m52 rattle from 2k to 3.5k ish

Post Wed Nov 30, 2011 4:48 pm

I've been enjoying my m52 conversion for quite a while now and it has been perfect up until a couple of days ago.

A rattle has become apparent when warm from approximatel 2 - 3500 rpm on part throttle.

I can't hear it under load or deceleration. Its been parked up and I haven't investigated further. It has suddenly started as I'm paranoid and always nurse engines and look and listen out for anything unusual.

Is this the infamous vanos seals? or could it be the chain tensioners? The engine is fine at idle hot or cold.

Post Wed Nov 30, 2011 5:33 pm

What year is the engine? Check this - http://www.e30zone.net/modules.php?name ... c&t=157294

Post Wed Nov 30, 2011 5:41 pm

I can't remember the exact year of the engine, it has a steel linered block (stud near starter). Is there a way of checking via engine num etc?

Thanks for the link, however mine is only noisy when warm, the bulletin states cold running up to 3000rpm. The noise definately carries on past 3000rpm, although I could only hear up to about 3750 (gets a bit fruity by then).

Post Wed Nov 30, 2011 6:17 pm

An engine ive had was the same, cold or hot doesnt matter, does the oil filter housing have a plastic lid? Black plastic cam cover?
Could the head have been changed in the past?

Post Thu Dec 01, 2011 4:50 pm

yes on the plasic lid for the oil filter housing, as for the cam cover... The cam cover is black, don't know if it's plastic or not and I think the vanos unit on the front is silver if I remembered correctly(not always a certainty

). I'm about a hundred miles away from the car at the moment.. I'll check tomorrow when I get back and post up.

From what I know the head hasn't been changed.

So if it does need the plate springs do you know how much the bits add up to? While I'm at it, if I have to remove the vanos I'll probably change the seals too... and chain tensioners... or should not meddle with them?

Post Thu Dec 01, 2011 5:44 pm

Most 95 engines had the alloy top oil filter housing and the old cast cam cover, the head will have a date stamp on it.

You have to remove the vanos unit yes, the spring plates are/were a couple of quid last time I bought some. Well worth changing the vanos seal, I have a few in stock

To change the tensioner guide rails is a head off job, changing the spring in the tensioner is about as much as you need to do TBH, very rare the cam chain guide or tensioner wears

Post Thu Dec 01, 2011 10:32 pm

Thanks for the replies... and the plug

, I'll be in touch tomorrow. Pretty sure I read somewhere that you were also offering some ecu software too? I've got an m50 manifold to put on too so will probably do the lot in one go.
Come to think of it I also need to rebuild the lsd!

Post Mon Dec 19, 2011 10:20 pm

Picked up the seals from the post office today, thanks DanThe.

Also ordered the bits from my local dealer £58 not including three new nuts. The spring is a few quid but the 2mm and 4mm plates added up to over £40.

Will be doing the fix over the holidays. Will post up my findings when I'm done.

Post Mon Dec 19, 2011 10:54 pm

Your keen, I only ever fit second hand spacer plates!

Post Mon Dec 19, 2011 11:22 pm

ooops, never thought of that. Not keen, just rushing around trying to get the bits together and I didn't think of that. Don't think I can cancel the order now, paid up and they're on order

Post Fri Dec 23, 2011 1:19 am

Before I get stuck in, I've got a few questions if anyone can help with I'd appreciate it.

Any pointers on where to look for the date stamp on the head? I've looked around and used my phone to check parts I couldn't access but I can't seem to find it.

I need to check somehow as I want to fit new cam cover gaskets and I've seen two different part numbers on realoem, is there much difference between the pre 95 and later ones?

Eurocarparts stock different cam cover gaskets, are any oem? e.g elring?

Also is there anywhere I can get oem inlet manifold gaskets from for less than the £5 a pop from the dealers?

Post Fri Dec 23, 2011 12:57 pm

Never had to replace inlet manifold seals before, they seem to last very well.
There are two types of cam cover gaskets, the tall type that pushes into the plastic cam covers and the older standard flat rubber type that is used on all the early covers

Post Fri Dec 23, 2011 2:32 pm

Thanks for the reply, mine has the plastic cam cover so I should be good to go now.

Just in case someone else has this problem in the future, I've found this video which might help with visualising what needs doing.

