noisy valves

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bill

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Der Gruppe;
I had to replace the failed head gasket on my '74 with 75,000+ miles. I put the head back on and adjusted the valves to .28mm (book recommends .25-.30). Started the engine and the valves are VERY NOISY.(They were silent before I had the gasket trouble.) I checked oil flow into the head and that is OK. I never adjusted the valves in the 10 years I've had the car so don't know what they were originally set at.
What is the wisdom for valve clearances on old, somewhat worn engines? More clearance? Less? It's laborious setting the clearances, having done it twice now, so any idea what to do next will save me a lot of time. Thanks for the anticipated expert advice from anyone.
 
Why did the gasket blow? Did it overheat bad, cross oil and water, just leak around the head?
Do you have the proper amount of oil?
Have you re-torqued the head in proper order. then re-done the valve adj.??
Is compression still same?
Is your gage metric vs SAE? long shot most are metric...being patient with the adjustment then tighten routine is key, the adj. cam moves very easily. You have done it twice, I know it is a back strainer, is this first time you have done valve adj. to a bmw head?
Do they all make noise, intake vs exhaust, front to rear??
Did you tighten them (adj. cam nut) down suitably?
Is the manifold gasket intake and exhaust tightened well, if loose it bleeds noise...but you should be able to tell the diff from header noise and valve noise (loose valves).

Metal is metal, age should not make you want to use different clearances.
Trying to help,
Jon
 
What is the wisdom for valve clearances on old, somewhat worn engines?
Click to expand...
Someone ask for old wisdom? (...or was that wisdom on 'old' valve train geometry?)
:mrgreen:

The wisdom is that if you can hear the valve train a clicking... at least you stand little chance of having done any damage...it's when they are too tight (and hence you hear nothing) that the too tight of a 'lash' (or lack of your proper clearance margin) does not allow the valve itself enough time to sit on it's seat..and thus have a chance to dissipate it's heat into the cylinder head... if not allowed recovery, the valve begins to burn at the edges and then fails altogether...especially with some of today's cheaper/emission related gasoline formulas.

As Shark mentions above, I would attempt to retorque the head after a few miles and 5-10 temperature cycles and then reset the valve train clearances COLD (Yes, yet again, or until morale improves?)...Making very sure that you are adjusting the valves at that cylinder's TDC, ie. where they are both closed all the way. If you think about it this might make some sense. Again, the valve lash setting is to allow the valve itself to sit for awhile on the seat and by heat transfer lose it's inherited heat, generated by being in the middle of a small (non-nuclear) but very violent explosion.

Edited to add: Something that helps greatly is a hand held device (called a remote starter switch) to turn the starter from the engine compartment so that you can get close enought to TDC on the cylinder you wish to adjust, without wrenching, scraping knuckles or getting tired and frustrated, as this procedure is critical to proper operation and requires patience and a very level head so as to not make a critical mistake...

Good luck!

Ran
 
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I followed the blue book on adjusting the valves, COLD. Shark: so many questions...let me say I have done valve work on BMWs and 280Zs before. I know the difference between metric and inches..my gauge has both, btw. Some or all of the rockers are making noise. I am POSITIVE all the rockers were tightened correctly..10 ft/lbs per the book. It isn't exhaust manifold noise. I suspect my clearances are too high at .28mm, so I may try a lesser amount, maybe .25mm. The valves never made any noise before I removed the head...which I did because I found coolant on #2 cylinder spark plug. With the head off I found evidence of water in 1, 2, and 3 (shiny areas around perimeter of pistons. ) The head was pressure tested (no cracks) and shaved .006 inches to correct warpage. Car has not overheated while I have owned it. I am stumped and a little worried about the noise...
Any help you can provide is appreciated....Thanks.
 
...and shaved .006 inches to correct warpage
Click to expand...
hmmm....leading me to suspect either overheating (you say not) or perhaps electrolysis between the head and block, causing a pre-mature gasket failure under sllght high temp condition...or excessive blow by brought on by failing rings...IMHO, this electrolysis would maifest as deep pitting in the head surface, and not warpage...yet would require similar grinding of the head surface to repair.

Ironically, both conditions are totally user controllable (fault is not in the M30 engine design) by simply adding a sufficient amount of coolant. year in and year out, to retard natural electrolysis action between dissimilar metals AND of course NOT TO, NEVER, DONT EVER operate the M30 engine in any type of overheated condition, that is if you value the integrity of your head gasket, and all that it touches. (ie. Push it!)

In your opinion (and it would help greatly) Bill: Just why have you assumed that only the head gasket was fautly and not some other condition that previously existed to cause it to fail in the first place? Or am I missing something?

pressure testing a head IMHO is not as good as magnafluxing the head to make sure no cracks are extant. That said, this is why many mechanics working on a high mileage M30 head issue will routinely (and perhaps wisely) suggest a complete head replacement with a fluxed head casting, as the cost of diagnosis and repair if you don't can exceed that cost somewhat exponentially.

Ran
 
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Jranmann:
Thanks for your input...I might try warming it up a few times to set the head a little bit. I have one more step to do to tighten the head bolts (third step is done after engine warms up per the gasket manufacturer (Elring)).
 
You're sure no piston slap or even main bearing noise? valve/rocker noise.

What did the oil look like while you did the head...burnt coffee or nice?? any metal if you had a magnetic drain plug??
 
