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Discussion Starter #1 (Edited)
After some months I finally arrived to the end of the cylinder head replacement. I will remind you that I bought a second hand head with valves and everything already mounted and seal rings replaced.

I have taken the opportunity to replace the sprokets by the ones of the 3.8.

After mounting the cams I have measured valve clearances finding bad values, as is normal for a new head. At the intake cam, clearances are from 0.15 to 0.20 with the exception of one of the intakes of cyl #6 which measured as much as 0.75 (a 4.25mm shim will be needed there, that's the maximum value specified at ETK). At the exhaust cam clearances are between 0.30 and 0.55 with only one of them measuring 0.25-0.30, say 0.275. My measuring gauges go in 0.05 steps.

I am trying to purchase the tapped depressor tool to be able to give the valves the correct clearance. By the way, do you know of any european shop where I can find it a a reasonable price?. I am having difficulties to buy it from USA.

In the meantime, since I am impacient and, since the gaps lower than the nominal 0.30 are only in the intake side, I decided to start the engine

The engine started immediately after turning the key but the idle is terrible, so much that I do not dared to run with the car. It sounds like a diesel with a lot of valve sounding, specially one of them (would that be the one of cylinder #6?). After a couple of minutes, when the engine took temperature things got worse and it stalled. I started it again but the engine is failing a lot, even a 2.000 plus rpm. I have removed the spark plugs and none of them show any evidence of oil or any other wrong deposit.

Do you think that the engine fail are only due to the unadjusted clearances or must it be something else?

Another question. I am showing the picture that Gabriel Dark put in a post some weeks ago. There I can see that the part of the chain between the two sprockets is loose in contrast with mine that is tight. What is the correct way to mount it? I have syncronized mine and checked several times that the marks are in the correct place.



By nihonto

Best regards, Ramon
 

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Hi Ramon
Would suggest taking your engine to someone who undertands them.
Get them to check it before you do anything else ( please)
The valve clearances are all over the place.
You say about no6 exhaust valves sounding noisy
With the 0.75mm clearance you measured, I would not have started the engine.
Get a compression / leak down test done ( after the engine has been checked
for correct timing)

Cheers
 

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Discussion Starter #3
Farrel, thanks for your answer. I am not so confident in the garages I know, at least not to put their hands in this engine. The last time I went to a pretended expert (Lamborghini dealer at Madrid), I ended up with the cams out of timing and intake sprocket at exhaust place and viceversa. The best source of information for these cars are by far this and the Yahoo forum.

I will make a compression and leakdown test before any other thing.

I have now triple checked the timing, before and after having started the engine, and it is absolutely correct.

Any advise about the chain? Should it be loose or tight between the spockets?

Regards, Ramon
 

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Discussion Starter #5
Thanks again, Farrell. That is like I had imagined and that way I mount it.

Ramon
 

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Until you have everything set up properly, it's very difficult to diagnose a rough running issue. If the valves were out by +/- 0.1mm I wouldn't worry, but with so many valves out of spec it *could* really affect the engine, but you never know.

As with most things- patience will cost you nothing. Impatience can be very expensive!
 

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Discussion Starter #7
The starting of the engine was just a check. I have not driven the car, just started in the garage at idle and a little more.

Does anyone know where can I buy the depressing tool (11 3 170) to make valve adjustement at a good price.

Regards, Ramon
 

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Discussion Starter #8
I have made an apointment with an old known mechanic who has a lot of experience with racing cars. He will come to my place next saturday to verify the car. He will make a compression test among others. Hope he can find the reason of the malfunctioning in case that it is something else that the valve clearances. Any suggestion of what other things to check?

Meanwhile I have ordered the right shims and the depressing tool. They will take some time since they have to come from Germany and USA respectively.

Regards, Ramon
 

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Discussion Starter #10
The month of august in Spain is a non existant month in many ways. Most people take holidays this month and shops, restaurants, even hospitals work at a minimum. Many garages are closed or almost and the ones that are open are overloaded. Last saturday the mechanic that had to come to my place didn't arrive for that reason. But at least he lent me the compression meter. This morning I have made a check and found a good compression values in the five first cylinders and "zero" compression at cyl #6. This is the cylinder where one of the intake valves had a 0.75mm. clearance, I suppose`this is not a coincidence. I will check if this or any other valve at cyl 6 stays open and will let you know my advances. Again, any suggestion?

Regards, Ramon
 

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Bent valve maybe, otherwise a massive piece of debris under the seat - it sounds like you may need to have the head off to look though
 

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Discussion Starter #12
Thanks Day, once again to dismount the thing, grrrrr. At least this time it will go faster after all the practice I have adquired.
 

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Discussion Starter #14
Have you set the valve clearances within specified tolerances yet Ramon ?
No David, I have not yet received the plates or the tool. Nevertheless the null compression at cylinder 6 indicates that one valve do not close at all so I will investigate the reason for that as per Day's advice. A lot of work to repeat but I do not see any other way to check the compression failure.
 

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Discussion Starter #16 (Edited)
Is it necessary to remove the whole head to check the valve closure ?
I will have, at least to remove the cambox to check the springs. Is one valve possibly down?. The next step is to remove the head, I'm afraid.

I am assuming the compression is gone through an open valve since I re-checked the compression a 2nd time after sealing the piston rings with oil and got the same result, no compression.
 

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This morning I have made a check and found a good compression values in the five first cylinders and "zero" compression at cyl #6. This is the cylinder where one of the intake valves had a 0.75mm. clearance, I suppose`this is not a coincidence. I will check if this or any other valve at cyl 6 stays open and will let you know my advances. Again, any suggestion?

Regards, Ramon
Did you turn the crankshaft +/-30 degrees back when fitting the camshafts, so the valves can't reach the piston when fitting?
Its almost impossible to keep the camshaft in the right position when fitting the cams. Since the cam has a will to turn when fitting, you'll easilly bent the valves. I'll bet 2 intake valves are bended.
 

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Did you turn the crankshaft +/-30 degrees back when fitting the camshafts, so the valves can't reach the piston when fitting?
Its almost impossible to keep the camshaft in the right position when fitting the cams. Since the cam has a will to turn when fitting, you'll easilly bent the valves. I'll bet 2 intake valves are bended.
Very true. It's not part of the factory instructions for cam installation on an S38 engine, but it is for the M50 for some reason. Also pistons #1 and #6 are positioned in the upper position (@TDC) so their valves are most at risk.
 

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Discussion Starter #19
Did you turn the crankshaft +/-30 degrees back when fitting the camshafts, so the valves can't reach the piston when fitting?
Its almost impossible to keep the camshaft in the right position when fitting the cams. Since the cam has a will to turn when fitting, you'll easilly bent the valves. I'll bet 2 intake valves are bended.
I left crankshaft at TDC and fitted the cams with marks in vertical position. It is difficult to prevent the cams from turning but I managed at the 3rd try. The first two times I stopped at the moment I noticed that the cams were turning while tightening the nuts.

Pistons 1 and 6 are in the uppper position at TDC but only intake #3 and exhaust #2 valves are pressed by the cams then as can be seen in the picture.



If I had to set the crankshaft 30º away from TDC it's not clear to me how to syncronize the cams then since I lose the reference point.
 
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