330ci compression loss on a cylinder.

[Gman85]

Hi folks.

Been a while since I have last been on here but thought I would approach some of you clued up petrol heads for some advice.

I have owned my 2002 330ci sport for just over 2years now which I brought on 49k. Have always had it serviced at regular intevals at the local BMW garage where the technician happens to be a close friend. Never had any major problems with it, infact. mechanicly it has been a dream! Its now just hit 86k majority motorway miles and have noticed a significant increase in the oil it uses. Ive had my friend at BMW take a look at it and there is no signs of any leakage. It just seams to be burning it off somewhere.It goes through approx 1.ltr to 1000miles and doing approx 500 miles a week.
Although BMW state that is acceptable, we all know thats not generally normal. We decided to check the compression rate on all 6 cylinders where 1 of them happend to have a lower compression rate than the other 5.
It was guessed that could possibly be the head gasket but worse case bore wear.
I have done some other researh which makes sugestions about using thicker oils, checking valve seals, the engine not being broken in properly, and that the use of certain fuels giving off high sulphur levels can cause the bore wear...?
Its led me to feel a little concerened as I now have no clue what to do! Would greatly appreciate any help or suggestions you guys can give.

Many Thanks

[S800VXR]

try using a thicker oil. My old 330 from yrs ago started using oil around the 110k mark, changed to slightly thicker oil and it was solved till I hit 190k but that was all hard driving. Stadard grade is to thin in my opinion, much the same as the crap about life long g box oil! Changed that at the samew time and vastly improved things.

[martin mrt]

The sulphur in fuel and bore wear issue you are referring to, is for cars with Nikasil engines, which doesn't affect you

Thicker oil to start with and see how you get on

[phelix]

The breather/oil separator can fail causing excessive oil consumption.

What were the compression figures?

A leakdown test would be revealing - it would identify where the compression loss is (valves, rings or head gasket).

[DVandrews]

I you have excessive oil consumption coupled with low compression on a cylinder then it points to ring/bore problems. To what extent was the compression lower on the bad cylinder? If it was within 10% of the average then that is normal, any more requires further investigation in the form of a leakdown test as already suggested. Can you post your compression results here? Was there significant oil fouling/deposit build up on any of the plugs?

Dave

Edited by DVandrews on Sunday 19th December 09:53

[8Tech]

Definately start using a high quality, thicker oil. Try a 15W50 and see if the consumption figures improve. If not, then I would try renting a leakdown tester as the dealer probably don't have one ( available from ebay) and see if you can see where the compression/oil is going.

I am a firm disbeliever in the BS given of these Longlife oils. They may stay in grade for the specified period but they still carry and absorb the same contaminants around your engine increasing wear and all this extended service interval BS is a marketing ploy to sell new cars, and sell lots of expensive parts to subsequent owners once the cars are out of warranty.

I always do a mid-period oil and filter change and general checkover on all the cars and use a premium quality synthetic oil and still save money over the cost of Longlife oil.

Same story with the sealed-for-life transmission oils. Absolute BS when the transmission manufacturer specified an oil and filter change interval for it. By the time it fails, it's well out of warranty so the dealer sells you a nice new transmission. Ca Ching, thank you very much.

8Tech.

[Gman85]

All plugs were clean, and from memory it was cylinder 5 that was slightly lower. I think they were all around 12bar except for cylinder 5, which was hitting around 9bar.
Speaking to my technician friend at BMW he says he can do a leakdown test in the new year, and in the mean time try a thicker oil. He recommended the magnitex..?

[Sir_Dave]

phelix said:

The breather/oil separator can fail causing excessive oil consumption.

This is wear id be looking 1st!! All 330's use oil, & this is normally the route of the issues.

[Gman85]

Yeah thats what i'll be looking to do in the new year. Thanx for the advice guys!!

Another thing I have noticed today is it appears there is only a little amount of exhaust fumes coming out from one of the exhausts. Its a standard twin exhaust but thought they would work evenly together.

Any thoughts on this or is that just normal and me beginning to be paranoid..?

[TheEnd]

There's a flap in the exhaust to keep it quiet at low speeds.

[phelix]

There's a vacuum operated flap that closes off one outlet, for noise reasons I think. See http://bmwfans.info/parts/catalog/E46/Coupe/Europe...

[Gman85]

How about when I rev it though. I noticed it stationary so got my partner to give it a rev whilst I looked at it and most of the smoke/fumes was coming from the left hole, when the right barely let anything out...?

[GPT]

Gman85 said:

How about when I rev it though. I noticed it stationary so got my partner to give it a rev whilst I looked at it and most of the smoke/fumes was coming from the left hole, when the right barely let anything out...?

On my E36 it opens around 2500rpm I believe.

There's also a vacuum hose you can block (e.g. with a golf tee) that keeps the valve open at all times. Google "Golf Tee Mod". I'm not sure if you can do this with the E46.

[taylor86]

You can do the golf tee mod on e46, and it is likely in your case that the flap has stuck shut, mine has stuck open. Might be worth getting yours moving again to help those exhaust gasses get out.