Post Fri Dec 23, 2011 6:32 pm

Good vid, just make sure you oil the plates and spring washer before fitting though

Post Fri Dec 23, 2011 8:13 pm

I thought that too, also the threadlock he quotes is the wrong stuff if its the same as the blue loctite I have.

The loctite 273 quoted in the pdf is proving difficult to get hold of for me, is it just your usual high temp bearing and stud permanent loctite needed? Been a while since I used some I can't remember the code... 272?

He also uses that tool to turn the exhaust sprocket, is there a diy way around this for re-fitting the vanos unit?

Post Sun Jan 01, 2012 1:08 pm

Managed to get this finished last night... Happy new year everyone

Turns out my engine already had the anti rattle spring kit fitted, but I replaced the spring because when comparing the original was a little flatter.

I also found that the sprockets weren't aligned properly, both sprockets weren't centered on their studs/bolts. I re-assembled with both sprockets central in relation to their studs/bolts.

Fired up straight away sounded good with a few revs while cold, then I took it for a new year drive and.....

The rattle/knocking noise is still there

Post Sun Jan 01, 2012 1:28 pm

I'm going to go out and check the timing chain tensioner, I hope that's it as it only rattles on trailing throttle and higher rpms....
Apart from that I'm all out of ideas, any help would be greatly appreciated

Post Mon Jan 02, 2012 2:09 am

I've checked the tensioner which is a two piece with a flat end and a spring inside and looks like this although it came apart straight away

Picture taken from bimmerforums

I shimmed the spring and took it for a drive but there was no difference. I'm starting to run out of ideas and I'm also getting quite fed up now

The vanos unit did have play in the splined wheel like in the video below

Although I've read that radial play, the side to side in the video is ok and required although I don't fully understand why.

I love the car and hate when I start to get frustrated after all the effort I've put into it...

Post Mon Jan 02, 2012 9:46 am

Can you get a video of the noise? Its normal for the vanos to do that.

Post Tue Jan 03, 2012 12:02 am

I'll get one tomorrow and post up, if you try to hold the car on a steady/part throttle at anything above 2500 rpm it sounds like its knocking its nuts off.

Post Wed Jan 04, 2012 9:08 am

Ok, got some videos last night with the window open and in a garage so you can hear the sound reflecting into the car just in case the phone didn't pick it up. Here they are: -

Cold start, no noise. (edit: see notes on video)

Running for a few mins, can hear the noise from 2-2.5k rpm then 2.8-3.3k rpm approx

Warm light revving

Any ideas? I want to get this done and dusted so I can do more fun things like fitting the m50 manifold I have sitting here.

Post Wed Jan 04, 2012 9:10 am

Also, is there anywhere that the temp gauge signal can earth itself onto? My temp gauge sometimes goes a bit crazy, I've had the clocks and temp gauge out and the nuts/contacts are all good.

Post Wed Jan 04, 2012 10:59 pm

That sounds crank related to me!

Post Thu Jan 05, 2012 12:10 am

Does sound really bad in person, like an engine knocking. I can't seem to work out why it's only on part throttle and only at those rpm's.

The oil I took out was dark but clean, no metallic particles at all. Am I looking at a bottom end rebuild..... I hope not. Can these be checked in situ?

I've only had the engine in the car for six months

Post Thu Jan 05, 2012 9:00 am

Has it done it since you fitted the engine? Did you know the engine before you had it? Sounds like something is loose or just touching something else, could it be something you did when fitting the sump?

Post Thu Jan 05, 2012 10:22 pm

I bought the m52'd brown e30 that was advertised on here a while ago. The one with the rear end shunt. The previous owner was a mechanic and had done the conversion himself, it had also had the headgasket replaced. I dropped it out with the subframe and swapped it into mine.

Since fitting, it has been perfect, no noise apart from a supercharger like whining. Which I think might be the tensioner or alternator bearings.

Also no oil or coolant consumption and sits steady as a rock half way on the temp gauge no matter how its driven even now.

While replacing the vanos seal I did notice that there were a few mis-matched bolts around the vanos unit(allen bolt in the bottom of the lifting bracket and 10mm bolt instead of a stud and nut underneath the solenoid) and also the fact that the sprockets weren't aligned centrally.

The noise just appeared, it didn't build up. I'm a paranoid fecker at the best of times so I'm always listening out and checking the engine levels.

