Hi, I'm chasing a problem and wondering if anyone else has seen this. Coolant is accumulating in the #5 plug well (front plug, driver's side). At first, I thought it was the thermostat housing leaking, so I changed the seal and tightened it to spec (a few months ago).

But last night, it started missing, and I got a P0305 code along with a flashing "check engine" light which eventually quit flashing and stayed on.

Checking the plug this morning, I found the plug well full of coolant which I assume was shorting out the COP and causing the misfire.

Has anyone ever seen this before? I don't know my way around this motor very well, so I'm not sure what all it could be. I need to check the thermostat housing again, altho I didn't see any signs of leaking from it. What else might it be? Could it be an intake gasket? Is that possible? Or, barring the thermostat housing, does this imply a head gasket? Thanks.

Doug

.

 

If you are sure the thermostat housing is not leaking look at the top rad hose going into it. If you still have the factory pressure clamps it may be leaking as it cools down and seals up when it is warm. Slide the clamp back and put a worm clamp on there if you think it is coming from there. The intake gaskets are a known issue on these trucks as well so it may be that. The plastic intakes themselves are also a known issue. I believe the older ones crack causing leakes.

 

Had to replace the plastic intake on my sons 2000 f150 5.4 v8. Found antifreeze in the valley as well as on the both side of cyl heads leaking down the back side of the engine. ( all 4 corners of his motor) Over tighting intake bolts on an old intake cracks the plastic where the o-ring seals are on the 4 corners! FIX was a new intake made by Dorman (better than the Ford intake),got in off of ebay for a good price shipped to the house. Also found what looked like oily stuff in the rad tank too. Fixed as well w/ the new intake.

 

Listen to RevBiker

 

Guys,
Thanks for your replies. Right now, I'm planning to install new intake gaskets. I was advised to get them from the dealer to ensure getting the best parts.

Regarding the thermostat housing, I don't see any sign that the hose is leaking there. I did tighten the two screws in the housing slightly. So far, the miss hasn't returned, but I doubt that fixed it - I'd expect it to eventually come back if I don't put in new gaskets. BTW, the hose does have a screw type hose clamp on it.

As for the plastic intake, I hope it's not cracked. I don't have any other indication that it is. I surely haven't been wrenching on it.

I received a reply on another forum which warned of pitting on the lower intake, and that a metal filler may be needed. So I intend to be prepared fix that as well.

Thanks again for your replies. I'll post a followup after I replace the gaskets, but that may be a couple months. I do my work in the driveway, and the weather here (in the DFW area) has not been cooperative this year. So I'm backed up on projects with 3 old beater Chevys in the queue ahead of my old beater F-150

Doug


.

 

Plano-Doug, You will find that all the plastic around the water ports will be cracked and falling apart from heat. Buy a dorman intake, comes with gaskets built in , works better than OEM type in my opinion! Don't buy the gaskets until you pull off the intake because I'm sure you will need a new intake.

 

If its a metal upper intake then all you will need is to replace gaskets as you said. I was thinking it had a plastic upper intake Sorry!

 

I'm late to post a follow up, but I repaired the leaking intake gaskets last February (2016). And the truck has been doing great since then. It doesn't leak a drop of anything.

This week it rolled over to 200k miles, and I post this pic to celebrate




BTW, here's some of the info I garnered doing the repair. For my 1997 Ford F-150 Supercab with 5.4 motor, the following parts were used:

Upper intake gasket part number (2 required): XW7Z-9439-AA
Lower intake gasket part number (1 required): F65Z-9461-AB
Permatex Liquid Metal Filler, p/n: 25909

The filler was used to repair some pitting on the mating faces of the intake and heads. I sanded it smooth using 320 grit paper and a piece of hardwood I milled flat on my belt sander. Having a perfectly flat block helps ensure even sanding with no rounding.

I got the filler at Autozone, I think. The gaskets were from the dealer.

Hope this helps someone else some time.

Doug

.