Mystery oil leak - 960 with 122,000k miles

tomoni40 · Post by **tomoni40** » 22 Jan 2011, 09:37

I have a 1994 VOLVO 960 with 122,000 miles on it. It has not been driven too much lately. It is a 6 cylinder engine, type designation “B 6304 S”
After been parked in the garage, I decided to star driving it again (I was overseas for 3 months). I drove it without any problems the first few days, when I discovered oil in the garage floor. I started looking for oil leaks from the obvious places in the car. No oil from the pan underneath, neither from the oil filter area.

After a more detailed inspection, I found oil in the back of the engine, under a round black plastic piece, and running down to the floor.

“SEE ATTACHED PICTURES

: 1

At first, and after doing a search on the web, I thought the leak was coming from the back of the engine from a leaky valve cover gasket, but, I understand that these cars do not use gasket, but instead are sealed with a very special type of sealant.
I was unaware of that, I started dismantling the top of the engine, in order to lift the valve cover, and replace the “alleged gasket”
After an exhausting couple of hours removing close to 60 bolts, and

“SEE PICTURE AFTER REMOVAL OF ITEMS”

ancillary items, I could not budge the valve cover, coming to the conclusion, that most likely this car do not have a cover gasket, but instead could have been sealed with a particular type o sealer.

Therefore after my first attempt with the valve cover gasket, I decided to continue searching for other places where the oil leak could come from.
I read some posting from people with similar type of problems like mine, and they talk about another possible leak problem caused by a plugged up PCV valve, that in these type of cars are known as “Flame trap” arrestors.
I took a closer look at my car, and I found, what I think it is the Flame trap arrestor located at one end of the air intake. I found a small amount of oil, at the bottom of the hose.
(SEE PICTURES ATTACHED)

Therefore, I would like to know what you guys think about this semi-challenging mystery, and tell me how to proceed next.
Any other clues about where the leak might come from are most welcome.

If you need any more information, and or pictures, please let me know.

Thanks a million in advance, and good hunting!

Post by **jimmy57** » 22 Jan 2011, 09:56

The item on back of head is the cam position sensor. THe cover carries the sensor and below it is a shutter wheel piece that works with the sensor and is bolted with one bolt to camshaft end.
The seal is behind the shutter wheel.
The seal can be removed with a screwdriver but the installation of the seal with the firewall in the way will require an installation tool. The tool will use a bolt and a big washer and a correctly sized sleeve to push the seal into place evenly.

You have Identified the flame trap and you might try cleaning it, the fitting it inserts in to, and all vacuum hose nipples and the vacuum line itself. Also replace the connector pieces of hose but not all hose will work.Some grades of rubber hose that size are comaptible with washer fluid but not oil and fuel vapors. Often the hose kept on the shelf at auto stores that will work is a braided layered hose that is labelled "fuel". Do the flame trap service first as pressure in the crankcase may be making the seal leak and it might (cross fingers, knock on simulated automotive woodgrain) stop the seal leak.

If it doesn't you may find the loan of a tool here.
The only tricky part is to get the cam sensor shutter wheel back in correctly. You're working blind and it can go on 180 degrees out pretty easily.

Post by **precopster** » 22 Jan 2011, 17:14

If the flame trap fix fails to cure the leak, you can then assume the rear cam seal(s) are leaking.

I just did the same job last weekend, and thanks to jimm57 have it running again.

The cam sensor removes with two torx 40 bolts which is close to the earth lead at your photo.

If you take out the 46 bolts for the cam cover, you need to place the engine at TDC and create some marks on your belt and pulleys (around the cam sprocket bolts too) for reference. DO NOT LIFT THE CAM COVER WITHOUT SETTING THE ENGINE AT TDC. Also you will need to remove the cam belt.

You can't get the cover off because of all the gasket goo that has set solidly. I hit one of my cam sprokets from underneath with a solid metal hammer to separate the halves. I tried softening the blow with wooden blocks but they had no effect (I had a spare cam sprocket so no big deal) The parting lugs at spaced intervals were no help.

