92 740: change old 02 sensor or not?

I took the old and new idler/tensioner rollers to a mechanic shop
where I had some suspension work done at once .....and he had the
spring swapped over to the new idler/tensioner roller in five minutes
and charged nothing for it!


back to the new subject:


The 02 sensor is about a $100 part. I believe they are more prone to
go bad than other sensors. Question is how do they go bad? I am sure
it is old, lots of miles, but just how many is unknown as the car was
purchased two years ago and had no service records with it. The ECM
is not setting any code for a bad sensor now. So I am wondering if it
is possible for one to go bad in a way that it still functions enough
not to set a code, but causes the mixture to be set too rich?

Thanks, geronimo

 

Usually they get lazy, if you measure the output with a multimeter it
should be bouncing back and forth around approximately 0.5V, if this
bouncing gets slow then the sensor should be replaced. Normally you'll
notice significantly reduced fuel economy too.

 

FWIW, I replaced the O2 sensor on my '89 240 a couple years ago, using a
Bosch 13913 sensor from Autozone... the only difference was that it didn't
have the long leads that I needed, so I cut the old ones off the old sensor
before I removed it from the exhaust system, cut the new connector off the
leads of the new sensor, screwed it into the exhaust (using the anti-seize
lube), and then connected the wires together using crimps... works fine, and
as I recall, the generic was around $35....

There are two white wires (heater?) and one black wire (signal?), so you
can't go wrong...

 

Yep, you can save a lot by going generic so long as it's still a Bosch
sensor.

I've heard they fail but I have yet to have it happen on a Volvo. My
mom's 245 was over 260K last I checked, still on the original O2 sensor
and still manages ~30 mpg highway and passes emissions just fine so I
have to assume the sensor is still ok.

 

Hey James, I noticed that I had to set the timing mark on the camshaft
pulley *way off* the from the mark on the back of the timing belt
cover, just like the damper pulley mark was way way off because it was
slipping due to no key. Well, I took the camshaft pulley off to see
why, and found that although at least it HAD a key...a round pin/tube
type of key.... the portion in the end of the camshaft had entirely
rusted away! So it too had slipped almost 90 degrees off. Maybe I can
make a new one out of an appropriately sized old drill bit.

But there is a big problem with the damper pulley.Have you ever had
key or wobbling problems with one on your 240s/740s? I made a new key
out of 3/16 barstock, which fits the groove in the damper pulley,
installed in pulley. Should have checked the crankshaft end out first
though! When mated up to the crankshaft I discovered that the crank
slot is 1/4 in. (or actually the metric equivalent of that)! It
must not be the original damper pulley! Also, the crank key slot
isn't a straight cut but is "scalloped" or curved. So I don't know if
one home-made out of straight barstock will even work right. I guess
it would be weaker if it doesn't follow the curve of the slot. The
crankshaft end and the timing sprocket LOOK perfect...yet when I
temporarily put the damper pulley back on, I see why the pulley was
wobbling/belts vibrating! Shoved all the way up against the crank
sprocket (front sprocket guide on), you can rock it back and forth
about 3/16 in.! It seems highly unlikey that there would be anything
wrong with the sprocket or crank end....yet I went over the mating
surface on the damper pulley with a file and it appears flat. There
wasn't a burr or high spot. Also it is a two-piece one with rubber in
the middle, and the rubber is very dry/cracked.....could separate
possibly. So I guess I will get a new damper pulley, Rock Auto has a
new one for $75.00. Very pricey! I figure the rubber on any similar
model/ year is liable to be in just as bad shape as mine is. Then I
will see what that does for the wobble. A new crank sprocket is about
$40.00. If the problem is the crankshaft....but probably isn't....I
am just totally screwed. Can't exactly take the engine down to a
machine shop.


Any advice on the problem?

On second thought...maybe I will ask the brother if he will take back
his car ;-)

Something amusing on the radio I heard: Neil Bortz was talking about
how it seems to him that liberal lefties prefer Volvos for some
reason. Then he says, "DO you realize that Volvo is the only car
model named after a body part?" ;-)


Geronimo

 

Yes, the dampers do fail. It happened to my wife while driving in town,
fortunately. There was a BANG and the power steering went dead. All the
warning lights came on and she saw something roll off the road behind her.
It was the outer part of the damper :-( Your '92 probably has about the
number of years on it hers did at the time.

Mike

 

If the key is missing just go to the dealer and buy a new key, or a
wrecker, from the sound of it you *really* could benefit from wandering
around a yard with some Volvo scrap, it's by far the easiest way to get
parts like this.

I've heard of the harmonic balancers failing but I've never had one do
that myself. I'm sure my time will come since my cars are older than yours.

 

I did actuallly have one fail on my now defunct 89 Volvo 740 sedan.
My wife was driving it at the time. There was a noise, the alternator
light came on , lost power steering, then the temp climbed into the
red. The outer part didn't fly off, but remained on the front of the
engine, kind of twisted around at a 45 deg. angle by the accessory
belts, and it rubbed a big hole in the timing belt cover. What a
mess.

Yea, This would all be a lot simpler if I could go get a key at a
Volvo dealer. Unfortunately it is a 150 mile drive to the closest
one...San Antonio.


Geronimo

 

Can you mail order one? Heck if it's the same key as a B21F uses I have
one you can have for the cost of postage.