850 oil smoke on idle

dannyboy · Post by **dannyboy** » 21 Sep 2006, 12:52

Hello everybody,
I am new on this forum I discovered today and found tremendously interesting. Already got great tips and hints from you guys thanks very much. To make a long story short (my Volvo story) I had 6 different Volvos since 1983 (3 240's sedan, 1 240 estate diesel 6 cyl) and now have a 740 2,3L EK 1988 showing 400,000 kms on the clock and a 850 2,4L 10V non turbo 1995 having 250,000 kms. Forgot to say that I am living in Belgium and that cars here might vary a little bit from those you have in the US but not that much anyway. I am now experiencing several troubles with the 850 and I hope I can get some help from you all as it seems that you are very knowledgeble (I am not too sure about my english).
Although I am not sure if I can post several questions on the same topic, I'll do so and you let me know whether its better to separate them:

1- My 850 is running (almost) perfectely well but since about a year ( 50,000 Kms ago) it has started to smoke after a few minutes idling like when you stop at a traffic light and then push the gas pedal, a puf (sometimes more) of white/blue (oil) smoke comes out of the tail exhaust pipe. That's the only occasion it does that, or when I leave it for a longer time at idle then it smokes even worse. But as soon as you accelerate or when I drive normaly on roads and highways (up to 160 km/h or more sometimes, 5,000 rpm) it does not smoke at all even after a long run and I release the gas and push it down again. I know that because a friend of mine followed me several times and he never saw any smoke on those occasions.
I am pretty dam sure that the engine itself is not faulty, compression ratio is OK, power is still there, engine is running fine and smooth, oil (full synthetic I recommend) consumption is about 0,25L per 1,000 kms which I thing is pretty much OK. Is it related to these tricky PCV or other "green" recuparation system, I don't have a clue and I really hope you can give me a hint on this.
2- A couple weeks ago I had to change my radiator (engine cooling system), of course disconnect the battery, and since then the idle rpm have slow down to 600/650 rpm instead of the 900/950 rpm recommended (forgot to say it's an automatic gearbox). Any idea of how I can reset to normal idle?
3- Next W-E I'll be changing both belts and tensioners on the car and I am very glad I could get a lot of fantastic information on this forum about that as well.

I do apologize for having been so long but I thought it might necessary to explain a bit more to start with.

I am looking forward to beneficiating (is that english?) from your experience and thank very much you beforehand

CarVolvo · Post by **CarVolvo** » 21 Sep 2006, 13:08

i would think if the oil is only coming out of your tail pipe and your not getting performance issues and the your not losing much oil from the system it could be normal engine wear.

If your getting and oil smell then you may want to look at the engine bay and see whats going on there. These cars can leak oil in several places.

One is the oil filler cap, which needs a gasket sometimes.

When you open the oil filler cap after running it for awhile..do you notice a lot of back pressure coming out?

If so it could mean your pvc or flame trap needs cleaning out. Its not a difficult job once you know where it is.

Also i have lots of little leaks on my volvo 850, i think i may need my main seal replaces as well as small leaks on the top corners on the engine... not bad for a car with that much mileage.. and i shoudl tend to them.

Also if you have a leak and its falling on the exaust manifold or pipes then that could cause smoke but not thrhough your exaust.

i dont know how dependable the 10 valve engine is compared to the 20 valve that i have so perhaps someone else can comment on that?

dannyboy · Post by **dannyboy** » 21 Sep 2006, 14:42

Thanks for your feedback. I was probably not clear enough. When I say it smokes after a few minutes at idle I really mean it smokes too much but then disapears as soon as you step on the gas. There is absolutely no oil leaks anywhere, the engine is clean just as brand new. Volvo mechanics here say they have never seen that before (can I believe them?) and that these engines can go for 700,000 kms without any problem.
I know where the flame trap is but before starting such a job I'd like to make somehow sure that this might be the cause.

Any clue about adjusting idle speed?

Many thanks

Post by **robert213** » 21 Sep 2006, 19:47

It is very easy for me to read and understand your English. You write better than most people here in the U.S.

You have a 1995 Volvo 850 with non-turbo 2.4L engine. I am having an almost identical problem. No light-blue smoke during hard acceleration. No light-blue smoke during normal acceleration. However, when my car sits at at stop light, after idling about 15-20 seconds, light-blue smoke starts to appear. If I allow the car to idle for 2 or 3 minutes, the light-blue smoke becomes very heavy, thick, and dense.

I have a turbo 2.3L engine, so I am planning to replace the hoses in my PCV system. With your non-turbo 2.4L engine, you should inspect your hoses and clean your Flame Trap.

Use search function of this board for "flame trap" to find more info.

Post by **MadeInJapan** » 21 Sep 2006, 20:46

Personally I would take the flame trap out and throw it away. It's just something that clogs up and causes problems, IMHO.

dannyboy · Post by **dannyboy** » 22 Sep 2006, 20:59

Thanks very much to both of you Robert and Made in Japan.
I understand from your experience that the PCV is most probably creating the problem and that there are two options. Either change the flame trap and hoses (or clean them) or remove the flame trap as Made in Japan is suggesting. In this last case what do you do with the existing hoses? Do you just let them to the open air? I mean don't you connect them together or somewhere else? If yes, I would appreciate a connection drawing showing how the hoses should then be connected.
I'll certainly do the job one way or another next W-E when I'll change timing and serp. belts.

Many thanks again for your support and I am looking forward to your comments.

Regarding my idle speed problem (too slow) would you suggest that I should post a new topic?

Post by **robert213** » 22 Sep 2006, 21:24

dannyboy wrote:Regarding my idle speed problem (too slow) would you suggest that I should post a new topic?

I find it difficult to believe that disconnecting the battery did anything to change your idle rpm(s). I would rather believe that -- during the process of replacing your radiator, you forget to re-connect a vacuum hose. I would inspect and verify that all vacuum hoses are connected to your throttle body correctly.

Do you have ODB tools to enable you to scan (read) your ECU's Diagnostic Trouble Codes?

dannyboy · Post by **dannyboy** » 22 Sep 2006, 21:36

I do agree with you. I had my battery disconected on many other occasions for other jobs and never experienced that problem. The only difference, and I forgot to mention, is that this time I also re-welded (electric welding) some of the exhaust fixings. Could the memory of the PC board have been affected by that and changed the idle rpm? I am not sure.

No, unfortunately I do not have that ODB tools. Is that the only way I could (re) adjust idle speed?