You need to make sure that there is no oil in the air intake filter box. If
that is OK and dry then make sure that the airway to the compressor is fine
with no oil contamination. Then remove the tube to the inlet manifold (the
long square cross-section box is a plenum chamber to even out the air flow
to each cylinder. It is possible that your 740TD may have Exhaust Gas
Recirculation fitted. If it has, the plenum chamber has probably become
clogged with carbon/oil mix. If possible get rid of the EGR gear. Ensure
that the plenum chamber is free of contamination. Do a compression check on
all cylinders and check injectors for leaking seals. Check glowplugs and
relay for correct operation and that the thermostat is working how it
should. Too cool a diesel engine gives coking up which can contaminate the
airways and reduce performance. Was the garage a Volvo dealer or just a run
of the mill garage? If they get stumped then take your car to a VW/Audi
commercial dealer whose mechanics should be well capable of restoring your
engine's good manners and general cleanliness. With these earlier diesels
the tappetts must be checked/adjusted every 20,000 miles, cambelt and pump
drive belt changed every 80,000 miles and take care when adjusting the
cambelt tension. The adjustment is carried out using the water pump as a
tensioner so most people change the water pump and gasket when changing the
cambelt to avoid coolant leaks. Your engine should be pushing out 109 bhp. A
great improvement can be had by retrofitting it with the intercooler from
the 760 GLE Turbodiesel (needs different inlet manifold, turning the turbo
outlet through 180 degrees, and fitting extra air hosing and different
brackets for the alternator). This is what a friend has done and has gained
a bhp increase to 122 bhp. They can be reliably tuned to produce 180 plus
bhp with a corresponding increase in torque. Whilst one of the causes could
be what James suggests it is not the first thing to plump for. The best way
to sort out turbos is first to determine if there is too much play on the
compressor end of the shaft. If you find too much then a core replacement is
cheaper than a complete turbo and sorts out the seal problem at the same
time (Turbotechnics are the guys to ask).
Best of luck and please keep us informed of your progress. There are quite a
few diesel nuts who like these quite impressive cars and can be found on the
Volvo Owners Club Forums. (http://www.volvoclub.org.uk
All the best, Peter.
700/900/90 Register Keeper,
Volvo Owners Club (UK).
"David WE Roberts" <email@example.com> wrote in message
> On Sun, 09 Oct 2005 18:17:45 +0000, James Sweet wrote:
>> "David WE Roberts" <firstname.lastname@example.org> wrote in message
>>> I have just bought a 740 turbo diesel from a garage.
>>> A couple of days later I opened the bonnet and the whole turbo side of
>>> the engine bay was black with oil.
>> It's been a while since I've seen under the hood of one of these, are
>> you saying the oil is leaking from the pipe that connects the boosted
>> air into the intake manifold? If that's the case there shouldn't be a
>> significant amount of oil there to begin with unless the seals within
>> the turbo itself are shot. First thing I'd try is to scrub the engine
>> real well so you can see what's going on, then assuming it's an
>> automatic (every 760TD I've seen was anyway) have someone plant their
>> foot firmly on the brake, put it in drive, and press the accelerator
>> enough to create some boost while you stand to the *side* watching under
>> the hood for leakage. Don't do this for very long without allowing the
>> transmission fluid to cool but a short period of time won't hurt
> (1) Yes, I am sure. It is the vertical pipe that goes up from the turbo to
> the intake manifold. The leak is at the top of this pipe, where it goes
> into the manifold (or at least the box before the manifold).
> (2) No it is not automatic; in the UK there are quite a few 740s with
> manual gearboxes.
> (3) I have already cleaned it off and test driven it; that is how I know
> where the oil is coming from.
> (4) The garage did the same clean, drive, check and confirmed where the
> oil was coming from before they tried to fix it.
> (5) You have actually answered my main question with "there shouldn't be a
> significant amount of oil there to begin with unless the seals within the
> turbo itself are shot".
> So; new questions.
> Is there anything apart from having 'shot' seals in the turbo which would
> put oil into the intake?
> Are shot seals easy to fix (the garage would be doing the fixing) or is
> this a sign of general wear in the turbo which means a new (or newer)
> They claim to have changed some seals already; which seals would these be
> if not in the turbo?
> Dave R