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Tue Jul 17, 2012 7:48 am

'72 weekender, type 4 engine. I searched, and read, and searched and read, and naturally, nothing that i found is the EXACT SAME problem as mine.

Ok, so I just got the timing and carbs adjusted, and changed the oil, and on the way home from the garage, once i got off the highway, smoke starts pouring out of my tailpipes (my dad was following, so he described this to me). Then it stopped, and it was fine. No power loss at any point, no noises, no lights, just smoke...white-ish, grey-ish, smoke...smells like oil.

Bus fires up fine, drives fine, just occasionally i get smoke out the back. Doesn't seem to be related to anything...hills, start-up, revs, gears, load, weather, mood, planetary alignment. Like i said, no power loss, no brake problems, and the smoke is not constant, nor is the smell. I checked the oil level when it first happened and it was high, and will check again tonight to see if levels have changed.

I'm wondering what's going. I don't expect that anyone can fix this via the internet, i'm just looking for thoughts. I am NOT mechanically inclined enough to tackle this myself, but would just like to understand better. ALSO, I need to drive the bus about two hours at the end of next week, and am wondering if that's (un)reasonable so I know whether i need to take action immediately.

TIA.

Tue Jul 17, 2012 9:00 am

jakeandgenny wrote: . I checked the oil level when it first happened and it was high, and will check again tonight to see if levels have changed. .
Definitely monitor that closely. What kind of carbs and fuel pump do you have?

Tue Jul 17, 2012 9:27 am

You should check out the crankcase ventilation system, especially if you have an aftermarket carb or aftermarket air filtration.

How about pictures of your engine.

Tue Jul 17, 2012 11:35 am

Thanks for taking an interest.

When I take a look at the oil level tonight, I'll snap some pics of the engine. I'm unsure exactly of the carb, but i know its aftermarket, and I know its not the highest quality. Again, I'll take a look tonight.

Could the culprit be the adjusted carb/timing, or perhaps too much oil when it was changed?

Either way, I'll check back in later with updates and photos.

Thanks again.

Tue Jul 17, 2012 1:14 pm

jakeandgenny wrote: Thanks for taking an interest.

When I take a look at the oil level tonight, I'll snap some pics of the engine. I'm unsure exactly of the carb, but i know its aftermarket, and I know its not the highest quality. Again, I'll take a look tonight.

Could the culprit be the adjusted carb/timing, or perhaps too much oil when it was changed?

Either way, I'll check back in later with updates and photos.

Thanks again.

I have run a quart over the recommended level for two decades so unless you have more oil than that in your engine the level shouldn't be a problem. Neither the carb or the timing should be the problem either unless things were horribly whacky. I am guessing it is some PO half a$$ attempt to deal with the ventilation system.

Tue Jul 17, 2012 2:31 pm

[quote="Wildthings"] jakeandgenny wrote: I am guessing it is some PO half a$$ attempt to deal with the ventilation system.
Or bad guides, or rings, or???, maybe it's got a Progressive and has been filling the case with gas while parked, not an issue short term but gas is not a lubricant and when it replaces oil engines don't last long.

I hope it's a bad breather too.

Tue Jul 17, 2012 6:08 pm

FWIW, i took pics and checked the oil. No shock, but the oil's lower than it was last i checked. So in two weeks, and 4 or 5 trips (about 30 minutes each) she's gone from just at the second line to just at the first line.

here's the pics:

In speaking with my father, we're thinking bad rings, but i'm unsure. What I'm really wondering is if i can drive this for a few weeks with a case of oil in the back and then attend to it, or is this an emergent situation.

Looking forward to hearing your thoughts. Thanks again.

Tue Jul 17, 2012 6:32 pm

That's remarkably clean :D
Where does the hose coming from the rectangular black box on top of the engine behind the carb go?

It's not an emergency until you can't see behind you anymore due to the smoke, maintain the oil level though.

Tue Jul 17, 2012 8:12 pm

also get the fuel filter out of the engine compartment

Tue Jul 17, 2012 8:52 pm

busdaddy wrote: That's remarkably clean :D
Where does the hose coming from the rectangular black box on top of the engine behind the carb go?

Yep we need to know where the hose from the black breather box goes. Can't see what is there at all. If it is plugged off or otherwise restricted that is probably your problem. I would think if the breather were just open you engine would be covered with oil and I can't see that it runs to the air cleaner which is the most common place to vent it.

Tue Jul 17, 2012 9:20 pm

Leaking brake booster.

Wed Jul 18, 2012 7:52 am

Wow, lots of great feedback, thanks a lot.

I do like to keep the bus as clean as I can. Its the one thing I can do.

So, bear with me as I reveal how truly mechanically disinclined i am.

Busdaddy/Wildthings: the black box and tube (t, do you mean A&B, or C? How do i tell if it restricted? Anything in particular i should look for? I'll take a look and see where that tube goes tonight.

Bugger: you suggested getting the fuel filter out of the engine compartment. (that's D, right?) if you can, could you elaborate?

udidwht: could you possibly elaborate on a leaking break booster? this is not something i had considered.

Thanks for the time and patience.

Wed Jul 18, 2012 8:24 am

"A" is the breather box which should have a hose attached at "B". The breather and hose need to be open and able to pass any and all blowby gases produced by the engine. It is common practice to vent the breather into the air cleaner so that the blowby and the oil it carries gets burned up.

I don't have qualms about a fuel filter being in the engine compartment so long as it has clamps on the hoses and is fastened down so it doesn't bounce around. I prefer a metal filter myself, but each to their own. Placing the filter before the fuel pump will protect the pump from foreign material though.

Wed Jul 18, 2012 8:24 am

Where is the routed to from the breather box?

There should be a hose from the right side of the breather box that connects to a fitting on the air filter.

- Andrew in Austin, TX -

Wed Jul 18, 2012 9:56 am

A ruptured diaphragm in the booster will allow brake fluid into the intake where it's burned causing white smoke. Follow your line from the booster back to the engine and verify there are no leaks. You won't find the leaky diaphragm by doing this but you also want to eliminate any vac leaks.

Wed Jul 18, 2012 10:40 am

Awesome, guys, thank you.

I'll check all this out when i get home from work and update then.

Wed Jul 18, 2012 10:57 am

When you step on the brakes what happens to the idle?

Wed Jul 18, 2012 2:45 pm

The smoke could be a brake fluid into the engine issue. But it's when the master cylinder leaks and dumps fluid into the booster. It's a result of a bad MC and not a bad booster. Although when brake fluid get in there it can wreck the booster.

Wed Jul 18, 2012 3:02 pm

Alright, as you can see, the tube from breather box goes to the filter:

FWIW, the tube was jammed pretty tight under those two pipes (name?).

udidwht: As far as I know, nothing changes when i hit the brakes while the bus is idling.

As usual, thank you. this is all a huge help.

Wed Jul 18, 2012 3:45 pm

jakeandgenny wrote: Alright, as you can see, the tube from breather box goes to the filter:

The hose is pretty long and has a dip in it. Snot can collect in the dip and cause back pressure. Did you remove it and try and blow through it? Whether or not it is your present problem, best to shorten it and route it so that any oily crud will drain back into the engine.