1989 Ford F350 w/ replacement 1990 351. Driven less than 1000 miles per year. Past month, adding coolant to overflow after it goes on short trips and then sits. But, I have not seen it leaking anywhere. Today while idling at warm up, puddle of coolant under bellhousing of transmission. Traced back to driver rear top side of motor. Appears to be spraying from under valve cover. Only does it after it is warmed up. Engine oil dipstick normal level and consistency, so it does not appear that there is an oil/coolant mixing. Few similar threads point to leaking hose (cant find one), or freeze plug. Definitely pressurized from the spray force. Cant get good look back there, feels like a rubber/silicone gasket and 190 degree coolant hitting my hand. Even if this is a freeze plug or head gasket, doesn't seem like it should have such force behind it? Hoping I am missing a hose somewhere. Photos below are from a video I took but cannot seem to upload. First is looking from topside near driverside front wheel. Spray is seen below and to right of 90 degree metal to rubber elbow. Bottom photo is looking up from behind driver steer tire. Hose immediately below in photo is some sort of hard line which is a few inches below the leak. Truck has sentimental value as I grew up riding around farm in same model. Thank you.

Topside view from driver's side.
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Blue circle is where coolant is spraying.

 

Well, there shouldn't be any coolant hoses back there, so you can probably rule that out.

The pipe is the Air cross over tube, just delivers AIR to the heads.

My guess would be the cylinder head is cracked... I don't see any other likely cause of a coolant spray in that location, but maybe I will learn something new today.

it shouldn't be too terrible to peel off enough parts to get a better look at it, and decide how you want to proceed.

 

I agree. No coolant hoses back there. There is a freeze plug in the back of the head I suppose a pinhole would spray coolant.

The thing to do would be to pressurize the system when cold. You should be able to see better back there with the upper plenum removed.

 

How is your temperature gauge when this is happening? Are you overheating?

 

This was my first thought too...

 

You can see the freeze plug in the head in the second photo and the leak appears to be well above it, almost at the valve cover.

 

Any chance your radiator or water pump is leaking and the fan is throwing coolant around?

 

Could it also be the intake manifold gasket where it meets the head?