oil pressure

[BUNK]

'64 164 cid just back from machine shop. new cam, new brgs, new rings, freshly bored +20, crank polished, reworked heads
My problem is: cold start w/ elect oil gage I get 80-85 # pressure
running warm at speed I get 40-45 #
But at idle it drops off to almost nothing on gage, but idiot light does not come on.
I could sure use some ideas,
Thanks, Bunk

[66vairguy]

NEVER assume a gauge is working correctly until it is verified. I'd hook up a known good mechanical gauge to check -- just me.

[PrismSky]

Could be an issue with the oil pump maybe it's worn or the relief valve is sticking. Double-check the clearances, especially with the new bearings. Thiker oil might help boost pressure at idle too.

[66vairguy]

BTW --- make sure the "IDIOT" warning light comes on when you first turn the ignition key on BEFORE starting the engine. If it does NOT illuminate, then you have a light, wiring, or switch problem.

[BUNK]

Thanks for all the tips. I failed, in my first post, to mention that I confirmed the pressures with a mech gage. Also, the rebuild included a new Clark's hi flow pump and valve. The idiot light does come on before start. It has a new bulb (also new complete harness). I'm running Valvoline 20-50 with zinc. And unless I've lost my mind and forgot how to use plastigage and feeler gage, all the clearances, rings, brgs and pump, are good.
I'm replacing the engine (62 Greenbrier) with a known solid engine and will have a great adventure ahead as I WILL find a cause and solution. Thanks, again to all.

[66vairguy]

Thanks for all the tips. I failed, in my first post, to mention that I confirmed the pressures with a mech gage. Also, the rebuild included a new Clark's hi flow pump and valve. The idiot light does come on before start. It has a new bulb (also new complete harness). I'm running Valvoline 20-50 with zinc. And unless I've lost my mind and forgot how to use plastigage and feeler gage, all the clearances, rings, brgs and pump, are good.
I'm replacing the engine (62 Greenbrier) with a known solid engine and will have a great adventure ahead as I WILL find a cause and solution. Thanks, again to all.

Thanks for the update. Just me --- but I would NEVER use a Hi-volume oil pump in a Corvair engine. The stock oil pump is more than adequate. I've read a number of articles on Hi-volume oil pumps and they just waste power, stress the distributor shaft gear, and heat up the oil. The ONLY time you would need one is for a very loose bearing tolerance drag racing engine. ALSO --- you are running a 20W50 oil that should only be used in a worn engine (bearings tolerances too big), or in one run at very high environmental temperatures, like over 100F! Even when track racing - 10W30 (synthetic for high temperatures) and a stock oil pump works fine with stock bearing clearances. At least that is my opinion based on the knowledge of folks I respect --- other's are free to disagree.

[Nashfan]

Thanks for all the tips. I failed, in my first post, to mention that I confirmed the pressures with a mech gage. Also, the rebuild included a new Clark's hi flow pump and valve. The idiot light does come on before start. It has a new bulb (also new complete harness). I'm running Valvoline 20-50 with zinc. And unless I've lost my mind and forgot how to use plastigage and feeler gage, all the clearances, rings, brgs and pump, are good.
I'm replacing the engine (62 Greenbrier) with a known solid engine and will have a great adventure ahead as I WILL find a cause and solution. Thanks, again to all.

Your cold pressures make sense given your set-up and so does you hot pressure at speed. The only thing that doesnt is your hot idle pressure. About the only thing that can cause that is the bypass not closing all the way at low speeds. Its worth checking to see that the plunger is smoothly opening and closing all the way. All it takes is a tiny bit of crud or perhaps a slight burr to cause that plunger to not return. I had that same thing happen but because nearly all of my driving never gets the oil even close to temperature the idle oil pressure always looked really good, and only noticed the plunger sticking when I had the engine apart. I cant remember for sure but I think the stickyness was caused by a slight burr somewhere on the lower edge of the bypass hole.

[Nashfan]

Thanks for all the tips. I failed, in my first post, to mention that I confirmed the pressures with a mech gage. Also, the rebuild included a new Clark's hi flow pump and valve. The idiot light does come on before start. It has a new bulb (also new complete harness). I'm running Valvoline 20-50 with zinc. And unless I've lost my mind and forgot how to use plastigage and feeler gage, all the clearances, rings, brgs and pump, are good.
I'm replacing the engine (62 Greenbrier) with a known solid engine and will have a great adventure ahead as I WILL find a cause and solution. Thanks, again to all.

