I'm at my wit's end (admittedly, it was a fairly short journey)

Here's the scenario: I just finished rebuilding a 6.9 for my boss's '86 F350. We made a few upgrades along the way. First of all, the block was bored .030 over, the crank was checked and found servicable and polished so the engine kit consisted of all std. Clevite bearings, (crank, rods and cam) along with new pistons/rings, cam/lifters, timing set and oil pump. The piston squirter nozzles were the press-in type and as they had to be removed for boring they were of course replaced with new ones. Since we decided to add a Banks turbo that I already had (non-wastegated style) I studded the heads. Also upgraded to ZF 5speed, which is another story in itself...

On assembly I checked all rod and main bearings to be sure they were indeed std. and plasti-gauged a couple of each and found them to be within spec, though on the high side.

On startup it has about 30 psi at idle running Delo 400 30w which drops to about 4 psi (checked with a mechanical gauge) and s l o w l y increases to about 20 psi at about 2K RPM. I haven't seen any higher reading than that with the engine warm, haven't run it over about 2500 at this point. It's got a total of maybe 20 minutes run time on it...

I perused many interesting theads on this forum which led me to check the pressure at the fitting on the left side/rear of the block (no change) and pull the oil cooler to check the relief valve and spring (looked like brand new-no sign of wear on the spring.)

No water in the oil, the new o-ring seals I installed in the cooler are good and not leaking, the oil level is good-just a hair under full checked with the engine cold.

With the engine idling if I crack the oil supply line to the turbo oil just oozes out, no real pressure there.

Today I pulled the fitting on the side of the block and hooked up an air hose to blow air pressure back through the oil system, hoping I could spot the source of the leakage. I removed the injection pump and can see the lifter galley plugs, still in place as well as the joint where the oil pump bolts to the block, no air is coming out at those points. I can hear it bubbling up through the oil in the sump so that tells me the majority of the air is going back through the pump and pickup tube, though I would expect some leakage past the bearings. Next I guess I'll pull the timing cover and see if I can see any of the piston squirter nozzles with a flashlight and inspection mirror to see if they're all still in place. After that I guess it'll just have to come back out so I can pull the pan and inspect and check clearances on all bearings and look for any other defects.

Any thoughts on this? I'm almost totally unfamiliar with these engines, other than having to rebuild this one. I'd sure like to get it working, I don't want to have to give him my Cummins...

 

TigerDan, I've seen your avatar before, but it still cracks me up.

Have you inspected the oil pump at all? and do you know what sort of oil pressure the engine had before the overhaul?

 

I haven't inspected the oil pump yet since installation (it's new, as I said) since it's still in the pan and I haven't torn it down that far yet.

As for pre-rebuild OP...well, that's a little hard to say. The engine isn't actually the one that came out of the truck, it was a core motor that I got with plans to rebuild it for swapping into my '68 but I wound up rebuilding it for my boss's truck instead, thinking it would reduce the downtime on his truck. It had been sitting for about 3 years before I got it and was not in the best of shape, which is why it had to be bored out.

 

My 6.9 builds 45 ibs with the starter cold and it hot idles with 40. with Delo 15w40. What kind of pressure did it have before? I know the older 6.9's did have some block problems. They would crack around the lifter bores. I have seen 2 that were cracked when I magnifluxed them.

 

As I said, I haven't run this motor, it was a non-running, basically core motor when I got it.

The block was supposed to have been Magnafluxed by the machine shop who bored it out so hopefully there are no cracks...

 

Hopefully they didn't miss any cracks. They can be hard to see. When I magniflux blocks I take a propane torch and warm the areas up to get a crack to swell. I have have seen cracks that would only show up this way.

 

What brand was the new oil pump, I have a new melling in mine and I am not happy with the out of the box quality control, 6 thousandths end clearance on the gears. I flat sanded the housing to get to 1.5 and that took a while. Pressure is 7 to 10 psi lower than before replacement, same bearings. When it comes out again, god forbid, i will put the old pump back in. New parts need to be checked carefully. btw the melling rep said , "well we cant check them all". So much for an old good name.

 

Offhand, I don't recall...I think most of the parts in my kit were Clevite, I'll check and see if I still have the OP box tomorrow.

I sure never would have thought it of Melling but your comment isn't the only one I've seen as of late about their decline in quality.

 

Was the filter header fibre disc assy still in place staked with an aluminum washer.....

There were some problems with cracks in the pickup tubes allowing air to enter the oil system instead of 100% oil.

 

Yes, the fiber disc was still in place and sound. Hadn't heard that about the pickup tube, I considered the possibilty that it might be sucking air but was unsure where to look other than the tube-to-pump joint...

 

Got it further apart yesterday...3 thou endplay on the Clevite pump, the pump housing cover bolts were not very tight, I'd say about 10 ft/lbs but I don't think that's it. The pickup tube looks beautiful and I see no sign of cracks anywhere although the gasket between the pump and pickup tube didn't look the best, didn't see a sign of leakage though.

I guess the next step is to pull each and every rod and main cap and plasti-gauge them.

Maybe I'll stick it all back together and fill 'er up with 90 weight...that should bring the pressure up!

Thanks for all the replies thus far, guys.

 

What brand of oil filter are you running? Is it known to allow good pressure (meaning do you have experience with this filter on other engines)? I know from the gas engines and racing circle track that there are a lot of junk filters out there that don't flow very good and/or come apart inside with a lot of pressure (not necessarily collapsed). Frams are totally junk-stay away from them. I don't know anything about Ford/motorcraft filters, but we always use Napa/Wix filters on all our race motors (over 8000 rpm)

 

I used to use Fram exclusively but they've really gone downhill. These days I use the Wix filters from Napa and that's what was on there.

I may have tracked down the source of the problem. It would seem that the flange on the pickup tube where it bolts to the pump is warped, I can bolt it securely to the pump with no gasket and slip a .005 feeler gauge it between them with no problem. I cleaned up my spare pickup tube and inspected it and will use it instead. I'm also not comfortable with the gasket I was using there. It was the only one in the Victor-Reinz set that came close to fitting and I wasn't happy with it at the time but put gasket sealer on it and used it. That, coupled with the warped flange may have been allowing it to suck air. After doing some other checks today I also find that I don't trust the mechanical OP gauge I was using and bought a new one. I'll reassemble the mess tomorrow and see what I have...

 

hook your pump up to a drill.

 

Actually, I did. I built a rig today to test the pump and found that the new pump did put out a few more PSI than the old one...not an impressive difference though.