Date: Thu, 8 Jan 2004 19:05:37 -0600
Reply-To: Larry Alofs <lalofs@RCN.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Larry Alofs <lalofs@RCN.COM>
Subject: Re: what causes low oil pressure
Content-Type: text/plain; charset=us-ascii; format=flowed
Ben,
You didn't mention the year of your van. In the later models, there are
two systems that can make the light come on, the low pressure switch on
the bottom between the push rod tubes and the high pressure switch near
the crankshaft pulley which is only active above 2000 rpm. If your van
is of this vintage, do you know which switch is involved? I believe one
of them is normally open and the other normally closed.
Larry A.
Ben S wrote:
> well recent events (see my "blown head gasket?" thread) and the "oil
> light discovery" thread have gotten me thinking about oil pressure.
>
> to recap what happened to me: i have put over 20k miles on my van in the
> last 4 months, and many of those miles involved strenuous hill climbing.
> recently, i moved up to south lake tahoe and decided to switch to a
> lower viscocity oil because of the colder weather. i did the oil change
> down in davis where it's warm and was driving back up the mountain that
> night when my oil pressure light came on. i stopped and ended up
> getting the van towed. after i mistakenly diagnosed my problem and was
> corrected by you guys, i drained out the 10w-40 that i had just tried
> for the first time and replaced it with 20w-50, which is what i had
> always used in the past with no problems. since that change, i have
> driven over a few passes with no issues; but yesterday on my way up to
> kirkwood, as i was climbing a particularly steep hill (meaning i was in
> 3rd gear at about 4k rpm for several minutes), the oil pressure light
> came on again! so i let off the gas and the light went off. after a
> few seconds, i tried to speed up again, and again the light came on. so
> i slowed way down and cruised up the rest of the hill really slowly in
> second gear and didn't see the light again. now for the record, i have
> a fram gold oil filter in there right now, and i have heard all the
> stories about non-german filters causing problems. however, just before
> my recent oil change, i made several trips over these exact same
> mountain passes, driving just as hard, with castrol 20w-50 oil, and
> never had a problem AND i was using a napa filter then, too.
>
> so although i know that i need to start using a real german filter (i
> just ordered a 4pack from cafe volks), i think there might be some sort
> of slowly deteriorating condition here--it seems like some subtle
> problem must be getting worse. what causes the oil pressure to get low
> enough to trigger the light? assuming that the oil was getting too hot
> and thin from all the climbing, why did the pressure go up so quickly
> when i let off the gas? the oil certainly can't cool down that quickly,
> and i would expect that a decrease in engine speed would decrease the
> oil pressure. and wouldn't my coolant temp gauge have registered some
> kind of increase if the oil was getting too hot to maintain pressure?
> but that temp guage was pegged right in the middle like it always is
> once the engine warms up. i don't think this problem is caused by a low
> oil level--i've been keeping a close eye on that. but could it be
> caused by a fault in the pick-up tube? or a failing oil pump? what can
> slowly degenerate and cause the oil pressure to drop under a hard load?
> has anyone else had problems running 10w-40 oil? my manual says that
> is safe for up to something like 75 deg F ambient temp, and it sure was
> a lot colder than that when i had this problem.
>
> thanks in advance for any help...
>
> Ben.
>
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