[Vwdiesel] New head gasket

[Shawn Wright]

On 25 Oct 2005 at 0:27, Libbybapa at wmconnect.com <Libbybapa at wmconnect.com> wrote:

> In a message dated 10/24/05 9:05:07 PM US Mountain Standard Time, 
> LBaird119 at aol.com writes:
> 
> 
> >   I think it was finally (sort of) decided that the "oil cooler" is 
> > actually 
> > an oil WARMER.  Those that have oil temp gauges know that the 
> > oil temp only rises above coolant temp when it's a turbo pulling a 
> > long hill.  Even then it's only 20F - 30F higher than coolant temp, 
> > as I recall.  It will however, warm up the oil much faster than it 
> > would on its own. 
> >   I believe someone actually found VW reference to it's purpose being 
> > for faster warm up and lower emissions, better mileage, etc.
> > 
> 
> I talked to someone who did a lot of testing with a gauge, running the cooler
> and then bypassing it.  All else being equal he claimed running with the cooler
> reduced oil temps on hills by a solid 30°F as opposed to bypassed.  He also
> claimed that once the engine was up to operating temperature the oil was always
> hotter than the coolant and so running the exchanger gave an across the board
> lowering of oil temps, just not as dramatic as on hills.  He did say that the
> oil took much longer to achieve N.O.T. with it bypassed, but ran hotter once
> there.  After doing testing he was fairly impressed at how well the thing
> worked.  My big issue is that I just can't see recycling that heat back through
> the engine.  When I get around to installing an oil temp gauge, I will do
> similar experimentation and post results.  I know Shawn has a gauge, maybe we
> could twist his arm to bypass the cooler for a test or two.  :-)  I am also
> curious if Shawn would comment on what his oil temps are normally on a long flat
> stretch after achieving operating temp.

I heard my name! :-)
Yes, your description is pretty much dead on. I notice my coolant temp reaches mid 
gauge very quickly, usually just as the oil starts to move above 120F on the gauge, 
so this certainly suggests that the coolant has lots of heat to pass to the oil very 
early on. 
During long highway runs at 55-60mph, oil temps are a steady 230F. Long hills will 
see the oil climb to about 250 after about 5 minutes of climbing, and 265 (the 
highest I've seen so far) on longer passes like Stevens Pass. When oil is at 240-
250, the coolant is still only slightly above 1/2 on the gauge, but once the oil gets 
over 250, coolant will climb to 3/4 or slightly more. (a real coolant gauge is next...)
If I get a chance I can try bypassing the cooler, but it may not be for a while. I also 
will note that if I just poke around the backroads, the oil temp can take a *long* time 
to reach 220F, since I assume the coolant is only around 190-200, so for the oil to 
get hotter, it needs to see some sustained boost at the turbo. This doesn't happen 
much until you're on the highway. All of this with a 1.6TD in a Vanagon. I suspect 
you'd have to be towing another Jetta to get oil temps like this in a Jetta... ;-)


Shawn Wright
http://zuiko.sls.bc.ca/~swright
'85 Jetta D 
'88 Westy 1.6TD 5 speed
 (see progress at http://members.shaw.ca/vwdiesels)
'82 Diesel Westy