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Discussion Starter #1
I have a 64.5 Mustang 289 4bbl with the 4spd toploader. I just rebuilt the engine. Pretty well stock except for a very minor upgrade on the cam. The block had to be bored 30 over, new pistons, etc.. Everything went well; all specs followed. It runs great BUT....
When it starts it pulls a little over 30psi oil pressure with 10w30 oil. As it warms up the pressure drops to almost 0psi. The oil pump is new. All of the bearings were checked with plastigage and torques were triple checked.
This is my first time with a Ford engine and I'm pretty confused.
Any ideas?

Thanks for the help!!
 

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I'm suspecting it's an issue with your oil pressure gauge or wiring. If the psi was dying off, then I would suspect an oil pump issue but it sounds more like a short is occurring...perhaps the oil psi sending unit might be defective as well
 
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When you replaced the cam, did you install new cam bearings and gauge them properly?
 
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Discussion Starter #5
When you replaced the cam, did you install new cam bearings and gauge them properly?
New cam bearings installed at machine shop. I simply slid the cam in when I put the motor back together.

I'm suspecting it's an issue with your oil pressure gauge or wiring. If the psi was dying off, then I would suspect an oil pump issue but it sounds more like a short is occurring...perhaps the oil psi sending unit might be defective as well
I took the oil sender off and plumbed a mechanical gauge in. Good pressure when cold and then steadily dropped to almost zero as it warmed up. Picked up another mechanical gauge as a double check. Same thing happened.
 

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I like to see at least 25 psi when hot and at idle, but sometimes that’s just not the case. At speed it should be at least 35 psi at 2k rpm.

I would guess that either your oil pump isn’t up to snuff, or your machine shop simply trusted that bearing specs were okay, as opposed to making sure they were optimal. I’ve seen more that one shop fail to ensure cam bearings were optimal. They require a little more effort the check, change, and refit.

As long as you are idling at about 18 psi hot, you SHOULD be fine, but as the engine wears, it may become an issue (or not). If it were me, I’d try to find a stronger pump.
 

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Sounds like there is 1) an oil pump issue and 2) machine shop related issue..... I would be starting with the oil pump (R&R) and secondly inspecting the intenrals including the oil for signs of metallic issues.... not a good situation here!
 
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You need to have a discussion with your builder. There are formulas for bearing clearances, oil pump flow and oil viscosity. Based on that, he should give you recommendations for an oil pump and oil viscosity.

For big cam, high power applications a builder will use larger clearances and will require a high volume oil pump and/ or 20w50 oil.
 

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Sounds like there is 1) an oil pump issue and 2) machine shop related issue..... I would be starting with the oil pump (R&R) and secondly inspecting the intenrals including the oil for signs of metallic issues.... not a good situation here!
Dropped the pan. Rod and main bearings look great. No metal in the pan or the oil. Guessing it’s a pump issue.

You need to have a discussion with your builder. There are formulas for bearing clearances, oil pump flow and oil viscosity. Based on that, he should give you recommendations for an oil pump and oil viscosity.

For big cam, high power applications a builder will use larger clearances and will require a high volume oil pump and/ or 20w50 oil.
I did the rebuild. It’s not a race motor or high horsepower. Basically stock. Plastigage on the rods and mains when I assembled. All torques triple checked. Everything per spec. Dropped the pan and checked the bearings. All looks good. No metal in the pan or oil. Going to try a new oil pump.
 

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I did the rebuild. It’s not a race motor or high horsepower. Basically stock. Plastigage on the rods and mains when I assembled. All torques triple checked. Everything per spec. Dropped the pan and checked the bearings. All looks good. No metal in the pan or oil. Going to try a new oil pump.
Your pump is pumping when the oil is cold, so it has to be pumping when it's not, so replacing it in kind is not advisable. I would change over to 10W-40 and see what happens with that. If things improve but not enough then you have a little more information, and can decide whether to try 10W-50 or go with a high volume pump.
 

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I'm glad that it's not as bad as what my gut said it could be for you!!!!! Keeping fingers crossed with the oil change!
 
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The other thing that you might do is take a valve cover off and crank the engine over without starting it, to see how much oil is flowing to the heads. Ford had "over oiling" issues in the heads for the FE "big block" engines for a number of years and there might be something similar going on with the small block.

That was an issue for me in my build that is fortunately well documented on how to fix. Two dollars worth of restrictors in each head oil gallery does the trick and keeps pressure on the main bearings.
 

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Did you install a high pressure oil pump? If so, then I'd agree with Yadkin. Too much oil getting pumped into the heads and not draining fast enough for the pump to pick back up. Maybe a bigger oil pan.
 

