Volvo 850 Turbo smoking, no power

Hello,

My girlfriend has a 1994 Volvo 850 Turbo. She told me that when she
first got it, it was very quick, which is what I would expect. Since
then the power had fallen off, so that by the time we started going
out this January, I'd describe the car as just adequate.

She was told by her Volvo mechanic several months ago that the turbo
"was going out." I would assume that that means that the bearings are
starting to go. At any rate, in early May we were going up to the
mountains in her car and it lost all power. At part throttle it would
miss, at or near full throttle it smoothed out, but still had no
power, it wouldn't do much over 60 mph on a level road.

We checked the oil and it was just under two quarts low. We topped
off the oil and got a hotel room, the next day the car ran okay.

When we got home, she took it to her mechanic, thinking that the turbo
had died and then had freed back up. The mechanic said the turbo
wasn't dead yet, but replaced the following:

Air mass meter, thermostat, CMP sensor, turbo hose@pipe.

After this it ran okay, adequate power. The turbo boost gauge worked
after he did these fixes as well, it hadn't worked for several months
before. It just barely gets halfway up the scale, whereas she told me
that when she first go it, it would go way up the scale.

About a month-and-a-half ago, we took it on a 1600 mile round trip.
It started smoking really badly. It was once again two quarts low on
oil. Topped off the oil and it didn't seem to be losing any more oil
although the smoking continued.

After we got home from the trip the smoking and oil consumption seemed
to stop. The power was okay the whole trip, although the fuel economy
was in the high teens instead of the low twenties.

Then the other day, on a 100 mile round trip, it lost power, just like
in May. The turbo boost gauge seems looked normal, around half scale
on the interstate. It was also smoking pretty bad. The instantaneous
fuel economy was about 8 mpg. Checked the oil and it was again about
2 quarts low. Topped off the oil and let it sit overnight and it has
adequate power again, although it misses a bit at idle. The smoking
seems to have abated, although the oil level is still good.

Any idea what could be wrong?

-Eric

 

i.e., early-mid June?

You don't say how many miles are on the engine, total, or how many
you've driven since early May but, omigod, six quarts of oil in three
months?!? Did your mechanic do a compression test? My first hunch would
be that you need rings, at a minimum.

Yup; sounds like rings.

And by the way: how can you let an engine even _get_ two quarts low in
the first place?!?

cheers,

Henry

 

Have your mechanic check the complete pcv system for blockage.
At the turbo inlet hose area there is a small plastic nipple
where the 3/16" pcv hose connects. This plastic nipple has a
brass insert and a smaller restricted hole inside the brass insert.
The hole inside the brass insert can and will block up and can
cause all of the symptoms that you describe.
Once a turbo fails, it does not unfail.
Sounds like the turbo is OK.
BD

 

Hello,

How would you recommend cleaning out the hole the brass insert? Is
this like a carburetor jet, where don't want to risk enlarging it? I
have compressed air and carb cleaner. What else would I want to look
for in the rest of the PCV system?

Thanks,
-Eric

 

I had similar symptoms. One thing you don't mention is the colour of
the smoke. I have an old oil-cooled turbo whereas yours is water
cooled but if the smoke is blue then you're burning oil and the turbo
may be toasted, if the smoke is white then you're burning coolant
(likely a similar turbo failure as in the oil-cooled type) and your
turbo is probably toasted. If it's thick black/grey smoke then it's
your fuel mixture and you need to change your O2 sensor (Lambda Sond).

Like BD said, a broken turbo won't unbreak itself.

Also, if your O2 sensor has failed (someone recently told me the 850
has 2 of them) then the rich mixture may also lead to a plugged (or
partially plugged) catalytic converter.

I had my cat completely bored out (i.e. removed) and got all my power
back (plus I can hear the turbo howl now). Then I replaced the O2
sensor and my fuel economy went up and the dark smoke stopped.

To sum up: if your O2 sensor(s) fail then the fuel economy goes down
and (more) smoke is produced, the particles in the smoke narrow and
eventually clog the channels in the catalytic converter, and the turbo
stops boosting, the needle on the guage stopping part way up.

I got this fixed last week and have been speeding and
grinning-like-a-maniac ever since!

blurp

83 240Turbo 320,000km and counting!

"In the absence of facts I will speculate wildly."

 

I assume that neither the Air mass meter or CMP sensor is an O2 sensor?

 

That's correct.

The air mass meter measures the air flowing into the engine. It's
located in between the air filter box and throttle body.
The CMP sensor = CaMshaft Position sensor - tells the computer which
cylinder is coming up to firing position since the flywheel position
sensor has no way of telling this. It's located on the back of the
camshaft that doesn't have the distributor on it.

