View Full Version : Anyone have a cooling system diagram?
Anyone have a cooling system diagram for a 2006? I got back from a 4 hour trip and noticed a puddle of coolant on the ground under the truck. It is dripping down a line that seems to branch off the lower radiator hose. The drip appears to originate from somewhere under the air cleaner. Too dark to see...
DmaxMaverick
11-23-2009, 19:56
Lower radiator (pump inlet) to under the air cleaner should be the coolant reservoir tank hose. Good luck!
..The drip appears to originate from somewhere under the air cleaner...
Could it be the coolant overflow tube? Mine comes out near the underside of the air cleaner..
In the light of day....
No evidence of overflow. The leak appears to be where the heater return line goes from aluminum to rubber. The rubber line then goes down under the fan and "T"'s into the lower radiator hose right before it turns and joins the radiator.
The system still had pressure in it this morning, 12 hours later??? I just installed a new cap and we'll see how it goes. Now to search on "bleeding the cooling system...
OK, all seems to be good. My theory now is that after I shut down last night the pressure got too high and forced the leak. I ran it for 45 minutes and it never developed as much pressure as it had last night while it was leaking.
We'll see, another long trip Friday...
I'm thinking the heater lines are made by the same people who make the trans cooler lines....
It looks like they used a spring clamp. If I can get it off I guess I'll try installing a worm clamp or two...
Pressure on the cooling system 12 hours later?????? Sounds bad!
Pressure on the cooling system 12 hours later?????? Sounds bad!
Agreed, but...
I make two 200 mile trips a week. To date I haven't lost enough coolant to turn the light on.
Nothing bad seems to happen on short trips.
If it were a [gasp!] head gasket, wouldn't you expect it to build pressure quickly, and blow coolant out the overflow?
Any other ideas?
(Just went out and checked. The cooling system still had pressure since yesterday. Sure seems like it's getting pressure from somewhere other than coolant expansion, but...)
More Power
12-04-2009, 10:08
Anyone have a cooling system diagram for a 2006? I got back from a 4 hour trip and noticed a puddle of coolant on the ground under the truck. It is dripping down a line that seems to branch off the lower radiator hose. The drip appears to originate from somewhere under the air cleaner. Too dark to see...
A very small head gasket or LB7 cup seal leak can allow a very small amount of combustion pressure to make its way into the cooling system over time while you're driving. This allows pressure to very slowly build. The surge tank cap should vent at 15-psi, but I don't have a lot of confidence in these caps. Coolant leaks at the various clamped fittings is a usual first indication of an overpressure problem. A rock hard upper radiator hose is another. My guess is that there's more than 15-psi in the system.
Jim
No cup seals; it's an LBZ (06 LLY).
What about the EGR cooler?
I don't even want to think about the head gasket...
What to do? Test the coolant for hydrocarbons? When I first noticed it, I let it run in the driveway for about 45 minutes and it didn't over pressure. I did the same thing this morning, for about 20 minutes and I could still squeeze the top hose until the sides touched. Couldn't do that before I cracked the cap (cold).
More Power
12-04-2009, 15:10
No cup seals; it's an LBZ (06 LLY).
What about the EGR cooler?
I don't even want to think about the head gasket...
What to do? Test the coolant for hydrocarbons? When I first noticed it, I let it run in the driveway for about 45 minutes and it didn't over pressure. I did the same thing this morning, for about 20 minutes and I could still squeeze the top hose until the sides touched. Couldn't do that before I cracked the cap (cold).
An '06? Still in Warranty?
There have been instances in the past where a head gasket was causing cooling system overpressure, but a HC test set didn't detect the presense of exhaust gases in the surge tank. I suspect this is because the leak was small.
The Ford 6.0L has a history of leaking EGR coolers, but I haven't personally heard this problem reported by any Duramax owner yet. I suppose a leaking EGR cooler could contribute to a cooling system overpressure problem, but I wonder. The EGR is fed by exhaust after the turbocharger, so exhaust pressures are not that high - a few psi at most, and only when pushing the engine hard.
I discussed this exact same issue a few days ago with a Duramax owner on the phone. He had access to a test cap with a hose and gauge, so he could monitor the cooling system pressure while driving. He was also planning to install an EGR blocker and remove/plug the cooling lines to the EGR - as a test. I haven't heard back from him yet, but that would be one way to know more about what's going on.
By the way, I'll be discussing all this in an introductory article that'll be available on about the ~15th. Lil Red has experienced this cooling system overpressure problem - in ways that sound almost exactly like yours. I'll be doing a head gasket/cup reseal article in the coming weeks/months.
Jim
Yeah, but lil Red is making a gazillion horsepower...
