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Oil Pressure Relief Valve
- Thread starter Tom H
- Start date
RootesRooter
Donation Time
Again, the "latest SV design" was a return by the factory to using the PRV used on 1592's. Except for perhaps a part number, they are identical in appearance.
Here's the factory service bulletin:
http://www.team.net/www/rootes/rsb/66_06.html
The fatter, steel-sleeved PRV was used in the Arrow/Hunter Range. When used with the later oil filter base, it works fine on Series Alpines and is rated at 45psi, the same as the original Series V PRV.
Here's the factory service bulletin:
http://www.team.net/www/rootes/rsb/66_06.html
The fatter, steel-sleeved PRV was used in the Arrow/Hunter Range. When used with the later oil filter base, it works fine on Series Alpines and is rated at 45psi, the same as the original Series V PRV.
Rootes,
Thanks. Note that with your link I now have some part numbers. If those part numbers (or hex head descriptions) are on my PRV I can now tell if I have an older or newer (but really older- i.e. SIV type) type PRV. Your previous msg did not have that link, leaving me with no way to tell which one I have.
Thanks again,
Tom
Thanks. Note that with your link I now have some part numbers. If those part numbers (or hex head descriptions) are on my PRV I can now tell if I have an older or newer (but really older- i.e. SIV type) type PRV. Your previous msg did not have that link, leaving me with no way to tell which one I have.
Thanks again,
Tom
Ken Ellis
Donation Time
The oil PRV modification was on my to-do list since this thread started. So I started browsing the engine "inventory" to find a suitable core. To my surprise, when I uncovered the "Jim Stone" engine, (acquired a few years back...) there on the oil filter block sat a pre-modified OPRV. I'll find out tomorrow if the filter block that's on the engine in the car is compatible, or if a transplant is required. But it's better than starting from scratch...
Thanks, Jim!
Thanks, Jim!
Attachments
Ken Ellis
Donation Time
Anyway, back to the main thread of discussion...
So yesterday, I had the opportunity to compare a modified PRV with un-modified, of the same type.
According to some garage-accuracy measurements (as opposed to lab-accuracy) I got the following info:
PRV plunger diameter: 3/8"
Surface area: .11 in. sq.
Force required to compress spring: about 10 lbs.
(Calculated) approximate pressure required to activate valve: 90 psi
Does this mean the pump is designed to run near 90 at least on occasion?
I did not analyze the "fluid circuit" to see if all oil goes thru the valve all the time, or if the relief valve only triggers when the normal path is "gunked up" due to clogged filter, etc., and then it discharges as a kind of safety valve to keep oil flowing -- possibly even around the filter (??)
Other interesting observations...
Available relief window: 2 windows of 1/4" by 1/4"
Modified valve opening: 1/2 of each available relief window = 1/4 in. sq. total.
Unmodified valve opening: 1/4 of available relief window = 1/8 in. sq. total.
(This could very well be because the valve is almost gritty-feeling in its operation. No amount of pressure would make it open as much as the unmodified one. Either that, or I was fully-compressing the spring.)
Now we find out if I've made any embarrassing math mistakes...
On edit: And I guess the other question is, to RootesRacer's point of gear loading --
if the pump is already "running at 90psi", is the load on the gears already there, anyway?
(That doesn't, of course, eliminate other possible dangers of high oil pressure...)
Hmmmm....
So yesterday, I had the opportunity to compare a modified PRV with un-modified, of the same type.
According to some garage-accuracy measurements (as opposed to lab-accuracy) I got the following info:
PRV plunger diameter: 3/8"
Surface area: .11 in. sq.
Force required to compress spring: about 10 lbs.
(Calculated) approximate pressure required to activate valve: 90 psi
Does this mean the pump is designed to run near 90 at least on occasion?
I did not analyze the "fluid circuit" to see if all oil goes thru the valve all the time, or if the relief valve only triggers when the normal path is "gunked up" due to clogged filter, etc., and then it discharges as a kind of safety valve to keep oil flowing -- possibly even around the filter (??)
Other interesting observations...
