[alberg30] Re: Atomic 4 sounds

[Steve Weingart]

From: Steve Weingart <shw at gate.net>

Frank,
>
>I took Steve's advice (warning) and adjusted the oil bypass screw. I got
>the pressure up to about 18 psi at idle (warm). If I rev the engine up
>to about 3K it goes up to about 25psi but not much more than that. aLL
>values in neutral.

That seems to show that you are on the track...

>
>As for the squeaking/clunking noise - it seemed to be coming from around
>the water pump/alternator power take-off. I disconnected the drive belt
>and the noise seemed to go away, though I don't know if this was
>temporary. Actually, the noise seemed to become reduced to a subaudible
>level (I can *feel* it) - maybe I'm just paranoid...

It could be that one of the gears/bearings in the power take off section is
bad (could be as simple as the water pump shaft bearing, if you are lucky)

>
>Question:
>
>1) Does the fact that the oil pressure does not vary a great deal even
>when at higher revs a sign that the oil system is faulty.

Something probably is wrong there.  I would suggest trying to take the
screw all the way out and then you should go fishing for the spring.  If
the spring is broken/collapsed, that may be it.  Otherwise I'm not sure...I
think that there is an screen on the oil pickup, it could be clogged...

>
>2) How does the bypass adjustment work? The manuals are very vague about
>this. 

The spring loaded ball or cone (loaded by the screw) sits on a vent in the
high pressure oil path at the outlet of the oil pump (I believe.  I have
gathered this from reading Moyer's news letter and the other A4 docs).
When the oil pressure exceeds the pressure that the spring exerts, the oil
'leaks' out of the high pressure system back to the crankcase.  

Since the force required to compress a spring a short distance is roughly
linear with displacement (if the coils aren't touching), it's a passable
simple regulator.  But as the oil thins with heat, more oil will squirt
through a gap of a given size, so you get some drop in pressure as the oil
warms.

>Can I access and rebuild/clean the oil pump without dismantling
>the engine? 

I don't think so.

>Is it possible to over-adjust the bypass screw (assuming
>that the pressure level according to the gauge is OK)?

I don't think so.  But, if you completely bottom the screw, there will be
no bypass and the pressure will go to and stay at, whatever max the pump
can put out, that my not be good.  I'm not sure.  I really would check the
condition of the spring first.

I would really suggest calling Moyer, he can probably do more for you in 15
min than the rest of us can in days.  I've spent a lot of time on my motor,
he's spent a lot of time on a lot of motors!

If I remember correctly, you had some pro do some work on your engine a
while back.  Was his work guaranteed?  Have you asked him/does he have
anything to say?

Good Luck,

Steve

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