<VV> Replacing Oil Pressure Regulator Spring

Frank DuVal corvairduval at cox.net
Sat Mar 24 00:08:13 EDT 2012


See, I told you someone would restate what I said in a more eloquent 
way! ggg

Thank you , Mark.

BTW, I have had customers in with "inflated" oil filters spewing oil out 
the now compromised gasket area. Yes, inflated and looking like a 
balloon on the ends.  The cause is a stuck plunger in the regulator, so 
there was no regulating! That gear pump will not take no for an answer,  
it WILL move oil.

Frank DuVal

On 3/23/2012 11:21 PM, Mark Durham wrote:
> Frank and all. The spring and plunger should not be regulating anything
> at idle. It is a pressure regulater, but at the other end, the top end.
> So, if you are getting 45 psi at higher rpm's, the spring stays closed
> to that pressure, then opens enough to return excess pressure. Pressure
> at lower rpm's is the pressure developed by the pump versus all the
> places oil flows through. If the pumps flow matches flow, there is no
> pressure. If flow capability is greater than the places oil needs to
> flow, you get pressure, up to the relief spring setting. that why at
> idle, pressure is normally lower. The pumps volumetric capacity at idle
> is not much greater than where it flows, at higher rpms the volumetric
> capacity to pump goes up, and so does the pressure.
>
> Yes, too much pressure can be bad too. One time I solved a engine dying
> problem when the engine got above 2500 rpms. The oil pressure relief
> valve had stuck shut, and every time the oil pressure climbed above 60
> psi all the lifters would over pump, open the valves, and kill the
> compression. So you would pull to the side of the road, by the time you
> would stop, it would bleed down and start right up again. Mark Durham
>
> Sent from my Windows Phone
> From: Frank DuVal
> Sent: 3/23/2012 14:18
> To: virtualvairs at corvair.org
> Subject: Re:<VV>  Replacing Oil Pressure Regulator Spring
> I'll take a stab at the explanation. Spring below includes the operation
> of the plunger in the description. The spring alone cannot  dump
> excessive oil pressure, the plunger does by exposing other passages in
> that rear cover.
>
> The spring regulates oil pressure, by bypassing excess oil back to the
> sump if the pressure is too high.
>
> Oil pressure will be greater when the engine is running higher revs.
>
> At idle, the available oil pumped through the passages of the regulator
> is less than at higher revs.
>
> Since the spring regulates to some pressure that keeps the light off at
> revs above idle, and there is less oil at idle,  the spring is not
> regulating the pressure below the light turn on setting at idle. There
> is simply not enough oil supplied by the pump to turn the light off. The
> regulation setting is determined by the spring, but that setting does
> not change with pressure of the oil. But when the oil pressure is below
> the setting of the spring, the spring cannot "pump" the oil pressure to
> a higher level. The spring can only lower oil pressure.
>
> So if the spring was weak and bypassing oil pressure at a low setting,
> that should also happen at speed, not just at idle.
>
> Flame suit on awaiting people who can write better to respond!
>
> Frank DuVal
>
> On 3/23/2012 1:03 PM, Joel McGregor wrote:
>> Hate to disagree but it could possibly be the spring.  I've had it happen with the exact symptoms he has.  Springs do settle especially after so many years and so many heat cycles.  Mine happened 20 years ago.  His light is coming on but how would the light being on or off tell you that it could or couldn't be the spring?
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