Ok. How does that answer the question?
No oil pressure at idle
- Thread starter indirect_connection
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Ok. How does that answer the question?
indirect_connection
Well-Known Member
Garage rebuild. Bottle brush honed and new crank/rod bearings. Clearance on bearings (plasti-gauge) were in spec, but I only checked in one spot for every journal.
harrisonm
Well-Known Member
I could be wrong, but I think you may have the answer to the low oil pressure question. I'm not trying to pee in your Cheerios, but a garage 'refresh' is risky on an engine you haven't heard or seen run.
That’s exactly what happens when u try to use an oil pump over. Should of replaced it. Change the pump and u will have oil pressure. I changed around 10 pumps in magnums that had low oil pressure. They were all pretty good after the pump change. Kim
Well your oil pressure is definitely getting away.
We all have tried to cheat the low oil pressure thing on wore out used engines. Install new oil pump and still low.
First rule of good oil pressure, make sure all of the Rod, Main and Cam bearings are within tolerance. This is what holds the pressure up. A new oil pump after 100,000 miles is a good ideal too, can you imagine how many gallons of oil that original oil pump has pumped in 100,000 miles . . yes they wear.
Guessing the cam bearings are wore enough after 100,000 miles that they are bleeding oil and letting the pressure go low. Have been building some 360s here lately and am putting new cam bearings in all of them. After the rebuilds we are getting 25 psi at idle and 75 psi at 2000 rpm with the stock replacement Melling 72 new oil pump, new rods, new mains, polished stock crankshaft and new Melling SPD-22 camshaft with melling matching lifters.
The 360 cam bearings that came out of these engines all looked really tough, and some of them the layers started coming apart. Even if the cam bearings look ok, they are soft and can be worn beyond factory tolerance anymore.
So my guess is worn cam bearings and a stock oil pump that is not up to par. Can't believe a thing people tell you about that used engine sitting there in the guy's front yard, that it was running when pulled. If it was a good running engine it would have still been in the car. There is a reason that engine was out in the yard and up for sale. Let's say a low oil pressure issue . . .
We all have tried to cheat the low oil pressure thing on wore out used engines. Install new oil pump and still low.
First rule of good oil pressure, make sure all of the Rod, Main and Cam bearings are within tolerance. This is what holds the pressure up. A new oil pump after 100,000 miles is a good ideal too, can you imagine how many gallons of oil that original oil pump has pumped in 100,000 miles . . yes they wear.
Guessing the cam bearings are wore enough after 100,000 miles that they are bleeding oil and letting the pressure go low. Have been building some 360s here lately and am putting new cam bearings in all of them. After the rebuilds we are getting 25 psi at idle and 75 psi at 2000 rpm with the stock replacement Melling 72 new oil pump, new rods, new mains, polished stock crankshaft and new Melling SPD-22 camshaft with melling matching lifters.
The 360 cam bearings that came out of these engines all looked really tough, and some of them the layers started coming apart. Even if the cam bearings look ok, they are soft and can be worn beyond factory tolerance anymore.
So my guess is worn cam bearings and a stock oil pump that is not up to par. Can't believe a thing people tell you about that used engine sitting there in the guy's front yard, that it was running when pulled. If it was a good running engine it would have still been in the car. There is a reason that engine was out in the yard and up for sale. Let's say a low oil pressure issue . . .
xLURKxDOGx
"An angel fat, at satan's feast"
You solved your problem. Time to do it right and stop guessing.
When I worked for Ford dealer, owners would trade in fairly nice 3 and 4 yr old F150s. When we started to get them ready for resale we would find "no heat". Then we would discover the thermostat had been removed, to keep the oil warning lamp off, for higher trade in value. It's a fairly well known cheat, among truck owners anyway. If the truck was otherwise really nice, 80K miles or less showing, new cam bearings and a thermostat at minimum. Most of them went onto the wholesale row.
All of the above are possible issues. Your oil pump bypass could be stuck open, didn't see that mentioned . Just looks like you will get to tear it down and cross your T's and dot your I's to find out.
indirect_connection
Well-Known Member
I'm going to drop the pan and change the pump, if that doesn't help it then out she comes.
I’ve been putting high volume pumps into them with lots of miles. U should be good with a standard pump. But even when I build a fresh engine it gets a hv pump. U can also get a high pressure pump. Kim
I think this may be the answer! I did the same thing with an HV pump and had good results.
Cley
512Stroker
We are all here because we are not all there.
