I have an 85 model 6.9 motor in my 83 truck. As tax returns are almost here, I started pricing an oil pump and cam bearings for it. It has basically 0 psi and for all the research I've done, the two main suspects are the pump and the cam bearings. Since I can do both for about 150 bucks, I wanted to ask if there is anything I need to know about changing these bearings. We have done cam swaps on lots of gassers, but never on a diesel. Are we gonna need any special tools, or is this gonna almost be a no brainer for us. I have had the heads and timing cover off of this motor before, and it seems to me to be a pretty simple set up. I was just wondering if there was something I needed to know that would be different than say a typical small block. Thanks for any input.

 

The first thing I would ask is:
Where are you getting this 0PSI oil pressure reading from? I hope your not depending on the OEM guage.

I've never heard of cam bearings wearing enough to reduce oil pressure to that level.

I'd think that if you had zero oil pressure, the engine would make so much noise that you'd know to stop running it.
And if the cam bearings are worn that bad, that most of the rest of the motor would be also.

 

If you have o oil pressure the engine will not just keep running.Cam bearings are not the only way you get oil pressure,the main bearings are very important in that respect.It depends on where you are getting this reading, check the cheap things first, make sure you have oil in the engine,oil filter isn't plugged and if the engine sounds quiet you do have oil circulating.

 

I have an aftermarket oil pressure gauge, I know the stock gauges suck. I say basically 0 psi, in reality it is probably about 5 psi. It will read about 10 then fall just around the time the fast idle kicks off. It has good oil and filter, so it's not plugged up anywhere. I was told that the cam bearings would be the next thing to check after the pump. The bearings are only 25 bucks so I figured I might as well do them while I'm at it.

 

I'd suspect the oil pressure relief spring, in the rear oil cooler header.

Where is your oil pressure guage tapped into?
Does the engine make noise?
How many miles on it?

 

The oil pressure guage is installed on the top and at the back of the motor (stock location?). No, the engine makes no noise-it has always been a real rattler, for many miles. The miles are the unknown. When the 83 motor quit, I was able to buy this motor, install the head gaskets, and get everything wrapped up and done in the truck for less than $500. It came out of a roll back tow truck. When the head gaskets went, the guy put a 460 in his truck. I got lucky on the price. Tell me about this spring. Where is it located? I know where the oil cooler header is on the motor, driver's side under the exhaust manifold, but I have never messed with it. I had someone tell me that unless you knew what you were doing, or had done it before, not to screw with it. I ordered the pump and cam bearings already, and they are in, so I can go get them today, but if it is just a spring, that'd save me about $160. Can that spring be bought? How hard is it to change? I hope someone sees this before I go and buy the parts. Thanks guys.

P.S. I disagree- the engine will sit and run without oil pressure. The first motor ran for awhile before it gave up, and still ran after it started knocking (really bad). I just don't want to trash this motor like the last one. This motor is still running fine, and it does show 0psi. I checked it when I fired it to move it up to the garage this afternoon. I even drove it down the block. I'm sorry, I should not have said that has 0psi. That's just what the guage shows.

 

what is the oil psi when driving the truck most of us idle about 7psi when oil is warm then while driving it is around 35 - 45 psi

 

Hello. the very first thing that you need to do is bleed all the air out of the line going to your oil pressure gauge................then report back with oil pressure readings a idle, and 1500 rpms................cam bushings can only be installed with the engine out of the frame or at least the trans and flywheel removed and it take a special tool.........if the cam bushings are the problem of 0 oil pressure....they have spun , which means the block has to be line bored for over size bushing................the bottom line is you do not guess about oil pressure problems.........you do the all proper test before turning a wrench...............
crossbones

 

As far as I've ever known, No One has ever found the specs for the spring. It's a Ford/IH only item. BUT you have to buy the complete rear header. It's staked into the header.

 

FYI there is a plug on the left side of the back of the block, located under the exhaust manifold/pipe joint. That is a direct main line from the filter........ might wish to check there to before teardown.

What quality level is the manual PSI guage........autometer????????? or Harbour freight....... Get a good snapon on the sender hole first and check it out.

 

The oil pressure reads 0. Cold at idle-0, Operating temp at idle-0, Any RPM above idle, cold or operating temp-0. I guess I will try the oil pump, if it doesn't work, it gets a 460. I am not gonna second guess this thing 50 ways from sunday when the parts are so expensive. Everybody says it's something else. I sure will not buy any specialty tools to replace something that I don't even know will fix it. Do not misread me here-I do not at all want to get rid of my diesel, for many reasons. One of the biggest reasons for liking this truck so much is that aside from regular routine maintenance, rarely do I have to buy parts for it. I don't mind the expensive parts, if they fix what is wrong, cause again, I rarely have to buy anything. How much is the oil cooler? I can tell you now that if it turns out to be the cam bearings- it's gone. I can fix 460's all day, for a lot less money, and a lot less headache. Sorry for the rant, sincerely, but I just got some money in my pocket to fix it. It has been sitting since last spring, and this truck is my baby. Hell, I've had it longer than my wife and 3 kids.

Okay, bottom line. Where do I start looking? I put the aftermarket gauge on it because ford's stock gauges are about as far from reliable as you can get for OEM gauges. I will double check my plumbing on it, because it's been on it for awhile. I think there is oil circulating because it sounds fine, as in normal. It doesn't even get hot.

Sorry again guys. I am getting tired of this, I just want my truck back.

 

plc7.3-I didn't know about that-I'll check it.

Also where exactly is the oil pressure being taken from if using the stock oil pressure sending unit? It would seem to make the most sense to start at the 0 psi reading, and work backwards from there. I want to again apologize for previous post. Not a good night around here. But I'll get serious tomorrow to diagnose the exact problem. I have tomorrow and the weekend to get this done, as I think the rain here in KC might let us work come Monday morning. If you guys can stay with me, I'll check everything. Speaking of which-I just went out and looked at that gauge. Plain jane no name oil pressure gauge. I do remember that I bought it at O'reilly's. You can see it move right at start up, but the high idle speed is no where near ready to kick off when it drops to nothing. What pressure it shows (10 psi maybe) only lasts about 5 to 10 seconds. Seeing as how the oil pump could be stock as far as I know, unknown mileage, It really wouldn't make me mad to do the oil pump anyway. Any one else have a take on this?

 

Is there a screen on those pumps that might clog. The way it comes up for 10 seconds at startup makes me think it might be starving. Just a thought. Joe

 

I'm with PLC, Double check your guage. If'n it's a cheapy, it might just be shot.

 

Ok I'll replace that. How do you get all the air out of the line to the guage like crossbones said? I have this type gauge in my 65, it has air in that line too, and it has never given a problem.