6.5TD S manifold swap and up grade

[FLSTSS]

Hey there everyone,

I had(have) a problem a while back with my oil pressure, I checked everything I could think of, then I dropped the pan and put in a hi-pressure pump, added another oil cooler. The pressure is better but not to my liking, it stays at 40psi when driving all the time, at idle warmed up around 10psi and after putting a load on it (going up a steep hill) and then idle op is 5psi or so , In the pan I found 3 things. 1 was something that reminded me of a bone fragment about the size of bottom half of the # 8 on your key board. I split it easy with my finger nail , 2 was about 3 pieces of something that looked like super thin silver foil (foil leaf thin) they were about the size of the # 0 on the key board. looking up into the piston bores they all looked as if they were new could still see all the hone hashing, it has 158000 on the clock.

Here what happened:

When I start the truck cold the OP is 50psi after the warm up I drive about a mile the OP goes to 40psi and 30psi @ idle, after another mile while driving OP is 35psi and 20 @ idle. After another 10 mins of driving water temp is 195, and max OP is 30psi and 10 @ idle It was never that low. A few more mins same WT driving pressure is around 25-30psi but the idle pressure is near 0 causing the check gage light to come on. If I let it sit in the driveway at idle it stays a 8-10 psi no lower. It just started doing this. I had a stalling- starting problem the truck stalled around 10 times before I had it towed home. I changed the batteries, OPS, oil and filter, the fuel filter, cleaned connections, check voltages. It now starts right up and runs, but now the new problem. I put a tee in the turbo oil feed line with a mech OP gauge and the pressure is the same as the factory gauge. changed the oil and filter again, still same thing. Pulled the filter housing off, oil cooler line pressure spring moves freely as I pushed it up, a bit of oil ran out. I don't hear any odd noises, I checked the engine with my stethoscope still nothing.

So what I am thinking is 1 of two things. 1st yank it out and get a rebuilt, or since the bores look good, rering it, t-chain, rod and main bearings (check the crank replace if bad) heads and a mainfold for a vin F L65.

Are these engines internaly or externaly balanced?
can I just swap cranks and maybe pistons too?
Are the rods press in pins or floating?
Is the cam different on the L56 vs L65 or is it just the heads and the intake and the EGR junk?
Will a intake manifold from a 96' F fit a 97' S ? How abot the exhaust manifolds?


Thanks for reading this post and any of your comments are welcome.

[JohnC]

What is the oil temperature when all this is happening? Maybe the oil cooler and/or bypass is fouled up.

When you had the pan off did you look at any of the bearings?

[More Power]

Beginning in the late 1996 model year, GM began producing 6.5's with piston oil spray cooling. A side-effect of this was lower oil pressure, when compared to earlier 6.5 engines. GM did increase the oil pump's capacity, but the oil pressure still remained lower than it was for the earlier non-spray blocks.

Never completely believe the dash oil pressure gauge when concerned about a low or high oil pressure reading. Temporarily install a known good mechanical oil pressure gauge to verify.

Your oil pressure readings wouldn't necessarily concern me enough to pull the engine. I'd run it....

The small "foil like" pieces found in the pan are interesting.... I have a set of 6.2L piston rings in the shop that I saved for show-n-tell. There are areas on the top Keystone rings where the plating on the ring face had fallen away. That might be it... I dunno. I wouldn't pull the engine for that either.

Run it....


Are these engines internaly or externaly balanced?
can I just swap cranks and maybe pistons too?
Are the rods press in pins or floating?
Is the cam different on the L56 vs L65 or is it just the heads and the intake and the EGR junk?
Will a intake manifold from a 96' F fit a 97' S ? How abot the exhaust manifolds?


The engines are externally balanced (balance weights are found in both the damper and the flexplate.) Yes, you could swap cranks. The piston pins are the floating type with spring keepers. The same cam is used for all variations of this engine. The primary differences between the L56 & L65 are the intake manifold, emissions system and fueling. The L65 manifold will bolt right on. The exhaust manifolds are the same between versions.

Jim

[FLSTSS]

Jim
Thanks so much for your input. I have been driving It, and runs great. One more thing if I was to change the intake and can the egr do you know wat has to be done with the computer? I hear about reflashing, I don't know what that is I have an Idea but wouldn't know where or how to get it done.

[More Power]

Yes, both the OBD I and II L56 can use the L65 programming... Kennedy would be the best one to ask for the finer points. He's the only 6.5 vendor I know of who does his own programming inhouse and has the ability to reflash (reprogram) the 6.5 PCM. :)

Jim