Noisy tappets

[Andy Law]

Just fitted a new cam and rocker arms on my BMW 525i (old type 2 valves cylinder)
Bought from euro parts,
Have adjusted valve clearance to factory settings,
But there very loud worse than before and get worse above 3000rpm.
have taken rocker cover off and went thru it all again double checking everything but still the same.
has any one got any ideas,could it be a dodgy cam grind?
cheers

[Chris Y]

Springs not stiff enough perhaps? Did you change them to suit the cam? If that's the case, and the valves aren't able to follow the cam, then you'd be well advised to sort it out quickly before the valves/seats are damaged.

[zefarelly]

sounds like it could be springs if its all of them tapping, if its just one or two I'd suspect cam or follower damage

does it sound like an old Cortina !!!

[graham bahr]

Originally Posted by Andy Law

Just fitted a new cam and rocker arms on my BMW 525i (old type 2 valves cylinder)
Bought from euro parts,
Have adjusted valve clearance to factory settings,
But there very loud worse than before and get worse above 3000rpm.
have taken rocker cover off and went thru it all again double checking everything but still the same.
has any one got any ideas,could it be a dodgy cam grind?
cheers

hmm i've fitted 100's of these mainly with parts from euro car parts and never a problem, did you replace all the rockers?

does it sound like just one tappet or several?

if it is a dodgy grind then watch each individul rocker as you rotate the engine, one that is noisey due to wear or a bad grind instead of gently and smoothly opening and closing at some point you will see a rocker suddenly snap further closed.

if only sounds like one are you sure its in the topend of the engine, and not a big end or a belt slapping against something.

you are checking the clearance between the adjuster and the valve not follower and cam arn't you?

are the adjusters fitted the right way round?

are you sure the cam timing is right?
has the head been skimmed quite a bit, these engines have very little valve piston clearance as std?

[Andy Law]

I'm going to do a few checks over the weekend to test if enough oil is getting to the rockers.
I have run the engine and also turned it over by hand with the rocker cover off and actually its not too bad at tickover but about 3000rpm it gets loud.
its definately coming from the valvetrain.
everything is correct ie;timing and adjusted correctly
this is really baffling
as for the head Graham i have had it skimmed twice since i've owned it
you say the valve to piston clearance is small on this engine is that why BMW do thicker gaskets.
the machine shop i had it done at said there's loads of clearance on these engines.
Out of interest Graham do you have anything to do with Barrtech motorsport up in cambridge as thats who originally owned my car.
Cheers for now all.

[graham bahr]

no i'm no connection with bartech, i know where they are but thats it.

if the engine sounded knocky from when you very first put it together then oil supply cant be at fault.

with regards to valve piston clearance, i wouldn't like to say that that is the only reason that you can get thicker headgaskets another is to stop the compression going above maufacturing specs with the head skimmed.

and i have SEEN valve piston contact with std cams and heavily skimmed heads, i'm not saying this is the case with your engine, but unless the machine shop meassured and checked the head thickness against the book they dont know it has already been skimmed several times and is now too thin.

as an experiement it might be worth opening the valve clearances UP by say 5 thou, ok it will get a more tappety but if the main knocking noise lessens then you know something is hitting something else it shouldn't

[graham bahr]

i've just remembered something, i did once see a car that had a nosey top end, it had a valve stem that was badly worn and was too short as a result, although the adjuster could get the valve clearance right it was working on the very edge of of the valve and would fall off the side of the valve when running

[Andy Law]

Found the problem,you were right Graham it was piston to valve contact.
My dad took the head of and you could see where the carbon on the edges of the valves on number 1 and 4 inlets had been chipped away.
Also the pistons had been touching the cumbustion chamber.
Measured the head and it was thicker by 8 thou in the middle than both ends,
Which kind of explains it all.
He then die ground the chamber where the pistons had been touching and fitted the thickest gasket that BMW do.
Have you found there a real bugger to bleed the air locks out of the water system on these cars.
But it all runs sweet now.
Cheers...

[graham bahr]

good glad its sorted.

yes bleeding them can be a real pain, unlike most cars its best to do it with a stone cold engine.

fill the cooling system with the bleed screw on the thermostat housing loose making sure you get water coming out of it before you even think of starting it, put the rad cap on then start it and it should finish bleeding its self it does help to blip the throttle, but if it gets well upto temperature and you cant feel all the hoses getting hot, then stop and let it cool right off before trying again, these engines never bleed hot, they airlock in the head and just boil any water that you do get in there straight away.

[norman-normal]

I'll give all of you some advice on this subject that will conflict with the factory recomendations, if followed it will save you a lot of money.
This applies mostly to very long 6cly, alloy, heads: they allways bow so as to be concave in the middle. If you shave it you will have high compression on the end cly and low comp in the middle, as is the case here.

Forget what the factory says; if the head surface looks good in other respects, bolt it back on torqing it from the center it three graduated sequences. Run it easy for a few hundred mi then retorq it , overnight cold. The alloy will conform to the block in all but the most extreme cases.
You will have no problems, your engine will run smoother, the wear factor (rod brgs, main brgs, valve gear) will be more evan. If you don't want the money you save send it to me.

[Andy Law]

I only had it skimmed after a head gasket failed and scored the surface of the head.The machine shop i used has gone downhill lately due to the owner taking less of a interest in it.
The guy said only took of 4 thou but it must of been alot more than that.
Thanks for that tip norman normal do you want a cheque or cash.

[norman-normal]

Well, Andy in view of the mess our respective leaders have gotten us into, GOLD would be very good, thank you.

[Andy Law]

I quite admire your president but that has nothing to do with this thread