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I have a 64.5 Mustang 289 4bbl with the 4spd toploader. I just rebuilt the engine. Pretty well stock except for a very minor upgrade on the cam. The block had to be bored 30 over, new pistons, etc.. Everything went well; all specs followed. It runs great BUT....
When it starts it pulls a little over 30psi oil pressure with 10w30 oil. As it warms up the pressure drops to almost 0psi. The oil pump is new. All of the bearings were checked with plastigage and torques were triple checked.
This is my first time with a Ford engine and I'm pretty confused.
Any ideas?

Thanks for the help!!
I've got a 2014 Mustang GT. It share the garage with a 1949 Ford F-2 with a rebuilt 239ci V-8. I purchased the truck in Feb and drove it 1-1/2 hours to get home and found that the Oil pressure was around 30psi when cold then dropped to near 0. No overheating or other problems. I Spoke with a local mechanic about that and he recommended using heavier weight oil - It had 10/30. I changed the oil to 20w50 and the pressure has risen to near 30 psi. The mechanic said the low pressure was caused by lower tolerances in the bearings after the rebuild. That shouldn't hurt the life of the engine but does result in lower oil pressure. So, you might want to try a heavier weight oil.
 

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I have a 64.5 Mustang 289 4bbl with the 4spd toploader. I just rebuilt the engine. Pretty well stock except for a very minor upgrade on the cam. The block had to be bored 30 over, new pistons, etc.. Everything went well; all specs followed. It runs great BUT....
When it starts it pulls a little over 30psi oil pressure with 10w30 oil. As it warms up the pressure drops to almost 0psi. The oil pump is new. All of the bearings were checked with plastigage and torques were triple checked.
This is my first time with a Ford engine and I'm pretty confused.
Any ideas?

Thanks for the help!!
Could you have missed an oil galley plug somewhere?

Lifters in wrong facing the wrong way
 

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Discussion Starter #17
The other thing that you might do is take a valve cover off and crank the engine over without starting it, to see how much oil is flowing to the heads. Ford had "over oiling" issues in the heads for the FE "big block" engines for a number of years and there might be something similar going on with the small block.

That was an issue for me in my build that is fortunately well documented on how to fix. Two dollars worth of restrictors in each head oil gallery does the trick and keeps pressure on the main bearings.
I’ll have to check that.

Could you have missed an oil galley plug somewhere?
Since this is my first Ford engine I can only assume I didn’t miss any as the machine shop included a note to be sure and re-install the oil galley plugs. The locations were marked and I put them in.

Lifters in wrong facing the wrong way
Ummmm....I’m not sure if you’re joking here. As far as I know they only go in one way. For lack of a better description the cup is up for the push rods to sit in.

Did you install a high pressure oil pump? If so, then I'd agree with Yadkin. Too much oil getting pumped into the heads and not draining fast enough for the pump to pick back up. Maybe a bigger oil pan.
New OEM spec oil pump.
 

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I have a 64.5 Mustang 289 4bbl with the 4spd toploader. I just rebuilt the engine. Pretty well stock except for a very minor upgrade on the cam. The block had to be bored 30 over, new pistons, etc.. Everything went well; all specs followed. It runs great BUT....
When it starts it pulls a little over 30psi oil pressure with 10w30 oil. As it warms up the pressure drops to almost 0psi. The oil pump is new. All of the bearings were checked with plastigage and torques were triple checked.
This is my first time with a Ford engine and I'm pretty confused.
Any ideas?

Thanks for the help!!
Did you replace the cam bearings? I've made that mistake
 

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You were right in installing a mechanical gauge to verify the issue. In my opinion, going to a heavier weight oil will just mask the issue. Think about what pressure is; resistance to flow. You could put gear oil in the crankcase and the pressure would be high, due to the resistance of the thick lube to flow. You would see good pressure, but would not have the correct FLOW to all the bearings etc. Just like what you are seeing with the cold engine, except with higher weight oils, they are more resistant to thin out as they get hot so the pressure does not fall off as much - and neither does the flow. That is why cold oil is harder on your engine - resistance to flow.
In my view, 30 psi cold at any rpm higher than idle is too low.
Based on what info you supplied and what you have checked, I think you have one of two issues:
1) Bad Oil Pump (not very likely but can happen).
2) You left a cup plug out of the block oil system and have an internal leak. The first place to look would be the front of the block where there are three 3/8 inch cup plugs one on both sides plugging the lifter oil drillings, and one for the main oil rifle feeding the Mains and Cam Bearings - See the red arrows in attached picture (At the back of the block, there should be three pipe plugs for these drillings).
Also, and here may be your issue, there is a 1/8th inch oil drilling about 5 o'clock from the front Cam Bearing - See Orange circle in attached picture. This is a cross drilling to oil the Distributor Gear and where it pilots in the block.
On the earlier 289s this was plugged with a cup plug in the front. On later small blocks, the drilling was left open but was covered by a different design Thrust Bearing. If you have the earlier design Thrust bearing, and no cup plug, there would be a pretty good internal leak. Symptoms would be as you described.
Bad part would be you would have to remove the front timing cover to check....
Good Luck.
778460
 

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Discussion Starter #20
Did you replace the cam bearings? I've made that mistake
Cam bearings replaced at the machine shop.

