I have a misfiring #4 cylinder on my '98 F150 5.4L (140k miles). I'm in the middle of a major tune-up when I notice some moisture back towards #4 cylinder at the heater hose J-tube coming out of the engine. I blew the standing water off with compressed air to get a better look, and in the process destroyed the dirt cork holding this little leak in. See pic below. Now I know why cylinder 4 is misfiring.

So the question is what's the best course of action? I'm planning on trading this truck in for a 2012 Raptor early next year, so I was hoping to squeeze another 6-8 months out of it.

I'm tempted to just epoxy the leak and cover it with a section of hose and a clamp. But I'm not sure I'll be able to get down into the fillet on the tube to apply enough pressure. The last thing I want to do is pass the buck to the next guy who buys this truck. On the other hand I'd hate to pull the manifold to replace this tube, especially for such a small leak. I also don't have time to wait for a replacement part since I need to be back on the road next week.

Is that tube replaceable without pulling the manifold? My Haynes guide mentions unbolting the heater hose tube as part of the process of replacing the manifold. This step is BEFORE the manifold gets removed, and I see a bolt right there, so I'm hopeful.

Will the epoxy fix by itself do the trick, or should I replace the tube, or do I need to replace the whole manifold? Any advice would be most welcome. Thanks!

 

The light of day (literally) has shown me that the tube is integral with the manifold. One I cleaned it up that became quite obvious. So it's J-B Stik time. Hope this stuff is as good as they claim.

 

That's a pinhole leak. I think if you dry it well and if it stays dry during the repair, that JB WILL plug the leak. I'd use the two part stuff though, first. Get the kind with the highest strength and try to force it into the hole. Then, after it has cured, apply the "stik" kind over it.

It might be a good idea to remove the heater hose and try to siphon the coolant out of the pipe before you repair the hole.

I think JB Weld is a miracle product.

- Jack

 

626-229 Dorman part number. I think?