I'm finding it difficult to isolate and identify where the noise is coming from, at 2k rpm it gets kinda noisy without the knocking/rattling.

Post Thu Jan 19, 2012 11:30 am

little update..

I bought a stethoscope and when listening to various parts of the engine, it sounds clearest around cylinders 5/6 at the top of the cam cover. I can also hear it at the front near the vanos but it isn't as clear, could it be transmitted to the opposite end of the cam..?

Pulled the plugs which were tight, bit of sooting around the base but the electrodes etc were nice and light brown.

I checked the manifold nuts and a couple on the rear bank were loose!! So hoping that was my problem I quickly tightened them and ran it up again but it made no difference

I'll jack it up and check for sooting when I get a chance just to make sure.

So where does this leave me...

I'm thinking dodgy hydraulic tappets, but why are they quiet at idle?

Something loose on the valve train, cams etc

Bearings..., as it's coil on the plug is there any way I can stop an individual cylinder without ruining the ignition system. Can I just pull the connector?

I really want to solve this as I miss driving my car. Got my motivation back again

Post Thu Jan 19, 2012 1:19 pm

That is not tappets, no way.
If you pull the vanos plug it will keep the vanos retarded throughout the rev range, the noise is in the midrange when the vanos advances the valve timing so could be related.

Post Fri Jan 20, 2012 11:41 am

Thanks Dan,
I'll give it a try tomorrow. Gotta run to work now. This has really got my brain thinking...
Still haven't done a compression test yet either so will give that a go at the same time and post up the results.

Post Thu Jan 26, 2012 8:18 pm

Not had time to look at this til today.
Ran the engine with the vanos disconnected.... Noise still there

Did a compression test...

1) 219.5 psi
2) 221.5 psi
3) 220 psi
4) 220 psi
5) 220 psi
6) 220 psi

Vacuum test showed 19.5 at idle down to 1 with throttle snapped open.

Pulled the cam cover off and left it at that for now. Think I'll jack the car up next and have a look at that rear manifold, how hard are these to pull off in situ?

Post Thu Jan 26, 2012 10:23 pm

Supafly wrote:Not had time to look at this til today.
Ran the engine with the vanos disconnected.... Noise still there

Did a compression test...

1) 219.5 psi
2) 221.5 psi
3) 220 psi
4) 220 psi
5) 220 psi
6) 220 psi

Vacuum test showed 19.5 at idle down to 1 with throttle snapped open.

Pulled the cam cover off and left it at that for now. Think I'll jack the car up next and have a look at that rear manifold, how hard are these to pull off in situ?

the rear manifold isnt that bad if you take the steering linkage off.

how do you do a vacuum test? ive never done one

Post Fri Jan 27, 2012 12:15 am

Really easy, just pull off a vacuum line either the fuel pressure regulater source or the servo pipe and tee into either. I just disconnected the servo pipe and plugged into that. After that it's just start the car and watch the gauge, rev it up and see what it tells you......

How to use a vacuum gauge
http://www.secondchancegarage.com/public/186.cfm

Luckily my car is LHD so that's some comfort.

Post Tue Feb 14, 2012 8:58 pm

Bump and updates..

Ran the engine with the vanos disconnected and it still made the noise.

Used a stethoscope and the sound is clearest above cylinder 6 and then 5...
Was sick of the car so left it to cool myself down for a few weeks just been out in the garage and was checking the tappets they're all rock hard and don't give under instant or prolonged pressure.

I did however go over the cam bolts and although one or two were ever so slightly loose.

The one closest to the spark plug (a7 I think) on cylinder 6 was loose and wouldn't tighten. Pulled it off and it looked like the threads were gone on the nut, took the cap off and there is scoring to both cap and camshaft which can be felt with a fingernail... Could this be the culprit?
Anyone know of anyway to make sure that this is the cause of the noise..?

Post Tue Feb 14, 2012 9:51 pm

If the nut was loose the oil pressure at that cap/lifter would be low, the oil pressure comes up the stud hole in the cam tray. The noise didnt sound like a cam but if its loose I suppose it could be flapping/vibrating a bit

Post Wed Feb 15, 2012 12:18 am

Was a bit quick of the mark posting up while I had a cup of tea....

The nut was loose because the stud had stripped it's threads. Anyone ever helicoiled one of these? or are there any other options..

I've not checked any other caps yet but they were all tight.