Maintenance FAQ for 7xx/9xx/90 Cars
Opening Caution. [JohnO] If doing
it yourself, do it with a cold engine as many O2 sensors are more likely
to cross-thread if done hot (although not so much so with Volvos). If you
doubt your skills with this, just take it to dealer and pay them to replace
it as it won't be that much for the labor (about 1 hour).
Tool Notes. Which tool do
I use to remove the O2 sensor? [Paul Seminara] Us a crows foot
or special slotted O2 sensor socket or "adapted" open/closed end wrench.
Replacement Procedure. [Editor:
Tom's notes apply to a 960 but the procedure is similar for 740/940]
[query] I'm planning to change my O2 sensor on my 960 wagon. Where
is that thing? How tough of a time will I have in removing it because of
heat-related seizing. [Response: Tom Irwin] OK, if you
are w/o a shop and hydraulic lift, I recommend the following... FOUR
JACKSTANDS Rated to 3,000 pounds apiece or better. I've been lifting the
car under it's mid-chassis reinforcement with a large wide-saddle jack.
A skinny jack will damage the underside of your car... Lifting the
whole side, place 1 jackstand each under the corner lifting points, at
FULL-EXTENSION... do the drivers side first... Ditto the passenger
side, BUT LEAVE the jack in place and lower it maybe 0.5" so it is a back-up,
in case the jackstands fail, but it is NOT bearing any load... (could cause
they whole deal to shift.) Lay down a HEAVY piece of corrugated cardboard...
Let's you SLIDE in and out from under the car real nice.
The O2 sensor is screwed in to the CAT,
up on top, there are four wires. FIRST! Go open the hood and locate
the O2 connector... it's kinda near the oil dipstick tube, about half-way
down. It should be clipped to a metal standard...release it...there is
enough slack to lift the whole assembly up higher for a better look.
It is a BLUE plastic connector with a RED slide-Lock passing through it's
mid section. Use a small thin screwdriver under the looped bail of the
red slide lock and pry it gently to the side, extend it as far as it will
go. Separate the 2 blue plastic halves make sure that the end
of the harness that goes down below to the O2 sensor is not wire tied anywhere.
Go back Down Under the car, pull the wire
down and cut any cable ties holding it to the dipstick or elswhere.
Now on the left side of the transmission there are 3 plastic snap-lock
clips holding the wires to the transmission pan. Squeeze them from
the inside with a thin nosed plier and release all three. On the
UPPER, TRAILING EDGE of the transmission tail bracket, there are 3 10mm
headed bolts holding the wire to the bracket. Remove all three.
A small 1/4" drive ratchet is great for this. Then remove the
ONE speed nut holding the wire up on a heatshield in front of the CAT.
Follow the wire... THAR she IS... sticking out of the top of the CAT, in
front of the honeycomb. It is a 22mm facet on the base of the
sensor. Get a 22mm socket with the sidewall slotted out for the wire to
pass thru (Editor: known as an "oxygen sensor wrench")... if you can...
but I just squirted a bit of PB Blaster on the base and let it sit for
a few minutes.
I ended up using a 22mm spanner wrench
open end to the sensor.. It cracked free quite easily... you may be so
lucky.. Then you just un-screw it. I know this is trite....but...."Re-Assembly
IS reverse order". REALLY! [Note from WBain] Use an anti-seize compound
on the threads (if the sensor did not come with any.) It will make any
future disassembly easier. [Caution from David Hunter] Also make
sure you are not cross threading it - easy to do on the O2 sensor.
Manifold Leak. [Problem:]I own a 1990 740 wagon with the B230F with
an exhaust leak at the manifold. Is this a common problem? Do the exhaust
manifolds warp easily? [Diagnosis:] The exhaust manifold gaskets on the
B230F tend to blow out every once in a while. Mine has a leak next to #1
but since it's not major or real noisy I'm waiting for the rest of it to
go or get worse. If you have to change the gasket be prepared to get new
bolts/studs and keep a stud extractor handy as they always break off.
