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sudden oil pressure drop

maybe 500 miles. heads were cracked, wasnt aware, water got into the oil. no idea how long it was that way before i purchased. previous owner bought at auction and never used. it was covered in moss. other than yellow gunk, inside of block looked good. these squirter nozzles, r they just a drilled orfice or a tapped hole with brass nozzle? dont remember seeing them.
 
12555506 date code on the block. i have a diagram of an oiling system from another gm v8, thought it may be similar. it shows a copper galley plug that normally seals the oil passage between the filter supply and return, but can come loose and descend vertically cutting off the supply to the engine. i tried to upload the diagram but it was too large. im wanting to try everything before resorting to pulling the cam.
 
gruss said:
im wanting to try everything before resorting to pulling the cam.
Click to expand...

Then look at a oiling diagram of THIS motor, it isn't like any other V8. Their are 2 pressure valves under the oil filter, both are replaceable and are known to stick, if anything has made it's way through the system their is a good chance something is stuck in one of them. The valves should always be replaced during a rebuild but very few do it...
 
thx, thats what i was suspecting. i saw a schematic of a 6.2 diesel, assumed it to be the same as 6.5, smaller bore. you know where i can find a diagram of this specific engine? it would certainly help to troubleshoot.
 
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gruss said:
maybe 500 miles. heads were cracked, wasnt aware, water got into the oil.
Click to expand...

:facepalm: Start looking for another engine, oil cooler, and turbo. Coolant in oil destroys bearings quick starting with the turbo bearings. Rust on the valve train is a major concern esp. if it sat with coolant in oil. It also likely got hot from cracked heads and air locked cooling system ruining the rings. It will run with freight train on fire blowby. 500 miles isn't any useful history - but I suggest you just found out why it was sold.

A 6.5 is just a punched out 6.2 where the differences be in slight head changes and rope to 1 piece rear mail oil seal. Our reference section has the complete military repair guide for this engine. Many of us run a 6.2 bottom end with 6.5 heads. Some run 6.2 heads as well, but, have injector and passenger side turbo manifold fit issues.

If you are lucky it just spun a cam bearing. Looking at the oil flow diagram you see @Will L. advice of priority oiling TO THE CAM BEARINGS! Unlike other V-8's that care about the crank bearings you loose major oil pressure with cam bearings on the 6.2/6.5 engines. I believe one of the Russian members lost a lifter and lost oil pressure.

The oil cooler and oil filter bypasses can be stuck wide open or even missing and have zero effect on the oil pressure as they only bypass the filter or cooler.

At the end of the day this is a throwaway engine: the crack prone GM blocks are not worth machining cost. Get a used Optimizer that is an improved casting or the best P400 if you can find one : those are worth machining. (Point of fact we patch the engines without machining. Deglaze cylinders for new rings is all.)

We got your back as engine swaps are common. So are improvements to get some power out of these forgotten diesels. VS. new stuff these are a bargain to work on.
 
any way to insp cam brgs without pulling cam? if not, is it possible to pull cam w/o removing heads? remove push rods and lifters do it? change bearings with engine still installed?
 
gruss said:
any way to insp cam brgs without pulling cam? if not, is it possible to pull cam w/o removing heads? remove push rods and lifters do it? change bearings with engine still installed?
Click to expand...

Did you figure out if you got a high volume oil pump for the squirter block? Post the part number you purchased if in doubt.

The cam bearings are not fun to change typically a machine shop should install them. Special tools etc.

What shape is this engine really in? Other than oil pressure low: how is the blowby? How did the cylinders look when you pulled the heads? Cooling system hold pressure now indicating good heads without cracks and no cracked cylinders?

Suppose @Twisted Steel Performance the oil cooler is plugged and the oil cooler bypass is also clogged full of junk. It may be a kinked, pinched, or internally failed oil cooler hose. Did you see anything in the oil pan or old oil filter? Sloppy job before and lots of RTV in the pan?

These engines ruin rings and crack to death if you get them over 210 on the dash gauge. GM's contempt for diesel owners "it should look like a low compression gasser" left off the "red" after 210 on the gauge. The taxpayer foots the bill for the 2nd re-design for the military engines to supposedly take the higher temp spec in the military manual: the GM cast sure as hell doesn't. Note: Fords 7.3 IDI also ruins rings like all the other IDI diesels if you get them hot.

IMO you should call one of the site vendors "Ted's" @Margaret about used surplus take out engines and decide from a cost and labor standpoint if it's just easier to swap the engine with a good surplus used one. Re-Ring with a deglaze it before dropping it in. I don't even remove the crankshaft to deglaze. (mainly to prevent more stress on already weak main webs.)

From your description this engine has been hurt. At this point re-check everything esp. the "proper" oil pump. What did the old oil pump look like internally? Hint: you have to look at the old parts you took off otherwise you can waste money throwing parts at it all day long and never fix it. New parts don't mean good parts - we are the lack of quality control inspectors nowadays.

After the re-check you are better off pulling the engine for a complete tear down and crack inspection. Even if it's just cam bearings the engine really should come out. Maybe if you or your buddy (hired help) are good at it you could do the cam bearings in the truck.
 
Yes you can do cam bearings without pulling heads.
Waterpump/ timing chain comes off. Valve covers, pull rocker arm assemblies, pushrods (which may be upside down cuz the last builder already broke design rebuild rules with the crankshaft), lifters come out and then cam comes out.

Cam bearing install tool is really a precise made circle bolted to a long ass handle you can hit with a mallet.
Not hard to do imo. Getting them into place for the rear one and removing the rear one is the hard part. And for the love of...dont drive the rear bearing in too far. I have made cam install tools by turning down aluminum seal installer kit from harbor freight.

Some people make a push installer out of 1/2 thhreaded rod. Too much chaos for me.

I know it sucks to be ripping apart a rebuilt engine, but this clearly was not done right. Imo, pull it out of the truck, diassemble completely and see exactly what you have. Otherwise, what disaster awaits in 13-14 months?

You might do better with one of the $500 units here:
http://www.thetruckstop.us/forum/th...-500-looks-like-alot-of-em.47154/#post-554725

Iwould still tear them Down before install just to know. The extra $250 you spend to reassemble your current one or any other used one will be $ well spent.
 
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