The timing system used is the same as the 850s so lots of posts on how to find timing marks. Also I have a bunch of photos from last week's cam seal replacement so let me know if you need some more info.

In my opinion I wouldn't tackle the rear cam seals (there are two of them) without a cam seal fitting tool. It is almost impossible to refit them without one of these as below. Also it is VERY difficult to remove them without splitting the top of the engine. Count on two days to get the work done. You may want to look at the front seals as when the cam cover lifts off you might as well do these also.

tomoni40 · Post by **tomoni40** » 23 Jan 2011, 10:12

Thank you guys for your prompt response. I will star with trying to clean,and replace the flame trap,and put new tubing,and hoses.I am keeping my fingers crossed,that doing that the problem will be solved,because to work on the cam seal,it looks like it is a huge task.There is no room between the black plastic cover,and the car wall.I will take a closer picture,and post it to show you,what I am talking about.
The Flame trap job,I will tackle this week,because the weather it has been too cold here in central Florida.I will star next week,which it will be a little warmer,and I will post the results.
Thanks again,guys.
"Let the force be with you"

Post by **precopster** » 23 Jan 2011, 10:47

Didn't want to frighten you, just that I can't work with inspection mirrors.

You, however could be better balanced and have been trained by Yoda himself. If this is the case buy an inspection mirror and try removing the cam seal without the whole disassembly routine I spoke of, just be patient with it and don't scratch the seal bore in the head or cam cover.

Good luck.

tomoni40 · Post by **tomoni40** » 30 Jan 2011, 13:13

O.K Guys. It finally got warmer here in Central Florida.Today it got up to 70 F. So is was time to tackle the oil leak project.
I put all the covers back together,and started taking apart the Flame trap and other stuff around it.

: Trap with Filter; Trap with Filter.JPG (324.6 KiB) Viewed 5456 times

: Filter or Strainer; Filter or Strainer.JPG (87.65 KiB) Viewed 5456 times

I found that the trap,and a small plastic filter or strainer ( photo attached) was full of gunk,and all the little holes on the plastic filter were clogged up with oil gunk. I took everything apart,and cleaned every single hole on the filter,and other parts.
I will try to put everything back together,tomorrow,the temperature will be 75 F( Great weather to work).
After putting all the parts back in their place, I will crank up the car to see what happens. Wish me Luck!
I will post to let you know about the results.
I am counting with Yoda's assistance!

tomoni40 · Post by **tomoni40** » 15 Mar 2011, 19:44

Problem mostly solved.I still have a very small leak at front,but no big deal.One of these days,I will look into it.In the meantime, I will drive the car like this. My sincere thanks,to all you guys for your assistance.
Now,my next challenge, is to fix the AC system,but that will be a brand new topic!
Thanks again! Keep up the good work.and "the force will be with you always"!

danr960 · Post by **danr960** » 16 Mar 2011, 10:17

tomoni40 wrote:Problem mostly solved.I still have a very small leak at front,but no big deal.One of these days,I will look into it.In the meantime, I will drive the car like this. My sincere thanks,to all you guys for your assistance.
Now,my next challenge, is to fix the AC system,but that will be a brand new topic!
Thanks again! Keep up the good work.and "the force will be with you always"!

From your initial pic, it also looks as though your oil filler cap gasket might be leaking, a $5.00 part, they do get hard with age and start to leak.

DanR '94 964 356,000 miles (122,000 on the new engine)

tomoni40 · Post by **tomoni40** » 14 Apr 2011, 08:41

I finally solved the small oil leak problem. I tied real hard all the bolts on the valve cover gasket,and that took care of the leak.
Thank you guys,for all your help!
Let the force be with you all!

Post by **billofdurham** » 14 Apr 2011, 12:39

Thank you for the update.

Bill.