Manifold Gasket & Studs Replacement. [See the section Turbo: Broken
Turbo Exhaust Stud] [Query:] My 744ti currently has 184,000k
mi. It is leaking a little at the exhaust manifold so it is time to replace
the gasket. I have noticed that it looks like it is the original gasket.
I am thinking about replacing the studs and the on the head when the gasket
is replaced. Is this a good idea or am I wasting my money. I want to do
the job right from the beginning.
Applying Penetrants. [Response
1: Onkel Udo] You might want to spray the studs w/apenetrating oil repeatedly
for the preceding days. When you reassemble, use antiseize compound
on the new studs and coat the exposed areas with a silicone spray or a
grease of some type. There is nothing more annoying than trying to
remove rusted-in-place nuts on exhaust flanges knowing that at least one
stud is going to shear off no matter what you do.
Using Heat. [Response 2: Don
Foster] If the original studs appear "eroded" (rusted away) and you think
you can remove them without snapping even one, then new studs would be
a cheap investment. I dearly love my oxy-acetylene torch. Every time I
use it, I kiss it. You might also consider replacing the big O-ring in
the oil cooler adapter at the same time -- they age, dry out, crack, and
start leaking at about the 10-year point with your mileage, and are a B*ITCH
to get to -- but with the turbo out, the area's wide open, and access is
In the Event of a Broken Exhaust Manifold
Stud. [Query:] How do I remove a broken exhaust manifold
stud, broken off below the surface. [Response: Paul Seminara]
Got a right angle reversible drill? Got a moto or air grinder tool? Got
some diamond bits? Got a locking collar type stud remover? Got the
appropriate size left hand cobalt drill bit? Got the appropriate drill
and tap? With the above tools it's actually not that bad (BTDT).
Start with the left hand drill bit (smaller
than the stud in question, correct size for stud remover) with the drill
in "R". Maybe the stud will come out maybe not. If not give the stud remover
a shot. DO NOT, I REPEAT DO NOT EVEN THINK OF USING AN EASY OUT.
If the stud remover fails or doesn't cut
it you must go into full dentist mode with your high speed tool and diamond
bits. Just follow the stud and don't go outside the envelope. When most
is gone simply drill the hole to the correct size for the tap. Clean hole.
Tap, clean and insert stud. Done.
[Cautionary Note] I have fixed broken
head studs three times before, on different cars. On all of them
I pulled the head and used a drill press and "easy-out" to remove the stud,
also lots of heat. You can buy an easy-out/drillbit set at most autparts
and machinist places. The drill press ensures an accurate hole (remember,
the head is softer than the bolt; you don't want to miss!) It was
Removing a Broken Stud with a Right-Angle
Drill. [Tip: Bob Mohr] Been there, done that. A right angle
drill will work just fine. I'd suggest using a diamond bit in a Dremel
rotary tool to put a nice, centered starting "dimple" in the middle of
the broken stud to prevent the bit from walking once you start. You shouldn't
have to buy a special diamond tipped drill bit. I went down to the local
industrial supply and purchased a cobalt bit that went through that old
stud like a hot knife through butter. Have a bottle of cutting oil nearby
and squirt a little in the hole every quarter inch or so to cool the bit
and flush out the shavings. I ended up drilling it out oversized and installed
a helicoil. It worked great.
Another tip if you don't
have a right angled drill. I used one of those fiberglass reinforced cutoff
wheels in a dremel to reduce the length of my cobalt drill bit. You have
to be careful chucking the drill bit, as it's tough to get it in straight.
Cutting down the drill bit gives you just enough clearance to get a straight
shot at most of the studs with a plain jane 1/4" drill.
DANGER, DANGER, DANGER! Do not
attempt to drill a hole in the stud and use an extractor/easy out. The
extractor can and probably will break off in the hole. Then, your available
options are reduced to pulling the engine and having a machine shop mill
out the extractor/old stud or spending 24 hours and a dozen diamond bits
to hog out the broken extractor millimeter by millimeter. It ain't fun!