Some valve train noise is normal

bill said:
Der Gruppe;
I had to replace the failed head gasket on my '74 with 75,000+ miles. I put the head back on and adjusted the valves to .28mm (book recommends .25-.30). Started the engine and the valves are VERY NOISY.(They were silent before I had the gasket trouble.) I checked oil flow into the head and that is OK. I never adjusted the valves in the 10 years I've had the car so don't know what they were originally set at.
What is the wisdom for valve clearances on old, somewhat worn engines? More clearance? Less? It's laborious setting the clearances, having done it twice now, so any idea what to do next will save me a lot of time. Thanks for the anticipated expert advice from anyone.
Click to expand...


1. Are you familiar with normal valve train noise?

You state the valve train was silent before gasket trouble. You also never adjusted the valves in 10 years. You left this reader guessing at how many hours or miles are on your engine - since its last valve lash check. Is it not possible that until your recent gasket travail, your valve lash settings were much tighter than recommended and you merely presumed this to be normal? Now that you have set things “by the book,” is it possible you are hearing “normal valve train noise,” but do not recognize it as such?

Valve “tick” is normal on these engines. If you are unfamiliar with this, consider listening to similar running engines, even on a much later models. Even without a comparison “control” model, consider using a mechanic’s stethoscope or similar (length of hose? Long screwdriver?) and determine the exact location of the noise. If the noise is uniform across the head, them maybe things are as they should be.

2. If the sound still seems suspiciously loud or abnormal, check for acceptable/correct valve gear(A) assembly, (B) wear, and/or (C) lubrication.

Were the rocker shafts assembled in the right order? All spacers, washers and springs? If they are not in the proper order, they are potentially dead weight and likely percussion sources.

Could the noise be from worn rockers or rocker shafts? You never disclosed what condition they were in, what you replaced, and if you reused parts, whether they were replaced in exactly the same order they were removed? There is also wear that occurs with start up even with new parts. Dry starts can account for a lot of wear.

Since you evidently have pressure in the head, what readings do you have? Could the plug from a rocker shaft be loose therein reducing your operative oil pressure? How about that sprayer bar (11421256294), is it distributing oil as designed? If not, are the mounting bolts tight? Did you use the correct copper crush washer? Are all of the spray orifices fully open or are they clogged or partially clogged?

3. Another likely noisemaker to consider could be the timing chain and tension apparatus. Listening carefully ought to indicate this as a probability and since you did not discuss this or other accessories, I will leave it at that. The only other thing I can think of at the moment is using oil that is far lighter than recommended.

Respecting whether there is a preference toward large or small gaps, unless I am coping with a specific issue, I prefer to set things in the middle of the recommended setting .011". This being said, some engines and driving styles might favor slightly different valve lash settings, e.g., an engine mated to an automatic trans that spends most of its operation at low speeds may enjoy different settings than an engine that often sees the tach redline.

Hope some of this helps!
Good luck!
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bill said:
What is the wisdom for valve clearances on old, somewhat worn engines? More clearance? Less?

It's laborious setting the clearances, having done it twice now, so any idea what to do next will save me a lot of time.
Click to expand...

FWIW, the factory recommended checking valve lash at 8000 mile intervals. Setting valve lash may be time consuming, but once set, future checking of the settings should get easier. Section 1:5 should provide a little wisdom regarding valve clearances.

hth

autobooks_manual_022.jpg
 
MMercury:
If some noise is normal as you say, then I am relieved. I live near a few other coupes and will make a point to listen for noise in them. I have had the car for 10 years and have put less than 2000 miles on it (unbelievable...I know) and never fussed with the valves because they "seemed" OK so I left them alone. It is possible they were too tight. Now that they are done by the book, perhaps the noise is normal...I hope.
I took the head off to deal with the coolant leak (and a regular misfire which disappeared after the engine warmed up), had it pressure tested for cracks (OK) and put the head back on with a new gasket. No other work was done on the head. Compression was good so I didn't have a valve job done. Shafts etc. were not touched. I ran the engine with the valve cover to check on oil flow and it seems OK at all the ho;es (oil is spraying on the cam lobes.)
I set the valves at .28mm, the mid of the recommended range (.25-.30mm). Maybe I'm being a little too nervous about the noise? Worst case, I'll have to use the head from Waldtraut, my '74 euro parts car....
Thanks for your help/
 
Double check your cam timing, too. One tooth off can create interference problems with the valves and pistons. It will sound like a valve tap. My coupe had this condition which I didn't discover until I tore the motor down for a rebuild six months after I got it.
 
Gump on engine theory and practice

Describing sounds is an art over which I have no mastery. Most cars with mechanical valve gear /solid lifters tend to sound like sewing machines. The design of the valve cover and other sound suppression and ambient sounds like exhaust and intake noise can harmonize things where you think you see the entire orchestra yet only hear the string section.

Hydraulically controlled valves as found in most US engines are much quieter than the systems used in your E9. (When neglected or dirty - hydraulic lifters too can make a racket.)

You mentioned resurfacing the head. I assumed the cam and possibly other valve train components were removed in the process. The best opportunity to inspect for wear and replace the inexpensive valve seals and possibly worn guides is, after all, with the head on a bench. I do not mean to suggest you have wear, but the best time to address it is with the head removed. Hopefully, whoever did the work gave everything a decent once over. But the issue is rarely that simple, since even if everything in the engine seems pristine, disassembly has a tendency to dislodge the unknown or unseen. "Engine disassembly is like a box of chocolates. You never know what you're gonna get."

Good luck.

 
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