OK let's look at coolant into the cylinders.
There are several places this can happen,
cracked head
cracked block
leaking head gasket
leaking valley pan gasket
cavitation

The fact you are not seeing compression in the radiator tells me the heads, block and head gaskets are probably OK.

The valley pan gasket blocks several coolant passages in the heads, it is possible that a failed gasket could let coolant into the intake port of the head and or the intake manifold.

Cavitation can let coolant into the cylinder or straight into the oil pan, where it goes depends on where the hole is in relation to where the piston stops at.

A good test for head gasket, cracked block, cracked head and cavitation is find an adapter that let's you hook shop air up to pressurize the cylinder through the glow plug hole.
When you do this test, you need to remove the rocker covers and loosen the rockers so all valves are closed.
When you apply shop air pressure to the cylinder, the piston will rotate to BDC which will then test all of the cylinder wall.
When you are ready to apply air pressure, remove the radiator cap and fill the radiator completely full.

When you put pressure to the cylinder, any leak in that cylinder will show up by raising the water level in the radiator neck.
Since normal compression pressure is 400+ PSI, you can use as much air pressure as your compressor will put out for this test.

If this test is repeated for every cylinder, when the water level raises you know where the problem is located.

I just noticed you have a small leak in the radiator, that would have to be fixed first.

With a little jury rigging that test could be expanded to test the valley pan gasket after you checked the cylinder.

First thing you need to do is install a block off plate over the intake manifold opening where the turbo hat is now.
You would need a fitting in the block off plate that would let you apply air pressure to the intake manifold.
When you applied air pressure to the intake, you would have to keep the pressure down to about 15 PSI.

Once again, any leak would show up as water level raising in the radiator neck.

The only bad thing about this test, is the leak could be at any of the intake runners, but that don't really make any difference since you have to change the valley pan no matter where it is.

The rest of the places that coolant enters the oil pan would not put coolant into the cylinder, so I guess there is no reason to go into them at this point.

 

Dave, didn't they eliminate the holes in the head that lead to the cooling system when they made the 7.3?

 

It has been a while since I had a 7.3 apart, but I think the holes are part of the head casting.

The IDI has a dry manifold, so the coolant passages just get blocked off by the valley pan when it is installed.

The only picture I have of the intake port side of an IDI head is not labeled 6.9 or 7.3.
There is a coolant passage right below the glow plug on every cylinder.

 

Well I'll be fixing the coolant leak tomarow and maybe get one of my buddies to come over get the engine to oprating temp with my coolant pressure tester on then power brake it and see if the presure goes up with boost that should tell me if it is coolant. I wish i had thought to do a clt when i had the inectors out could have just lossened the valves and stuck a ruber tip air gun in the injector bore.

also do thouse dealies that turn color when theres compresion in the coolant work for diesels?

One last thought I doubt its cavitation or the valley pan because I'm not burning coolant.

 

when i was fixing the coolant leak i noticed a thin layer of what looks like oil on the walls of the upper radiator tank.

 

Well to day it locked up big time in the morning got it started when I went to leave work started right up relized i had forgot some thing went back in came out and found a big pudle under my engine. Coolant was coming out of my up pipe, not good.

So after i shho air on it is its in the cylinders how do I tell the diference between cavitation and a blown head gasket?

Also i noticed that I'm now maxing at 6 psi instead of 7.

The wierd thing is it doesent burn coolant.

 

George, Try this. When you park it for the evening let the pressure of the coolant system. If you have to get one of those Stant caps with the lever so you don't cook yourself.

See if it still gets coolant in the cylinders. I have seen head gaskets that let coolant in but not really build much pressure. They let the coolant when the motors is shut down. The coolant pressure is up and it pushes it's way in.

They will do some goofy things sometimes. My wifes old Taurus would lock up every time if I didn't let the pressure off the coolant system in the afternoon but it wouldn't push any out of the rad while it was running.

 

When the head gasket went on my 6.9 (174K miles)
no differnce in ower running down the road
didnt burn coolant
there was a mild leak at the rear of the passenger side head
after 2 days it would burn a little coolant on start up
4 days it would lock up when I went to start it

 

I really hate to say this, one of my cracked block engines ran just fine.
It put pressure in the radiator when it was running, but no white smoke.
When I shut it down, hydrolock.

Get in and just very quick bumps of the starter till the engine made a complete revolution, then fire it up and ran great.

If I took the radiator cap off as soon as I turned the engine off, no coolant in the cylinders and it would fire right up.

Using the air pressure in the cylinder will not tell you what the problem is, but it does tell you where you need to focus your attention when you tear it down.

This picture is one of my sleeved 7.3 engines, look between the black lines for the crack.
Also notice the coolant in the #1 cylinder.

 

Well me and some of the guys at work were looking at it and there is no presure in the cooling system stuck a funle in the rad filled with water no bubles at all, put my coolent presure checker on it presurised it started the truck presure droped 1/2 psi and more with increased engine rpm. So we saw the service manger walking around and asked him since he was a doing this stuff back when these engines were in everything, he couldn't think of any thing.

Some how I have a leak that will let 13psi one way but not let compresion or cumbustion the other way.

I know its possible for a head gasket cracked head or block to do this but it still doesn't make a lick of sence.

I'm going to get my jeep registered tomarow and then pull my cross over to see wich side its coming from well actaly i guess I don't need to since there was a bit of coolant coming from the dirves side exaust manifold. And next pull it apart and take a peek in side and see what doesn't have carbon on it.

Man its so much funner when I get to say that and its not my vehicle and I'm getting payed for it.

Guess the land yacht is going into dry dock.

 

The more I think about it, the more I think it might be the valley pan.



If the valley pan is leaking from the coolant passages to the intake port, you could fill the intake runner with coolant.
As soon as an intake valve opens, the coolant goes into the cylinder.

That is the area I had trouble with running high boost, but my boost was going into the coolant passage pressurizing the radiator.

Very possible yours is going the other way.

Who painted the engine Ford blue when it was apart?
What engine was that, a 6.9 or 7.3?
I know that one of you guys did that, who do I owe credit for the photo?

 

That would be mine.




And thanks for calling it "ford blue", some one else kept calling it GM blue......

The heads were remaned and came that color so I just went with it.

 

I would think if that were the case then It would leak all the time or atleast in low and no boost conditions or when the engine is up to temp. And I am getting zero white smoke. But I might as well check since all the possibilities don't exactly add up, and you are wiser than I when it comes to these engines. I'll go pick our IDI gurus brain tomarow and barow the borascope and look around in my intake and see what i can see.

 

Also I'll check the service manaul at work to see if the 7.3 still had thouse passageas.

Thanks for the help.

 

Not something pleasant to think about but a crack would leak more when the engine is cold. For that matter prahaps even a head gasket leak could to the same??