Available relief window: 2 windows of 1/4" by 1/4"
Modified valve opening: 1/2 of each available relief window = 1/4 in. sq. total.
Unmodified valve opening: 1/4 of available relief window = 1/8 in. sq. total.
(This could very well be because the valve is almost gritty-feeling in its operation. No amount of pressure would make it open as much as the unmodified one. Either that, or I was fully-compressing the spring.)
Now we find out if I've made any embarrassing math mistakes...
On edit: And I guess the other question is, to RootesRacer's point of gear loading --
if the pump is already "running at 90psi", is the load on the gears already there, anyway?
(That doesn't, of course, eliminate other possible dangers of high oil pressure...)
Hmmmm....
RootesRacer
Donation Time
I can assure you that the valve will not run at 90psi and that the pump sees the same pressure that the relief valve does.
Not sure whats wrong with the numbers but you need to know the piston area and the load at which the window begins to be uncovered by the piston.
This will be the "minimum" pressure it should regulate at.
I agree the piston area should be about .110 in^2.
I would expect about 4.4lbs of force to actuate the piston to its dump ports at 40psi.
I am unaware of "other" dangers of high oil pressure besides mechanical loading.
Enlighten me.
Not sure whats wrong with the numbers but you need to know the piston area and the load at which the window begins to be uncovered by the piston.
This will be the "minimum" pressure it should regulate at.
I agree the piston area should be about .110 in^2.
I would expect about 4.4lbs of force to actuate the piston to its dump ports at 40psi.
I am unaware of "other" dangers of high oil pressure besides mechanical loading.
Enlighten me.
Ken Ellis
Donation Time
Could be a failure of my garage-based measurements, of course. I ended up using a kind of hanging produce scale, pushing down on the device while a rod depressed the cylinder. Not an elegant setup, to be sure.
I also don't know what pressure the modified device is set to, for the given engine it was on. I'm confident that engine had reasonable oil pressure, though.
The "other dangers" mentioned includes the whole "pinned" and/or floating bearing issue, which is certainly above my pay grade -- but it's also beyond me to just dismiss it... And, of course, Chuck's blown oil filter. That I can understand!
I stalled out on the "how much does the window have to open to decrease the pressure" question, and the function of the valve in the system.... Is it a occasional use self-resetting circuit breaker, or more of a continuously operating pressure regulator? Seems to be the latter?
I also don't know what pressure the modified device is set to, for the given engine it was on. I'm confident that engine had reasonable oil pressure, though.
The "other dangers" mentioned includes the whole "pinned" and/or floating bearing issue, which is certainly above my pay grade -- but it's also beyond me to just dismiss it... And, of course, Chuck's blown oil filter. That I can understand!
I stalled out on the "how much does the window have to open to decrease the pressure" question, and the function of the valve in the system.... Is it a occasional use self-resetting circuit breaker, or more of a continuously operating pressure regulator? Seems to be the latter?
RootesRacer
Donation Time
Could be a failure of my garage-based measurements, of course. I ended up using a kind of hanging produce scale, pushing down on the device while a rod depressed the cylinder. Not an elegant setup, to be sure.
I also don't know what pressure the modified device is set to, for the given engine it was on. I'm confident that engine had reasonable oil pressure, though.
The "other dangers" mentioned includes the whole "pinned" and/or floating bearing issue, which is certainly above my pay grade -- but it's also beyond me to just dismiss it... And, of course, Chuck's blown oil filter. That I can understand!
I stalled out on the "how much does the window have to open to decrease the pressure" question, and the function of the valve in the system.... Is it a occasional use self-resetting circuit breaker, or more of a continuously operating pressure regulator? Seems to be the latter?
The bearing issue should not be a problem, we arent talking about changing the pressure by an order of magnitude, only 25% or so.
Normal oil filters are good to over 100psi, many engines produce in the 60 to 80psi range and 80 is excessive for an alpine. Whoever popped the filter probably had a mal-adjusted valve that produced several hundred PSI off the cold oil.
The relief valve is a continuous regulator. Under running conditions (at pressure), the piston uncovers just enough of the dump port to get the pressure to drop, then the piston drops a bit and covers the port.
