Oil loss diagnosis- 2005 545i
 

Hi,

I have a 2005 545i with 122k miles that is losing about a quart of oil every 2,000-3,000 miles. I had two different mechanics recommend I replace the valve and timing cover gaskets, so I did that (cost ~$1,800) but it had no affect on the rate of oil loss.

The same mechanic checked and says the problem is a combination of the brake vacuum pump ($650 to fix) and the alternator bracket ($950 to fix.) I see that these are common problems.

Are there any tests or things that should be checked so that I can be sure that these repairs will stop the oil loss? Note that is see no evidence of oil leaking onto the driveway-- there is oil on the engine block/compartment but not leaking under the car. I understand there is a drip pan that might be catching the leaks.

Is it possible that a good portion of the oil loss is caused by oil burning inside the engine-- perhaps valve seals or other sources of internal leaks could exist???

The blue book value of the car is about $8k, so the idea of sinking another $2k into it (it needs brakes as well) might not be worth it. A coolant hose burst last summer, leading to a $1,600 repair to replace the pump, thermostat and hoses.

I'm thinking maybe I should cut my losses and trade the car in before something catastrophic happens.

Thanks,
Dave

Believe it or not, oil consumption of a quart every 2,000-3,000 miles is quite normal for a nine year old German car with 122,000 miles.

If you are not seeing any smoke during operation (upon startup, upon acceleration after long idle or during hard acceleration on the highway) then I wouldn't be too concerned about oil getting past rings or valve stem seals. You may want to look at your CCV to insure they are operating properly.

But the fact that you are seeing some oil on the block indicates at least some "sweating" or slow seeping of oil from one or more seals or gaskets is taking place. Again, this is very common on all German cars getting up in age (they just don't seem to do as good a job on gaskets as the Japanese do).

If you are driving 12K miles per year the extra oil consumption is costing and extra 4 to 6 quarts per year, which depending upon which oil you use will cost you $20-$60 per year.

I know we enthusiasts want everything to be perfect on these cars, but IMHO you would be best off to keep a very close eye on the consumption to catch a problem if it suddenly gets worse (like maybe an alternator bracket gasket), but other than that just enjoy the car.

They can add dye to the oil to see where it's actually leaking.. that would make a lot more sense than throwing $1800 at it.

Pretty much every gasket in that engine is suspect. Most will leak, only a matter of time. Alternator bracket is a biggie.

Thanks-- no smoke that I can see, so perhaps you are right, I can continue tracking it and in the meantime, it is just a couple quarts of oil.

Thanks, I didn't know that was possible. I'll look into it with my mechanic.

I did it to my cooling system a while back and it was really neat.. that + a UV/black light makes it quite obvious where leaks are. Mine was a water pump gasket.. you could see a trail of what looked like highlighter running down the engine and follow it right up to where the gasket was leaking