Hello all,

I've got a 98 F150 that had a rod knock. Rather than fix it, I got a junkyard engine from a 2000 E150 that ran great (heard and tested it before I pulled it). I swapped the lower intake manifolds between the 2 since the van engine only had a single IMRC motor. I put brand new gaskets on it, dabbed some Right Stuff in the corners, tightened them down in the correct sequence, etc. I started the engine before filling the coolant to be sure it ran after all the work and it ran perfect (ran it for less then a minute without coolant). I started filling the coolant and about 2 gallons in I noticed a drip under the truck. Put the lift up and saw a small leak from between the intake and the heads/block.

I did some research on here and saw that there was an updated lower gasket (I had ordered gaskets for a 98), so I pulled everything apart again and found that mine were the 3mm thick ones. I went to the dealer and picked up some genuine Ford gaskets from a 2000. The parts guy said they were the most recent part number he had before Ford switched to O-rings (part numbers YF2Z-9439-AA and YF2Z-9439-BA). They still measured 3mm thick, but they were the best he had and I need to get this truck out of my shop.

So I get back to the shop and check them against my old Carquest gaskets and they look exactly the same, the only differences I found was the Ford gaskets were blue and the thickness was less consistent. I cleaned up the head and intake again, dabbed some more Right Stuff in the corners, torqued it down in 2 stages in the correct sequence again, etc. Topped off the coolant again and it's still leaking, just on the opposite side this time (passengers).

I have no idea what's wrong. I checked the heads and lower intake for cracks and found none, both are perfectly flat in every direction. Looking at the gasket, the only way for it to leak coolant is to either fill the valley with coolant then seep out, or make its way past 4 layers of gasket and a cylinder.

Is this a common problem? Am I overlooking something stupid? Did I get the wrong gaskets yet again? I don't see how I could even fit 4mm thick gaskets in; getting the bolts lined up is hard enough with the 3mm thick ones.

Thanks for any help you can provide. I mainly work on BMW's but this is a friends work truck and he needs it back asap.

 

Is the coolant passage the same on both engines where it goes into the engine?

Did he overheat his old engine? Maybe the intake is warped?

 

Same passage locations, the lower intakes actually have the same part number I just figured out. The gasket is mainly blocked off on that passage anyways, there is only a 2.5mm wide hole for coolant to pass through.

The old engine wasn't overheated as far as I know. I checked the intake with a straightedge before I put it on the second time though and it was perfectly flat in every direction.

 

I tried loosening and re-torquing the intake, no difference.

I don't understand how it can possibly be leaking outside the engine looking at the gasket.



The back cylinders aren't flooded and when I pulled the intake the first time there was only traces of coolant in the valley.

I'm going to pull it off again and try to use the old intake.

 

maybe there is a coolant pipe broken above it? Or is there a cross over pipe from head to head?

Sorry im not very familiar with the 4.2 coolant setup, just trying to help brainstorm

 

The coolant crosses between the 2 heads through the lower intake.

I finally got it to stop leaking. After inspecting the gaskets carefully, I noticed that the o-ring portion seemed to be slightly folded over around the coolant holes. I figured it might be catching when I torqued the manifold down, so I coated the intake side of the gasket and the intake itself with a thin layer of oil before torquing it down. The bolts lined up much easier like this and it no longer leaks!

I also ended up using the manifold that came with the new engine, although I don't think that was any part of the difference since they were exactly the same.

Thanks for the brainstorming help Patman!

 

Yea I always use Wurth HHS lube, basically aynthetic grease spray on any coolant or AC oring or sealing surface

and you're welcome, glad you got it!!