That pesky M20 tick Videos added

[Eddie25]

I know I've posted on this topic before as it's driven me to distraction over the years but I read an interesting article yesterday that might help shed some light on it.

Essentially my M20 sounds great when it's cold but when it gets even slightly warm starts to tick.....really tick. Not just your classic M20 sewing machine in my view.

The head was completely rebuilt a couple of years back with new CAT cam (274 iirc), new valve guides, oil seals, rockers, eccentrics, the works. The injetcors were also ultra sonically cleaned and a BTB 3 thrown in for good measure. But it's ticked horrendously ever since. T

he valve clearences have been set and reset but to no avail so it only leaves the injectors imo, which are apparently batch fired and can tick louder than the valves.

Even so I thought to myself BMW can't have sold this car new like this and reading an American article others agreed.

One theory was that BMW didn't, it's the changes in petrol. The lack of sulphur and higher ethanol content in petrol isn't lubricating the injectors like it used to. So the solenoids are alot more audible. For similar reasons the valves snap back harder against the seats.

So what's the answer? Something to increase the lubrication in the fuel? More modern/quieter injectors? Would even consider a acoustic cover. I watched a youtube video where a guy was running a very small amount of 2 stroke oil in his fuel (on a BMW motorbike) to take away the injector tick.

But all the above said why would it only do it when cold? Richer mixture, full pressure does seem a little low however on mine (around 2.5 bar).

Apologies for war and peace Any experiences will be much appreciated.

[bab-91]

Why not try a fuel additive for a month then report back?

http://www.piaggiospares.co.uk/spares/p ... tAodfEwA0g

[scjimbo]

Why not try a fuel additive for a month then report back?

http://www.piaggiospares.co.uk/spares/p ... tAodfEwA0g

When I first bought my 30, the guy who sold it to me said I needed to use a lead additive. I did this for over a year. This later turned out to be a load of bobbins.

However the engine was a lot lot quieter when running it. Trouble is it costs a fortune. I'll put up with the tick

[Eddie25]

I like the looks of that

The only additives I could find were fuel system cleaners, which is the opposite of what I was looking for. Will order up a bottle and let you know of any changes.

Thanks Bab.

[maggspower]

My first port of call now would be the manifold. Tubular manifolds always make engines sound more metalic and clattery. The BMW log manifold is so robust and heavy I think it goes a long way to dampening down these noises.

The other manifold related issue is leaks, a manifold or front section exhaust leak sounds exactly like a metalic tick. With yours happening once warm I would be looking for a crack or more likley a leak around the exhaust port/flange joint.

Adding any oil to fuel is a bad idea, it alters the octane rating of the fuel in the wrong direction and will just promote carbon build up within the chambers.

Definitly check out your fuel pressure, it should be running at 3bar above manifold pressure. A weak mixture will promote detonation, something m20s seem to be a little prone to (which I'm sure is why BMW kept dropping the compression ratio). Detonation is another horrid metalic sound, but usually only happens at full throttle from low revs. Do sort this, it is an engine killer.

I have had, have driven and I own m20s that run without ticking, so IMO it is not the fuel or its composition.

[bab-91]

When I first bought my 30, the guy who sold it to me said I needed to use a lead additive. I did this for over a year. This later turned out to be a load of bobbins.

However the engine was a lot lot quieter when running it. Trouble is it costs a fortune. I'll put up with the tick

I don't know, we have a mad Polish cleaner in work and he swears that old cars need a fuel additive. I dismissed it and put it down to fuel quality in Poland but after reading Eddies post, I remembered him saying.

I like the looks of that

The only additives I could find were fuel system cleaners, which is the opposite of what I was looking for. Will order up a bottle and let you know of any changes.

Thanks Bab.

Hopefully its not snake-oil! Good luck!

[Eddie25]

My first port of call now would be the manifold. Tubular manifolds always make engines sound more metalic and clattery. The BMW log manifold is so robust and heavy I think it goes a long way to dampening down these noises.

The other manifold related issue is leaks, a manifold or front section exhaust leak sounds exactly like a metalic tick. With yours happening once warm I would be looking for a crack or more likley a leak around the exhaust port/flange joint.

Adding any oil to fuel is a bad idea, it alters the octane rating of the fuel in the wrong direction and will just promote carbon build up within the chambers.

Definitly check out your fuel pressure, it should be running at 3bar above manifold pressure. A weak mixture will promote detonation, something m20s seem to be a little prone to (which I'm sure is why BMW kept dropping the compression ratio). Detonation is another horrid metalic sound, but usually only happens at full throttle from low revs. Do sort this, it is an engine killer.

I have had, have driven and I own m20s that run without ticking, so IMO it is not the fuel or its composition.

Thanks Maggs that's actually just jogged a memory. The tick is very audible from underneath the car, around the x-pipe. I've replaced the ring gasket between the front and mid-section and used exhaust paste at the joins but it didn't seem to help.

One thing I did pick up on is that the BTB front section has no gearbox steady bracket. Can a standard BMW be used? Or do BTB make a part? I wondered if that long distance without mountings was aggitating the noise through vibration if that makes sense?

[Eddie25]

Also the fuel pressure has me a bit lost.

There is no evidence of a fuel leak around the FPR and if you remove the vac pipe the pressure jumps right up to over 4 bar so it seems to be working correctly.

Doesn't the ETA run at 2.5 bar? Also my car was CAT prepped, so not sure if that made any odds to the FPR BMW went with?

