How tHow to stop my manual drive 1995 VOLVO 850 Turbo from smoking (burning oil) through the tailpipe?

[dtmmoore2]

My car was running fine with regular oil changes and never an engine overheat. A few weeks ago I noticed some backfires for the very first time in the lead up to a breakdown, with the engine shutting down completely as I was accelerating in fifth gear. To be precise, I heard one or two muffled backfires from the rear of the vehicle on successive days. The car continued to drive as usual so I did not think I had a problem. Wrong. My mechanic discovered that the cap and rotor had self destructed.

Some background: a couple of years ago I had a no start situation. The problem turned out to be a worn out relay box related to the ignition system that sits just under the plastic cover that protects the top of the radiator. However, a new cap and rotor were installed before the relay was found to be the culprit. I suspect that perhaps the rotor arm was not tightened down sufficiently (or the use of loctite threadlocker would have been advisable), because the arm of the rotor was shorn off and the plastic encasing the contact had disintegrated/melted away. Would like to know if this is something that happens from time to time or was this really unlucky.

The car sat for thee weeks before my mechanic could get to it. When he started it finally, he reported that it was smoking blue smoke out the tail pipe, advising me that it was burning oil. I suspect that backfires caused by the rotor's disintegration over a couple of days resulted in excess engine pressure and this had cause the engine damage that has resulted in my car smoking. The car does not smoke immediately upon start up. I can drive for a little while before it begins to smoke. Apparently there is hardly any visible blue smoke when I am driving. However, once it warms up, it will steadily smoke while the engine is idling at a traffic light for example or when parked and left running (not clouds of smoke, but a steady stream nonetheless).

From the driver's seat, the engine is performing the same as it always has with absolutely no reduction in power or turbo boost since the smoking suddenly began. My mechanic did an oil and filter change. Normally I provide him with 10W-40 Synthetic Liquid Molly. However, ironically, for the first time I provided 10W-30 Liquid Molly for this oil change. As I need the car to drive some 650 km roundtrip from my home to a summer cottage several times each summer, and I have been told it will likely be an expensive repair once the problem is actually diagnosed, my mechanic suggested that since it is not smoking while it is in motion, I should simply use thicker oil for the time being. The owner of a European auto wrecking yard suggested I install a new Volvo brand oil filter (rather than some other brand) and replace the oil with 10W-50. The fact that engine compression seems normal (although it has not undergone a compression test) suggests that the piston rings are not worn out enough to be the reason for this sudden smoking situation.

Have not checked the turbo for shaft play but, as I said, the boost seems normal, for now at least. There is oil covering the bottom of the turbo housing. There is oil coating the oil return line to the crankcase, but that has always been wet to some degree and has never caused noticeable oil consumption in the past.

I have had my mechanic drain a half litre of oil to provide room to pour in some Bardhal No Smoke No Leak as a temporary (or potentially long term solution) given that several mechanics are telling me the car is too old to be attempting to fix. Does anyone know if this product is worth a shot, or should I save my money and put it towards buying some 10W-50 and a new filter instead.

If it turns out that the valve stems seals need to be replaced (it seems that until they are actually examined, a labour intensive job, it is difficult to know if this is what is causing the engine to smoke) I can buy a used turbo head for $150 but I am told that is a fairly labour intensive job to have it swapped into my car (does six hours seem right?). My mechanic actually installed a used engine into this car in 2014 (following an overheat caused by a water pump leak and the absence of low coolant sensor warning) so he is familiar with the 850. But obviously for the most part, he earns his living doing routine maintenance on newer cars, and my car would be a "when he finds the time" project that he is not thrilled about.

There is also a turbo repair kit that I could buy to recondition the turbocharger, but I am told that you need a special tool to disassemble it and the right equipment to balance it before it can be reinstalled. Does that sound right?

