My mother in law has a 94 850 with 132K miles. For the last 3-4 months she has been complaining of the car stalling under various conditions. She took it to a couple of 'knowledgable' mechanics but they could find nothing nor could they reproduce the issue. Classic.
We visited this past weekend for 3 days. I spent 2 days before that researching the issue on the web. I can tell you there are hundrends of reports of this happening to the 93-96 850 from all over the world!! From what I have seen the vast majority has between 99K - 150K when this happens.
Her stallings occured under different conditions and lately they were becoming frequent. The car would stop on decelaration to a traffic light. While accelerating on the freeway. While making a funky, off-camber left turn and sitting idle on traffic. Prety much all the stalling issues reported.
So, having only 2-3 days I tried most of the remedies that have been proposed here and on other forums & sites. Here's what I found and what I did:
- changed the Fuel Pump Relay (103) in the fuse box. Was getting a bit too hot for my liking (electronics engineer) and the contacts did not look that great either.
- replaced the fuel filter since she bought the car used and there were no records of this having been done before. Although the filter was not the original (did not have the undercoating) it looked like it was it's time when it was removed.
- Removed & replaced the entire Flame Trap assembly (flame trap, O-ring & holder). <$10 from the dealer and quite easy to do . Although the flame trap on the car wasn't in such a bad shape, the holder was very badly covered and covered with gue & carbon deposits. Stange.
- Removed and thouroughly cleaned the Throttle Body & housing. Now that, was a job. A little tricky to take the TB out mostly because of the vacum hoses running on that plastic elbow housing on top of the TB. Removed the 4x 10mm screws on TOP of the TB to make my life easier. Not as daunting as most would imagine but do take your time. The TB was covered handsomely with carbon deposits. Do I call it heavy? not really for a car with 132K. I removed the TB since it was so much easier to clean out plus, it allowed me to also clean the intake & the EGC hole which WAS quite clogged. Nicely 2-hour job.
- Since I was there, I removed and checked the flexible hose from the air filter to the TB. I was surprised to find that that was coated with oil? fuel? not exactly sure but definitely not to my liking. This was even worse on the plastic casing that was connecting this hose to the TB (which houses the flame trap). I guess if all that junk would go to the flame trap, it is logical to assume they would also coat the housing and hoses but the condition of the flame trap to the rest of the assembly was day and night. Maybe the previous owner replaced the flame trap not too long ago but did nothing to the housing? A little odd since she's had the car ~ 4 years now.
Overall, being a weekend warrior/mechanic I found all the info I needed on various sites including this with some excellent diagrams and photos. For those intimidated, I had never touched another Volvo before and I did all this in about 5 hours taking my good time plus I changed oil, flushed the brakes and a few other things like that. With the Fuel Relay & the Fuel Filter, cost was $129.75 in parts from the local Volvo dealership.
Now, the car is running much nicer and stronger. There are still a couple of things I would have liked to have time to check but if this keeps on coming, I will next time I visit. For one, the ECU is reporting a mixture too lean/ too heavy which I thought would go away after the work. It didn't. I'm guessing the O2 sensor needs a good cleaning or even replacement (there is an excellent page on the net about cleaning and reusing it).
Also, there is a strange -to me- noise when the car key is in position 2 or 3 from the engine bay. Sounds like and electrical humming and it is fairly loud and noticable with the hood open but not at all when it is closed. I narrowed it down to the area where the pulley & TB/ Idle Air Motor is housed. That WAS there before and is still there now. Since I have never worked on Volvos and the 850 before, does anyone know what the heck that is and if it should be there? Did not sound like it was coming from the ignition cap which is housed outside the black box covering the TB/Pulley/Idle Air motor.
Thanks!
will do the trick nicely. If on a pinch, I have used *a little* oil for sealing minor gaskets but YMMV. Dry would be a last resort for me and would require a little more tightening of the screws. If the TB contact area has imperfections or gook you cannot take out, try a little buffing with a drill/dremel but obviously use a light buffer. You really don't want to take any part of the surface off as sealing would become really hard.