Date: Sun, 12 Sep 1999 18:14:42 -0400
Reply-To: Bob Donalds <bostneng@FCL-US.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Bob Donalds <bostneng@FCL-US.NET>
Organization: Boston Engine Exchange
Subject: Re: oil pressure problem
Content-Type: text/plain; charset=iso-8859-1
Michael Y. Feng wrote:
>
> Hi,
>
> I was driving my 87 Vanagon out of town, and the oil pressure light and
> buzzer came on after driving up a long grade. I immediately pulled over
> and shut off the van. I waited about 10 seconds and started it up again.
> This time no light for the next few minutes as I was almost at my
> destination. As I drove home about the same distance, the oil pressure
> light and buzzer came on again as I got very close to home. I shut it off
> for a few seconds, started it up, and drove a little bit. It came on
> again, though. Then I walked the rest of the way to my girlfriend's house
> to eat dinner.
>
> I actually read my idiot's book by John Muir, and I think the oil pressure
> relief valve may be sticking. In other words, as the engine gets hotter
> the oil never passes through the oil cooler. The oil temperature
> constantly goes up and eventually the oil breaks down. The oil level was
> fine; as a matter of fact I just put in Mobil 1 oil a few days ago.
> There's no oil leaking onto my driveway either. So, my diagnosis is that
> the oil pressure relief valve is probably at fault.
>
> Question 1: do people on the list agree with my diagnosis?
> Question 2: how in the world can I get that oil pressure relief valve off?
> I've tried John Muir's screwdriver with pressure and a vice-grip to no
> avail. Any other suggestions?
>
> TIA,
>
> Mike Feng
>
> P.S. To those of you who answered my oil drain plug question, I finally
> found one in the tenth parts store I called for $2.05.
Mike
this is something I wrote for the vanagon.com pages its called low oil
pressure at
warm idle
I have had more than one 2.1 water boxer engine brought in for
rebuilding with
symptoms of low oil pressure. Despite having put in the longest spring
the customer
could find for the pressure relief and adding thicker oil, the engine
still had low oil
pressure at a warm idle. These findings had been confirmed with a oil
pressure gauge. So as I disassembled this engine I was very careful to
check for excessive clearances.
It turns out the clearance between the rod bearing and the crankshaft
rod
journal had gotten to the point that it allowed the oil light to come on
at warm
idle. While the crank usualy measures ok the rod bearing has worn and
the clearance has almost doubled. Unfortunately the more common results
of this problem in the 2.1 is that the rod winds up hanging out of a new
vent hole its has created in the top of the
crankcase. The 1.9 on the other hand is not known for throwing rods
unless it was
run low of coolant or oil.
The one thing that has been consistent in all the 2.1 engines I have
stripped and measured is that the large end of the connecting rods are
no longer
round. With this problem in mind I started paying more attention to
the big ends
of all the water boxer con rods that came into the shop. The first thing
I found was
that the 1.9 and the 2.1 con rods are the same size and length. In fact
they are the
same rods. My inspections showed the 2.1 rods had consistently more
distortion at
the big end. What is the difference between the two applications of the
same con
rod? The stroke is longer in the 2.1 engine so the rod angle is
greater, plus the 2.1
make more power witch puts more strain on the rods. It’s clear to me
from my
days at the race track that nothing distorts con rods faster than
exceeding the
power curve but the fuel injection has a nifty rev limiter built right
in. This
doesn’t explain why we see rod distortion in one engine and not the
other. Next I
went to the Bentley book to compare the torque specs. The 1.9 rod has a
reusable
rod bolt that call for a torque of 33-ft. lb. and the 2.1 rod bolt has
torque of 22-ft. lb. plus ½ turn. The manual also says not to reuse con
rod bolts on the 2.1 engines.
The conclusions
1) NEVER reuse the 2.1 rod bolts
2) NEVER reuse the rods without having the big ends rebuilt ever!
3) NEVER rely on Plastagauge alone it does not always show if it’s out
of round
or if the cap is shifted.
4) Consider rebuilding your 2.1 waterboxer engine when the heads start
to leak if it’s got a hundred thousand or more miles on it. Keep in
mind the core may not be
rebuildable if you wait longer. There is no doubt the increased rod
bearing clearance is one of the major reason for the 2.1 engine
catastrophic failures.
.
More than one person that has told me that they got only six thousand
miles
from the 2.1 long block they rebuilt before a rod blew through the case.
They also told
me they reused the rod bolts and the rods had not been measured or
rebuilt. These facts speak for themselves. I see this problem on a
daily basis and thought I should pass on my observations.
hope this helps
Bob Donalds
Boston Engine Exchange
www.bostonengine.com