Trying to Make a Used PI Intake Manifold Worthwhile

[IPreferDIY]

The aluminum crossover sealing surfaces ended up being way worse than I had figured. I thought sandpaper with WD-40 would be enough, but there's significant pitting. And where the o-ring under the thermostat housing is long and straight, there is a really bad spot where the aluminum has a nasty crevice. The corresponding part of the o-ring had been either indented from the corrosion or eaten away. It's surprising that there hadn't been any signs of leakage.

I'm no expert, but for those who end up putting on a new intake manifold, you should give some thought to putting a protective coating on the aluminum crossover sealing surfaces before installing it. Some kind of suitable sheet gasket that could be cut to size would seem to be ideal for a new one.

For my pitted one, I'd have to find a way to get the pits down to metal for the RTV to stick to. Soda blasting is apparently suitable for cleaning aluminum surfaces, but it might not be enough for the corrosion. I would guess that glass beads with reduced pressure would be fine in the circumstances. Either that or I could take my chances with sodium hydroxide, which will apparently clean things up nice but will eat away the aluminum in short order. Maybe if I'm lucky, the crossover that's currently on my car will still be in good shape.

[IPreferDIY]

Got some tubing and baking soda to try out a popular el-cheapo soda blasting setup:



I only have a pissy little two gallon compressor, so I don't have high expectations, at least for the aluminum. If I can get the grooves in the plastic to clean up, then I'd call it a win. Still not sure if I'm going to partially fill the grooves with JB Weld, but even RTV around the o-rings or on its own would need clean surfaces.

[IPreferDIY]

Almost got lucky at a U-pull yard. I took the intake manifold off a 2006 LTC that had some alternator bolts on the fuel rail and vice versa. It was obvious someone had worked on it, but it turned out that the plastic under the thermostat housing was broken and someone had merely applied RTV. I ended up getting the crossover anyway to save me from having to drill and tap the one I've got.

Interestingly, the bulging around the air intake ports was not nearly as bad as on mine. I guess there's some kind of degradation that goes on. I didn't have a known good straight edge on me, but with what I found I was able to determine that the bowing was about the same.

Someone had already taken an intake manifold off a 4.6L Exploder, and the plastic was broken, but I took the crossover from that one too for the helluvit. This one had bulging around the air intake ports that wasn't qauite as bad as mine.

I also found a recently replaced aftermarket NPI intake manifold on a 98 LTC, and I got the crossover from that one too. There was only one bolt per side holding the crossover on, and the bolt holes don't line up with the Ford ones, so I'll probably return that one even though it was in much better shape than the others. I still have to take a close look at them all before the return period expires.

[IPreferDIY]

Ended up keeping only the Explorer crossover since it seemed to be in the best shape and had two metal heater hose nipples (one big, one small) in the crossover. Got a credit for the other two and ended up scoring another intake manifold for a little over $30 with taxes. It must have been replaced relatively recently, since it was on a 2004 LTC but had an intact insulator and things looked better than the one I got from the 2011 CVPI. There was some crud building up on the inner side of the o-ring, but the plastic seems to be in nice shape. Ended up forgetting about the credit and put the whole amount on a credit card.