Thanks for the update. Just me --- but I would NEVER use a Hi-volume oil pump in a Corvair engine. The stock oil pump is more than adequate. I've read a number of articles on Hi-volume oil pumps and they just waste power, stress the distributor shaft gear, and heat up the oil. The ONLY time you would need one is for a very loose bearing tolerance drag racing engine. ALSO --- you are running a 20W50 oil that should only be used in a worn engine (bearings tolerances too big), or in one run at very high environmental temperatures, like over 100F! Even when track racing - 10W30 (synthetic for high temperatures) and a stock oil pump works fine with stock bearing clearances. At least that is my opinion based on the knowledge of folks I respect --- other's are free to disagree.

Never is a pretty strong word. Theres times and applications were an HV pump is very much justified. The big reason to use one is to cool the bearings down!! If you are just driving around like normal grocery getting in a light load cruise for sure you dont need one but when the revs and loads come up and stay there like for racing, you are getting outside what GM intended.
Some facts about journal bearings are that only at low speeds and light loads are they really working like "perfect" hydrodyamic bearings would suggest where the journal stays centered in the bearing. As the loads and speeds come up, the point of max pressure gets closer to the bearing shell and the temperature of the oil also goes up and of course thins out some more. I've read some pretty geeky papers on journal bearing testing where they measured the temperatures in a few spots around the bearing and found that at the point of max pressure (close to 180 degrees from the load) that the oil temperature gained 30 degrees from the inlet oil temps! Its a very reasonable thing in light of that fact that if you want to do something about that, you HAVE to flow more oil to cool them back down. Oil being such an awful coolant, the instant it hits a cold thing instantly thickens up and stops flowing very well and is more of an insulator, which is to say the hot thing stays hot in spite of the fact that the oil may be cooler than the hot thing! To do more "oil cooling" means to flow a lot more with a thinner grade. By going thicker on the grade and loosening the clearances to "get more flow" doesnt work very well because it makes the off centered effects worse and increases the contact pressure in the worst spot, making the oil get even hotter and behaving more like an insulator in the looser parts, basically exacerbating a bad situation. I do know someone that has been trying that old idea of extra loose bearing clearances with an HV pump and extra thick oil (20w-60 !!!!) and all that has happened is his cold oil pressure goes over 100psi and his hot oil pressure goes down to 45 and he does have some "banged up" rod bearings. Its exactly the same reason why Nascar stopped doing that back in the 1980's (according to a guy I met that was on a Nascar team then.) Others that have used an HV pump and an XW-50 seem to get excessively high oil temperatures just like the 20w-60 example, but also when they went back down to a XW-30 with no other changes, their oil temps seem to come back down to something a lot reasonable, and its a hell of a lot cooler than a stock Corvair will normally do at sustained high revs and loads. Yes HV pumps are hard on the drive gears, but these days theres better designed gears that are MUCH easier on things, like this one pictured below.

[joelsplace]

Where did those fancy gears come from?

[Nashfan]

Where did those fancy gears come from?

I bought those from Melling supplier, they are only available by buying the complete HV small block pump assembly.
That SBC HV pump is the same size as the old 7 lobe 409 pump that we use for HV pumps. It is freaking UNREAL how smooth
and effortless those Shark Tooth gears turn compared to the older straight cut gears.

[66vairguy]

Nashfan - Yeah "never" was an overstatement, but I did qualify it by saying large bearing clearances for racing require a high volume oil pump.

Yes more oil flow cools the bearings, but the only way to increase bearing oil flow is by looser clearances, or HIGHER oil pressure and excess oil pressure is NOT good for bearings. The term "floated bearing" comes to mind, and I've seen it happen.

Anyway --- bunk is NOT going racing and I would NOT use a high volume oil pump for a street use engine.

Good point about a sticking oil pressure regulator piston. I'll add I've seen one caused by the spring binding in the piston. Apparently someone was trying to increase the spring tension (a no-no) and deformed the spring so it bound up inside the piston.

[vairmech]

