Date: Mon, 17 Aug 2009 14:00:33 -0700
Reply-To: Rocket J Squirrel <camping.elliott@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Rocket J Squirrel <camping.elliott@GMAIL.COM>
Subject: Re: Not quite a backfire . . .
In-Reply-To: <00d501ca1f74$faf443e0$6501a8c0@PROSPERITY>
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On 8/17/2009 12:57 PM Scott Daniel - Turbovans wrote:
> I think you have a 1.9 waterbxoer engine.
> if so, the temp gauge sender, a single wire sensor, is on the thermostat
> housing.
> And it's on the return hose, and seems that it would be on the colder
> side of the t-stat, I believe.
So if the engine stops getting fuel, it will cool down, and the thermo
would close. The coolant would stop flowing (?) past the temp gauge sender
-- would it just pool there? Without a source of heat that chunk of t-stat
might get pretty cool? Just guessing.
> The temp sensor for the fuel injection is also right there too, and
> you'd think they would be pretty careful about where they put that sensor.
Yeah, dunno if they considered long descents with foot off gas and cool
outside temps, though.
> low 50's ambient........it could very well be that dropping to very low
> temp on the gauge is normal under those conditions.
> I have driven up and down both sides of that pass, and I sure don't
> remember seeing the temp drop way off on the steep west side decent.
Of course it would be helpful for someone else to do a long drop (20 to 30
minutes) in cool temps using the engine for braking, i.e., foot off gas
for like, 95%, of the time. 2nd gear on AT, for me, and report back on
what their temp gauge says. Such a person would of course need to live
someplace mountainous, and have nothing better to do.
> Last time I was there was about a year ago, in an 83 Westy, with 2.1
> engine running the 1.9 cooling system. I sure don't think my temp needle
> dropped to near zero,
> but ......whatever !
Well, yeah, it's not like I'm an expert on these -- or any -- engines.
It's entirely possible that I have had two defective thermostats. The
first was replaced when doing the water pump just because of this long
downhill in gear no fuel cool temps cooling issue. Just to see if it made
a difference. It didn't and on or around that time the list sort of
reached agreement that what I was seeing might be normal under such
conditions. So I've given it no further thought. It was the engine miss
that caught my attention and I had to think about it for a bit -- even
while writing my post -- to figure out what I think happened: a fouled plug.
Does it sound reasonable that an engine spinning at 2k-3k rpm for 10-20
minutes, with fuel cut off, could get an oil-gunked plug that needs a few
sprays of gasoline to unfoul it? Last time the compression was tested
(2008) the cylinders were in the quite reasonable range. 79,000 miles.
--
Mike "Rocket J Squirrel" Elliott
84 Westfalia: Mellow Yellow ("The Electrical Banana")
74 Utility Trailer. Ladybug Trailer, Inc., San Juan Capistrano
Bend, OR
KG6RCR
> thanks for the note back.
> Scott
> ----- Original Message ----- From: "Rocket J Squirrel"
> <camping.elliott@GMAIL.COM>
> To: <vanagon@GERRY.VANAGON.COM>
> Sent: Monday, August 17, 2009 12:39 PM
> Subject: Re: Not quite a backfire . . .
>
>
>> On 8/17/2009 11:36 AM Scott Daniel - Turbovans wrote:
>>
>>> The coolant temp should not drop to a very low reading during a long
>>> descent in the summer.
>>
>>> I would be thinking about a thermostat not working correctly if I saw
>>> that on one of my vans.
>>> This is the main thing I wanted to comment on.
>>
>> With no pressure on the gas pedal, the fuel is totally shut off, so the
>> engine is not firing on any cylinders and after about 20 minutes with
>> cool
>> air blowing past it, it will lose heat. I first observed this in
>> 2007/2008
>> on the long drop down from Laguna Mountain in San Diego county and there
>> was quite a lot of to and fro on this matter until the list sorted this
>> out as being basically an off engine in cold air being spun by its
>> crankshaft. This is the second thermostat, and the behavior is the same.
>> It was probably in the low-50's outside, and that's cool enough to suck
>> heat out of the engine quickly. The Laguna Mountain descents were in the
>> 30's and lasted 20 or 30 minutes. I don't think an engine can stay warm
>> with no fuel when driving @ 40 mph and spinning at 2,000 to 3,000 rpm
>> very
>> long.
>>
>> Where does the thermal sensor for the dash gauge sit w/r/t the
>> thermostat?
>> engine side or rad side? Gotta be the engine side -- right?
>>
>>> re
>>> With no fuel in the cylinders for so long, a
>>>> plug got fouled with oil. Unburned fuel got into the exhaust
>>>> manifold and
>>>> ignited there, causing the mild explosions we heard.
>>>
>>> Yes....backfire like sounds can be from fuel in the exhaust system
>>> getting ignited.
>>> however, by your own logic and indications observed ( 02 meter ) you
>>> believe that the throttle switch shut off all fuel to the injectors,
>>> so how could there be unburned fuel in the exhaust system, if that were
>>> true ?
>>>
>>
>> Ya didn't read my post well enough. When we hit the flat Mrs Squirrel
>> pressed lightly on the gas pedal, which would start gas going into the
>> intake. Any cylinder with a fouled plug, due to long downhill @ 2,000 to
>> 3,000 rpm and no gas, would send that unburned fuel into the exhaust
>> manifold. To go "cough" as it popped out there.
>>
>>> that sure is a special area.
>>> They only just opened McKenzie Pass *now* ?? In August ?
>>
>> It's true -- they were re-paving it and now they are re-striping it.
>> I am certain that the re-paving was needed due to a$$holes like that Jack
>> Elliott fellow driving inappropriate vehicles over the pass. See
>> http://socal2bend.blogspot.com/2008/08/massive-trucks-migrate-to-eugene.html
>>
>>
>>> on the Eugene ( west ) side of the pass, about a mile or so from the
>>> pass itself, on the north side of the road, is a delightful small lake
>>> with some campsites around it. Always wanted to camp there once.
>>> There is also in that area, another *really* nice little lake, with
>>> free unrestricted camping, with campsites around the lake.
>>
>> Yes sir, I agree. I gotta get me some Forest Service maps pronto -- the
>> area is peppered with intriguing places to camp. Right now, being
>> stuck in
>> a wheelchair, I gotta stick to more developed places. Which suck, but we
>> gotta work with the present conditions.
>>
>> --
>> Mike (aka "Jack" Elliott)
>> 84 Westfalia: Mellow Yellow ("The Electrical Banana")
>> 74 Utility Trailer. Ladybug Trailer, Inc., San Juan Capistrano
>> Bend, OR
>> KG6RCR
>
>
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