[T3] Re/ Runs Great...but very hot...

[Jim Adney]

On 19 Jun 2011 at 22:12, J. Jonik wrote:

> For decades now, when I put an engine together, I've eliminated the
> thermostat and have bolted, not just wired or screwed,  the two flaps
> in open position.  Philadelphia weather isn't the Yukon. 

It should be noted that VW installed the thermostats even in cars 
destined for northern Africa, areas MUCH hotter than Philly.

I'm afraid that's a definite no-no, in spite of the fact that it's a 
common practice. For the people who make this mistake, the assumption 
is that cooler is better, which is wrong. The engine has a design 
temp, which is somewhere between 165 and 250 F, depending on what 
part of the engine you're talking about. The faster it gets to that 
temp the better. If you run your engine cooler than that, the FI will 
think it's not warmed up and try to compensate. The bearing and ring 
clearances won't be right, and the fuel won't vaporize correctly, 
leading to excess fuel condensing on the cylinder walls. This washes 
the oil off the walls and leads to excess cylinder and ring wear. The 
excess fuel will then end up in the crankcase, as you've noted, 
although your description seems extreme.

It is well known that the majority of engine wear occurs during 
warmup. By removing the thermostat, you're prolonging the warmup 
time, and for many trips, or in cooler weather, the engine may never 
warm up properly.

> Don't understand how gas-diluted oil wouldn't heat up engine....being
> that the gas would reduce the lubrication. No? 

Gas certainly does reduce the viscosity of the crankcase mix, but gas 
diluted oil is a poor lubricant, so wear is increased. The decrease 
in viscosity would mean that less energy would be dissipated in the 
oil, but any increase in metal-metal contact and wear would mean an 
increase. I don't know which would dominate, so I'm not sure whether 
this would help warm up the engine or not. My guess is that it would 
not. What I can be sure of is that this is not a desirable situation. 

> Any tricks to be sure that IS gas in the oil?  Will it catch fire
> easily if I take some out and put a match to it?   But would plain oil
> do that as well?     Smell?...can't tell.   I'd need one of those Wine
> Sniffing experts or something. 

I've had mechanics tell me that if you put a drop on your finger you 
can watch to see if it wicks down along the little fingerprint 
ridges. You could compare this with fresh oil to see if you can tell 
a difference.

You could try lighting it on fire. A little in a bottle cap should 
work. I think straight motor oil is pretty hard to set on fire unless 
you have a wick.

-- 
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Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA
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