Coolant leaking from...somewhere

RSchanz

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Yes. This makes it MUCH easier to R&R your heads.

Yes cavitation and a pin hole are the same thing. The fix is to have the cylinder sleeved. You will have to tear the engine down to the bare block to have this done. A compression test won't help at all. the compression only goes up when the piston travels to the top of it's stroke which is above the level of the pin hole. A leak down test may work if the piston's below the pin hole. If the hole is toward the bottom of the cylinder, then the piston won't be able to travel down far enough to get the rings below it. Then you won't know of the air you're hearing in your oil fill is from the ring gaps or a pin hole.

So really the only way to determine if this is the actual issue would be to inspection/repair head gasket and put on new valley pan... then of course inspect any other obvious areas where a coolant leak may occur? If none of these things seem to be the issue then I have to assume cavitation?
 

IDIBRONCO

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The only real way to check for cavitation is to pressure check the bare block with the correct block off plates. Unless you have WAY better eyesight than I do or if there's another way that I don't know about.
 

71 Highboy

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The only real way to check for cavitation is to pressure check the bare block with the correct block off plates. Unless you have WAY better eyesight than I do or if there's another way that I don't know about.

This is what it took to find it in mine. Block off plates. The machine shop that bored for me did not do this the first time, and after I assembled and installed, it still pressurized the system. The machine shop had also provided a new set of heads. I thought one might be cracked in the port, because t would hydro lock. Let the water out and it would run. So they wanted to disassemble and inspect. Found the pinhole and sleeved one cylinder. Running fine til this past weekend. IDIBRONCO, if you see my post about stud re torqueing , please reply.
 

71 Highboy

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I did and I didn't think that there was much that I could add to what had already been said at this time.


IDIBRONCO I was referring to a post I tried to start for my own truck. It does not have a dot by it in the listings, so I must not have done it right. 70 views and one response. Going back to look at the truck again today. Looked thru the threads. Seems 80-85 lbs is the torque value for studs on a 6.9. Any help appreciated.
 

RSchanz

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Oh lordy.... so, head gasket/valley pan replacement then hope that the leak doesn't continue as this would mean cavitation and sleeves?
 

IDIBRONCO

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IDIBRONCO I was referring to a post I tried to start for my own truck. It does not have a dot by it in the listings, so I must not have done it right. 70 views and one response. Going back to look at the truck again today. Looked thru the threads. Seems 80-85 lbs is the torque value for studs on a 6.9. Any help appreciated.
I don't see the dots that you're talking about, but I was talking about your thread called (something like) Re-tourquing 6.9 ARP Studs Help. Like was already mentioned, it wouldn't hurt to recheck the torque on the nuts and maybe go a little bit over specs. When I stud my 6.9 this summer, I'm planning to torque to 100 instead of the 85.
 

RSchanz

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Well, yesterday I looked under her after a 20 minute drive because I felt like the temp gauge was slightly higher than normal and there was that water leak again. Coming down the drivers side onto the clutch housing and front driveshaft.

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Only happens when the truck is running. I don’t come back to it pooled under it after it sits. I’ve read other threads which leads me to believe it’s most likely either:

head gasket
Oil cooler?
Water pump??
Cracked head?!?! (Ugh)

I think it’s safe to rule out freeze plugs because it’s only happening while it’s running, right? Is it peculiar that the severity of the leak seems to vary? I’m guessing that when the leak is slower it just evaporates on the block before it gets any lower.

With any suggestions on what it could be if you could provide insight on best ways to check for leaks in that area it would be appreciated.

Thanks in advance, esp. since this has been such an ongoing issue.
 

IDIBRONCO

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My first thought is that you have two different coolant leaks. At first, you were talking about it coming from above the lift pump and now it's coming down onto the front drive shaft. This leads me to believe that it's head gaskets. The first thing that I'd do is to retorque both sets of head bolts. If that doesn't work, I'd pull the engine and install new head gaskets. You should also install a new valley pan since it's been in question.
 

RSchanz

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Yes, it does appear to have dripped from two different areas. I think you’re totally correct that the valley pan needs replacement regardless but this can be secondary after retorquing head bolts.

So the coolant never seemed to leak like this prior to the radiator replace. I noticed coolant disappearing but chalked it up to the radiator leaking at the top. Think the radiator could be faulty and somehow be creating more pressure in the system than it should?
 

IDIBRONCO

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Think the radiator could be faulty and somehow be creating more pressure in the system than it should?
I would think that it's able to build pressure in the cooling system now that the radiator isn't leaking. When it was leaking, there wasn't much pressure build up (if any) in your cooling system.
 

RetiringColt

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Maby I missed it but what psi is your new radiator cap rated for? I believe anything over 9psi is too high for these engines. Do you have a coolant Pressure tester or access to one? since you have a known leak, I'd suggest over pressurizing the system a few pounds to recreate your leak. Unfortunately once a leak starts it will more than likely need new parts to stop it. Hopefully it's a set of head gaskets at the most.
 

RSchanz

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Cap is 13psi, could always try switching to 7 or 9 to at least make the leak less severe. It looks like its coming out of the back corner of both of the heads. I can rent the pressure tester from O'reilly's again. Last time I did it the pressure maintained at 13lbs for about 5 minutes then I relieved it. However at that time I didn't know where the leak was clearly coming from.

I've got a time slot at a good mechanic near me for Tuesday because I can't take the engine out of the truck where I'm at and if it's both heads I would imagine I should remove the engine rather than doing it in the truck. Probably make this decision after I get the ridiculous quote back from him. Other problem is the truck needs to drive 45 minutes to get to him haha.

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IDIBRONCO

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For what it's worth, both of those pictures look like oil to me, not coolant. I'm thinking seeping valve cover gaskets. Maybe a poorly sealed valley pan.
 
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