Both Seminara and I both went through this torture! [Tip 2:
Dick Riess] Have done it with the 90 degree drill, unfortunately w/o diamond
bits and kinda made a mess, but my machine shop friend let me use his Time
Cert outfit to fix it. Evidently the Time Cert is used extensively on hopping
up the old aluminum VW engines. They just don't come out. So if you mess
up the threads, there is still hope. BTW, I am going to have to get
some of those diamond bits from Paul---they sound like a life saver and
you can count on needing them eventually.
Replace All with Stainless.
[Response 3: John B ] wouldn't fix the stud problem if it's not a
problem. OTOH, if you break one stud in the process, might
as well replace them all. I think IPD has a stainless steel
Turbo Notes. When you pull
out the manifold/turbo, then's the time to replace the turbo/tube and tube/block
gasket and O-ring. Even if you don't pull the entire manifold/turbo
out to replace the exhaust gasket (best case) the turbo oil tube is a lot
easier to reseal with the manifold loosened (and the two bolts holding
it onto the turbo removed). How's your 02 sensor? It's easy
to get to with the manifold out.
Painting the Manifold. [Tip from
Tom Irwin] Don't paint your exhaust manifolds, even with hi-temp
paint, no matter HOW COOL it looks! The paint burns off under the bolt
heads and relieves bolt compression. Almost ALL were under torque spec.
[Editor] Probably OK to paint IF you don't paint under the bolt heads.
Converter Diagnosis. [Tip from Fluke Corporation:] Using a Fluke
Digital Multimeter with the 80T-IR/E Extended Range Temperature Probe,
you can easily and quickly assess catalytic converter efficiency. For this
test, first run the engine until the engine is warm and stabilized. (For
engines with electric cooling fans, let them cycle a few times prior to
the test) Then shut off the engine and disconnect a spark plug wire on
one bank of cylinders. (Note for V engines: If there are dual converters,
you will need to perform this procedure on each bank of cylinders.
Restart the engine and block the throttle
to maintain 1000 RPM with the one cylinder not firing. Measure the inlet
temperature of the converter and compare it to the outlet temperature.
You should see a differential of 50 degrees F. or more if the converter
is working properly. If the temperatures are less than 50 degrees apart,
then the converter needs to be replaced. Before replacing a converter,
be sure to determine why it may have failed. If it is a very high mileage
vehicle, it is probably just expired. If it is low mileage, you should
perform a thorough check of the vehicle to determine the cause.
For normal engines with a misfiring cylinder at 1000 RPM, you can expect
that the temperatures observed will be in the 600 to 900 degrees F. range.
Converters. The cat thread was my doing since I raised the question
regarding my '85 740 GLE. To sum up all of the advice I received, replacing
the cat should be done if it is indeed in faltering condition--although
people seemed to vary in their senses of urgency for having the replacement
done. The reason for having it replaced--besides making passing emissions
dicey in some states--is that the cone in the converter can come loose
and plug the exhaust or can break up into pieces and shoot back through
the exhaust into the muffler, etc.
I also called around about aftermarket
cats and found one for $100. Herzog-Meier 800-858-6608 sold the VCNA aftermarket
for $305 since I'm a IPD customer (you have to tell them this to get the
20% discount!) If you can replace it yourself maybe that would be a good
idea (I can forward you the email I received from the car parts place).
If you can't then I suggest taking it to Midas or somewhere that specializes
in that stuff and replaces them on a regular basis. My Volvo guy was quoting
prices of up to $350 installed. Based on some advice from a list member,
however, I went to Midas two days ago and had it done in an hour for $208
not including tax.
[Another Query:] The catalytic converter
on my 1989 740GL Wagon needs to be replaced. One shop said that they do
not recommend after-market parts, since the performance is never as good
as with the manufacturer's parts. Another shop didn't see any problems
with using an after-market catalytic converter for about $350, compared
to manufacturer's (Volvo's) price of $1300. To me this is a large difference.
