[urq] Engine rebuild ?
laraa at sympatico.ca
Sat May 16 09:41:10 PDT 2009
Listers, please correct me if I'm wrong, I am sure I forget something
There is 4 way for oil to get evenly into the 5 combustion chambers : worn
oil rings, worn valve guide/seals, dysfunctional oil separation circuit,
To rule out the oil separation circuit, take a look at the inside of the
intake manifold, there will be lots of oil in there. You can remove the
throttle body and look in it from there.
To rule out turbo, look at the hoses between turbo and intake : same story,
lots of oil in there if bad, probably pooling in the intercooler.
Your compression tests show a tight engine (you have 8 bar, wear limit is at
5 bar...) but this don't tell the conditions of the oil rings. Forged
pistons and stout engine block are very durable : in fact, I only
reinstalled new rings on the original pistons on my rebuilt engine. The
bores were fine and needed only gentle honing. So compression was still
good. However, there was lots of "coking" in the rings slots, probably from
cheap oil and high temps. You may have the same problem : high mileage can
cause oil rings to stick in their groove. No cheap solution, except dropping
the engine and replacing the rings.
Valve guides are very durable, both of my WX heads had absolutely no wear on
the guides/seats when we dismantled them.
Also, from the pictures of the plugs, could be the valve seals. I had a Ford
V8 engine with that problem, and plugs were like that. It turned that the
rebuilder installed the wrong seals on the guides, and they popped after a
while. But only three cylinders were very bad. To see if the oil goes in the
engine from there, try to have a look at the back of the intake valves :
you'll have to use a "periscope" or a similar device, or remove the intake
manifold (which is not that difficult).
Your plugs are identically fouled, so it makes me thinks the problem is
upstream of the intake where the oil can be evenly distributed before
reaching the cylinders. Or it's general wear on the oil rings from the 313
000 km, because the rebuilt head is only 74 000 km and should not leak like
Now you have a 5 step "procedure " :
- Remove throttle body, look for oil.
- Remove turbo hoses, look for oil.
- Remove intake manifold, look for accumulated grime on the back of the
- Remove exhaust manifold and look for the same on the back of the exhaust
- Remove the engine to replace the pistons rings.
Listers, does it makes sense ?
Original message :
Here are the facts:
The previous owner replaced the head with an unused head prior selling the
car to me in december 2001 at 236000 km.
Had no oil problems (1:3000) and changed oil (Castrol RS 10W60) and filters
every 10000 km myself but the turbo went bad (power loss) and the exhaust
manifold cracked one day and decided to fix it.
In nov-2006 at 300000 km the turbo was rebuild and a new Dialynx exhaust
manifold was fitted amongst other things.
After 6 months I noticed the oil consumption increased dramatically from
1:900 in 2 months to 1:500-600 in 1 month and so on.
This went on and on for months adding oil every 500-600 km (at first the
usual Castrol and later the cheaper Valvoline VR1).
On 2-sep-2007 I performed a simple compression-test (8.0-8.4-8.0-8.4 Bar)
with a medium-warm motor and checked the turbo for leaks by doing simple
rev. tests (negative).
On 8-sep-2007 I changed the Bosch W4DPO plugs and today, 14000 km later,
they look like this (please sit down first):
The Champion ad in my Haynes manual says "HEAVY DEPOSITS" >> "A build up of
crusty deposits, light-grey sandy colour in appearance. Fault: Often caused
by worn valve guides, excessive use of upper cylinder lubricant, or idling
for long periods."
So in okt-2008 at 308700 km I decided to fix the valve-seals and while
reading the above from Champion, I ask myself if the PO who changed the
valve seals, could have access to the valve guides and why didn't he say
anything if they are worn??
WRT the plugs: I also replaced the (original) Audi coil on 23-dec-2008 and
5700 km before I changed the Bosch plugs, with the BERU SS120 (OEM P/N 035
905 105 A) because the OE coil was NLA, but I don't think the new coil has
anything to do with the current condition of the plugs.
Any ideas? Please send your reply directly to the list, otherwise your much
appreciated reply will be deleted by my spam filter, thanks.
If you need more info, just ask. Thanks again.
1986 quattro GV (313000 km)
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