--
Mike F.
Thornhill (near Toronto), Ont.

NOTE: new address!!
Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)

 

Hello,

I found the following bench test info for O2 sensors. I sounds easier
than most of the tests I've seen using propane enrichment, etc.

It was at: http://mr2.com/TEXT/O2_Sensor.html

Testing O2 sensors on the workbench.
Use a high impedence DC voltmeter as above. Clamp the sensor in a
vice, or use a plier or vice-grip to hold it. Clamp your negative
voltmeter lead to the case, and the positive to the output wire. Use a
propane torch set to high and the inner blue flame tip to heat the
fluted or perforated area of the sensor. You should see a DC voltage
of at least 0.6 within 20 seconds. If not, most likely cause is open
circuit internally or lead fouling. If OK so far, remove from flame.
You should see a drop to under 0.1 volt within 4 seconds. If not
likely silicone fouled. If still OK, heat for two full minutes and
watch for drops in voltage. Sometimes, the internal connections will
open up under heat. This is the same a loose wire and is a failure. If
the sensor is OK at this point, and will switch from high to low
quickly as you move the flame, the sensor is good. Bear in mind that
good or bad is relative, with port fuel injection needing faster
information than carbureted systems. ANY O2 sensor that will generate
0.9 volts or more when heated, show 0.1 volts or less within one
second of flame removal, AND pass the two minute heat test is good
regardless of age. When replacing a sensor, don't miss the opportunity
to use the test above on the replacement. This will calibrate your
evaluation skills and save you money in the future. There is almost
always *no* benefit in replacing an oxygen sensor that will pass the
test in the first line of this paragraph.


How hard is it to remove an O2 sensor from the exhaust system without
damaging it? Can you rely on the computer diagnostic codes to tell
you whether the O2 sensor is bad?

 

One thing this "test" misses is checking the heater. The other pair of
wires are to heat the sensor - either to speed its response from cold,
or maybe the sensor won't get hot enough to work without the heater
working.

Most often they just come right out with no problem, but every now and
then you get a seized on that resist all efforts to get it out. In that
case the threads are so damaged that you can't reuse it. If you do take
yours out with the idea to reuse it, make sure you have some anti-seize
compound for the threads for reinstall.

Most of the time the computer diagnostic will let you know if a sensor
is bad - often in fact it's too sensitive and condemns sensors that
appear to be working fine. However, there are cases where the
diagnostics will not pick up a bad sensor - I even had on my S70.


--
Mike F.
Thornhill (near Toronto), Ont.

NOTE: new address!!
Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)

 

Hello,

I'm trying to find the nipple that you're talking about. The main air
hose appears to flow from the air cleaner endwise into the turbo.
Between the main air hose and the turbo appears to be an intermediate
place.

This intermediate piece between the main air hose and the turbo has a
vertical hose coming off of it. I'd estimate that this vertical part
looks like it's probably a 9/16" to 3/4" in diameter. Pointing
backwards towards the firewall from this vertical hose there appears
to be the 3/16" hose that you're talking about.

There appears to be somtehing else that connects to this vertical hose
pointing towards the front of the car. I've disconnected the hose
that connects to the nipple that points toward the firewall and have
tried to see inside it with a mirror-on-a-stick and a flashlight, but
can't see the brass insert.

Is this the right piece? How do you safely clean it?

-Eric

 

Eric,

I have to remind you that my limited experience is based on the 240 so
the location and ease of extraction will likely vary between the 240
and the 850.

On the 240 Turbo the O2 sensor is in an impossible place, on the
underside of the exhaust manifold crowded by the turbo and several
other hoses and wires. No room for a wrench to get good purchase. In
order to remove it (as there was no socket that was the right size AND
deep enough) we had to shear the end off of it with a long screwdriver
and a hammer and then use a regular depth socket to remove the
remnants.

What came out needed no testing to determine its status: It was white
and caked with deposits (it looked calcified although I realize no
calcium is involvoed). The slits in the tip of the sensor were almost
entirely sealed up with the white chalky build-up so replacement was
the correct course of action. Now had we destroyed it to remove it and
then found that it was shiny and new-looking I would have been out
some $$ and feeling foolish.

I believe there is a way to test the O2 sensor in situ so you don't
have to go through the hassle but, again, the procedure and desired
readings I have are for the 240.

Hope this helps somewhat.

blurp.

 

There are several sockets specifically for oxygen sensors. They make
getting the sensor out of your 240 turbo a 2 minute job, assuming you
have a long enough extension.

--
Mike F.
Thornhill (near Toronto), Ont.

NOTE: new address!!
Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)

 

Distibutor cap cracked?...happened to us, 850 T5.