I am wondering if anyone else has any experience with replacing the catalytic
converter [Response: Zee] Euclid Foreign Auto Parts, near Cleveland,
OH can sell/ship a decent aftermarket cat. for about $150 (Euclid"s tool-free
number: 1-800-837-5110. You must ask for Tina and mention the Brickboard
bulletin board for the discount.) I have had a good buying experience
with them over Christmas when I ordered a Bosal downpipe (it's the one
just in front of the cat. that goes between the cat. and the exhaust manifold).
$69 +$10 tax and shipping, sent to my door within two days from Rochester,
NY. (I live in PA) What you want to look for when buying any after-market
part is that the part meets or exceeds O.E.M. specifications (Original
Equipment Manufacturer). You have to ask, or tell parts suppliers you want
this, or they can sell you cheap, Asian look-alikes.
Replacement: Brands [Editor: Numerous questions about which brands
to buy are addressed below.]
[Response 1:] I replaced the exhaust
system on my '87 740 Turbo last summer with a Volvo kit. The kit which
includes all the hangers and clamps for the car was about $285 and only
took me about an hour to install. The kit includes everything from behind
[Response 2:] I bought the Volvo
kit because I have heard that they last longer than the muffler shop kits.
Having had a few 240s over the years, I have visited the muffler shops
a lot. However, the 240s have so much exhaust plumbing compared to a 740,
I would expect the 240 to go through them faster. I figured that at $285,
it would cost me about that much to have a muffler shop do the work. Then
I will have to deal with the periodic returns to have the system replace
under warrantee. Figured it was worth a try.
[Response 3:] I bought a replacement
system mfg. by Starla, just received yesterday. All parts made in Sweden.
EVERYTHING from the rear of the cat back, including clamps and hangers,
was $245 including shipping. Bought from RPR.
[Response: Vladimir Kordac] Stay with
Volvo or a quality after-market system. Forget Walker, Maremont etc. with
their 2yr "lifetime" crap unless you want to eek out a few more years out
of the present system! I put in a complete Bosal system recently
from down pipe to tail pipe including cat, that went in flawlessly. Total
cost was approx. $325. Bosal is supposedly comparable to OEM. We'll see.
[Response: Rob Bareiss] Either the IPD
system or the factory Volvo exhaust kit will make you happy. You will also
find parts stores which stock "Starla" brand original fit exhaust components.
The stuff is great quality. Goes on just like Volvo's. Lasts as long
as your originals did, and costs about the same (a bit less). We use a
lot of Starla and Volvo brand parts at our shop, and the difference between
those, and the "M" or "W" brand junk we throw away is amazing. Get
the real stuff, you'll be much happier you spent your money WELL and ONLY
Replacement: Procedures. To remove the front muffler pipe from
the cat. pipe, I put a reinforced cut off wheel on my Dremel tool and slit
the muffler pipe just deep enough so as not to cut the cat. pipe. Pried
open the slit on the muffler pipe and everything came apart. (Also need
to slit the joint behind the front muffler so that it can be separated
from the over-the-axle pipe, but here you don't have to be so careful with
how deep you cut.)
Installing the Volvo kit was a dream.
All the parts FIT! None of the pipe ends were dented requiring hammering
to make them go together. The pipes had smooth curves, not ribbed curves
as often found on after market kits. Furthermore, the system is probably
better sized for the car which hopefully will result in less trouble for
us turbo owners.
[Response: Gary DeFrancesco]
These hack muffler shops are more trouble than they are worth. I have not
had the pleasure of getting into the exhaust system of a '89 740, so I
don't know what the differences are with the earlier 740s. Assuming the
basic design and arrangement is the same, and speaking from experience
with my '87 and '88 740Ts, I would go with the Volvo exhaust system. The
kit Volvo sells has everything you need behind the cat. It even includes
the hangers. My dealer hit me just less than $300 for the kit, and it went
in like a dream. It took me less than an hour to do the job.
In your case, you have to deal with the
muffler pipe being welded to the cat. One approach would be to cut
the muffler pipe off several inches down stream from the weld. Then using
a die grinder, remove the remains of the muffler pipe from the cat pipe.