You were right in installing a mechanical gauge to verify the issue. In my opinion, going to a heavier weight oil will just mask the issue. Think about what pressure is; resistance to flow. You could put gear oil in the crankcase and the pressure would be high, due to the resistance of the thick lube to flow. You would see good pressure, but would not have the correct FLOW to all the bearings etc. Just like what you are seeing with the cold engine, except with higher weight oils, they are more resistant to thin out as they get hot so the pressure does not fall off as much - and neither does the flow. That is why cold oil is harder on your engine - resistance to flow.
In my view, 30 psi cold at any rpm higher than idle is too low.
Based on what info you supplied and what you have checked, I think you have one of two issues:
1) Bad Oil Pump (not very likely but can happen).
2) You left a cup plug out of the block oil system and have an internal leak. The first place to look would be the front of the block where there are three 3/8 inch cup plugs one on both sides plugging the lifter oil drillings, and one for the main oil rifle feeding the Mains and Cam Bearings - See the red arrows in attached picture (At the back of the block, there should be three pipe plugs for these drillings).
Also, and here may be your issue, there is a 1/8th inch oil drilling about 5 o'clock from the front Cam Bearing - See Orange circle in attached picture. This is a cross drilling to oil the Distributor Gear and where it pilots in the block.
On the earlier 289s this was plugged with a cup plug in the front. On later small blocks, the drilling was left open but was covered by a different design Thrust Bearing. If you have the earlier design Thrust bearing, and no cup plug, there would be a pretty good internal leak. Symptoms would be as you described.
Bad part would be you would have to remove the front timing cover to check....
Good Luck.
View attachment 778460
Thanks for the response. I’m going to get a new pump in and see if that resolves the issue. If not I’ll proceed to removing the timing cover. I know for sure I put the plugs in the back of the block.

Well it isn't the oil pump. Guess I’ll pull valve covers and check for over oiling in the heads needing restrictors and then pull the front cover and check for missing oil plugs 🤷‍♂️🤷‍♂️
Rod and main bearings look good. Still sticking with 10w30 oil. I think a thicker oil is masking a problem unless there is some solid evidence that the stock 289 typically runs low pressure.
seriously hoping it’s not cam bearings. I’ve had a couple of motors go through a machine shop before and never had a problem. Plus the shop i went to came highly recommended by some friends who race. Sooooo........dam.

You were right in installing a mechanical gauge to verify the issue. In my opinion, going to a heavier weight oil will just mask the issue. Think about what pressure is; resistance to flow. You could put gear oil in the crankcase and the pressure would be high, due to the resistance of the thick lube to flow. You would see good pressure, but would not have the correct FLOW to all the bearings etc. Just like what you are seeing with the cold engine, except with higher weight oils, they are more resistant to thin out as they get hot so the pressure does not fall off as much - and neither does the flow. That is why cold oil is harder on your engine - resistance to flow.
In my view, 30 psi cold at any rpm higher than idle is too low.
Based on what info you supplied and what you have checked, I think you have one of two issues:
1) Bad Oil Pump (not very likely but can happen).
2) You left a cup plug out of the block oil system and have an internal leak. The first place to look would be the front of the block where there are three 3/8 inch cup plugs one on both sides plugging the lifter oil drillings, and one for the main oil rifle feeding the Mains and Cam Bearings - See the red arrows in attached picture (At the back of the block, there should be three pipe plugs for these drillings).
Also, and here may be your issue, there is a 1/8th inch oil drilling about 5 o'clock from the front Cam Bearing - See Orange circle in attached picture. This is a cross drilling to oil the Distributor Gear and where it pilots in the block.
On the earlier 289s this was plugged with a cup plug in the front. On later small blocks, the drilling was left open but was covered by a different design Thrust Bearing. If you have the earlier design Thrust bearing, and no cup plug, there would be a pretty good internal leak. Symptoms would be as you described.
Bad part would be you would have to remove the front timing cover to check....
Good Luck.
View attachment 778460
Well I might be a little concerned. Here is a pic of the front of my block. I have an opening above the front cam bearing that doesn't look to be made for a cup to plug it. Maybe it runs down to the distributor gear for oiling? And the drilling you mentioned is also at the 5 o'clock position and not plugged. Also attached is the block number. It looks to be a correct as a 1964 Windsor block, 2 bolt mains. My 455 Buick seemed so much simpler back in the day.....Thanks for the help!
289 front of block.jpg
289 block number.jpg
 
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