325 still knocking after valve adjustment,..

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I posted earlier about my 325 with 145k miles that knocks for the first few minutes until it comes up to temp. Well, adjusting the valves didn't help any. They were fine except for
two that might have been slightly loose by .01" or so. Could it be that one of the many sensors that control timing is defective? Maybe they kick out after they've done their job at cold start and the engine runs right after that.
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I can't remember whether you said or not (before) whether the knocking was in frequency with the cam or with the crank. There is such a thing as piston slap although I have no direct experience of it myself.
You need to try to find where the sound is coming from really and only someone experienced with the different failure sounds could probably tell you that.
I had a car once that was tapping and it turned out to be shapnel imbedded in the top of the piston. My dad's Saab had the little ends go. My GM sounded like the cam was on the way out but turned out to be water pump bearings.
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wrote:

I can't remember whether you said or not (before) whether the knocking was in frequency with the cam or with the crank. There is such a thing as piston slap although I have no direct experience of it myself.
You need to try to find where the sound is coming from really and only someone experienced with the different failure sounds could probably tell you that.
I had a car once that was tapping and it turned out to be shapnel imbedded in the top of the piston. My dad's Saab had the little ends go. My GM sounded like the cam was on the way out but turned out to be water pump bearings. -----
Mine was Connecting Rod Bearings on #1 and #2 pistons in my '88 325is. It was heard the best when letting off the gas next to a wall or highway barricade/lane divider (to get the echo). That particular job was quoted as $2500 and the engine comes out. I did it for $60 including a new oil pump and bearings for all 6 pistons, and the engine stayed in the car (but I did have to lift it up about 3 inches off the motor mounts). Open to close took about 5 hours and a lift from the local auto hobby shop. Turns out the previous owner had a gasket failure and some coolant got into the oil. They fixed that, but the coolant ate little "worm tracks" into the Conn Rod Bearing shells. This created a low oil pressure situation and contributed to the "thunk" I was hearing. Oil pressure would be OK after a few extra seconds, but I knew something was wrong. After replacing the shells on all 6, it was fine.
Bill in Omaha '86 535i
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Your car uses HYDRAULIC valve lifters. These are thin devices that are rougly the size of a small stack of nickels. The lifters are prone to getting an internal build up that restricts the free flow of oil, OR the oil flows properly but the spring inside gets stuck in such a manner as the lifter is slightly collapsed when cold.
1.) There is very little you can do for this beyond adding a detergent product (automatic tyransmission fluid works here) to clean the contaminants out and hopefully regain full operation of the lifters. There are a variety of detergent-products you can add, automatic transmission fluid is what we used in the old days before the specialty products that may or may not work better.
2.) Before we got hydraulic lifters, valve noise was common. A slight tap from the lifters (where the rocker arm contacts the top of the valve) is not a problem. It is an annoyance, but it is not a problem.
3.) Cold weather plays into this trouble because the oil gets thick when it is cold, and thick oil does not flow through the very small orifices inside the lifters, causing them to tap until the oil gets warm. One of the available remedies is to use a lighter weight motor oil in winter. If you are using 10w40 now, try switching to 5w30 for winter use, then back to 10w40 for summer.
Hydraulic lifters expand to fill the space between the valve stem and the rocker arm so there is no noise coming from the valve train. When the cam lobe rises, the rocker arm presses against the valve stem, pushing the valve open. Because the valve has a very strong spring, some of the oil inside the lifter will get pushed out as the rocker arm pushes the valve. When the cam lobe falls, the rocker arm releases the valve which is closed due to the very strong spring mentioned earlier. There is a small spring inside the lifter to cause it to expand again to fill the gap that forms between the rocker arm and the valve stem. When the lifter expands, oil flows in and the valve train sits and waits for the cam to roll around again and start the whole process over.
The problem you are noticing is that the lifter is not fully expanding when it is cold, and the tap you hear is the result of the small gap between the rocker arm and the valve stem. The cause of not expanding can be dirt/sludge inside the lifter, blocked passages impeding the flow of oil, or thick oil that is slow to run through the passages. Of course, a combination of all of these is possible as well. One other possibility is a broken spring inside of the lifter, but this would make a sound that remains after the engine gets warm.
I said earlier that the lifter goes between the rocker arm and the valve stem, but this is not always the case. The lifter can go between the cam lobe and the rocker arm, and on a push-rod motor it will almost always rest on the cam lobe, with the push rod fitting between the top of the lifter and the rocker arm (the configuration of a push rod motor is not really germain to this discussion since your BMW does not use that design). The point being, the physical location of the lifter is not important, the job it does is what I wanted to describe. Once you understand what a lifter does, finding it is easy. The job of the lifter is to fill the small gap that exists between the rocker arm and the valve stem. There are engine designs where the cam makes direct contact with the valve stem through the lifter, in this instance the lifter will need some form of device to hold it in place. (Your BMW does not use this design either ... )
Bottom line, You worry too much.
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Jeff, you're completely off on this. If you go back and actually READ the previous thread, you would discover that this is an '88 325i with M20 engine, which does not have hydraulic tappets.
FloydR
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wrote

