[T3] Breather cap

[Phil Ostronic]

My guess is that it started with the timing slip caused by the point gap changing, perhaps due to wear of the fiber rider, or perhaps it just slipped.
 
Next, as a result of bad timing you had a backfire or miss that sent a pressure pulse back through the intake, which vented by popping the cap off.  Then of course normal driving will eventually splat oil through there, perhaps more with the oil thinner from higher heat from poor ignition timing.
 
Someone long ago put my cap on and excluded the spring.  On my old Squareback it used to pop off with the spring, but back then you could get a good new part from the dealer.  My current Fastback locks the spring, and has never popped off.  I suppose it’s relying on the weight of the washer underneath to partially close off the venting, which seal better with the spring.  So far no ill effects from leaving it out.
 
The starter probably had nothing to do with it.  The heat soak from long freeway trips will often get them to a higher temp than normal, which can bring on an incipient failure.
 
-Phil
===============================
Date: Tue, 22 Aug 2017 22:53:56 -0500
From: Daniel Nohejl <d.nohejl at gmail.com>
To: "type3 at vwtype3.org" <type3 at vwtype3.org>
Subject: [T3] The road trip blues

#1?We?d been driving for a few hours and were cruising I-29 on our way to Kansas City up a slight grade at 75mph when I thought I felt a miss. A few minutes passed without incident but soon, the motor seemed to loose a slight bit of power and I could only go 70. After a few moments, Jessica thought she smelled something and I soon noticed it too. Of course, I thought the car was on fire, but when we pulled over there was oil leaking onto the muffler. In fact, there was oil everywhere as you can kind of see here:

https://www.thesamba.com/vw/gallery/pix/1683355.jpg

That infernal cap!! We had one that would pop open once or twice a year. We?d take it inside and perform Jim?s trick on it: we?d stick it over the end of an appropriately sized pill bottle and boil it. The cap would have to be tapped in with a mallet and would generally stay put for 6 months until it popped again. Well, this time we were visiting a Type 3 guy in Oregon and he gave us another cap he had off a spare engine. It worked fine for a little while and then it started popping up every other day or so. Each time, it?d fit back a little less tightly and now this :(

We have the cap taped down with ultra-high-temp tape and even still it won?t seat all the way. You can imagine that b/w this and the oil everywhere that we?re having quite a smelly drive now: burning oil, oil vapor, etc.

Questions: 

a) I can imagine a correlation b/w a slight loss of power and the opening of the breather cap, but can someone explain it?

Point gap had gone from .016 to about .010 in only a few thousand miles. Got it back in spec and retimed it. It?d idle great then stall, bump-start, then stall, then hesitate while driving and then we said ?screw it, let?s just drive?. Getting back on I-29, there was a last bit of hesitation which vanished in a big puff of white smoke out the tail pipe as we headed down the on ramp. Drove 100 miles to and around KC and besides the oil smell, it?s been more or less back to normal. 

b) Is it really just bad luck/coincidence that the starter crapped out at the same time as this oil incident?
=====================================
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.vwtype3.org/pipermail/type3-vwtype3.org/attachments/20170823/1ec3e92e/attachment.htm>