Coolant leak I can’t locate

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Joey c

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hey guys read everything I could find last couple days and been digging around trying to find this leak. It’s an 03 v8. I replaced all plastic coolant parts and radiator back in may of last year. Sitting in a drive thru few days back and sounded like a water faucet turned on under my car. Coolant is dumping out from where the engine and tranny connect. I’ve look d and looked and all plastics seem okay up front I can find no sign of a leak in the thermostat housing or neck that connects to block. They still look great being less than a year old. I do hear a loud hissing coming from under the throttle body when I shut it off and it persist for about 3-5 seconds after shutdown and I see steam rising from under the throttle body but can find no leak. I removed all plastics and throttle body’s to have a look but can see nothing evident. Put it all back together and same issue. Even once I shut it down I get a steady flow falling on the ground from back of engine for about 10 seconds and then it stops. I’ve read about the hardline under the intake splitting and I’m just wondering if that should be my next thing to check or has this been discussed somewhere I haven’t read yet. Thank for the feedback everyone.
 
Joey c said:
hey guys read everything I could find last couple days and been digging around trying to find this leak. It’s an 03 v8. I replaced all plastic coolant parts and radiator back in may of last year. Sitting in a drive thru few days back and sounded like a water faucet turned on under my car. Coolant is dumping out from where the engine and tranny connect. I’ve look d and looked and all plastics seem okay up front I can find no sign of a leak in the thermostat housing or neck that connects to block. They still look great being less than a year old. I do hear a loud hissing coming from under the throttle body when I shut it off and it persist for about 3-5 seconds after shutdown and I see steam rising from under the throttle body but can find no leak. I removed all plastics and throttle body’s to have a look but can see nothing evident. Put it all back together and same issue. Even once I shut it down I get a steady flow falling on the ground from back of engine for about 10 seconds and then it stops. I’ve read about the hardline under the intake splitting and I’m just wondering if that should be my next thing to check or has this been discussed somewhere I haven’t read yet. Thank for the feedback everyone.
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Did you replace your Aux Water Pump and the DCCV? Also did you go aftermarket on your thermostat housing?
 
Thermostat and all housing components were replaced with motorcraft parts. All oem. Was not aware of the auxiliary water pump? Could you tell me more about it. I have not replaced the dccv valve but I’m fairly certain it’s not the suspect. I had replaced one in my first gen years ago but this leak doesn’t seem to originate from that far forward or that low. A lot of steam rising from behind the intake and under throttle body.
 
Actually I do know of the water pump I had replaced that also on my first gen years ago. I misread and thought there was a second water pump you were referring to.
 
Joey c said:
Actually I do know of the water pump I had replaced that also on my first gen years ago. I misread and thought there was a second water pump you were referring to.
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On the Gen 1 for sure there is a Water pump and then the Aux Water Pump. I am not sure if the Gen 2 has one though I am having trouble finding a part number for it.
 
I was not aware of this part where is it located on the engine. Is it under the dccv?
 
There’s a lot of gurgling/hissing going on from just under the throttle body but like I said I can see no leak at all up there but it just pours out from the back so something is letting it gush out at a fast rate. Lots of steam rising from aroun intake manifold front and back.
 
Joey c said:
I was not aware of this part where is it located on the engine. Is it under the dccv?
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1.gif

It's number 21 on the diagram
 
Yes I do know that part from replacing a dccv on my first gen. I do also see what looks like the same part on my second gen but pretty positive that’s not the suspect. It’s bone dry and way to low and forward in the engine to be the leak. Unless it could be faulty and causing the leak elsewhere is possible? I’m curious what’s under the intake manifold as far as coolant lines go? I know the Im doesnt have coolant running thru it but what about under or behind it?
 
It's not a hard line under the intake (there is none on the 3.9), it's the throttle body heater hose. Take the intake manifold off and replace the throttle body heater hose that runs from the top of the engine (at the base of the 45 degree pipe) to the throttle body. There's no mystery here. It's certainly not the aux pump or the DCCV. I don't know why those are being discussed for this.
 
Thank you for the info joe and dale y’all never cease to amaze with the knowledge of these cars. Was hoping to not have to remove im but I will start on it this afternoon weather permitting. I’ll update how it goes and again thanks for sharing.
 
joegr said:
It's not a hard line under the intake (there is none on the 3.9), it's the throttle body heater hose. Take the intake manifold off and replace the throttle body heater hose that runs from the top of the engine (at the base of the 45 degree pipe) to the throttle body. There's no mystery here. It's certainly not the aux pump or the DCCV. I don't know why those are being discussed for this.
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It that hose just Gen 2 specific or does Gen 1 also have this hose under the intake?
 
Gen 1 has a different hose under there with the same function.
 
DaleGrib said:
On the Gen 1 for sure there is a Water pump and then the Aux Water Pump. I am not sure if the Gen 2 has one though I am having trouble finding a part number for it.
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V8s have the aux pump. V6s do not. It's not about gen. It increases coolant flow to the heater core at idle
 
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