The PCV system has not been serviced since the 2014 engine install but I do not drive it that many kms each year (not more than 7 or 8000 kms/year). But this is a sudden smoking situation so I would think, unless someone believes otherwise, that this is likely not the problem.

I do not want to risk doing any further engine damage, but on the other hand I may have little choice but to drive the car as is with the thicker oil, although I would hope that the risk of another breakdown, or causing much in the way of further engine damage, would be low.

Any thoughts on what I should do next (besides getting rid of this amazing car that has served me well since 2009) would be very much appreciated.

[scot850]

You have covered most of the options here.

For me there are 3-4 possible issues:

1) Damage to the turbo seals, but I would expect that to be more of an issue all the time not just when engine is warm.
2) PCV system is blocked - try the rubber glove over the oil filler and held on with elastic bands to see if it inflates. No inflation means you PCV is likely ok
3) Backfires may have damaged piston rings or valves. Have the cylinder compressions checked.
4) Valve stem seals are failing or damaged. A seal conditioning product may work.

A couple of othe issues to check:

1) Make sure your injector seals are good and the injectors are not leaking.
2) Have your coolant temperature sensor checked as well as the connector (ECT).

Lastly, a back fire may have damaged your catalytic converter or O2 sensors.

Neil.

[dtmmoore2]

Thanks Neil.

Can issues with those last two items you mentioned (injector seals etc. and coolant temperature sensor) possibly contribute to burning oil/smoking tailpipe, or are these separate issues you brought up that are worth checking to make sure they are good.

I forgot to mention that the engine light is always on because of DTC's related to fan speed (DTC 514) Power Stage Group B (DTC 532) long term fuel trim (DTC 232) and Front Knock Sensor (DTC 143). .. these are longstanding issues that have never caused any problems in terms of how the car runs. However, when I checked the trouble codes a few days ago, the MAF sensor code was thrown as well (DTC 121). I tried unplugging it and plugging it back in but the code persists. I have replaced the MAF on a couple of previous occasions. I would not have thought that a bad MAF sensor can have anything to do with oil burning and tailpipe smoking but perhaps I stand to be corrected on this. Even with the MAF trouble code, my engine is running normally (i.e., idling steady at normal rpms), apart from the smoke of course.

As I was, saying my spotter advised that the car was not smoking as I drove it past him so I am wondering why that does not provide the biggest clue to what is going on (i.e. it only smokes steadily when the engine is idling, and the smoking is noticeable enough, but nothing approaching billowing clouds of smoke). I am going to have this checked once more and if it remains true for the most part, but lets say it turns out it does in fact smoke while I drive it, but only when the turbo is actually boosting, would that point to the turbo seals. What if it only smokes when I shift through each of the gears? As for the piston rings and you mentioned potential valve damage, if that was the case, would I not necessarily notice some change in the engine performance before and after a few backfires?

[dtmmoore2]

To be clear, the car is no longer backfiring now that the cap and rotor have been replaced.

[scot850]

The last 2 items are as follows:

If the engine is running rich (so it may not be oil but soot) and you had a back fire, with the likelihood the seals in the injectors have never been changed they may be leaking air now.

The car may be smoking a little, but when idling it will not clear the oil as fast as when running. That is more likely the valve seals. This should also be noticeable when jumping hard on the throttle after running at a slow steady speed or when you have been driving at speed and take your foot off the throttle.

Fan speed is possibly the engine fan control which I believe on your car is above the radiator. These are prone to failure, especially the wiring and connections. Check those very carefully. Also check the ETC is work correctly. Again the connector on the back of the power steering pump is a know weak spot with age (DTC514)

Does your engine heat up normally? Does the engine temp show at 3 o'clock when warm? This could also be your DTC232

The last code may not be what it claims DTC143. It may be the knock sensor but it is also on the same circuit as the A/C high pressure sensor and the altitude sensor which is on a bracket on the inner fender near the hood RH hood latch and windshield washer filler. When I had this issue it was the altitude sensor but it came up as the knock sensor. Used parts are the way to go as they can be pricey.