SNIP---
Never is a pretty strong word. Theres times and applications were an HV pump is very much justified. The big reason to use one is to cool the bearings down!! If you are just driving around like normal grocery getting in a light load cruise for sure you dont need one but when the revs and loads come up and stay there like for racing, you are getting outside what GM intended.
Some facts about journal bearings are that only at low speeds and light loads are they really working like "perfect" hydrodyamic bearings would suggest where the journal stays centered in the bearing. As the loads and speeds come up, the point of max pressure gets closer to the bearing shell and the temperature of the oil also goes up and of course thins out some more. I've read some pretty geeky papers on journal bearing testing where they measured the temperatures in a few spots around the bearing and found that at the point of max pressure (close to 180 degrees from the load) that the oil temperature gained 30 degrees from the inlet oil temps! Its a very reasonable thing in light of that fact that if you want to do something about that, you HAVE to flow more oil to cool them back down. Oil being such an awful coolant, the instant it hits a cold thing instantly thickens up and stops flowing very well and is more of an insulator, which is to say the hot thing stays hot in spite of the fact that the oil may be cooler than the hot thing! To do more "oil cooling" means to flow a lot more with a thinner grade. By going thicker on the grade and loosening the clearances to "get more flow" doesnt work very well because it makes the off centered effects worse and increases the contact pressure in the worst spot, making the oil get even hotter and behaving more like an insulator in the looser parts, basically exacerbating a bad situation. I do know someone that has been trying that old idea of extra loose bearing clearances with an HV pump and extra thick oil (20w-60 !!!!) and all that has happened is his cold oil pressure goes over 100psi and his hot oil pressure goes down to 45 and he does have some "banged up" rod bearings. Its exactly the same reason why Nascar stopped doing that back in the 1980's (according to a guy I met that was on a Nascar team then.) Others that have used an HV pump and an XW-50 seem to get excessively high oil temperatures just like the 20w-60 example, but also when they went back down to a XW-30 with no other changes, their oil temps seem to come back down to something a lot reasonable, and its a hell of a lot cooler than a stock Corvair will normally do at sustained high revs and loads. Yes HV pumps are hard on the drive gears, but these days theres better designed gears that are MUCH easier on things, like this one pictured below.

[/quote]

I have to disagree. Take the top off of the engine and run the oil pump, how much oil comes out? rotate the engine and watch the oil come out the different rod journals. I'm talking room temp 10W-30. The stock oil pump puts out 3-9 GALONS a minute. With your top cover off did you see even 3 gallons go through the engine? Then, where does all that extra oil go? It does NOT go back into the oil pan, it goes right back into the inlet of the pump, it does not pass "go" and it doesn't collect $200! All that extra oil does not cool the bearings because it doesn't even get there. I run .002-.003 rod and/or main bearing clearance at times on the race car turning 7000+ and with a STOCK oil pump, cold pressure is 75-80 psi and hot 300 degree oil is still 55 psi at speed and 15-20 psi at about 900 rpm all with a synthetic 10W-40 oil.

So, the bottom line is either the engine is mot built properly or the oil pump is not set up properly.

[guthrie1068]

A few years back I bought a gauge and adapter for the top of the oil filter from someone on the forum, installed it and immediately got worried. My oil pressure at cold start was around 45 or so, but once the car warmed up and was on low idle it dropped to somewhere around 10. I asked (on the other forum at the time) and was told not to worry about it, that was normal and everything would be fine. It was also suggested that I use a straight weight oil, like 30 or 40. I tried that and it did nothing. When I changed my oil this summer I put 15-40 diesel engine oil in it. Still running the same oil pressure. It's not pulling 7000 rpms, so like Ken said, I think it'll be ok.

[Nashfan]

SNIP---
Never is a pretty strong word. Theres times and applications were an HV pump is very much justified. The big reason to use one is to cool the bearings down!! If you are just driving around like normal grocery getting in a light load cruise for sure you dont need one but when the revs and loads come up and stay there like for racing, you are getting outside what GM intended.
Some facts about journal bearings are that only at low speeds and light loads are they really working like "perfect" hydrodyamic bearings would suggest where the journal stays centered in the bearing. As the loads and speeds come up, the point of max pressure gets closer to the bearing shell and the temperature of the oil also goes up and of course thins out some more. I've read some pretty geeky papers on journal bearing testing where they measured the temperatures in a few spots around the bearing and found that at the point of max pressure (close to 180 degrees from the load) that the oil temperature gained 30 degrees from the inlet oil temps! Its a very reasonable thing in light of that fact that if you want to do something about that, you HAVE to flow more oil to cool them back down. Oil being such an awful coolant, the instant it hits a cold thing instantly thickens up and stops flowing very well and is more of an insulator, which is to say the hot thing stays hot in spite of the fact that the oil may be cooler than the hot thing! To do more "oil cooling" means to flow a lot more with a thinner grade. By going thicker on the grade and loosening the clearances to "get more flow" doesnt work very well because it makes the off centered effects worse and increases the contact pressure in the worst spot, making the oil get even hotter and behaving more like an insulator in the looser parts, basically exacerbating a bad situation. I do know someone that has been trying that old idea of extra loose bearing clearances with an HV pump and extra thick oil (20w-60 !!!!) and all that has happened is his cold oil pressure goes over 100psi and his hot oil pressure goes down to 45 and he does have some "banged up" rod bearings. Its exactly the same reason why Nascar stopped doing that back in the 1980's (according to a guy I met that was on a Nascar team then.) Others that have used an HV pump and an XW-50 seem to get excessively high oil temperatures just like the 20w-60 example, but also when they went back down to a XW-30 with no other changes, their oil temps seem to come back down to something a lot reasonable, and its a hell of a lot cooler than a stock Corvair will normally do at sustained high revs and loads. Yes HV pumps are hard on the drive gears, but these days theres better designed gears that are MUCH easier on things, like this one pictured below.

