My son's 97 F150 4.6L threw an error code P0304. Wasn't the first time as it was getting coolant in the plug well. Thought it was the heater hoses but it wasn't. When we found coolant in plug #5 we decided it was coming from the intake manifold. My son ordered a replacement manifold (Dorman plastic) and over the Thanksgiving holiday we replaced it as well as plugs, wires, etc. Truck runs great now but...every 4 or 5 days there's a very small puddle of coolant under the truck. It drips from the front of the transmission and I'm fairly certain the new manifold is leaking. I'd like to understand the problem before taking it apart again. Does anyone have ideas why it would only leak every 4 or 5 days?

Thanks,
Jim

P.S. tylercc, I asked him to send me a picture of the transmission cooler lines. I'll post it to your thread when he does.

 

And yes I cant wait to see pics of trans lines....LOL

 

But you also said misfire and coolant on plug... So possibly two things were issues..

 

There was definitely no evidence of coolant under the manifold when I took it off. It was cruddy and dirty but no coolant so I would have had to damage it to cause a leak. Frankly, I didn't even notice the line there. The leak is small and infrequent now, he said it hasn't gone down noticeably in the reservoir. What would cause it to only leak occasionally and what would that line be called if I tried to buy it?

 

If the leak is towards the front of the engine..... I would suspect a water pump leak. I've done plenty of water pumps on Ford trucks. That's how the leaks start. Sporadic at first.

Put cardboard under it when it's sitting so you can get an idea exactly where it's dripping from. Then look behind the water pump pulley and see if that area lines up.

 

The coolant is dripping from the front of the transmission. It would make sense that it's coming from the valley. Is it possible to for the water pump to leak into the valley? I haven't seen that before.

Thanks,
Jim

 

No....the water pump is below the valley. If the pump was leaking it would be coming out of the bearing weep hole which is just behind the pulley.

 

So here's a photo I took before putting the new manifold on. As you can see there is no coolant in the well. It looks like antifreeze would have to get pretty deep in there before it would leak out the back though.

 

Read this...

https://www.fordf150.net/forums/viewtopic.php?t=94566

 

Thanks Lawrosa and PJMax! I appreciate your efforts to help me understand this.

I can see the pipe your referred to in the photo I posted but it wasn't leaking at the time. I've also read though that there's an o ring where it connects to the block. Maybe I bumped it and it started leaking. Do either of you know if the coolant would leak out the back of the valley without having to run over the top of it? If not coolant should be visible under the manifold.

Thanks again,
Jim