A Drummel tool will also work, but it will take longer. The first thing
to do is slit the muffler pipe open length wise. Then carefully slit the
muffler pipe next to the weld to free it from the cat pipe. The idea is
to not cut into the cat pipe while doing this. It will take a gentle touch
and some time. Once the muffler pipe is off, then the weld can be removed
with a grinder wheel. However, if the weld is far enough onto the cat pipe,
you may have little or no need to remove the weld bead if the new muffler
pipe does not go on the cat pipe as far. This will be a PITA job. But the
cost of a new Volvo cat may convince you to get creative. (Don't know what
a cat for you car cost, but Volvo wanted over $850 for my '88 740T!)
This leads to another approach to the
job. Replace the cat with a good quality after market unit. There are some
decent ones out there for reasonable cost. Just make sure it is a direct
fit unit and the pipe diameters are not restrictive entering or exiting
the cat chamber. With a new cat and the Volvo exhaust kit, you should be
able to replace the exhaust system in an hour or two.
[Response: Vladimir Kordac]
You'll have a small problem with that welded cat. May have to cut back
beyond the weld and use a small adapter piece to mate cat and front muffler
(resonator). What kind of shape is the rest of the exhaust? Unlike
hunting an electrical problem that may take me hours-years, changing an
exhaust is a no-brainer. And results are dramatic. Usually the worst part
is getting the old stuff off; however, since I was replacing everything,
I didn't have to mess with cat connections or any
other frozen areas. In the past I would
get out the Dremel or rotary cutoff tool to slice through clamps and pipe
ends. It would help a great deal to elevate car on all fours.
[Response: Warren Bain] On installation,
don't forget the Permatex anti-seize compound on the threads, it
makes removal a dream. I use it on all my exhaust systems and the bolts
just turn right off with out any problems.
Brackets Keep Breaking. [Query:] 've replaced the exhaust bracket
about three times during the past 5 months every since I replaced the system.
The bracket keeps on breaking/splitting at the same exact point all the
time. Does anyone know why this is constantly occurring? [Response:
Paul Grimshaw] Check your motor mounts. Bad mounts can put greater
torsional strain on the pipes. If they're sagging or twisted, replace both
of them. Also suggest changing the tranny mount at the same time.
Next, loosen all of the pipe joints, replace your bracket. Now lightly
wiggle the pipes to find their (untensioned) resting point. Make
sure that no areas of the pipe are touching the chassis. Make sure
that at full droop, your 740's rear axle is not hitting the cross-over
pipe. Now tighten things up carefully. [Response 2: Dana]
Make sure you still have the spacing ring in between the two pipes and
that all the exhaust flanges are in place and not stretched out to far.
I had a problem with my bracket and clamps loosening up every 1000 miles
or so. Turned out the bracket was a manufacturing defect and the
clamps I used couldn't hack it.
Smell: Leaking Injector Seals? [Query:] I have a problem with
my 760 Turbo that my mechanic can't solve: when accelerating hard, with
the ac and the fan on, a strong smell of exhaust comes out of the vents.
when the fan and the ac are off, there is no smell. Can anybody help with
this? The mechanic says that it can not explain why there should be any
smell of exhaust coming in, which, by the way, happens also with the recirculation
button turned on. [Response: Steve Seekins] I suspect that what you
smell is not exhaust, but raw gas. I had this problem on a couple of turbo
cars. The source was injector seals. When they get bad on a turbo,
they suck air into the manifold at idle and off throttle (whenever the
turbo gage is in the vacuum zone). However, under boost, the manifold is
pressurized and fuel mist from the injectors is forced out past the injector
seals and then gets sucked into the vent system by the intake at the front
of the windshield. It is worst under heavy load when manifold pressure
is highest and more fuel is being injected, and you only get it when the
vent system is operating or the windows are open.
Check at idle with can of spray carb cleaner
or unlit propane torch jet. Spray or direct jet at each injector base in
turn. Any change in engine rpm indicates leaking seal. Also check intake
manifold gasket area and look for combination of bad hose from fuel pressure
regulator and leaking pressure regulator.
FAQ for 7xx/9xx/90 Cars
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