Hey Guys I need help understanding a few things because I have just had one massive headache over this thing. I've got an '88 460 first year with EFI, etc. it has around 80,000 miles. I just took the engine apart and redid all of the seals and the top end. All bearings and oil rings and cylinder walls were all in great shape. I took it apart because I was having oil problems... I thought that was caused by oil getting into the coolant because the coolant did have oil in it, and I also was under the impression that it was burning oil because I kept losing oil pressure after a few hundred miles and would have to add oil for it to go away.

So anyway, the engine is back in. I've driven it again about a few hundred miles and it was doing great. I put a new oil pressure sending unit in a few days ago that would allow me to have a real gauge because the factory one just doesn't do anything. I wired it up correctly all it would do was go all the way to its full sweep when the engine was running and I didn't have time to diagnose that so I drive it the past few days. The first day was fine. The second day the stock gauge and the gauge I put in kept doing a flip flop, the oil pressure on the stock gauge would go up from L to the NORMAL range and the aftermarket one would drop all the way down to 0. This was only for a split second but they kept doing this intermittently. I took the truck on a maybe 30 mile trip at high speeds high RPMs and afterward, the tappets were just going crazy.

So I thought oh boy what's going on am I burning oil again. At first, they calmed down a bit after just slowing down the engine and doing a cool-down, but yesterday I couldn't drive without all the tappets tapping away. These are new tappets btw. So I checked the oil level, Perfectly fine in the upper part of the crosshatch part of the dipstick. The tappets wouldn't quiet down until I added oil, but the engine just isn't running smooth or sounding good like it did after the rebuild a couple of weeks ago. Some guy was talking before about how the oil is getting stuck up in the heads, but with this problem, I continually have dry starts every time I start the engine for the first 5 seconds or so. Also, this is a new oil pump that I did prime correctly. There's no way the oil gets stuck up in the heads that long and doesn't get to the rest of the engine. I'm not overheating at all and have no loss of power or anything. Just an insane amount of noise which obviously tells you oil isn't getting there.

Yesterday, the CHECK ENGINE light was going on and off intermittently so obviously the computer was detecting something. The tappets were also clicking intermittently and sometimes only one or a couple. This leads to my main question, Is the oil pressure in this engine computer controlled? Did me using an aftermarket electric gauge sending unit that I wired into the system compromise this, or do I have a more serious problem? Like I said and as it appears it looks like I am burning oil but there is no smoke, and as checked, the oil level is good. I am just somehow losing oil pressure after long high RPM runs and then it stays that way. The worst part of this is there is no consistency in the problem it is always changing. Very frustrating.

Thanks guys hopefully someone more adept than my limited mechanic skills can help me with this...

 

The ECU has no control over the oil pressure. I recommend you ditch the electric OP gauges and replace with a mechanical gauge so you really know what is going on.

 

Okay, I thought that was the case. I tried that a while back but couldn't get it to not leak. I Will invest in a higher quality gauge I guess. Is it possible that the problem is being caused by too much oil and my dipstick is just reading incorrectly? Meaning I am getting air pockets or a similar or related issue. @jas88

 

UPDATE:

I had checked the oil level without wiping off the dipstick before. If you wipe off the dipstick THERE IS NO OIL ON IT. However, I can run without any apparent lubrication problems, and obviously, the oil is getting to that level. This probably means I'm having a drain-back problem yeah? Does anyone have a clue what this is?

 

Maybe your oil is too thick or too thin for the engine. What weight are you running?
Since you just re-did the top end, are you sure you got the lifters adjusted correctly? Were they on the base circle? I assume you have hydraulics. With noisy tappets and also your idle and oil problem, it sounds like you have a mix under preloaded and over preloaded lifters.
To check the oil, standard procedure is to have truck on level ground, engine turned off, pull the stick, wipe it clean, put it back in all the way, hold it there for a quick moment, then pull it back out to check. I usually do this twice, just to be sure - especially if the oil is fresh and hard to see.

 

@66F250_4x4 I am running 10W-30 which is the factory recommended for higher than freezing weather temperatures. The lifters are non-adjustable the rocker arms just torque down and seat on the head. The problem is intermittent and will go away with added oil.

 

I ran 5W-30 previously and upped it to 10W-30 hoping it would fix this issue prior to the rebuild I did a few weeks back.

 

Either way its 30 weight by the time the engine is warm - should be OK. You could try a 20w-50 real quick, if you do suspect that might help - if you are losing pressure due clearances, that would help. You said the bearings look great - did you measure them?
The oil pressure gauge problem could have been an electrical problem (poor ground), or could have been showing bad oil pressure. Maybe you should check that your block is well grounded while you're at it. I would get that mechanical installed ASAP and check the pressure. Perhaps you've had two bad pumps.
Are these new lifters? Pushrods? If so, sure you got the right ones for the application?
Maybe you have a cam lobe problem. Did you have a look at it? I've read you can put new lifters on an old cam, but also that you should do a regular break-in at first start.
If you're really burning oil that fast, the plugs (one or more) may show it. Have you looked at the plugs?

 

I did a rough measure of them and they seemed like they had good tolerances. The problem is poor ground. They are new lifters and pushrods and I am sure they are correct. I did sort of break them in on the old cam but I was under the impression it wasn't really necessary. I did look at the cam. It had some wear on the edges, however, I judged that it was ok to keep. Maybe I should have judged otherwise. I will look at the plugs.

 

I am going to drain the system, put a Motorcraft filter on, bypass the oil filter, and use 15W-40 diesel oil and see if I have better luck. Also going to retorque the heads and the rocker arms. and check my oil pressure for real to see when I am losing it. May also pull the pan again to see if the pickup tube has a crack.

 

put some quality zinc break-in in there and that's quieted them up good.

 

Okay guys I have more specific data. Under load, I have great pressure going up with the RPMS. After I let off and idle I momentarily loose oil pressure and then it comes back. I also do not have pressure for the first 3-4 seconds of start up, or when changing gear (Drive to Reverse). What the heck is happening?

 

Okay, so I was perceiving what was going on wrong. I lose pressure when I am BRAKING or TURNING but not when I am hard accelerating or at high RPMs steady. This obviously means that the oil is somehow sloshing out of the way so much that the sump is not picking any up. I don't really get how this is possible. Could I maybe have a larger than 6qt oil pan with a stock sump? Goes away after sitting still at a light for a few seconds but that whole braking time you hear plenty of clicks and the pressure gauge is going everywhere.

 

Or could I have a cracked or damaged pick-up tube so that the oil level in the pan has to be high up on it or it will start sucking air? That would really suck because I just had the engine out and I thought that the pickup tube was okay and getting that thing with the engine in is a big pain/ barely possible. Anyone wanna chime in if they have ever had this problem?

 

I don't have this problem at cold starts.