Well, except for that tiny problem, my explanation is good ...
I find it odd that there are no lifters though.
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wrote

Umm, didn't Floyd say no hydraulic tappets? That generally means the valves are actuated by solid (mechanical) lifters, unless it's a rotary or 2 stroke motor.
Tom K.
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The M20 motor has a rocker arm that rides the cam and directly opens the valve when the cam lobe rises. There are no lifters of any sort in these motors. If the adjustment on the eccentric (on the valve end of the rocker arm) is too far out, they will "tick" and that may be loud enough to be annoying. If you have a knock, that is an issue that an experienced (read "shadetree") mechanic can isolate with an old wooden handled screwdriver. There are other, perhaps more accurate, ways to do it but I've learned the old guys do it best with what they had back when. Find an older guy with a nice street rod from before you were born and he'll be able to tell you what's going on.
On Tue, 18 Dec 2007 19:51:23 GMT, "Jeff Strickland"

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Well, in that case if there is still a tapping then either the tapping is not the rockers OR the rockers are still out of adjustment.
I haven't seen the inside of an M20, but I was thinking that pretty much all motors used a hydraulic tappet or lifter in the valve train somewhere. I've owned old cars and trucks that did not have hydraulic lifters, so I get the idea. But, I just thought that engines came with hudraulic parts to avoid the noise that comes from valve lash. I guess I was wrong on this one ...
wrote

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On Wed, 19 Dec 2007 00:44:39 GMT, "Jeff Strickland"

Believe it or not, most performance engines up until just a few years ago had solid lifter or rocker arm type arrangements. Hydraulic lifters were designed for ease of maintainance and as mentioned to quiet the valvetrain (and stop the customer from complaining). Ferrari and Lamborghini I believe are the holdouts on hydraulic lifters unless they've done it in the past year ot two...
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wrote:

I know all of that, and I thought that BMW motors -- while performance is very good -- were essentially luxury products where noise (or the lack of it) would take precedence. I assumed, wrongly I've been told, that BMW motors would employ tappets to reduce/eliminate valve noise.
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Jeff Strickland wrote:

Well, you think the Earth is like 10,000 years old, too. Dumbshit.
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Michael Yeager wrote:

Honda likes their mechanical valve adjustments, at least on their 4-bangers. I haven't kept-up with them in recent years, but I'd bet they, and others, still do...
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On Dec 19, 9:44 pm, Michael Yeager > quiet the valvetrain (and stop the customer from complaining). Ferrari

..and BMW. My 2001 has no hydraulic tappets.
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You must have an M car; BMW I6 engines since the M50 in 1990 have had hydraulic tappets, and the V8's do, too. Only the engines in the M cars have solid lifters.
FloydR
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Michael Yeager wrote:
> Believe it or not, most performance engines up until just a few

Sorry - wrong.
Ferrari has had hydraulic lifters for about 10 years that I know of - and that's on engines that turn > 8K RPM. No valve adjustments, but they did use timing belts - which require engine removal to replace at 15k intervals (which is why you see Ferrari's available cheap at around 15K miles.. people don't want to pay the money to have the belts replaced.)
http://cgi.ebay.com/ebaymotors/1997-Ferrari-F355-Spider-6-Speed-Nav-DVD-Tubi-Serviced_W0QQitemZ260189556157QQihZ016QQcategoryZ6212QQcmdZViewItem
There's a nice 10 year old with hydraulic lifters and recently replaced timing belts.. :)
Haven't looked at Lambo's..
Just looked, hydraulics:
http://www.caranddriver.com/roadtests/7699/lamborghini-gallardo-page5.html
Hmmm..
99% of the facts on USENet are made up on the spot..
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That's nice to know, not sure I care for the arrogance of "Sorry - wreong" but that's the way it is. There have obviously been a few advances in hydraulic lifters over the years. The last time I dealy with them they tended to float and subsequently fail at RPM levels over about 6500. This was a pushrod motor as well, I'm certain that makes a difference.

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Michael Yeager wrote:

Michael - do you really think I care? It's not arrogance when you ARE wrong and ARE stating things as FACT when they are not. A tiny bit of fact checking goes a long ways towards credibility.
76% of statistics on the Internet are made up on the spot..
I just do the things the voices in my wife's head tell me to..
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At this point, fuck you... Notice in the above paragraph the term "I believe". Seeing as the topic refered to an E30 BMW and not a 2007 Ferrari, the statement "I believe" was appropriate. I did not state anything as hard fact other than the fact that the M20 engine did not have lifters (hydralic or otherwise). Take your pompous arrogant little bitch ass back to the honda group where you belong...
Douchnozzle.....
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wrote:

At this point, fuck you... Notice in the above paragraph the term "I believe". Seeing as the topic refered to an E30 BMW and not a 2007 Ferrari, the statement "I believe" was appropriate. I did not state anything as hard fact other than the fact that the M20 engine did not have lifters (hydralic or otherwise). Take your pompous arrogant little bitch ass back to the honda group where you belong...
Douchnozzle..... -----
So... was the problem resolved or what? We know the M20 valves are driven off a rocker arm riding the cam.
Bill in Omaha '86 535i
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