[bobbob455]

Hi folks, I have a 2003 E46 316i with the N42 engine. It has 90k on the clock, and has been well looked after. Yesterday, I removed all the plastic covers from the engine, and installed a new MAF & coil to cylinder no.2. This may be unconnected, but, when I started the engine with all the plastics off, there is a very distinctive tapping noise that seems to be coming from the top of the engine. The tapping increases with the revs. It is not the quiet tapping noise from the fuel injection, but sounded more like a duff hydraulic valve lifter.
Performance (as much as you can get from an N42) seems unaffected.
I put in a bottle of hydraulic tappet seal rejuvenator last night, and ran the car for approx 15 miles before leaving overnight. This morning, the rattle was gone...initially, but came back after 30 seconds or so, and got gradually louder as the engine warmed up.
There is a noise like a compressor/pump that always comes on when the engine is cold, I may be wrong, but the rattle seemed to start when the pump cut out, which it always has done after 30 seconds or so.
Looking on here, there seems to be several things that this noise could be, either a worn hydraulic valve lifter, vacuum pump, or vanos unit.
I welcome any advise, as I don't want to be replacing expensive parts that don't need replacing.
The cam chain tensioner has already been replaced with the modified one.

 

[dailydoggy]

unfortunately the N42 is notorious for rattling...it could be dodgy timing chain tensioner,or hydraliuc tappet,valvetronic,the noisy pump thing is prolly a cold start emissions air pump....

 

[bobbob455]

Thanks, does the rattling get worse? Or is it something that I can try to live with without major issues?

 

[dailydoggy]

depends wots rattling if its timing chain it may destroy the engine if it jumps...

 

[bobbob455]

The timing chain & tensioner (modified) were changed 3 years ago, so I don't think it's that. I'm tempted to try the hydraulic tappets, as these are probably the cheapest parts to replace, but if anyone can advise me as to a more definate problem, advise would be gratefully received.

 

[dailydoggy]

ya cant give a definite problem diagnosis from a forum post and unforunately it could be anything...it needs investigating...

 

[Wrayth]

Try cleaning out the spray bar underneath the cam cover.

Also...what oil are you using?

 

[bobbob455]

I use 10/40 oil, & flush the engine prior to changing, it was last done 6 weeks ago.

 

[vsz]

Why would you use such a thick oil? It`s not even BMW LL spec I bet.
Use LL01 or LL04 spec oil for this engine. Worst case LL98.

 

[bobbob455]

I know it's not long life oil, but I change it every 6 months/5000 miles

 

[bobbob455]

Pretty sure I've narrowed it down to a vanos unit, just need to establish which one.

 

[Wrayth]

10 40 is way too thick. I would swap to a 5w 30 and see what happens first before you start to strip the engine apart.

 

[dailydoggy]

way too thick...it might have done damage by now tho...

 

[bobbob455]

5-30 is best for a low mileage engine, but as parts wear, a slightly thicker oil will give better protection, maintain oil pressure better, and will not be burnt as rapidly as 5-30.

 

[dailydoggy]

10w will over stress any aluminium engine from cold its way too thick in cold temps....10w is for cast iron block engines for a reason...

 

[bobbob455]

The repeated motion of the engine's cylinders moving in and out of the engine block can create wear over the engine's lifespan. As the engine wears, the fit between the cylinders and block becomes looser, which can significantly increase wear and decrease usable life as the engine develops more gaps between the moving parts. A thicker motor oil, such as 10w-40, provides a more solid lubricant to compensate for the excess wear of high-mileage engines. Many experienced mechanics recommend shifting to a higher viscosity motor oil later in the engine's lifespan in order to compensate for these imperfections.

Read more: What Is the Difference in 10w-40 Car Oil and 5w-30 Oil? | eHow

 

[Wrayth]

The repeated motion of the engine's cylinders moving in and out of the engine block can create wear over the engine's lifespan. As the engine wears, the fit between the cylinders and block becomes looser, which can significantly increase wear and decrease usable life as the engine develops more gaps between the moving parts. A thicker motor oil, such as 10w-40, provides a more solid lubricant to compensate for the excess wear of high-mileage engines. Many experienced mechanics recommend shifting to a higher viscosity motor oil later in the engine's lifespan in order to compensate for these imperfections.

Read more: What Is the Difference in 10w-40 Car Oil and 5w-30 Oil? | eHow

You have a point.

But I personally think a 10w oil is way to thick and as doggy states.....you sacrifice cold start protection with a 10w.

On higher mileage engines and LPG coverted cars where a 5w 30 is recommend we use a 5w 40.

 

[bobbob455]

There is very little difference between the cold viscosity of 5 vs 10 oils, yes 5 will give slightly better protection on start-up, but if I know this, and allow the engine to warm up gradually, and not thrash it until normal temperature is reached (as we all should anyway), I don't think there is a problem with using 10w oil. Add to that the fact that my engine has done 90000 miles, and I am convinced that it is the best oil for my car, also, I never have to top it up between oil changes.

 

[Wrayth]

Each to their own I guess. But for me, when selecting which oil to use and especially on a customers car, we select the oils very carefully especially if the customer has the same 4 cylinder engine notorious for bottom end failure and rattles..........I would not use a 10w on these. But like I said....each to their own.

 

[rhyd330i]

How long have you been using 10w40 and flushing the engine out? I wouldn't recommend either for these engines. Decent 5w30/5w40 will keep your engine clean, especially as you change it regularly.