325 still knocking after valve adjustment,..

"adder1969" wrote in message

On Dec 18, 12:42 pm, cosmo wrote:
> 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.

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
 >> Stay informed about: 325 still knocking after valve adjustment,.. 

"cosmo" wrote in message

>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.

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.
 >> Stay informed about: 325 still knocking after valve adjustment,.. 

"Jeff Strickland" wrote
> "cosmo" wrote
>>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.
>
> Your car uses HYDRAULIC valve lifters.

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
 >> Stay informed about: 325 still knocking after valve adjustment,.. 

"Floyd Rogers" wrote in message

> "Jeff Strickland" wrote
>> "cosmo" wrote
>>>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.
>>
>> Your car uses HYDRAULIC valve lifters.
>
> 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.
>


Well, except for that tiny problem, my explanation is good ...

I find it odd that there are no lifters though.
 >> Stay informed about: 325 still knocking after valve adjustment,.. 

"Jeff Strickland" wrote in message

>
> "Floyd Rogers" wrote in message
>
>> "Jeff Strickland" wrote
>>> "cosmo" wrote
>>>>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.
>>>
>>> Your car uses HYDRAULIC valve lifters.
>>
>> 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.
>>
>
>
> Well, except for that tiny problem, my explanation is good ...
>
> I find it odd that there are no lifters though.
>

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.
 >> Stay informed about: 325 still knocking after valve adjustment,.. 

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"
wrote:

>
>"Floyd Rogers" wrote in message
>
>> "Jeff Strickland" wrote
>>> "cosmo" wrote
>>>>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.
>>>
>>> Your car uses HYDRAULIC valve lifters.
>>
>> 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.
>>
>
>
>Well, except for that tiny problem, my explanation is good ...
>
>I find it odd that there are no lifters though.
>
 >> Stay informed about: 325 still knocking after valve adjustment,.. 

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 ...



"Michael Yeager" wrote in message

> 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"
> wrote:
>
>>
>>"Floyd Rogers" wrote in message
>>
>>> "Jeff Strickland" wrote
>>>> "cosmo" wrote
>>>>>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.
>>>>
>>>> Your car uses HYDRAULIC valve lifters.
>>>
>>> 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.
>>>
>>
>>
>>Well, except for that tiny problem, my explanation is good ...
>>
>>I find it odd that there are no lifters though.
>>
 >> Stay informed about: 325 still knocking after valve adjustment,.. 

Get a long screwdriver and put the metal end on the cam cover and
your ear to the handle end (make sure your hair/necktie etc are well
away from belts and pulleys) and listen. Then put the metal end on the
block and listen. That should tell you where the problem is - ie tick
or slap.

On an '88 M20 at that mileage I would expect a pit of rocker wear
which would put a slight groove in the underside of the rocker so even
getting the clearances 'spot on' there would still be a bigger gap
than the feeler guage suggests - flat feeler v grooved rocker. Learn
to live with it. I had the same with an M20 320i - UK 6 cylinder E30
coupe.

Piston slap - well time for another engine or car!

John
 >> Stay informed about: 325 still knocking after valve adjustment,.. 

"Floyd Rogers" wrote in message

> "Jeff Strickland" wrote
>> "cosmo" wrote
>>>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.
>>
>> Your car uses HYDRAULIC valve lifters.
>
> 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
>

I was going to post the same as Jeff, however although big sixes in the
1980's had hydraulic tappets, I was not sure about this model.
 >> Stay informed about: 325 still knocking after valve adjustment,.. 

R. Mark Clayton wrote:
>
> I was going to post the same as Jeff, however although big sixes in the
> 1980's had hydraulic tappets, I was not sure about this model.

The big 6's in the 80's also had rockers with eccentrics.. no hydraulic
lifters. And several current BMW engines use "solid" lifters and rockers.
 >> Stay informed about: 325 still knocking after valve adjustment,.. 

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

>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 ...

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...
 >> Stay informed about: 325 still knocking after valve adjustment,.. 

"Michael Yeager" wrote in message

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


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.
 >> Stay informed about: 325 still knocking after valve adjustment,.. 

Michael Yeager wrote:

>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...

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...
 >> Stay informed about: 325 still knocking after valve adjustment,..