I have to disagree. Take the top off of the engine and run the oil pump, how much oil comes out? rotate the engine and watch the oil come out the different rod journals. I'm talking room temp 10W-30. The stock oil pump puts out 3-9 GALONS a minute. With your top cover off did you see even 3 gallons go through the engine? Then, where does all that extra oil go? It does NOT go back into the oil pan, it goes right back into the inlet of the pump, it does not pass "go" and it doesn't collect $200! All that extra oil does not cool the bearings because it doesn't even get there. I run .002-.003 rod and/or main bearing clearance at times on the race car turning 7000+ and with a STOCK oil pump, cold pressure is 75-80 psi and hot 300 degree oil is still 55 psi at speed and 15-20 psi at about 900 rpm all with a synthetic 10W-40 oil.

So, the bottom line is either the engine is mot built properly or the oil pump is not set up properly.
[/quote]

One of your competitors that is running an HV pump and had tried a number of xw-50 was seeing the same oil temps you do, tried 10w-30 and now gets 260 oil temperatures, which I would think would be a pretty decent demonstration of the benefits of doing it that way.

[66vairguy]

I have to disagree. Take the top off of the engine and run the oil pump, how much oil comes out? rotate the engine and watch the oil come out the different rod journals. I'm talking room temp 10W-30. The stock oil pump puts out 3-9 GALONS a minute. With your top cover off did you see even 3 gallons go through the engine? Then, where does all that extra oil go? It does NOT go back into the oil pan, it goes right back into the inlet of the pump, it does not pass "go" and it doesn't collect $200! All that extra oil does not cool the bearings because it doesn't even get there. I run .002-.003 rod and/or main bearing clearance at times on the race car turning 7000+ and with a STOCK oil pump, cold pressure is 75-80 psi and hot 300 degree oil is still 55 psi at speed and 15-20 psi at about 900 rpm all with a synthetic 10W-40 oil.

So, the bottom line is either the engine is mot built properly or the oil pump is not set up properly.

I'm with Ken. Years ago I read a well done article on high volume oil pumps developed for other engines. What the article discovered was high volume oil pumps RAISED the operating oil temperature! As Ken said all that excess oil volume above a the maximum pressure is circulated via the pressure regulator through the pump so the extra energy the higher volume pump uses ends up as HEAT in the oil. There is also the issue of the extra power needed to drive the HV oil pump putting extra stress on the distributor shaft and gear.

A buddy with a very nice V-12 1939 Lincoln called to say his engine builder recommended he put in a high volume oil pump. The theory was the Lincoln V-12 had a reputation for sludge build up (back when motor oil was not very good). I said the V-12 had a limited oil pressure system and most of the lubrication was done by "splash and sling". With todays modern synthetic detergent motor oil he would not have an issue with the stock oil pump. Of course the "more is better" reasoning convinced my buddy to approve the high volume oil pump. A few hundred miles later the "rebuilt" engine stopped!!!! The oil pump drive shaft wore badly and finally sheared!!!! On tear down the engine oil galleries were full of metal debris and the crank was ruined!!!! This ended up in court and the next engine builder put in a STOCK oil pump. Thousands of miles later and the Lincoln is still running fine.

Chevrolet built over a million Corvair engines and I have not found ONE instance of a stock, from the factory, properly maintained, Corvair engine having a problem with a lack of oil volume from the oil pump. If it aint' broken -------------

[Nashfan]

I have to disagree. Take the top off of the engine and run the oil pump, how much oil comes out? rotate the engine and watch the oil come out the different rod journals. I'm talking room temp 10W-30. The stock oil pump puts out 3-9 GALONS a minute. With your top cover off did you see even 3 gallons go through the engine? Then, where does all that extra oil go? It does NOT go back into the oil pan, it goes right back into the inlet of the pump, it does not pass "go" and it doesn't collect $200! All that extra oil does not cool the bearings because it doesn't even get there. I run .002-.003 rod and/or main bearing clearance at times on the race car turning 7000+ and with a STOCK oil pump, cold pressure is 75-80 psi and hot 300 degree oil is still 55 psi at speed and 15-20 psi at about 900 rpm all with a synthetic 10W-40 oil.

