# 1967 Low Oil Pressure



## Wyatt318 (Mar 9, 2020)

When I’m driving the oil pressure is close to 40psi but when I’m at idle it goes down to 5psi.
I changed out the oil sending unit and I still have the problem. Could it be my factory gauge?
And the grounds are good.
I run 10W40 regular oil and Wix filter.
The oil pump has less than 500 miles on it.
Serious problem?


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## PontiacJim (Dec 29, 2012)

Wyatt318 said:


> When I’m driving the oil pressure is close to 40psi but when I’m at idle it goes down to 5psi.
> I changed out the oil sending unit and I still have the problem. Could it be my factory gauge?
> And the grounds are good.
> I run 10W40 regular oil and Wix filter.
> ...


What oil pump did you use? There is a 40 PSI pump, 55-60 PSI pump, 80 PSI pump.

Rebuilt engine?

Correct Pontiac lifters if rebuilt and not Chevy lifters?

Check/"Zero Lash" the lifters to make sure you don't have excessive clearances allowing extra oil to flow/bleed off?

Could be the gauge - you can purchase an inexpensive manual gauge to verify - that would be what I would do after you know what oil pump was installed.


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## Droach6498 (Nov 1, 2020)

PontiacJim said:


> What oil pump did you use? There is a 40 PSI pump, 55-60 PSI pump, 80 PSI pump.
> 
> Rebuilt engine?
> 
> ...


I have high oil pressure at idle its 70, on my freshly rebuilt 67 400. Im thinking it could be the bypass, do you need a bypass? I have thr stock one with bypass installed but I have a Kauffman housing with no by pass and am thining of starting there instead of remoing the engine, again, replacing a new oil pump and finding its still high, the o.p.


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## PontiacJim (Dec 29, 2012)

Droach6498 said:


> I have high oil pressure at idle its 70, on my freshly rebuilt 67 400. Im thinking it could be the bypass, do you need a bypass? I have thr stock one with bypass installed but I have a Kauffman housing with no by pass and am thining of starting there instead of remoing the engine, again, replacing a new oil pump and finding its still high, the o.p.


I would not recommend using the oil adapter that does not have the bypass. The bypass should be run on a street engine. An oil filter bypass is built into the oil filter adapter on a Pontiac and the bypass valve is a built-in safety features which activates when there is excessive pressure in the oil filter. If you eliminate it or plug it, you may blow oil past the oil filter seal OR blow up the oil filter due to high oil pressures.

Do you have any oil galley restrictors that limit oil to the lifters? Have you pulled the valve covers to see if both sides are getting the same oiling? If you had threaded pipe plugs used to replace the front oil galley freeze type plugs, it is possible that the threaded plug was installed too deep and this will cut off oil to the heads and may raise oil pressure because the oil is not flowing and "leaking" out as it should. Any blockage can raise oil pressure. You oil clearances, lifter bores, and valve train allow oil through to lubricate the engine - so all these things are like a controlled leak that allows oil to flow. Stop up the flow, and the oil pump is pumping hard against the blockage and the oil pressure will go up, rather than leak out and allowing oil pressure through.

What PSI oil pump do your have? If you have the 60 PSI oil pump, either your gauge is wrong or the oil pump's bypass valve is not operating correctly - may be stuck shut. If you have the 80PSI oil pump, then 70 PSI may be correct at a cold idle on a new engine. Once warmed up, the oil pressure should drop. Heavy oil, like 20W-50 can cause high oil pressure as the oil is thick and creates higher oil pressure. Switching to a 10W-40 may help drop your idle oil pressure. Even a 10W-30 is a good choice depending on you bearing clearances. Your engine builder should know what your bearing clearances are when he rebuilt the engine. 

Filter selection can create higher oil pressure. I prefer the Wix/NAPA Gold oil filters as they are less restrictive. If you use a filter having what is called smaller "microns", the different is like trying to filter oil through a screen door mesh versus the mesh of a chain link fence - the holes in the door screen are much smaller and does not allow the oil to flow very fast/well through it versus the larger openings in a chain link fence which would allow the oil to flow with very little resistance.