Doesn't the egr pressure have to be at least as much as the manifold pressure?
But, then, if it was the egr cooler I'd expect it to leak back down over night. The more I think about it the more I think it's probably a head gasket; something that takes a *lot* of pressure to leak a little gas, enough that the cooling system pressure is insufficient to make it leak back down over night. The cap is probably venting pressure on the long trips but not enough volume to cause coolant loss.
Any of you guys that work on these things for a living have any experience with this?
Porter Seal, anyone? ;)
Yes, it's on warranty, but I have a history of not being able to convince dealers I have weird problems...
Those pressure testers do not vent excess pressure. Reminds me of a night I spent in the emergency ward with second degree burns over most of one side of my body... (OK, it did finally vent, but not in a controlled fashion...) :eek:
mastertech
12-04-2009, 21:57
as a gm tech i see a lot of this in the same area remove the air cleaner box and look at the coolant line that comes from the fire wall it should be metal follow it tell it goes to rubber by the radiator there is a clamp there that i have seen that gm for got to relase from the factory insert a screw driver and pop it or just replace it with a regular clamp if that is not it take the hose that comes off of the bottle (over flow hose) and push compressed air into it and you will be able to see the leak really good now becareful when you releae it
Yes, that is where the leak is. Are you saying the clamp is in the "open" position and I need to release something so it tightens up? I'll take another look. What do you think about the over pressure issue? should it still be pressurized after sitting overnight, or is that a sign of another problem?
Thanks for your input!
[Later that same morning...]
OK, I eyeballed the clamp. I see what you mean. Unfortunately for me it has been released all these last 40K miles. Guess leaky head gasket is still the #1 suspect... :(
Any dark discoloration on the walls of the tank?? If you want to test the EGR cooler,, I have a EGR cooler pressure tester adaptor but I've yet to see one leak. I just did a set of headgaskets on a LBZ for a similar issue. If you decide to go with studs, let me know. I sell ARPs.
mastertech
12-06-2009, 19:22
ya checked that clamp let the pressure out of the cooling system and then start the truck and let idle for 10 min take the cap off and fill the bottle just below the neck and watch it if it starts to rise you have a problem gasket or head if you do gaskets do both sides
THEFERMANATOR
12-06-2009, 21:43
I had the same exact leak on my 01 DMAX in my swap. It ended up being that heater line right next to where the rubber hose hooks to it. There is a metal mounting tab welded onto it and mine had cracked right at the weld all the way through the tube and would leak down right under the air cleaner.
http://i162.photobucket.com/albums/t271/THEFERMANATOR/DURAMAX%20ALLISON%20conversion/HPIM1014.jpg
OK, the verdict is in. It's a head gasket... :(
So, let me pose a hypothetical question. Let's say the dealer is taking a LBZ apart to replace the head gaskets. If there was an EGR blocker plate, would they find it? If they find it, will that create a warranty issue? Hypothetically, of course...
DmaxMaverick
12-08-2009, 20:12
OK, the verdict is in. It's a head gasket... :(
So, let me pose a hypothetical question. Let's say the dealer is taking a LBZ apart to replace the head gaskets. If there was an EGR blocker plate, would they find it? If they find it, will that create a warranty issue? Hypothetically, of course...
Sorry to hear that, John.
Hypothetically, no. However, this is not a hypothetical world, with all the corporate politics, yes they would. Any competent tech (and you hope you get a competent tech) will find it. Whether or not he cares, is the question. If he goes by the book, or close to it, it will matter. He will see, and report, you have an emission system modified engine, which will preclude any responsibility to the engine warranty. Either ask first (off the record, of course), or return everything to stock. That's an awful big chunk of change to gamble with, and once branded, always branded. Going to another dealer will be pointless, as would an appeal. Having a warranty repair approved, then rescinded for any reason, will certainly be on your truck's permanent rap sheet.
mastertech
12-11-2009, 22:39
Gm has come out with a new pocedure for Gm tecs that will shock every one. if your truck is under warranty they are required to take a pic of all calibration codes cvn and part # that are in the truck and any and all aftermarket add ons. if it is chiped and it has a power train issue they can block the warranty for that repair and any other repairs that you may need. chiped, will block any and all issues with drive train diffs, drive line seals injectors head gaskets ect. if it is lifted axles diffs drivelines and seals transfercase trans axle bearings ect. you get the picture. this just came out about 5 months ago they are cracking down if it alters the factory settings or the performance of the truck they can and will warranty block it. some hidden programers say that they are untraceable. that is not true i am a GM diesel master tech and we know how to find them now so beware. even if you flash the computer it has a tatle tale system in the programing now that will tell the tech:mad:
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