As to the valves and piston damage, they were listed as possibles. Piston rings may not be maintaining the full compression or you may be getting blow by.

Lastly you mention the turbo. This is a possible but I was trying to eliminate the easy stuff before heading in there!

Neil.

[befarrer]

My guess, turbo exhaust seal leaking oil into the exhaust. It will only smoke when the turbo gets hot enough. In my experience, valve seals smoke on first start, then not much after, rings smoke at high intake vacuum, like at idle and after engine deceleration. I would check PCV, the lower mileage means more condensation and warm ups that the system has to handle and more likely to plug.

[scot850]

Our friend befarrer is a wise man, however, I do disagree with the valve stem statement that it only smokes on start up. Yes it smokes on start up, but also when you accelerate hard or lift your foot off the gas and when breaking.

Having said that his knowledge of turbo issues is way ahead of mine!!

Neil.

[dtmmoore2]

Update: PCV system passed the rubber glove test (no inflation). In answer to another question, the temperature indicator points to 3:00 pm when it warms up and this has not changed despite the sudden onset of smoke a few weeks ago following my rotor arm disintegration, which was preceded by a at most three or four backfires I heard emanating from the rear of the car.

I have been learning more about when it smokes and when it does not.

When I first start it up, there is no smoke whatsoever. I have not left it idling long enough to know how long it takes to start smoking after a cold start (ie. starting it after it has been parked overnight) but judging by the fact I can drive several blocks and then get out to check the tailpipe leaving the engine running and not see smoke, it might take a while.

I had a mechanic who happens to work at a garage specializing in Scandinavian cars watch as I drove past a few times. He didn't notice any smoking while I was driving past. But once I stopped and got out of the car leaving the engine running, I saw that it was smoking.

However, if after observing this smoking, I get back in and do some hard accelerations (which feel completely normal from the driver's seat (i.e., same turbo boost, same power of acceleration), and then come to a stop, and then leave it on and get out, I find it is not smoking.


I still have not had a compression test done but now that I keep thinking, and I stand to be corrected, that the fact that the car still powers up the same when I am jumping onto the highway or accelerating in the fast lane, that the test would show normal compression range on all cylinders. The car has not misfired once since the cap and rotor were replace two weeks ago. I had barely any oil consumption before, but since the car began smoking, I have not noticed any increase in oil consumption.

I am going to continue to monitor the smoking to see if I can reconfirm what I have set out above about the time when it is smoking out the tailpipe.

I really would like to eliminate the smoking by getting to the root of the problem somehow. One mechanic I spoke to did not think that a few misfires/backfires would cause sudden internal pressure build up in the engine sufficient enough to in turn cause damage resulting in oil burning and smoke at the tail pipe. Except what other possible explanation could there be.

I have added some Bardahl No Smoke No Leak (similar in consistency to really thick molasses syrup but much lighter in colour) hoping that when added to the 10W-30 Liquid Molly I would see less smoking, but to my annoyance it hasn't made any difference. And there is no sign on the dip stick of their being much in the way of oil consumption, but I have probably not driven more than 20 miles since I added the Bardahl. I have picked up some 20W-50 and will likely try replacing the 10W-30 and then add some more Bardahl. Before I do that, I will get the cylinder compressions tested. I will let you know what I find out. Thank you for your replies!

[dtmmoore2]

Update: PCV system passed the rubber glove test (no inflation). In answer to another question, the temperature indicator points to 3:00 pm when it warms up and this has not changed despite the sudden onset of smoke a few weeks ago following my rotor arm disintegration, which was preceded by a at most three or four backfires I heard emanating from the rear of the car.

I have been learning more about when it smokes and when it does not.

When I first start it up, there is no smoke whatsoever. I have not left it idling long enough to know how long it takes to start smoking after a cold start (ie. starting it after it has been parked overnight) but judging by the fact I can drive several blocks and then get out to check the tailpipe leaving the engine running and not see smoke, it might take a while.

