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Pedrocalima

Yet another engine noise case

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Hi all

I'm quite new to the forum even if have used info I found here before.

My father is restoring a 2002 in Brazil and I'm trying to help him but I'm living in Finland so I don't have first person contact with the car.

The M10 2 liters has been completely rebuilt with new pistons (higher compression), a LYNX manifold with a weber 40 and a 280 camshaft. The engone went to the dino and 3 things took my attention.

 

1) The max torque and power came in quite lower revs than expected. The mechanic mentioned that it might be that the camshaft is not well aligned with the crancshaft. He mentioned about moving a tooth but if that would be too much he would need a adjustable gear. Does that make sense?

2) He was playing with the distributor and that made the power measurements move all over the place. He is used to work on american V8s and said that for those cars there are kits with springs and weights to adjust the curve of the distributor, but not for the one on the 2002. He said he opened the distributor and made some changes. Is that something that people often do? I know I can go with a 123 but that is another 400 Euros...

3) My father told me that there was a strong "valve" type of noise coming from the engine on any RPM. The mechanic agreed but said he didn't figure out what is the reason and where it's coming yet. To this point I researched  a lot and could be valve adjustment, piston slap, lubrication issues, exhaust manifold leak, and the list never ends. As the engine has been just rebuilt everything should be right but who really knows. From the video bellow would someone take a good guess?

 

Thanks in advance!

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The 280/284 camshaft isn't that aggressive, so I would expect that your power numbers would be on the lower end of the RPM spectrum.  I would first dial in the ignition, by mapping the curve for that distributor.  With the Lynx and carb setup you aren't able to pull the right vacuum to help that distributor reach its maximum advance.  So, set the 25 degree flywheel ball at 2200 RPM (Ti Spec) and use a variable timing light to see what kind of advance you are getting through the full RPM range.  If you aren't getting enough advance with out the vacuum assist, you could have it rebuilt with new springs and weights to mimic the Ti curve, or pony up and buy the 123 Ignition distributor, to eliminate this issue.

 

Just for fun, I would re-adjust the valves to see if that noise changes, but it sounds more like an exhaust leak to me.

 

Mark92131

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1 hour ago, Mark92131 said:

With the Lynx and carb setup you aren't able to pull the right vacuum to help that distributor reach its maximum advance.

On a power run, vacuum advance is normally zero and the advance runs on mechanical only.  Maximum advance occurs on cruise operation.

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The cam timing (the relationship between the cam and the crankshaft) can be used to adjust where max power appears in the engine speed range. This is not a huge range of adjustment however, and your mechanic would need to be careful that there is enough space between open valves and the piston top. The standard arrangement sees the cam timing based on TDC from the factory though the actual position of the cam varies depending upon how much has been cut from the head or block in its lifetime. Shorter the head and block, the closer the cam is to the crank and the shorter the timing chain needs to be. Often people may use an adjustable timing sprocket to ‘lose’ some of this extra timing chain length, more as a way to advance the cam timing back to its standard location. 

 

As for the noise - did your mechanic bleed the air from the hydraulic timing chain tensioner?

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It seemed like part of the noise in that video was being caused by the inductive pickup rattling on the valve cover. The mechanical fuel pump drive rod can also make a lot of noise. Time to get the stethoscope out.

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2 hours ago, Chris_B said:

It seemed like part of the noise in that video was being caused by the inductive pickup rattling on the valve cover. The mechanical fuel pump drive rod can also make a lot of noise. Time to get the stethoscope out.

 

 

and find a real BMW mechanic who works on these cars

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I was going to guess the noise was coming from the fuel pump, based on the first video; but it is not as pronounced when the camera is on the driver's side, so now I am leaning towards an exhaust leak.  

 

As for the distributor questions, hopefully the mechanic has an adjustable timing light, to be able to assess the performance of the distributor and determine how much total advance there is and at what rpm it peaks, as well as how much advance there is at idle.  Hopefully, what happens in between is smooth and not sticky. 