[maggspower]

Yes you can use a standard BMW gearbox mount, but you have to remove the middle bolt as the pipes on the X piece are too close for it to go through.

[Eddie25]

Yes you can use a standard BMW gearbox mount, but you have to remove the middle bolt as the pipes on the X piece are too close for it to go through.

Thanks again Maggs. I'll get a steady bracket and have a good look round for leaks.

I suppose really the BTB should be ceramic coated, to help keep down the engine bay temps but this might also help dampen some of the mechanical noises transferred?

I do love a well set up M20 and I'm positive mine isn't happy it's just getting to the bottom of it. Another fault is jumping up to around 1100rpm on idle and hunting intermitently. The ICV has been cleaned, blue temp sender replaced, intake boot replaced and been smoke tested for vac leaks but it's still at it.

Bloody thing.

[HairyScreech]

All BMW engines from about 1960 onwards are capable of running on normal unleaded with no issues. Forget any fuel treatment for an e30.

[DanThe]

I don't know, we have a mad Polish cleaner in work and he swears that old cars need a fuel additive. I dismissed it and put it down to fuel quality in Poland but after reading Eddies post, I remembered him saying.

Perhaps thats why he is cleaning toilets and not fixing engines for a living?

[bab-91]

I don't know, we have a mad Polish cleaner in work and he swears that old cars need a fuel additive. I dismissed it and put it down to fuel quality in Poland but after reading Eddies post, I remembered him saying.

Perhaps thats why he is cleaning toilets and not fixing engines for a living?

You could be onto something there In 7 years I've never seen him clean, just laps the ward, pushing a mop bucket. I should probably check he's not a patient.

He has a list of car trivia. Bosch fuel pump on merc 190d will run on uncooked vegetable oil.

[Eddie25]

All BMW engines from about 1960 onwards are capable of running on normal unleaded with no issues. Forget any fuel treatment for an e30.

Absolutely capable no doubt but it seems logical to me modern petrol formulation may make for noisier mechanicals?

I'll try and get another video up this weekend. When it ticks it really ticks but I think Mags might be onto something with the BTB.

[Eddie25]

Apologies for the mobile phone videos but haven't come out too bad, also wasn't sure how to embed them;

Cold;





Warm;

[Eddie25]

Bump

Does it sound rough? or am I just being fussy?

[Eddie25]

Anyone?

Would just like to get it running better before Ultimate BMW, that'll probably be it's last outing this year.

[maggspower]

Its so hard to tell anything from videos, no matter how good the quality. Remember you are the one in the best position being right next to the thing

Get a long screwdriver, and hold it on the engine in various places, hold your ear close to the end you will be able to hear if there are any rattles within the engine. Its just to give you and idea and will not be definitive, but you will hear the cam, and can do it with the injectors too.

To me it does not sound overly tappy, like I said any tubular manifold will make the engine sound more pronounced as there is just less material to dampen it down. And check for leaks as well remember theres now 4 joints on the X pipe and check the lambda sensor bung is in there tight.

See you at the pod otherwise.

[Eddie25]

Its so hard to tell anything from videos, no matter how good the quality. Remember you are the one in the best position being right next to the thing

Get a long screwdriver, and hold it on the engine in various places, hold your ear close to the end you will be able to hear if there are any rattles within the engine. Its just to give you and idea and will not be definitive, but you will hear the cam, and can do it with the injectors too.

To me it does not sound overly tappy, like I said any tubular manifold will make the engine sound more pronounced as there is just less material to dampen it down. And check for leaks as well remember theres now 4 joints on the X pipe and check the lambda sensor bung is in there tight.

See you at the pod otherwise.

Thanks Maggs. I'm in the midst of a big move/relocation to Oxfordshire (closer to POD ) so got bills hitting me from all directions at the moment but hoping I can get the E30 fettled in time.

It's got idle issues which I suspect is the ICV. It's been cleaned so looking like a replacement part will be needed.

[e21jps]

Heres some wide experience and a cure!!.... bare with me i will explain why this happens

the reason they TICK is because the valve clearance is too wide and most people set them the wrong way, the setting is supposed to be 010 (0.25mm) at the valve but on anything but new refurbished head the little eccentrics on the rocker always wear a hollow in the end of the valve so when you stick your feeler gauge in there and set them it bridges this hollow and holds the eccentric further away so you might actually end up with 013-014 which is way too wide... and they tick!!

the solution is to set the clearance between the CAM and the rocker BUT YOU HAVE TO TAKE INTO ACCOUNT THE ROCKER RATIO.... so setting by this method you need to set at only 006-007

Nine times out of ten you will have a nice quiet engine again...... the other 1 time you will probably have badly worn rocker faces with little hollows in them from the cam so not much you can do

Another problem is oil that is too thin, thats why its better when the engine is col. Old M20's like oil on the higher end of the range something like 20/50 will help its not the reason for the tick its just something that helps fill all the larger clearances on a worn engine and will keep it happier (and quieter)

[basketweave]

Hey mate, good to see you on here. Do you recommend setting the tappets when its cold or hot? I had better results with my "tick" when I set them hot. I am going to try 6 thou at the cam.

The one thing is, I did have the tick straight away after I built the engine, with had a full head reco but I left the eccentrics the same. I have since bought new eccentrics but have not fitted them.

I look forward to seeing my ITB setup

Simon