Date: Sun, 10 Dec 2000 00:02:02 -0500
Reply-To: Dennis Haynes <Dhaynes57@EMAIL.MSN.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Dennis Haynes <Dhaynes57@EMAIL.MSN.COM>
Subject: Re: 82 Diesel Vanagon - what caused cam bearing to fail?
In-Reply-To: <008201c06219$309ffe30$12bdd6d1@bill>
Content-Type: text/plain; charset="iso-8859-1"
How did it fail? Did the bearing cap crack or did the bearing start to
transfer metal to the cam? Cracked bearing caps are caused by the pistons
hitting the valves when open. Usually caused by the timing belt jumping
time. The bearings failing on the bottom is usually caused by the cam belt
being over tightened. This is especially nasty in a diesel because this will
also wear out the injection pump bushings. Another possible problem could be
the wrong oil or the oil was contaminated with coolant. Antifreeze is
extremely corrosive when heated and mixed with air. If this is possible,
then the main and rod bearings should also be inspected. Lots of shops are
now using 5w-30 on everything since most new cars call for it. The VW diesel
does not like this. Especially with the steel cam riding directly on the
aluminum heads. The oil also needs to have a CD or better rating for the
Diesel application. Before replacing the head for $1700, I would look for
other options including a complete engine. I have some good used heads here
and I can get new ones for a lot less than that. Hope this gives some help.
Dennis
-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com]On Behalf
Of Barbara Hardy
Sent: Saturday, December 09, 2000 2:50 PM
To: vanagon@GERRY.VANAGON.COM
Subject: 82 Diesel Vanagon - what caused cam bearing to fail?
Our '82 Diesel Vanagon has just been diagnosed by the local VW dealer as
having a failed cam bearing, and we're trying to decide what could have
caused this, and what to do about it.
We're afraid that the dealer may have caused this problem, but we can't
prove it now. The details are..
At 135K miles - head gasket replaced at the VW dealer.
1500 mile trip to Vermont.
Change oil.
Back to VW for the routine head retorque.
49 miles later - a very loud clacking sound started coming from the engine,
so hauled it back to dealer.
Dealer diagnosis: 4 of the 5 cam bearings are shot, and the timing belt has
jumped a couple of teeth. The mechanic said that he has never seen anything
like it, but apparently the head lost oil pressure only to the cam bearings
(nothing else that needs oil was apparently harmed).
He says the head is getting pressure fine - 80-90 lbs, the oil pump is fine,
and there is no blockage to the head ports. I asked if he could suggest a
reason why no oil would get to the head and he said that it was possible
that he put the head gasket on wrong initially, but had that been the case,
we wouldn't have gotten 100 miles beacuse the head ports would have been
blocked.
The mechanic suggests that when we changed the oil, the engine lost oil
pressure somehow long enough for the cam bearings to go out. He says the
next step is to replace the head, which will cost us $1700 (ouch!!).
So, the mechanic does not know what caused the problem in the first place. I
asked about the valves, and he told me that this engine is non-interference
(!!). I talked to a couple of other VW mechanics and they assure me that
this is not true. I don't know if the piston heads were damaged. So I am not
sure how much confidence in this mechanic.
Possible explanations suggested to me by others are:
- the cam bearing caps were tightened by mistake
- the wrong thickness head gasket was put on, and when it was retorqued,
that closed the gap between the valves and the pistons, hence the noise, the
bearings, and the timing belt.
- the timing belt jumped somehow and caused the damage (belt was not
replaced when head gasket was).
Does anyone have any other suggestions for what might be going on here? We
want to ask the dealership to cover some of the cost, but is this
reasonable? My family is moving to Montant shortly, so there is a time issue
here, too. I plan to talk to the dealer on Monday morning.
Many thanks!
Barbara Hardy