The smaller "micron" filters do filter well, but are for the synthetic oils like 0-10W or the 0-20W oils the newer cars use. The oil is so thin, that is can go through a smaller "micron" filter. If you use a 20W-50, or even non-synthetic oil, that oil will not go through a smaller "micron" rated filter material and then the filter now becomes a restriction for oil flow. So you want to be very careful selecting an oil filter and not get one having the finer and smaller "micron" rating used for modern cars and the lightweight synthetic oils.

You also want to use the largest oil filter you can fit. They make some really small ones that can be used when you use headers, but smaller filters may also cause higher oil pressures just because they are small and don't have a large surface for the oil to pass through because they are small - so this can also act as a restriction.

I would not tear the engine out just yet. I would look at other options and try a few things first. May be something very simple.


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## lust4speed (Jul 5, 2019)

Droach6498 said:


> I have high oil pressure at idle its 70, on my freshly rebuilt 67 400. Im thinking it could be the bypass, do you need a bypass? I have thr stock one with bypass installed but I have a Kauffman housing with no by pass and am thining of starting there instead of remoing the engine, again, replacing a new oil pump and finding its still high, the o.p.


As Jim said, you are much better off with an oil filter adapter with the bypass functioning. The bypass in the adapter really has almost nothing to do with actual oil pressure. The relief spring on the adapter is set to open with about a 2-1/2 pound pressure difference if the filter becomes a restriction. Say your filter fails (very unlikely), then the bypass opens up allowing oil to flow around the filter and observed pressure would only go up that 2-1/2 pounds. Your oil pressure is mainly determined by bearing clearances in a properly assembled engine.

Tight clearances raise pressure and loose clearances lower pressure. 70 on startup on a cold engine is within spec with a 60 PSI rated pump. Figure the oil can be thick enough that it still has some trouble flowing around the ball in the pressure relief. I started off with 10w30 oil on my fresh rebuild and had assembled the engine with clearances on the tight side and ended up with over 80 on the cold start. I simply went down to 5w30 and cold starts stayed down around 70 PSI. Same with hot oil and observed pressure. Too high you drop down the second number, and too low you raise it. Wyatt318 is already at 40 on the high number so the next oil up would be the 20w50.

Wyatt318, the oil filter adapter is a non-player and don't waste any time on it, but you could have some debris stuck in the oil pump bypass. Sometimes you can run it through the gears and dislodge debris in the upper RPM runs, but I haven't been that lucky. The pump itself will be fine after the spring and checkball are removed and the offending garbage is removed and the pump put back together. Hopefully the gauge is wrong and placing a temporary mechanical gauge in line will show better pressure. No easy way to get to the oil pump and it will be a pain.


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## Droach6498 (Nov 1, 2020)

PontiacJim said:


> I would not recommend using the oil adapter that does not have the bypass. The bypass should be run on a street engine. An oil filter bypass is built into the oil filter adapter on a Pontiac and the bypass valve is a built-in safety features which activates when there is excessive pressure in the oil filter. If you eliminate it or plug it, you may blow oil past the oil filter seal OR blow up the oil filter due to high oil pressures.
> 
> Do you have any oil galley restrictors that limit oil to the lifters? Have you pulled the valve covers to see if both sides are getting the same oiling? If you had threaded pipe plugs used to replace the front oil galley freeze type plugs, it is possible that the threaded plug was installed too deep and this will cut off oil to the heads and may raise oil pressure because the oil is not flowing and "leaking" out as it should. Any blockage can raise oil pressure. You oil clearances, lifter bores, and valve train allow oil through to lubricate the engine - so all these things are like a controlled leak that allows oil to flow. Stop up the flow, and the oil pump is pumping hard against the blockage and the oil pressure will go up, rather than leak out and allowing oil pressure through.
> 
> ...