It will dither there controlling pressure till the flow increases or decreases with RPMs.
When the oil is cold (more viscous) the piston will have to move farther for sufficient area to dump the pressure which results in higher oil pressure, that is the oil pressure is impacted by viscosity proportionally.
Conversely when the engine oil is hot and its viscosity falls the pump may not have enough capacity for the OPR to dump, in which case the piston will not uncover the dump port and the oil pressure is whatever the pump provides to the internal leaks (bearing flow, rocker shaft and rubbing block jet).
If it takes 10lbs for the piston to reach the dump port, that valve is set too tight. Try adjusting to 6 or 7lbs and give it a try.
IMO 60psi hot is a decent figure for an alpine engine that sees 7000RPMs.
If yours doesnt, 50psi hot is probably better.
Ken Ellis
Donation Time
Good explanation of the valve's function in the system -- thanks!
I'm going to try to improve my measurement accuracy, first, and then measure the adjustable one prior to install. I'll note some pressure vs. rpm points both before and after the changeover. Then I'll check the spring pressure of the one I remove -- which is pretty consistently 30 psi at non-idle speeds.
If my car ever sees 7k, that means I missed a gear. I try to avoid that!
Thanks again!
I'm going to try to improve my measurement accuracy, first, and then measure the adjustable one prior to install. I'll note some pressure vs. rpm points both before and after the changeover. Then I'll check the spring pressure of the one I remove -- which is pretty consistently 30 psi at non-idle speeds.
If my car ever sees 7k, that means I missed a gear. I try to avoid that!
Thanks again!
65beam
Donation Time
oprv
ken,
if you go to the te/ae web site you'll find tiger tom's info on these valves. he solved the problem decades ago. i think it tells how to convert the valve to be adjustable. valves built to tom's specs have been in my engines since the early 80's and they work great.
ken,
if you go to the te/ae web site you'll find tiger tom's info on these valves. he solved the problem decades ago. i think it tells how to convert the valve to be adjustable. valves built to tom's specs have been in my engines since the early 80's and they work great.
Hi Ken. I had completely forgotten that I'd modified the valve. I did that in the 80's (with the help of a friend who had access to a drill press, something I lacked at the time) when Tiger Tom first posted his article on "curing Alpine LOP" in the TE/AE newsletter. As I recall, I didn't have low oil pressure at the time, just thought a little higher would be better.
Are you using that engine or is is just now part of your parts inventory vs. mine?
Ken Ellis
Donation Time
Jim,
It is "on-deck" as the ready-to-go replacement engine. It was slated to be
in the car, until the acquisition of the drivetrain package you saw last
year. I think once I get the front end rebuilt, I might go for "yours" as the
slightly hopped-up option. As I recall, Chevy rods, and a KB cam are
already in place? I'm thinking Vizard mod head, lightened flywheel,
electronic ignition and maybe fuel injection... No blowers, though! I've
got a few other projects ahead of that one, though.
Recently-removed original number engine needs a good going through, and I'll keep that one bone-stock. Engine #4 was pulled from the car below. It's mostly good for parts. (Pic below.)
Always use the right size fuses.
It is "on-deck" as the ready-to-go replacement engine. It was slated to be
in the car, until the acquisition of the drivetrain package you saw last
year. I think once I get the front end rebuilt, I might go for "yours" as the
slightly hopped-up option. As I recall, Chevy rods, and a KB cam are
already in place? I'm thinking Vizard mod head, lightened flywheel,
electronic ignition and maybe fuel injection... No blowers, though! I've
got a few other projects ahead of that one, though.
Recently-removed original number engine needs a good going through, and I'll keep that one bone-stock. Engine #4 was pulled from the car below. It's mostly good for parts. (Pic below.)
Always use the right size fuses.
RootesRooter
Donation Time
I've always depended a lot on my oil gauge, while running a stock PRV, to tell me how fresh or not-so-fresh my engine is. I'm not sure I could do the same if I was running one of these modified PRV's.
