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Discussion Starter · #1 ·
Today, we changed out the glow plugs, and what I thought were some leaky fuel hoses on top of my 7.3 IDI. In the valleys of the glow plug ports was coolant! It seems to be coming from where the intake manifold meets the head.

I've owned this for only a few weeks, working on it when I have the chance. The fluid is in the same place on both sides, too-- the third glow plug on each side from the front of the block.

In changing the oil, there's no water/coolant in it. The engine doesn't overheat, and doesn't seem to be loosing coolant. I have a bad feeling about this.

Can anyone shed some light on what might be the problem?

Thanks in advance,

Lefty
 

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These fans (and others) move a huge amount of air even without the fan clutch engaged. If you have any small coolant leak forward or rear of the blades, the fan will pick it up and spray it anywhere and everywhere on the top of the engine. And antifreeze is slow to evaporate compared to water. You might first want to check for a slight leak at the top rad hose clamps, signs of a leak at the radiator top tank seam, etc.
 

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Discussion Starter · #3 ·
Don't think so.

This is in the rear, and it appears coolant is leaking either between the intake manifold and head, or and this is ugly: out of the rearmost injector on that side.

Strange, because the engine seems to be running well, and it then stops leaking when the block is warm, and it's not sucking down coolant, no white puffs in the tailpipe, not water in the oil, no oil in the water, but it boils off the antifreeze when it's warm, I can see it bubbling.

My guess: cracked head or head gasket, or both. Dirty words :(
 

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Discussion Starter · #4 ·
It seems that there are cups underneath the injector housings, and they leak. Now checking how to repair this.
 

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It seems that there are cups underneath the injector housings, and they leak. Now checking how to repair this.
Various series of 2 cycle Detroit Diesels have full length copper sleeves (cups) around the injectors, these engines---no. And you can have a cracked head or bad gasket and it would be practically impossible for coolant to make its way up and out of the top of an injector. The only thing you have sealing off the injector from the combustion chamber is a soft copper washer and with the injector tightened to 35 ft.lbs. against it, unless there's a large gob of debris on one side or the other of it, it's pretty leakproof.
 

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Discussion Starter · #6 ·
What would cause coolant on top of the block?

It seems like it's bubbling up between the intake and the head, so head gasket?
 

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The fluid is in the same place on both sides, too-- the third glow plug on each side from the front of the block.
Is the coolant just down in the indentation for the glow plugs?

It seems like it's bubbling up between the intake and the head, so head gasket?
It would seem strange that both head gaskets would leak in the same place on both sides.


It seems that there are cups underneath the injector housings, and they leak. Now checking how to repair this.
Have no idea what your saying here. There are no cups around or underneath the injectors.

Your saying three different things. Can you take pictures and post them here?
 

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If its between the intake and the head wouldn't that be the intake gasket? The head gasket goes between the head and the block.
 

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If its between the intake and the head wouldn't that be the intake gasket? The head gasket goes between the head and the block.
Right, some V8 configuration engines have a water passage in the intake manifold running from one head to the other but looking at a Navistar manual these engines do not. I was wondering last night if he means head to block seepage at the edges of the head which is not uncommon on these and some other diesels.
 

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Right, some V8 configuration engines have a water passage in the intake manifold running from one head to the other but looking at a Navistar manual these engines do not. I was wondering last night if he means head to block seepage at the edges of the head which is not uncommon on these and some other diesels.
I was thinking the same thing. Even some of the larger in line engines would seep a little when cold. If he re-torques the head bolts, that MIGHT stop the leak. As a get-by in case the re-torqueing doesn't work one (1) bottle of Bars Leaks would work in this case. Until he can replace the head gaskets. If you use any more Bars Leaks, it WILL RUIN your heater core.
 

