[T3] Heads are toast, rebuild time

[Jacob Adam Schroeder]

On Wed, Jan 29, 2014 at 10:47 PM, Jim Adney <jadney at vwtype3.org> wrote:

> On 29 Jan 2014 at 21:56, Jacob Adam Schroeder wrote:
>
> My thinking was backwards when I made that suggestion. Rich running
> resulting in carbon buildup on the valve seats would make the
> clearances increase, not decrease. Sorry.
>
>
Ok, that makes sense.  The built-up carbon would decrease the clearance at
the valve end (when the valve was open) because the valve wouldn't full
close (carbon in the way).  Thus, the clearance at the rocker arm would be
increased.

I still don't understand what might cause this, but maybe the BR
> heads are just defective. This seems odd, since I get the impression
> that you've had this engine for some time and this problem just
> started. Perhaps the person you loaned the car to did something to
> cause this (or am I confusing your situation with someone else's.)
>
>
I have had the engine for some time.  I rebuilt the engine completely in
1997 at got these new heads at that time.  Since then, I have maybe put 10k
miles on it.  As far as loaning it to somebody, you are mistaken and,
unfortunately, I have nobody to blame but myself.



> I believe you said that you don't have the thermostat installed. In
> that case, especially in cold weather, your engine would never really
> get fully warmed up and the FI would always be in startup (rich)
> mode. That would explain the poor gas mileage. Normally, I would
> expect gas mileage in the 22-24 mi/gal region, so I don't think
> you're far off.
>
> Running without the thermostat and flaps is always a bad idea,
> especially in cold weather. It's especially bad with the FI, which
> responds to engine temp. Carbs are different: If they have chokes
> they warm up independently of the engine, or they simply don't have
> chokes.
>
>
You are correct about my missing the thermostat. It was that issue which
got me thinking about pulling the engine in the first place.  My constantly
shifting plan is now to pull the engine, remove and inspect the heads (if I
do this, I'll take pictures) and see if anything is obviously wrong.  If
its something easy to fix, we'll button it back up and install the
thermostat along the way.  If not, then at that time I'll consider whether
to rebuild the heads or the whole thing.

Perhaps there's something about rich running that would make the
> valve seats wear quickly. I've not heard of this, so I'm skeptical
> about the possibility. One thing you should probably check would be
> your charging system. With the engine running at medium rpm after a
> warmup drive, the battery voltage should be 14.1 - 14.4 V. If it's
> below 13.5 V you should replace the voltage regulator with a Bosch
> 30-019. Low system voltage will make the system run rich.


The last time I checked, I had 14 volts at idle at the battery and maybe
14.2 at mid/high RPM.  I could not get it any higher even with increasing
revs.  I have not done anything to the generator since I took it from the
old engine and put it on the new one in 1997.
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