 

Surely he knows to disconnect the vacuum advance while setting timing.  As Jim mentions, vacuum advance is not a power-feature, but comes into play during light throttle situations.  There is an ongoing debate over whether to use ported or manifold vacuum for the distributor and I am in the ported camp, but I do not know what is available on a DCOE carb for vacuum.  Using manifold will bring in full vacuum advance at idle.

 

On 8/11/2019 at 1:21 AM, Pedrocalima said:

2) He was playing with the distributor and that made the power measurements move all over the place. He is used to work on american V8s and said that for those cars there are kits with springs and weights to adjust the curve of the distributor, but not for the one on the 2002. He said he opened the distributor and made some changes. Is that something that people often do?

 

I've heard that back in the day you could purchase weights and springs kits for our cars, but it is hard to find parts for the distributors now.  There are ways to tweak the curve a bit by bending tabs in the advance mechanism, or by swapping in different springs, or weights, but the interaction between those things is a bit complex and there's no telling what he's done or how much he knows about such things.

 

One nice thing about the 123 craze is that it finally has people sharing their advance curves, so you can look through the threads and see what someone with a similar setup ended up with.  I think @Mark92131 uses that carburetor setup... (see his advice above).

 

Most of the Bosch distributor threads say "send it to a pro, or go with a 123... best thing I ever did for my car!!"

 

I'm guessing yours has a PerTronix installed, or something similar; as opposed to running points, but the dwell angle is an important first adjustment in the timing procedure.  Based on the position of your vacuum pod, the points will be at the back of the distributor, which makes them difficult to adjust.  The distributor can be re-clocked to make adjustment easier, but if points have been eliminated, that doesn't matter.

 

Distributors are a thick topic.  

 

Tom

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 Mine sounded like that when the fan was "tickling" a slightly large gob of weld on my I.E rad. Nudged it back 1-2mm and bingo.   Maybe take the fan belt off,  it would isolate it to the engine or the pulley drive. 

 

P.S Idea just stolen from TobyB :) 

 

 

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20 hours ago, jimk said:

On a power run, vacuum advance is normally zero and the advance runs on mechanical only.  Maximum advance occurs on cruise operation.

 

Just as a reference point, the Weber DCOE and the Lynx manifold have no connections available to supply any vacuum to that stock distributor, unless you tap the Lynx, (but that really isn't the vacuum you really want).  The issue I have refers back to the Blue Book, which states that the maximum centrifugal (mechanical) advance for the 2002, 2002 Ti and 2002 Tii is 16 degrees, so with no vacuum connection, Pedrocalima's motor will top out at 16 degrees of advance with that distributor, unless the weights and springs are modified, or he switches it out for a 2002A distributor (21.6 degrees of mechanical advance), or he finds a way to tap the DCOE 40 above the throttle plates, or he buys the 123 ignition distributor.

 

I have a very similar setup in my Cabriolet, (Weber DCOE 45) and tried tapping the Lynx manifold to supply vacuum to the 123 Ignition distributor to add or subtract advance in specific conditions (cruising, WOT, etc.).  The problem I found was that using manifold vacuum wasn't linear based on RPM, it was never zero and varied based on RPM, Load on the motor and the gear I was in (for example, I would see 24 inHg reading for 4000 RPM in 3rd gear, 3000 RPM in 4th gear and 2500 RPM in 5th gear).  If the vacuum above the throttle plates was linear based on RPM, then I could use it to build a 123 File with a static Centrifugal Curve of 16 Degrees and a MAP curve that added the appropriate advance based on the Abs Pressure (kP) for specific RPMs.  Without that predictable linear vacuum readings, I zeroed out my MAP curve and just use the Centrifugal curve mapped to the timing curve for the "026" distributor on the 1600 Ti.

 

Mark92131

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the distributor will top out at 16 degrees, but the engine will have 32 degrees. 

 

16 degrees of advance in the centrifugal curve does not mean that his ignition advance can only be 32, that depends on how he clocks the distributor. 