So, the bottom line is either the engine is mot built properly or the oil pump is not set up properly.

I'm with Ken. Years ago I read a well done article on high volume oil pumps developed for other engines. What the article discovered was high volume oil pumps RAISED the operating oil temperature! As Ken said all that excess oil volume above a the maximum pressure is circulated via the pressure regulator through the pump so the extra energy the higher volume pump uses ends up as HEAT in the oil. There is also the issue of the extra power needed to drive the HV oil pump putting extra stress on the distributor shaft and gear.

A buddy with a very nice V-12 1939 Lincoln called to say his engine builder recommended he put in a high volume oil pump. The theory was the Lincoln V-12 had a reputation for sludge build up (back when motor oil was not very good). I said the V-12 had a limited oil pressure system and most of the lubrication was done by "splash and sling". With todays modern synthetic detergent motor oil he would not have an issue with the stock oil pump. Of course the "more is better" reasoning convinced my buddy to approve the high volume oil pump. A few hundred miles later the "rebuilt" engine stopped!!!! The oil pump drive shaft wore badly and finally sheared!!!! On tear down the engine oil galleries were full of metal debris and the crank was ruined!!!! This ended up in court and the next engine builder put in a STOCK oil pump. Thousands of miles later and the Lincoln is still running fine.

Chevrolet built over a million Corvair engines and I have not found ONE instance of a stock, from the factory, properly maintained, Corvair engine having a problem with a lack of oil volume from the oil pump. If it aint' broken -------------

Your V-12 example would fall into the category of maybe not thinking this HV pump mod all the way through. Probably they used straight 30w (big mistake) and did not open the bypass hole. Then, of course the cold pressure goes way too high and the extra output is overdriving the bypass. The bypass hole is originally sized for the pump in mind and once you go bigger on the pump and insist on using an extra thick monograde thats a recipe for disaster. I agree that using a better oil should have been the first move to get rid of the sludge problem.

I think we agree that too much pressure is hard on things, and we also agree that when the oil is too cold and therefore too thick, all or most of it goes out the bypass, so very little flow goes out to the engine. Best thing to do to limit the cold pressure is to go THIN on the WINTER RATING. Yes the bypass goes to near wide open still but not for nearly as long when using a thinner winter rating. I've been running a HV pump for 50000 miles now and Im not seeing the horror stories that come with using those, but I did think it through- bigger bypass hole to handle the extra volume to prevent the bypass from being overwhelmed when the oil is cold and thick. I also started running a 0w-40, which is way the heck thinner than a 10w-30 or a 5w-30 when the oil is cold, like at startup. Even with the stock pump, it would get to around 60psi and stay there for a few miles using 10w-40, 5w-50, 5w-30 (I think this engine also had a higher pressure spring in it). With the 0w-40 and the HV pump now the distance and time it takes for the oil pressure to settle back down got pretty much chopped in half and only went to 50psi instead of the 60psi before. That bypass is a very fooling thing, its almost always engaged to one degree or another anytime the engine is above idle. With NO bypass, even with only 5psi of oil pressure at idle, the oil pressure would be 125 at only 5K engine rpm!! Its job is to keep the pressure rising in a proportional way with rpm, NOT rising at the SQUARE of rpm which it has to do without a bypass. To "flow more" at any given pump speed with a bigger pump will do no such thing unless the resistance is lowered, and BY FAR the main resistance in the system is just the damn viscosity of the oil. If you have to depend on the oil getting excessively HOT to lower its resistance to flow, then oil cooling will NOT be effective because it will already be too hot... basically everything has reached an equilibrium at too high of a temperature. Reducing the viscosity allows more oil to go out to the engine, just like heating the thicker oil does, but since the thinner oil didnt require the excessive temperature its flowing more at a colder temperature. And now the colder thinner oil can actually cool the bearings if theres enough oil flow! Another example I can give on this thinner oil higher volume pump idea to cool the oil comes from my own car, not very scientific. Nearly all of my driving is a low rpm cruise with occasional hits of boost. With the stock pump and either 5w-50 (I thought I needed this because of the turbo and being aircooled), or 10w-40 or 5w-30, in my 10 mile trips to and from work, although the oil would not ever get to temperature (meaning 180+), I found out the hard way that its a bad idea to wipe the oil off the dipstick with my fingers because the oil would invariably be so damn hot as to just about cause blisters! When using the HV pump and 0W-40, and same trip, same speed and air temps this same finger test showed that the oil was BARELY warmer than my fingers were. It was actually slightly cooler than my water pumpers would do over the same trip. Tried this same test again with 10w-40 and of course the oil got just as hot as before.