Well, I continue to have problems with my PRV. I'm in the middle of a 7000 mile road trip and my oil pressure is erratic. Sometimes ( but just sometimes) in the morning the pressure goes way above 40 or 45, up to 60 or 70, so I am careful not to rev much until the engine is quite warm. I think the PRV sticks closed. Sometimes if I rev a bit too much (like 4500) when not fully warmed it seems the PRV sticks open and I can't maintain 40 psi at 3500. And every time I pull the PRV and look at it , it seems OK, but when I actuate it with a screwdriver it seems a bit sticky until I exercise it a few times.
Well today I caught it "red handed" . For the first time I saw for sure that it sticks! Early in the day, only a couple miles on the road. Engine fully warmed up but not really run hard yet, and it seemed that my pressure was lower than it should have been - not 40 at 3000 rpm like usual. So I pulled the PRV for about the 5th time on the trip and THERE IT WAS . Stuck partly open - about 30% open, as I held it in my hand!
So now I know for sure that the PRV is erratic and sticky. I'll live with it for the rest of this trip, pulling it when needed. But when I get home I plan to solve this. Maybe a delrin piston? Or brass? or maybe just disassemble and polish the piston. Or maybe I need to polish the inner edges of the ports on the side of the tube. It seems that it typically gets stuck on the edges of the ports.
But I wanted all to know I have SEEN the PRV stick open!
Tom
Well today I caught it "red handed" . For the first time I saw for sure that it sticks! Early in the day, only a couple miles on the road. Engine fully warmed up but not really run hard yet, and it seemed that my pressure was lower than it should have been - not 40 at 3000 rpm like usual. So I pulled the PRV for about the 5th time on the trip and THERE IT WAS . Stuck partly open - about 30% open, as I held it in my hand!
So now I know for sure that the PRV is erratic and sticky. I'll live with it for the rest of this trip, pulling it when needed. But when I get home I plan to solve this. Maybe a delrin piston? Or brass? or maybe just disassemble and polish the piston. Or maybe I need to polish the inner edges of the ports on the side of the tube. It seems that it typically gets stuck on the edges of the ports.
But I wanted all to know I have SEEN the PRV stick open!
Tom
RootesRacer
Donation Time
I've seen it too....
You most likely have burs/ridges worn from years of the piston rattling in the sleeve.
If you clean it up good with a lathe, brass should work OK.
Making the piston longer so its not prone to "cock" would be beneficial.
Not sure if delrin can hold up to that kind of temp and chemical requirements but I'm not a plastics expert.
Keep an eye on the oil pressure, particularly when you drop revs!
You most likely have burs/ridges worn from years of the piston rattling in the sleeve.
If you clean it up good with a lathe, brass should work OK.
Making the piston longer so its not prone to "cock" would be beneficial.
Not sure if delrin can hold up to that kind of temp and chemical requirements but I'm not a plastics expert.
Keep an eye on the oil pressure, particularly when you drop revs!
Eleven
Platinum Level Sponsor
Tom,
That PRV is not going to get better and will ruin your trip. My wife said you called and would be in Bellevue Friday or so. When you get to my house, fire my Aline up and get it out of the garage, (you'll see why) and put yours in. Take the PRV out of mine and any other parts you need (Just don't leave the stripped hulk on the sidewalk, the neighbors and all). You can mail it back when you get home. It seems to work fine so hopefully you can cruise in peace!!!
If I don't see you, sorry to have not met you. The big red tank on the side with all the crap on it is water based parts cleaner, works pretty good it you need it.
Tracy
That PRV is not going to get better and will ruin your trip. My wife said you called and would be in Bellevue Friday or so. When you get to my house, fire my Aline up and get it out of the garage, (you'll see why) and put yours in. Take the PRV out of mine and any other parts you need (Just don't leave the stripped hulk on the sidewalk, the neighbors and all
). You can mail it back when you get home. It seems to work fine so hopefully you can cruise in peace!!!If I don't see you, sorry to have not met you. The big red tank on the side with all the crap on it is water based parts cleaner, works pretty good it you need it.
Tracy