 

Less advance built into the curve means more advance at idle, to get the same all-in numbers.

 

I sort of skim these posts about MAP stuff and making sense of manifold vacuum's relation to timing and I just get confuseder and confuseder.

 

I love a simple diaphragm and spring taking its signal from above the throttle plates pulling on a pin to rotate the points plate.

 

I love points too... and little weights and springs and things going round and around.

 

These things are worth celebrating, in my twisted brain.

Such wonderful tinker fodder.

Tom

 

Edited by '76mintgrün'02
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17 hours ago, '76mintgrün'02 said:

I just get confuseder and confuseder.

 

Me too, makes my head hurt sometimes.  Your post prompts so many questions.  So does 12.5 Degrees of centrifugal curve at the distributor yield 25 degrees BTDC at the flywheel (the ball) with the distributor clocked at TDC?  Or is 16 degrees of centrifugal advance at the distributor, 16 degrees BTDC at the flywheel with the distributor clocked at TDC?  I always assumed that for the most part, the advance curves in the blue book for models and specific distributors for these models reflect a combination of centrifugal and vacuum advance, (tii distributors with no vacuum pod being the exception).  So if a Tii distributor has a max centrifugal of 16 degrees and no vacuum pod, and 16 degrees is 32 degrees at flywheel or 16 degrees is 16 degrees at the flywheel, how does it get 25 degrees at 2400 RPM or 2700 RPM (US Version)?

 

Is 2700 RPM the approximate speed to see the "all-in" centrifugal advance based on the stock weights and springs, (this seems to be the RPM used at the top values of the advance curve)?  If 16 degrees at the distributor is 32 degrees at the flywheel, we are way over the blue book 25 degree at 2700 RPM, if 16 degrees at the distributor is 16 degrees at the flywheel we are way under the blue bool 25 degrees at 2700 RPM.

 

My guess is that 16 degrees at the distributor is 32 degrees at the flywheel and 16 degrees is the mechanical limit of advance, but the springs and weight in the Ti distributor restrict the advance to 12.5 degrees or 25 degrees at the flywheel.

 

Mark92131

 

 

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As much as I like discussing distributors, I think we are getting into more detail than this thread needs, since the topic of this one has to do with a ticking noise.  He did ask about the distributor though, so some of this might apply.

 

All in advance rpm depends on when the weights hit their stops and that varies, depending on the particular distributor.  

 

Timing needs depend on the particular engine and its fuel delivery system.

 

Those blue book graphs made sense when these cars were new and totally stock.

They are drawn for the mechanical advance only

and show half of the advance that you see at the crank/flywheel.

 

There are separate graphs for the advance/retard pod curves.

 

The BB is 25 degrees btdc and merely a reference point for using a basic timing light to set timing.

They put it 'mid curve' for whatever reason(s).

 

Set timing for total advance and hope that leaves you with happy idle advance.

If there is no detonation and you are getting maximum power you win.

You can use an acceleratorometer like this, if you don't have a dynamometer

acceleratorometer.thumb.jpg.9651a38c8c21d343b53da026aac48b75.jpg

 

my car goes up to eleven

 

(hoping the OP gives us an UPdate)

Edited by '76mintgrün'02
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1 hour ago, '76mintgrün'02 said:

You can use an acceleratorometer like this, if you don't have a dynamometer

acceleratorometer.thumb.jpg.9651a38c8c21d343b53da026aac48b75.jpg

 

my car goes up to eleven

 

This. This is all I needed today. Now I go home and sleep happy. 

 

It's also 9:17am in Germany and I just go to work. 

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1 hour ago, '76mintgrün'02 said:

You can use an acceleratorometer like this, if you don't have a dynamometer

You can also download the BMW M POWER METER App for ios - allows you to have your eyes on the road instead of watching that thing while flooring it.

I've also formerly used the dynolicious app with surprisingly precise results compared to a real dyno but it's not longer maintained.

 

 

 

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