I am wondering if these might be symptoms of my catalytic converter about to fail or if I need to look in another direction on my 01 V70 non-turbo.

1. Recently I have noticed a decrease in performance that is especially noticeable at speeds between 0-50mph above that it isn't as bad but noticeable. I also notice a foul odor from time to time.

2. Also have found that I now have a small oil leak again near the crank seal. About 3 months ago I replaced all the seals and flame trap box and hoses. Yesterday after I pulled in the driveway I turned the car off to check the oil and noticed smoke coming out the dipstick tube which never happened before till I noticed the decrease in performance.

3. Back in November we started to notice a rattling noise at exactly 2k rpms but would only do it at exactly 2k rpms and at speeds below 45mph. Now we hear a rattle at 2-4k rpms which starts out loud but gets softer as the rpms go up but it only happens when the car is in drive. It almost sounds race exhaust like on WRX's but not quite as loud.

4. Since the performance issues started my gas mileage has gone down dramatically. I am now getting only 19-20mpg in the city and max of 23mpg hwy. Before I was getting 22-24mpg city and 30-32mpg hwy.

5. I did get a CEL about 7 months ago and was told by the independent Volvo shop that I use to go to that the code pointed to a bad catalytic converter. They cleared the CEL and it has not come back.

I wanted to see what you guys might think before I throw alot of money into buying a catalytic converter and new o2 sensors.

 

Typically will get a CEL for O2 sensor or cat issues. An experienced tech should be able to listen to it, feel how much pressure coming from exhaust, to determine if it's restricted or not.

I would do all the basics first; ck compression; sudden decrease in compression in one or more cyls will give these symptoms too. Ck stupid stuff like make sure there's not a dead bird in your air box, etc.

Are you sure you did the PCV correctly? Clogged PCV could provoke the oil leak and mess up other stuff too.

How many miles on the clock?

 

It has 159k miles on it. When I replaced the seals and flame trap with hoses I also replaced the water pump due to it weeping along with the timing belt and components.

After I replaced all those items the leaks went totally away and didn't come back till recently as one small leak at the crank.

As far as replacing it correctly. As i've done on all my other volvo's when replacing the flame trap box I removed the intake manifold, unbolted the box, removed the clamps and hoses, install new box and clamps on the hoses, reinstalled the intake manifold with a new gasket and hose from the box to the intake. There are no leaks around the box as there was prior.

I've had two other tech's look at it and say that it sounds like a bad cat and also feels like it from the exhaust.

The air box is totally clean and has a brand new air filter.

I did a few months ago get a CEL showing a cat issue. The light has not come back since. About 2 months after the CEL I started getting a rattling noise from the cat which has gotten louder over time. The noise didn't get really loud till this week when the performance issue started at the exact same time.

A few friends who are master tech's for vw and audi think that my cat is clogged which is causing excess pressure since it can't get out properly which is causing my oil leak and performance issues.

I just wish my V70 didn't have that darn odd ball cat which is part of the exhaust manifold.

 

RE: cking for restricted cat, from Volvo's BasicTesting.pdf:

Exhaust System Backpressure
1) Exhaust system can be checked using a vacuum or pressure
gauge. Remove oxygen sensor or air injection check valve (if
equipped).
2) Connect a 1-10 psi pressure gauge, and run engine at 2500
RPM. If exhaust system backpressure is greater than 1 3/4-2 psi,
exhaust system or catalytic converter is plugged.
3) If using a vacuum gauge, connect vacuum gauge hose to
intake manifold vacuum port and start engine. Observe vacuum gauge.
Open throttle part way and hold steadily. If vacuum gauge reading
slowly drops after stabilizing, exhaust system should be checked for a
restriction.

 

As you suggested earlier I did a compression test and found all cylinders were getting between 150 and 148. I also did a test for the CAT and I have pretty much ruled out that being my issue now.

One thing I did notice when I pulled my ignition coils out that # 3 and #5 had really hot coil boots. the #3 coil boot seemed the worst and also noticed the spark plug in that cylinder was worn differently than #1,2,4 and 5 was similar to 3 but not as bad. I pulled the boot off #3 and found the spring was very thin compared to a normal one. I went out and purchased a new coil boot which has a new spring with it. After installing everything and starting the car the first think I noticed was that it sounded like it was running alot smoother than before and my wife agreed. Upon driving the car I now have my acceleration back and also the shift lock is gone which may have been a misfire that would happen if we had to quickly slow down due to a car turning and we would speed back up. We also noticed that the car ran alot quieter while going down the road than prior. Also all the plugs and cylinders looked like they had unburnt fuel.

I did go ahead and replace the rest of the boots and springs to see if it made any difference but in the end it didn't. I did notice that my fuel economy did improve a bit compared to before but still not as great as it was. One thing we have noticed is that it is now randomly having power loss as before it was constant. I'm thinking about replacing the ignition coils to see if that changes anything but another thing i'm wondering is if it may be the MAF. I've read in a few threads that this can cause the same issues and not throw a CEL. I'm also kinda confused as how to test the MAF because I've read if you unplug it while the car is running and it stays running then the MAF is bad and if it dies then the MAF is ok. When I unplug mine it stays running it almost seems to me that my idle smooths out a bit. Is there any other way to test the MAF?

