[T3] Tight exhaust valves

Thu Dec 26 09:51:36 PST 2013

Well, your engine probably isn't running hot, interior heat has little to do
with head or oil temps, a lot to do with outdoor air temp and many other
things, you cant judge your engine temp by the heater temp.  Fuel
vaporization is also not a way to measure engine temps, that issue I don't
think is fully understood as myself and many others with bone stock setups
never have an issue with starting cold or hot without any initial priming.
My personal feeling is that some pumps don't leave the 20psi of residual
pressure that they are supposed to when shut off and that leads to the
problem, but Jim can chime in here as he's the fuel pump expert.

Mofoco heads are Junk, that's the problem, the material used to cast them is
too soft and the seats are likely sinking into the heads.  Using quality
valves IS important, I think its TRW or genuine VW these days or toss them,
and I don't know what MoFoCo uses (other that what they could get cheap) but
issues with them stretching or breaking is probably many thousands of miles
down the road and not something your going to have to deal with now, but no
absolute guarentee's.  

Sinking seats isn't a huge problem so long as they don't come loose, and if
they do, they don't have anywhere to go so its not instantly catastrophic.
Sometimes they eventually settle in but if you run out of adjustment range
first that's a problem.  Its possible that the seat material isn't hardened
properly as well, that could also be the issue.  Keep a close eye on them
though and keep track of how much you adjust out each time, you don't want
to run with tight valves too long or they could burn.

Keith

Top Notch Restorations
topnotch at nycap.rr.com 
http://www.a383ina68.addr.com/radiorest/main.htm
71 Squareback "Hothe"
65 Notchback "El Baja Rojo"
65 Squareback "Eggcrate"
87 golf "Winterat"
93 RX7 "Redstur"

-----Original Message-----
From: type3-vwtype3.org-bounces at lists.vwtype3.org
[mailto:type3-vwtype3.org-bounces at lists.vwtype3.org] On Behalf Of Jacob Adam
Schroeder
Sent: Thursday, December 26, 2013 12:11 PM
To: type3 at vwtype3.org
Subject: Re: [T3] Tight exhaust valves

Keith,

Great question.  I am not measuring my head temps with any sensor, if that
is what you mean.  I'm running a stock setup.  Is it advised to measure the
head temp nowadays and is this an easy install?  If so, maybe I'll post a
new thread down the line for help in that regards.

I could tell my car was running hotter for two primary reasons: (1) the
heat in my car was very good during this time (forcing me to dial down the
heat and/or open the windows) and (2) after a drive I could tell more fuel
was being evaporated from my fuel line than normal--meaning extra cranks to
start and/or extra time on the fuel pump button (Jim's kit) to pump out the
air.

I rebuilt this engine back in 1997 and at that time used heads from
MoFoCo.  They are not the correct heads for my year (no crankcase vent) but
they do have the FI sensor port. I have a set of proper Type 3 heads for my
year (with the vents) that I'd like to get refurbished for future use.

As far as the tight exhaust valves, the searching of forums makes me think
either (a) my valve seats are sinking into my head or (b) my valves are
stretching.  Neither one of these sounds very good and I'm hoping there
could be a more benign cause or that either (a) or (b) (to a small extent)
is not necessarily catastrophic or simply part of engine break-in  (I maybe
have 10,000 miles on this since the last rebuild).

Jacob

On Thu, Dec 26, 2013 at 7:49 AM, Keith Park <topnotch at nycap.rr.com> wrote:

> What do you mean by "noticeably hotter"?  how are you measuring your head
> temps?  Usually tight exhaust valves are a result of cheap aftermarket
> heads
> but running too hot can certainly do it, but REALLY hot, not something
your
> likely to see in the winter time here.
>
> Keith
>
>
> Top Notch Restorations
> topnotch at nycap.rr.com
> http://www.a383ina68.addr.com/radiorest/main.htm
> 71 Squareback "Hothe"
> 65 Notchback "El Baja Rojo"
> 65 Squareback "Eggcrate"
> 87 golf "Winterat"
> 93 RX7 "Redstur"
>
>
> -----Original Message-----
> From: type3-vwtype3.org-bounces at lists.vwtype3.org
> [mailto:type3-vwtype3.org-bounces at lists.vwtype3.org] On Behalf Of Jacob
> Adam
> Schroeder
> Sent: Thursday, December 26, 2013 10:43 AM
> To: type3 at vwtype3.org
> Subject: [T3] Tight exhaust valves
>
> My car ('72 FI Squareback) had been running noticeably hotter lately and
> started leaking a little oil from the valve cover gaskets (probably due to
> excessive heat), so I decided to check my valves while I was replacing the
> valve cover gasket.  It had been ~ 1500 miles since the last time I
> checked/adjusted my valves.  Each of my intake valves was still .006, but
> each of the exhaust valves (on all 4) were tight.  Tight as in practically
> no clearance.
>
> The fact that there was no clearance on any of my exhaust valves was a bit
> concerning to me.  I was able to adjust them all to get .006 again, but
I'm
> still a bit spooked out.  What could have caused these to get so out of
> whack in such a short time and does this indicate a more severe problem?
>
> Is there anything else I can do to further diagnose this issue or should I
> just keep driving it and see what happens?
>
> Thanks,
>
> Jacob
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