Wow thanks PJ yeh Im going to take my time about lifting the engine I bought the pump 2 1/2 years ago so I dont remember I'll look for the receipt. The oil is 20/50 and I'll try thinner oil maybe just for a bit see if it lowers, is there numbers of the filters with larger screens like 100 microns 80 microns etc? I removed the passenger valve cover it all looks clear havent got to the drivers side
Have you ever run your engine without the valve covers? I know it would make a mess. But as far as i know theres no restrictors i do have Kaufman aluminum heads.
I read your piece about the rubber particle in your oil restrictor or galley Im afraid its something like that I'll never figure out. Im a pessimist.


lust4speed said:


> As Jim said, you are much better off with an oil filter adapter with the bypass functioning. The bypass in the adapter really has almost nothing to do with actual oil pressure. The relief spring on the adapter is set to open with about a 2-1/2 pound pressure difference if the filter becomes a restriction. Say your filter fails (very unlikely), then the bypass opens up allowing oil to flow around the filter and observed pressure would only go up that 2-1/2 pounds. Your oil pressure is mainly determined by bearing clearances in a properly assembled engine.
> 
> Tight clearances raise pressure and loose clearances lower pressure. 70 on startup on a cold engine is within spec with a 60 PSI rated pump. Figure the oil can be thick enough that it still has some trouble flowing around the ball in the pressure relief. I started off with 10w30 oil on my fresh rebuild and had assembled the engine with clearances on the tight side and ended up with over 80 on the cold start. I simply went down to 5w30 and cold starts stayed down around 70 PSI. Same with hot oil and observed pressure. Too high you drop down the second number, and too low you raise it. Wyatt318 is already at 40 on the high number so the next oil up would be the 20w50.
> 
> Wyatt318, the oil filter adapter is a non-player and don't waste any time on it, but you could have some debris stuck in the oil pump bypass. Sometimes you can run it through the gears and dislodge debris in the upper RPM runs, but I haven't been that lucky. The pump itself will be fine after the spring and checkball are removed and the offending garbage is removed and the pump put back together. Hopefully the gauge is wrong and placing a temporary mechanical gauge in line will show better pressure. No easy way to get to the oil pump and it will be a pain.


Thanks I wonder why KRE sells oil adapters without the bypass. I just hope it lowers dont want to remove the engine & instll it always a first time though


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## PontiacJim (Dec 29, 2012)

Droach6498 said:


> Wow thanks PJ yeh Im going to take my time about lifting the engine I bought the pump 2 1/2 years ago so I dont remember I'll look for the receipt. The oil is 20/50 and I'll try thinner oil maybe just for a bit see if it lowers, is there numbers of the filters with larger screens like 100 microns 80 microns etc? I removed the passenger valve cover it all looks clear havent got to the drivers side
> Have you ever run your engine without the valve covers? I know it would make a mess. But as far as i know theres no restrictors i do have Kaufman aluminum heads.
> I read your piece about the rubber particle in your oil restrictor or galley Im afraid its something like that I'll never figure out. Im a pessimist.
> 
> Thanks I wonder why KRE sells oil adapters without the bypass. I just hope it lowers dont want to remove the engine & instll it always a first time though


The micron rating in my book is just confusing and "new age" crap. We never heard of this stuff back in our time. I understand it all, but it can get confusing. Just get/use a WIX or NAPA Gold (same brand as WIX except cheaper with the NAPA name on it and it is plastic wrapped instead of a box).

The chances of the oil bypass being stuck shut or open is rare. If it was stuck closed, oil pressure would continue to rise as an oil pump keeps pumping higher and higher pressure as the RPM's go up. This is the function of the bypass check ball and spring - it opens at a set oil pressuer, like 60 PSI, and as the RPM's increase, the excess oil pressure is diverted through the bypass to maintain 60 PSI. Once the RPM's drop, the bypass ball closes at 60 PSI and below.

If the bypass ball is stuck open like mine did, the oil pressure will build verrrrry slowly as the oil pressure gauge creeps up and you have to give it RPM's to make it go higher. With the bypass stuck open, it acts like a BIG leak and you can't build up oil pressure fast or very well. When this happens, oil pressure is not pumping much oil to the bearings and this accelerates the bearing wear and eventually they wear out like mine did and the clearance become so big that one day you don't get any oil pressure anymore.

The race guys use the oil filter adapter without the bypass as they want high oil pressure going down the track. They also use a racing filter which has a much higher burst pressure as the cannister is a heavier gauge metal and the filter material is much more porous so you can flow more oil at higher pressures - remember, drag racers change oil frequently and also tear down their engine a lot to replace bearings and check the internal parts. You see this on TV when the dragsters are in the pits rebuilding the engine under the canopy. The average racer does not do this after every race, but they typically do it at least once a year and more for others.

