hoses: I've gotten to the point that I look first for vacuum leaks first, no matter what the problem is; rust around the windshield-first check for vacuum leak! I like to pull and remove and check every single hose and connection. I no longer check just looking at them-I want to make certain they are seated tightly. Vacuum has accounted for the vast majority of any problems I experienced with my '78.

Adjust your valves first if they are due like you said. Valve adjustment affects the FI. I've had erratic idle when my valves get too loose. Also be sure your are getting good, hot spark. Basically, be sure the bus is in good tune before futzing with your mixture settings.

Thanks everyone for the feedback! So, the idle drops dramatically after pumping the brakes on a warm engine- too lean! I am planning on checkin all my vacuum hoses in the next few days and might try to adjust valves this weekend ( a little nervous bout that one as I have never done it by myself, but I can read and have all the tools to do so, I also have new valve gaskets). Is there any IAC members in Boise that may be willing to trade knowledge for carpentry projects, $, or beer? Thanks again. Kris

Good for you! Have faith in your abilities. just work carefully, without distractions, and take notes if you need to. I look at the valve adjustment as a Zen-like exercise. No clutter in the mind, clean tools at hand, clear picture as to what cylinder, what valve I am on...it is a pure experience. I love doing it.


The picture? I just like the guy. Wish I could have met him.

Jivermo wrote:Colin's Rich/Lean test:

Here is a quicky check anytime.
At a stop, lightly pump the brake pedal quicklyquickly.
If idle drops dramatically - too lean
If idle goes up ridiculously - too rich
If idle drops mildly and recovers when you stop pumping the brake pedal lightly and quicklyquickly - just right

Vacuum hoses: I've gotten to the point that I look first for vacuum leaks first, no matter what the problem is; rust around the windshield-first check for vacuum leak! I like to pull and remove and check every single hose and connection. I no longer check just looking at them-I want to make certain they are seated tightly. Vacuum has accounted for the vast majority of any problems I experienced with my '78.

Thanks jivermo! Is the best way to check for vacuum leaks to pull off hoses one at a time and look carefully, hold up to light, etc? As far as connections, do you hose clamp all vacuum hoses? Some if mine have them some don't? Carb cleaner, wd-40 method- when sprayed on hose, does it bubble if it is leaky, kinda like a punctured bike tire tube? This method makes me a little nervous due to the kaboom effect!

http://www.ratwell.com/technical/VacuumHoses.html

Well, I'm pretty much a novice at this bus game, but I've been paying attention a bit, especially under the watchful eye of the Sensei when he is about. We're not looking for bubbles; we are listening, as we spray, to the engine RPM's. If there is a vacuum leak, the spray gets sucked in and give a momentary boost in the combustion chambers, causing the engine to speed up. When it does, you're in the general vicinity of the leak. The leak is sucking, not blowing, although in some quarters it's a moot point. I like to run through the hoses and the "S" boot, pulling them off and really going over them if I suspect a leak. I learned not to just trust my eyes when I had a leak on the intake elbow hose (see "F" in Ratwell's pic) where it attached to the aux. air regulator. I had been on some rough roads, and it came off of the regulator, but would sort of catch itself back on, and then off, and then on again. Looking at it, everything looked good. Only when I finally reached down and pulled on it did I discover that it was not seated at all! There had been no clamp on it. Now I clamp all of 'em. I blow through the hoses or run compressed air through them to check for holes. I've reinforced the ends of the larger hoses with Gorilla Tape. Good luck!

Thanks my man, Friday is the day! Valve adjustment and hose checkin' day. One possibly silly question - spray one hose at a time from fitting to fitting? Is there anything to worry about as far as spraying, like my eyebrows getting burnt off or worse? Thanks for all yer insight. Kris

yondermtn wrote:You can use gumout or WD-40. I think some people use an unlit propane torch. Have a fire extinguisher ready.

Have you replaced your Temp II sensor? I believe you can test it per the Bentley or replace it for about $20.

The temp ll is checked and Aok, need a for extinguisher tho! Good tip, thanks yonder.

One hose at a time, with small bursts of carb cleaner. You're not at a BBQ, spraying to kill the bugs. Don't go crazy...slow, steady and thoughtfully. You have a legitimate anxiety about fire...but you can go overboard with that. By the way, are all your gas hoses in good condition? That's a more likely danger scenario.

That was helpful, yet funny. I have replaced every fuel line in the past six months and no leaks! Safety first

not to throw a red herring in there, but if it only does it when you pump the brakes it could be the diaphragm on your brake booster...however, agree with the rest - look for a vacuum leak elsewhere first, as it will be much cheaper to fix.

Hello folks. Valve adjustment day. From what I have read and seen, the notch mark on the distributor where no. 1 fires should be in front. On mine, the notch is kinda pointing towards no. 4. When adjusting to TDC, to adjust no.1 exhaust, where will my distributor point to? Still to the notch or where the notch should be? Does this makes sense? Thanks kris

Got it, duh. For no.2, the distributor points to no.2 when pulley rotated 180' ccw from TDC. Does this mean my distributor is installed incorrectly?