Been concentrating my nightly readings on FTE to IDI internals and rebuilds. Have been able to understand a fair amount, but am still left with questions.
My truck has 172k miles according to the odometer. I do know it sat outside for about 3 years before i got it...then it sat for 2 years at my house before getting a chance to tear into it. So..after not being driven for about 5 years i didn't expect the engine to last too long before the overhaul...and here we are...the teardown.
I believe i lost a head gasket. Exhaust was coming out of my radiator.
So, the motor was pulled this weekend.
The motor had no oil leaks...anywhere. The valve covers came off and the rocker arms have no sludge at all. It's very clean inside. Same thing under the valley pan. It seems very clean.
I haven't pulled the heads yet...seems i don't own a 7/16" 12-point socket.
Judging from how clean it is under the valley pan and valve covers...seems encouraging.
What do ya think? Sounds like a failed head gasket?
It's an April 1985 engine, so i believe it to be the weaker block and heads.
I don't want to have it bored or anything...but if needed it will happen.
I was thinking to have it magnafluxed to check for cracks, new bearings, new rings, all gaskets/seals, head studs, and have the heads rebuilt.
The future will call for an ATS turbo...anything i should plan ahead for?
I'm a total newbie...am i on the right track?

 

id replace the head bolts with some studs.

 

definetly...they seem a bit small to hold down such a large head

 

If you give the motor too much boost youll lift the heads and blow a head gasket with the stock bolts.

 

6.9 blocks up to serial #u2u17900 had a thinner casting around the block heater. It is very common for these blocks to crack.


6.9L Old Style Block

Block Casting Number:


On left side of block (beneath oil cooler) 1805440C1
Note: Some 440 blocks are truly new style and must be visually inspected by raised donut around the block heater, frost plug (right rear). Old style below serial number 173828.
Visual Identification: *No counter bored area for block heater
*No defined area on side of block for dip stick
*Thickness of cast iron around block heater 3/8" (.375")
Head Bolts: *7/16, 12 point socket is used to torque head bolts
*Block tapped with 7/16-14 for head bolts

6.9L New Style Block

Block Casting Number: 1807996C1 Note: Some new style blocks have casting
number 440. Above serial number 173828.
Visual Identification: *Has counterbored area for block heater
*Very defined relief area cast in side of block for dip stick tube.
*Thickness of cast iron around block heater 15/32" (.470")
*Latest style (not all new style 6.9) has ribs around head bolts, rear two on left side go from head gasket surface to pan rail - same as 7.3
Head Bolts: *Same as old style 6.9

 

I haven't had a chance to pull the oil cooler and check the casting number yet. But, the valve cover sticker says it's an April '85 engine...leading me to believe it is gonna be the weak block.
If that's the case - between an early 6.9 and a 7.3, what's the better engine? ...an early 6.9 with a weak block that may crack or a 7.3 with thin cylinder walls and not much of a chance at anybody rebuilding? Neither of these engines are as good as an '86 or '87 6.9, but is there a better choice between the two?
I think my rebuild plans will change a little bit...instead of doing the 7.3 rockers and head studs to prepare for a turbo...i'll just do the head gaskets and throw it back in the truck. Or is the early 6.9 worth a "future-turbo rebuild"?
Out of curiousity...any idea why the block cracks? Is it because that area of the block becomes hotter than the rest of the block because the truck is plugged in?
With the naked eyes-it's not cracked right now...and i won't use that type of block heater anyways...i installed a tank-type water heater from JC Whitney in my '65 F350. This type of heater is thermostatically controlled and actually pumps the water through the whole engine...not just heating one area 'till it's scalding hot.

 

I checked the casting number...seems I have an early style 6.9 according to the number.
But as far as the raised donut area for the freeze plugheater element and the block is fairly robust where the dip stick enters the block, they both seem pretty stand-out. I tried to post pics...hasn't worked yet. But i'll keep trying.
By the way...am I on the right track as far as thinking I have a blown head gasket?
My symptom was exhaust gas coming from my radiator. Enough pressure that blew coolant out the top of the coolant reservoir.
Under the valve covers is surprisingly very clean. No sludge...at all. We've done head gaskets on our 6-cylinder Jeeps a couple times and we've had to scrape sludge off with a putty knife and the smell....yuck.
Seems like someone has been in this engine before judging by the RTV on the Intake Manifold. Maybe they cleaned it then...or this is just the way it is.

 

Diesel oil has some good detergents in it to handle all the soot that makes it's way in the engine.
One reason you must use CD or CE API designation oil in diesel engines.

Also oil changes at 3000 to 5000 miles, don't let much sludge build up.

Over 300,000 miles on my original engine when I tore it down, still clean inside.

Use of the stock block heater is what the cracks are all atributed to, since that is where the crack always is.

I would still take an 84 6.9 over a 7.3, I can get around every problem the 6.9 has.
Getting around thin cylinder walls.....junk yard.

The external heater should eliminate the crack problem.
Several areas of the valley pan were sealed with RTV originally.

 

Thanks Dave, i'll rest better now knowing my early 6.9 will still be a better beginnig than a 7.3.
Just got in...pulled the passenger side head.
Of the 4 cylinders, 3 have a good sized puddle of coolant in them. The coolant is covering about half the piston in each of them.
All 4 did have some white speckles...chalky stuff. Came off with a rub of the finger...maybe some diesel residue?
None of the 4 pistons showed any terrible glow plug tip markings.
The head gasket had stains where it had been leaking out of some of the coolant passages. There are no cracks in the gasket.
Tomorrow i'll pull the other head and try to see what we've got to start with.
Tomorrow i'll also take more pictures.