You can run the engine with the covers off, but have some rags handy. Keep the engine at idle. Don't let too much oil hit the headers/exhaust manifold as you don't want a fire. Typically the oil burns off and smokes and I have never had one catch fire, but never let that much oil coat the exhaust either. I would do one side at a time.

They make oil deflectors that clip on the rocker arms, but these are for stock rocker arms. I suspect you have roller rockers and they won't work with roller rockers.

I would go with a thinner oil and see how that works. I am not a fan of 20W-50 unless you are racing where the engine heat is elevated, or live in a really hot climate like Arizona.

New rebuilds always have higher oil pressure until the engine wears/breaks in. It could take a few thousand miles or so. As the clearances open up a little more, you may find that the engine runs better because it is "looser." One reason race engine have more bearing clearances to reduce friction - but need heavier oils.

Again, I would think positive and not worry too much at this time. It's just like having your first child - you worry all the time and want everything just right. After the third child, you haven't a care in the world about things being right. LOL


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## Droach6498 (Nov 1, 2020)

PontiacJim said:


> I would not recommend using the oil adapter that does not have the bypass. The bypass should be run on a street engine. An oil filter bypass is built into the oil filter adapter on a Pontiac and the bypass valve is a built-in safety features which activates when there is excessive pressure in the oil filter. If you eliminate it or plug it, you may blow oil past the oil filter seal OR blow up the oil filter due to high oil pressures.
> 
> Do you have any oil galley restrictors that limit oil to the lifters? Have you pulled the valve covers to see if both sides are getting the same oiling? If you had threaded pipe plugs used to replace the front oil galley freeze type plugs, it is possible that the threaded plug was installed too deep and this will cut off oil to the heads and may raise oil pressure because the oil is not flowing and "leaking" out as it should. Any blockage can raise oil pressure. You oil clearances, lifter bores, and valve train allow oil through to lubricate the engine - so all these things are like a controlled leak that allows oil to flow. Stop up the flow, and the oil pump is pumping hard against the blockage and the oil pressure will go up, rather than leak out and allowing oil pressure through.
> 
> ...


Wow thanks PJ
So I took my car for a drive today and about 5 miles into it I looked at the oil reading was 60psi running I pulled into a parking lot stopped & idling went to 40 psi. And the best thing is the temp never went over 180 stop & go traffic 82 degree day. What a releif, now the factory gauges and a new brake booster master cyl as the lifters are tapping and I cant install new valve covers the booster is 1/8" away from th v.c. driver side


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## Baaad65 (Aug 29, 2019)

My 461 built by Butler in 2014 has an 80 psi pump and I'm running Driven HR 10w40 recommended by Butler and Driven with a Wix filter. I have a new electric gauge inside and a mechanic outside both hooked to the filter housing. On start up I'm around 90 psi, when it's hot around 20 but jumps fast with increased rpms. The motor probably now has about 2000 miles on it and I don't know the clearances they used. I would find out the bearing clearances that might answer some questions, but put a Wix filter on and run 10w40 and let it break in....don't sweat it I think you're ok.


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## Droach6498 (Nov 1, 2020)

Baaad65 said:


> My 461 built by Butler in 2014 has an 80 psi pump and I'm running Driven HR 10w40 recommended by Butler and Driven with a Wix filter. I have a new electric gauge inside and a mechanic outside both hooked to the filter housing. On start up I'm around 90 psi, when it's hot around 20 but jumps fast with increased rpms. The motor probably now has about 2000 miles on it and I don't know the clearances they used. I would find out the bearing clearances that might answer some questions, but put a Wix filter on and run 10w40 and let it break in....don't sweat it I think you're ok.


I am I was driving it today and about 5 miles into it the op dropped to 60 I pulled over and at idle it was 40 talk about a load off. I already had to pull the engine as when installed the pan leaked bad the builder made up all kinds of excuses, timing,it didnt leak when he cranked it etc thought I was plagued


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