Did you cut open the oil filter and look for thrash? If you find any thrash you know what you have to do.
I would try some 10W-40 or even 20W-50
I always go with a high volume pump
Dartswinger70
Well-Known Member
did you have all oil holes lined up with bearings? I believe the oil goes to the mains first then to the sender but dint quote me on that. something could be restricting it, how was the bearing clearances. I believe my 340 with high volume pump is like 40 psi at idle and goes up from there. My bearing clearances arent lose though.
Alot of new bearings are coming through defective no oil holes i had to file oil holes into a 5.0 ford rod bearing recently. Well it was 2014 LOL!
Alot of new bearings are coming through defective no oil holes i had to file oil holes into a 5.0 ford rod bearing recently. Well it was 2014 LOL!
Dartswinger70
Well-Known Member
Was that on a YT video? that sounds vaguely familiar
Dartswinger70
Well-Known Member
I usually do that every time, yes you can check an old pump but they are affordable enough to go with new like a timing chain.
Not that I know of.Was that on a YT video? that sounds vaguely familiar
diymirage
HP@idle > hondaHP@redline
No, he clearly said it was a friend...and I doubt anyone on here would claim that about uncle tubyWas that on a YT video? that sounds vaguely familiar
Dartswinger70
Well-Known Member
Well..I was referring to a certain Dyno shop up north ut I think Uncle T might been involved in that "just a little"...
I do. Quite proudly.
cudamark
Well-Known Member
Yup, I've run across that a few times too.
indirect_connection
Well-Known Member
So I ordered a Melling high volume pump. Almost thinking it’s a counterfeit. Ordered on eBay, the casting on the cover looks tougher than those I’ve seen pictured, and there were visible machining marks inside. It was a PITA to install in the car but I got it. The reward is evidenced below. Hopefully I didn’t do too much damage during the time it was operating with low pressure.
100,000 mi all bearings should have bean replaced.
Bret Tschacher
Well-Known Member
No you would not be wrong on that point. Higher RPM would definitely see a reduced pressure if the suction side is restricted. Oil pressure is totally dependent on clearances in the complete system. Since rods have side clearances they are usually not a big factor considering the mains only allow metered flow. Some engines such as Ford FE's allow unmetered flow to the rockers which has always been a pressure issue in those engines. There is simply far too much oil fed there and by restricting it you can increase pressure to the rest of the engine dramatically. On to the rest of the equation. Since rod bearing clearance is a big issue and will make noise lets go on to the rest. If the mains are loose, you will see pressure rise with RPM and fall at steady throttle, if you ease off the throttle and see pressure go up a bit then you have too much clearance there. Cam bearings will lower pressure and there is nothing that will change that short of thicker oil either when cold or hot, hot will be lower. You have 5 feed holes directly to the pump that are letting more oil bleed off around those bearings ALL THE TIME hot or cold. Cam bearing clearance is about as critical as you can get in an engine ! Since the cam spins half the RPM clearances are held much tighter than rods and mains. There is less heat here, and with all those springs pushing in the same direction, depending on engine oil system design, some engines feed oil from the top and others feed oil from the bottom. Those that feed oil from the bottom are less affected than the other way, as oil is fed to the cam journal from the bottom the downward pressure keeps the cam closer to the feed hole restricting bleed off, the other way around gives the opposite affect. The other thing that affects oil pressure is the pump itself, clearances in there, end clearance in the pump/gear assembly, clearance between the gear teeth and then there is the pressure relief valve and spring ! Obviously if the engine is old the pump is worn since it gets all the crap from the rest of the engine first hand from the bottom of the pan before it gets filtered out !!!! Oil pumps are for sure easier to deal with then cam bearings. That should be the first thing to address on any engine that has problems. Just ask a shop tech that has worked on newer LS engines or any other engine that uses an aluminum body pump, AMC, Buick, Toyota, Ford in some cases, there are others but what's it matter. I don't recall seeing a MOPAR with an aluminum pump body. As we all know Aluminum expands more and faster than iron so it starts with too much clearance and gets worse. The result is obvious. GET it out of there and put in a good one. And before you put it in take it apart and check those clearances. End clearance in a pump body is easy to fix and it is the worst worry as oil that flows under those gears is not picked up by the next tooth as well as what gets from one tooth to the next. From that point you can roll in new bearings on the crank but if that isn't enough well you know what comes next. Pull that engine and disassemble it for new cam bearings. Those are your options. Thick oil wastes power!
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