I had a mechanic who happens to work at a garage specializing in Scandinavian cars watch as I drove past a few times. He didn't notice any smoking while I was driving past. But once I stopped and got out of the car leaving the engine running, I saw that it was smoking.

However, if after observing this smoking, I get back in and do some hard accelerations (which feel completely normal from the driver's seat (i.e., same turbo boost, same power of acceleration), and then come to a stop, and then leave it on and get out, I find it is not smoking.


I still have not had a compression test done. I keep thinking, and I stand to be corrected, that the fact that the car still powers up the same when I am jumping onto the highway or accelerating in the fast lane, that the test would show normal compression range on all cylinders. The car has not misfired once since the cap and rotor were replace two weeks ago. I had barely any oil consumption before, but since the car began smoking, I have not noticed any increase in oil consumption.

I am going to continue to monitor the smoking to see if I can reconfirm what I have set out above about the times when it is smoking out the tailpipe.

I really would like to eliminate the smoking by getting to the root of the problem somehow. One mechanic I spoke to did not think that a few misfires/backfires would cause sudden internal pressure build up in the engine sufficient enough to in turn cause damage resulting in oil burning and smoke at the tail pipe.

I have added some Bardahl No Smoke No Leak (similar in consistency to really thick molasses syrup but much lighter in colour) hoping that when added to the 10W-30 Liquid Molly I would see less smoking, but to my annoyance it hasn't made any difference. And there is no sign on the dip stick of their being much in the way of oil consumption, but I have probably not driven more than 20 miles since I added the Bardahl. I have picked up some 20W-50 and will likely try replacing the 10W-30 and then add some more Bardahl. Before I do that, I will get the cylinder compressions tested. I will let you know what I find out. Thank you for your replies!

[dtmmoore2]

Update:

Since my last post, I have been driving the car and simply monitoring the engine oil level. I was surprised that a recent 1000 km round trip did not result in any noticeable oil consumption. The car ran perfectly at highway speeds and by that I mean the power from the engine felt as it should.

However, this may have given me a false sense of security. I was in the midst of another 200 km drive and was approaching my destination when the engine shut down as I was driving at highway speeds. Upon opening the hood, I found that a significant amount of oil was sprayed over the top of the engine and the hood. It looks like the oil escaped past the oil filler cap gasket. The car would not fire up and I thought I had blown the engine and that this might mean the end of line had been reached for my much beloved car. To make matters worse, my breakdown occurred at the worst possible location, a highway construction site, which required an immediate tow as i was blocking the highway and reducing a very busy four lane highway already reduced to two lanes, into a one lane highway. While waiting for a tow truck to arrive, I quickly added some oil that I had with me but the engine refused to start.

As i was in a different city where I needed to stay over, I had the car towed a short distance. I then tried to start the engine once more and was quite surprised that it fired up for maybe two or three seconds before shutting down again. However it would not fire up again and yesterday I had it towed back to my garage, only to find out that he has stopped working for a time. Another mechanic with seemingly no experience diagnosing engine trouble with a Volvo 850 that was lending a hand over the weekend had a very quick look and listened to it as I turned it over and said he believed the engine had compression which has given me hope that maybe the engine has not been blown after all. The onboard diagnostic provided no codes at all which has never happened before in the past thirteen years I've been driving it. The mechanic said first thing was I need to replace the oil cap, but he suggested that the engine shut down or at least the fact it now won't start might not be related to the expulsion of oil. I checked the schrader valve at the end or the fuel rail and it sprayed gasoline.

At a loss as to what to do next other than having it towed to a volvo specialist to find out what the issue is and whether a new/used engine would need to be installed. Should that be required, I am guessing it will not be easy to find a replacement engine given the age of the car.

Any thoughts on this situation would be very much appreciated.