 

First according to my info your compression is on the low side; ck your owners manual but isn't the compression ratio around 10.5 to 1 on this engine? If so, should be up around 180 psi on a perfect engine; even my tired NA is around 170 or more. Low compression will definitely impact performance and gas mileage.

So how did you rule out a plugged up exhaust? Wondering if a lot of back pressure could reduce a compression reading; possible i guess.

Also am very surprised you didn't get any CELs if you had ignition misfire..hmm

Re: testing the MAF; usual symptoms is runs crappy at idle; runs better (at idle) when unplugged. If you want i could dig up the diag procedure for it from the manual i have..

 

I did try unplugging the MAF and drove it around and noticed right away that my throttle response was dramatically improved and that my idle at stops and in park were dead steady at 800-850 rpms compared to with it connected and after putting the car into park it would go between 600-1000 rpms. A friend is shipping me a MAF from his S60 that unfortunately got totaled last week.

Also someone in another forum suggested a seafoam treatment in the gas and intake. I put a full can of seafoam in a full tank of gas on Friday and took it on a 400 mile round trip and noticed a significant improvement in my fuel economy. That trip I got 28mpg which is what I use to average when traveling to and from the mountains.

I just put seafoam in the intake and noticed that cruising down the hwy was alot smoother than before.

I did notice some shift flare and slight hesitation at random which seems par since it has been around 50k since I performed a transmission flush and acted that way before I did the last flush. I have read a few people suggest adding Seafoam Trans Tune before doing a flush. Have you had any experience with it?

 

I am chasing a similar problem on my 2001 V70. The MAF on the way sound very promising. Like you I had codes for catalytic efficiency but mine would return after clearing! I changing the downstream o2 sensor and fixed that code but not my performance issue.
I had some strange values on my scanner too... Like negative numbers for the o2 sensor. I will explore possible vacuum leaks next but will unplug my MAF asap thanks.

To rule out the cat, I pressure tested at each o2 location and it passed, well below the 1.5lb back pressure a number I got from others on this site.
I must say I never had any sulfur/ egg smell like you mentioned which sounds a little suspect to me.

I just did this CAT test so it is fresh in my mind, so bear with me as l list the steps for you or another reader.

In case you re-visit the cat you will need to make 2 adapters that tread into the o2 sensors. I can recommend an easy method with no tapping- just grinding. The goal is to make a “T’ prior to one pressure gage then pinch off the ¼” ID tubes from each cat for each reading.

Start by using 2 each of the following item list:

1. Autolite # 45 spark plugs, bench grind off the top crimp (wire connection side) discard the insulator.
2. 2" long x 1/4 NPT black iron pipe nipples (clean pipes & plug body) with alcohol & sandpaper.
3. Seal the pipe into the spark plug thread body (18mm x1.5) with “quick steel epoxy putty” good to 500F smoothing the ID with tooth pick so it remains open.
4. Teflon tape on both thread ends.
5. Add brass fem 1/4 NPT x barb to match hose and another for your pressure gage (total of three ).
6. The two tubing lengths can be long enough to reach the driver’s seat to a "T” plastic 1/4 barb and a short piece of tubing to the barb of low pressure gauge.
7. A vice grip can be used to pinch off the tubing of each hose as you hold the throttle at 2500 rpm and take you readings.

 

I actually just had to revisit the cat issues because it started having issues with starting and once it did start it would hardly move. I did purchase a new cat made by DEC but when it came in it was somehow damaged in shipping which caused almost all the matrix inside to break apart. I did do a test fit thou and found that cat heat shield and the preheat hose heat shield no longer fit at all on the new cat. I also did a test with the new busted cat and car started instantly and also had all its power back.

I just returned the defective cat yesterday so I'm waiting on my refund so I can order another cat. I called around to a few local Volvo shops and was told that they ran into the same issues with the heat shields on the DEC converters for the 01 V70 non-turbo's. They said the one made by Davico works perfectly so I'm gonna order one of those as soon as I get my refund in the next few days since nobody locally can get them.

Here is a picture of the old and new cat. I can't believe how much of a size difference there is.

 

Yes those two cats are very different and I just bought running shoes like yours too. Lol
You got the new one with shiping damage..wow somone else has my kind of luck!!
I have the turbo and it has a long extention pipe with braided covering and the cat is about 3 feet from the manifold..it looked expensive $$.
Thanks for the update.

 

The cats for the turbo model's are alot easier to find and cheaper than the non turbo's. The cat in my 01 V70 non-turbo was only used in 01-02 V70's.

When I would go to a euro parts store and get a price for a converter they would try to sell me the one for the turbo model and tell me there is no such thing as a converter that is part of the exhaust manifold. I had to get the parts associate and the owner to come out to the car to prove it to them because they said I didn't know what I was talking about. The look on their faces when they saw that converter was priceless .