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I was thinking the same thing. Even some of the larger in line engines would seep a little when cold. If he re-torques the head bolts, that MIGHT stop the leak. As a get-by in case the re-torqueing doesn't work one (1) bottle of Bars Leaks would work in this case. Until he can replace the head gaskets. If you use any more Bars Leaks, it WILL RUIN your heater core.
Yeah, it used to be standard practice to retorque the 3 heads on the NTC Cummins fairly frequently. I'd like to find out from a RELIABLE source if Bars Leak has a negative effect on the SCA's in coolant. Bars Leak isn't an oil, but I know the Fleetguard people say any oil at all in the coolant system prevents the SCA from adhering to the cylinder walls and the system has to be thoroughly flushed with Dawn detergent.
 

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Discussion Starter · #12 · (Edited)
The coolant seems to be bubbling up where the intake meets the head. It's not a small amount. It stops once the engine is up to heat. Not much coolant is missing at all. At first, it's like a sieve, then it slows to a stop.

A Ford service tech said that the intake manifold gasket can deform and do this, but it's been years since their shop has taken an IDI apart.

Perplexing.

Seems like it's arriving to the top, outside location of the block, near the injector, which doesn't seem to get dry, even when I wipe it, until the block is up to normal temp. Starts up nicely. Goes down the road nicely, e.g. under load. It has tire problems, another discussion.

Thanks for thinking about this; I've never seen such a thing.
 

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The coolant seems to be bubbling up where the intake meets the head.
Think you might want to post a pic. If you mean intake manifold when you say "intake", there is no coolant passages anywhere near that area. Coolant runs up around and through the cyl head then back down into the block at the forward end of the left head then through the right head. You could take the intake manifold completely off and you'd see no coolant passages or coolant, just air intake ports. I guess nothing's impossible, but a cylinder head crack allowing for a coolant leak up in that area would be one for the record books. Heads most always crack at the web between the intake and exhaust valve down in the combustion area of the head nowhere near the intake ports.


I understand what the Ford mechanic is referring to, like I said, the Ford gas engines allowed coolant to run through a passage in the end of the intake manifolds but both the Navistar and Ford shop manuals show plainly that this is not the case with the IDI diesel engines.
 

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Discussion Starter · #14 ·

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That's the exact pic from the Ford shop manual like I have and was referring to. As you can see, coolant is confined in the head and block and isolated from the intake manifold. You can also see the port in the block where coolant flows over to the right head, not through the manifold.
 

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Discussion Starter · #16 ·
This means the head is likely cracked, if the coolant is bubbling up..... so it's a head job.
 

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I think maybe we're both talking about the same thing, just having a major problem to communicate! :) Let us know what you find.
 

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Discussion Starter · #18 ·
This means head removal and a reman head needs to be installed.

Could some kind soul provide links to the procedure? I'm guessing it's unlikely that it can be done inside the engine compartment, so it'll likely mean an engine pull.

Or, maybe it's time to put a Jasper in it and be done with it. Any links/recommendations are appreciated.

Thanks,

Lefty
 

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Yeah, it used to be standard practice to retorque the 3 heads on the NTC Cummins fairly frequently. I'd like to find out from a RELIABLE source if Bars Leak has a negative effect on the SCA's in coolant. Bars Leak isn't an oil, but I know the Fleetguard people say any oil at all in the coolant system prevents the SCA from adhering to the cylinder walls and the system has to be thoroughly flushed with Dawn detergent.
I never worried too much about that. At that point you're going to tear into it soon. You might just be waiting for tine and/or money to start the project. At which point you'll be cleaning things up anyway.

As far as the leaks go. I would pull the head off and have them checked for cracks. It sounds like they cracked for some reason. Freezing? That is a fairly thin area there, Probably the weakest point casting wise on the heads.
 

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If you have the manual that shows the coolant flow, then you have a pretty good description of how to do it. Something an old man (at the time) once told me. "The crankshaft goes round and round, the pistons go up and down, and they all come apart and go together one bolt at a time." Now I'm the old man. It's true. Watch how you take it apart, put it together in reverse order, and follow the torque recommendations and sequence in the manual.
 
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