N62 Smoking Experiences - Fixes

[Thecastle]

So, I have the (mis?) fortune of owning a BMW X5 with the (95k miles) N62 4.8 engine, and she at least used to smoke like I'm batman smoking. I'm writing this to help others in the same boat. Living in Houston I have several good friends with Ph.D.'s in organic chemistry/petro chemicals (specifically materials/chemicals). I'm an engineer and wanted to figure out a low cost solution to this problem, so I talked with them about the causes of seal failures on BMWs.

So my car is typical of the BMW issue where it will smoke after an extended idle. I really noticed how bad it was when I backed up my travel trailer, let it idle. Then turned it off, and back on and huge clouds of smoke, and it would also smoke on extended idle. Or sitting in traffic and floor it, smoke!

1st I replaced my CCV / pipes, then changed my oil to liquid Moly. This significantly reduced my smoking but did not eliminate the I'm Batman issue. After repeated visits to my indy we determined that it was leaking valve stem seals was the cause of my cars smoking (how n62/n63 typical)

Anyway, I talked with my chemical friends and what they said is that viton/rubber oil seals come with plasticizers to increase pliability (key to sealing on oil seals). Heat/time causes these compounds to both break down and evaporate out of seal materials in a car engine. The higher the temps the faster the process of plasticizers leaching into your engine oil and the loss of flexibility and sealing properties. Once the plasticizers are lost the seals can become brittle and with the mechanical sealing stresses form cracks resulting in total failure. I suspect that BMW uses low quantities of plasticizers and bonding agents which is why they fail so frequently, along with high engine temps.

If your seals aren't cracked, but simply less pliable, it is possible to add solvent plasticizers to the oil that will restore the flexibility of the seals (you can do this to your dash too to prevent cracking). This is not the same things as seal swelling which is a bad thing (aka adding brake fluid). This is just restoring the original properties of the seal.

So for me, I added one commonly available plasticizer (there are others that will work just fine and I'm not endorsing one product). Lucas Oil Leak Stop. I have to admit that I've been very happy with the results. No smoking, no oil leaks and the car runs great, it took about 300 miles to stop smoking, but I've been running it for 5K miles with no smoke or mechanical issues. No more I'm batman, and no embarrassing smoking as I back my trailer into a campsite in pristine wilderness with folks watching... (try it in a national park and you'll get some really dirty stares)

If your seals aren't torn or cracked this will restore the seals to their original pliability and save you from spending the money to replace the seals. In my case the valve stem seals are the culprit for my smoking.

BTW I realize this MAY not be a forever fix, but neither is replacing the valve stem seals. The same gradual loss of plasticizers that caused the leaks on your 1st set of seals will re-occur with the replacement seals. That is why some folks add plasticizers as preventative on BMW vehicles. Maybe this is the long term solution?

[Nanniepoo]

I have an '08 with the 4.8 engine with 138k miles. We've put about 10k miles on it since we bought it. Not sure if it's lucky or not, but no smoking. Hopefully it had been done prior or else it sounds like it is imminent, as most don't make it this long. PO owned it from 100k until we bought it and only did oil changes. I got what records I could from the local BMW dealership, supposedly they could only pull there's, not another dealerships, and there was no record of it being done since about 45k...Plausible it had been taken care of by another dealership, not as likely it was done by an indy because it was under warranty until 100k.

For now it is our main cruiser so does get a good amount of highway miles, but it's my wife's DD, which is all city. I'll keep an eye on this thread, might be something we start doing routinely.

[Thecastle]

You maybe lucky, or your symptoms are mild enough you haven't noticed..

The test if you want to know the health of your valve stems is the following;

1) Warm the engine up completely.
2) Park the car and let the engine idle
3) wait about 5 minutes or so
4) have a friend stand outside the car looking at the exhausts (best) or have the hatch open and look through the rear view.
5) floor it!

If your seals are bad usually you'll get some smoke if you do this test. IF no smoke, your in good shape.

[Nanniepoo]

Originally Posted by Thecastle

You maybe lucky, or your symptoms are mild enough you haven't noticed..

The test if you want to know the health of your valve stems is the following;

1) Warm the engine up completely.
2) Park the car and let the engine idle
3) wait about 5 minutes or so
4) have a friend stand outside the car looking at the exhausts (best) or have the hatch open and look through the rear view.
5) floor it!

If your seals are bad usually you'll get some smoke if you do this test. IF no smoke, your in good shape.

To be honest, after a full suspension swap and new calipers on my E36, just going through a gushing oil cooler gasket on the E70, and replacing the alternator on our backup car, right now I'm quite content being ignorant for the time being. Especially considering there's a very low chance of either my wife or I driving the vehicle in this way that we would be affected by barely leaking seals.

If we start to notice oil loss or something I'll definitely keep this test in mind though.

[getafewlives]

Originally Posted by Nanniepoo

To be honest, after a full suspension swap and new calipers on my E36, just going through a gushing oil cooler gasket on the E70, and replacing the alternator on our backup car, right now I'm quite content being ignorant for the time being. Especially considering there's a very low chance of either my wife or I driving the vehicle in this way that we would be affected by barely leaking seals.

If we start to notice oil loss or something I'll definitely keep this test in mind though.

How long did it take for your oil cooler gasket to start gushing? Like was it instant, or did it drip and leak for weeks/months? Mine is leaking now, but I would rather wait to spring to deal with it.

[Nanniepoo]

Originally Posted by getafewlives

How long did it take for your oil cooler gasket to start gushing? Like was it instant, or did it drip and leak for weeks/months? Mine is leaking now, but I would rather wait to spring to deal with it.

I'm not sure. Unfortunately had a couple leaks going at the same time, so not really sure when it actually started. But when it went, it WENT. Car was completely un-driveable. There's still the stain left from the oil from where I moved it from the driveway to the street. It's a constant line, not a drip here and there, and then a sizeable stain where I parked it.

[getafewlives]

Interesting, is this something that could be good for preventative maintenance to restore the seals before there's an issue? Or is it best to try and use at the first sign of smoking?

is there a possibility of the product causing damage or wear to other parts of the engine?

[Thecastle]

Originally Posted by getafewlives

Interesting, is this something that could be good for preventative maintenance to restore the seals before there's an issue? Or is it best to try and use at the first sign of smoking?

is there a possibility of the product causing damage or wear to other parts of the engine?

Thats a really good question. I'm going say yes I don't know.

What I can say is that using plastisizers like amorall and others on your dash clearly keeps them from drying, loosing their pliability and cracking due to heat and sun exposure. SO in most materials its a good idea. I'll ask my chemists...

My gut would say, it probably would be a good idea (but it will add cost). Probably optimal to use it at higher mileage, or when you first start to leak, if its not too late.

[fast4d]

I used lucas power steering stop leak on our x5 4.8

still working about 10k miles.

I have a bottle of lucas oil stop leak on the shelf. I have not seen any smoke yet.

oil consumption is about half quart per 3000 miles.

not sure if I should add some as a preventative measure....

VC, timing cover, oil cooler leaks have been fixed with new gaskets.

[Sam617]

How many quart of Lucas Stop Leak should I use with an oil change?