Trying to Make a Used PI Intake Manifold Worthwhile

[IPreferDIY]

I’m hoping to do a PI intake manifold swap on my 2000 MGM at some point, but a new manifold is currently beyond what I can justify spending money on. The problem with used ones (unless I get lucky and find an all-aluminum one) is that the plastic breaks down where it mates with the crossover and at the heater hose nipple. I’ve attached a few photos obtained from the internet showing the crossover problem.



(FWIW, the recently inaccessible Photobucket photos can still be accessed through Google image search results despite not showing up in the resulting links.)

I’ve seen people repair broken nipples by threading the hole and installing a threaded nipple with JB Weld. I might be inclined to do that as a preventive measure (or maybe come up with some kind of insert to be secured inside the nipple with RTV), but I won’t give that much thought until I actually have a decent manifold in hand.

For the crossover mating areas, I’m contemplating the following to try to prevent future failures:

1. fill in the gasket grooves at least half way with JB Weld, and
2. apply RTV in and around the remainder of the grooves when putting the crossover back on.

What I would be hoping to achieve is lots of adhesion within the grooves to prevent the thin parts from wanting to give way. The only other thing I can think of is putting RTV in and around the grooves before inserting the gaskets. Either way, the coolant would be looking to find a way between the RTV and either the plastic or the aluminum that it’s stuck to. Does something like this have the potential to be a long-term remedy?

[gadget73]

They also split along the front edge of that crossover where the casting mark is.

Honestly I'd keep my eyes open for one thats not this design and bag trying to repair it. There is a reason they abandoned that style.

[Mr Bean]

The one from Ford Racing isn't that expensive. Rather than mess around with junk save up some money and get a new one.

https://www.summitracing.com/int/parts/fms-m-9424-p46/overview/

Otherwise find a used, good one from a newer car at a junkyard. Plenty of late model Panthers around. Also, I've never seen one deformed as bad as your images. I am sure as long as you don't get one from a cab with 600k on the clock it will be fine.

[IPreferDIY]

They also split along the front edge of that crossover where the casting mark is.

Honestly I'd keep my eyes open for one thats not this design and bag trying to repair it. There is a reason they abandoned that style.

Are you saying the aluminum crossover splits? I've never heard of that before.

The one from Ford Racing isn't that expensive. ...

If I was an American in the U.S., I wouldn't hesitate about getting a new one, but getting one up here at the current exchange rate is way too much for what it is. Good thing I'm not in a rush.

... Otherwise find a used, good one from a newer car at a junkyard. ...

That's the plan, but what I'm hoping to do is make it better so I never have to worry about it again. An all-aluminum one would be great, but I imagine there's virtually no chance of finding an affordable one in my area, especially one not designed for extensive mods.

[sly]

Maybe if you can find a used Professional Products all aluminum intake... http://www.jegs.com/i/Professional-P...54061/10002/-1

But other than that, finding a clean PI intake in a yard and just getting new gaskets for it would probably work better for ya if you're really strapped for cash. They're not that hard to remove, but you need your torque settings when installing them so you don't break them.

[gadget73]

no, the plastic coolant crossover piece splits.

[knucklehead0202]

Maybe if you can find a used Professional Products all aluminum intake... http://www.jegs.com/i/Professional-P...54061/10002/-1

But other than that, finding a clean PI intake in a yard and just getting new gaskets for it would probably work better for ya if you're really strapped for cash. They're not that hard to remove, but you need your torque settings when installing them so you don't break them.

That would be my route. Outside of California nobody will give you shit about a good intake manifold so go for it. They can be found for much better prices too. Almost went ahead and did it anyway on my '98 but wound up getting the shitty dorman one put on at a shop when mine shit the bed. Don't fuck around with used plastic intakes, for the love of god.

[IPreferDIY]

I would've thought it would have been obvious from my first post that I was talking about improving on the aluminum crossover design, which is clearly still a piss-poor design (not to mention the stupid plastic heater hose nipple). The only potential keeper that I bothered to pull the alumimun crossover off of at a U-pull yard had deteriorated plastic under the crossover, so I imagine it will happen to all of them eventually.

One idea that came to mind was bonding the aluminum crossover to the plastic parts with JB Weld (which would also be used to fill the grooves in place of the gaskets), but I would guess there'd be an issue with different expansion rates and eventual failure of the bond.

[IPreferDIY]

Does anyone have any experience with Exploder 4.6L 2V PI intakes? According to the following video (in the section starting at 2:38, and specifically at 3:26), the Exploder 4.6L 2V PI intake is usable with modifications:



The mods start at 20:25. Basically, there is no heater hose nipple on the back end of the Exploder intake since there is one on the aluminum crossover, which can be taken out. What he did was tap the back end, remove some material, and epoxy the nipple there. I would think that could last longer than the original plastic nipple on a new intake.

An alternative that I'm pondering for such an intake is using my current aluminum crossover, putting the nipple on the passenger side of the crossover where my temp sensor currently is, and moving the temp sensor to the thermostat side (where my crossover currently has a plug).

Any thoughts?

[sly]

Extend the wires for the ECT and that nipple in the crossover should work fine. Of course, you can also put the nipple where the plug currently is with a longer hose and have no issue. 15-17 ft-lbs on the crossover torques. Much more than that will crack the damn thing. One thing you may consider is the head cooling mod if you do this. Then you don't have to jack with tapping anything.

http://www.modularmotorsportsracing.com/cart/index.php?main_page=product_info&cPath=3&products_id=439&zenid=76947e32mhqj1s3jtj3cujvi35

Basically a core plug (freeze plug) is removed from the back of the heads and these taps put in. Then run hose from one to the other and plumb the heater core into the upward exit.

[Mr Bean]

Explorer intake is same as Panther intake.

[IPreferDIY]

... One thing you may consider is the head cooling mod if you do this. Then you don't have to jack with tapping anything.

http://www.modularmotorsportsracing.com/cart/index.php?main_page=product_info&cPath=3&products_id=439&zenid=76947e32mhqj1s3jtj3cujvi35

Basically a core plug (freeze plug) is removed from the back of the heads and these taps put in. Then run hose from one to the other and plumb the heater core into the upward exit.

I had stumbled across that mod recently but didn't give it any attention. Since the cooling mod is based on a lack of flow at the back of the driver's side head, it looks like it would definitely be better to feed the heater core from the back of the heads than from the crossover. Here are a couple of other points from what I just read about the cooling mod:

1. Without serious mods, it wouldn't really be necessary, but it couldn't hurt either. (Since I have no plans for major mods, I'll just stick with what's cheap and easy.)
2. Since you want the hottest coolant out, it would apparently be better to drill and tap the intake manifold on the driver's side to put another nipple there.

I might try the second approach. I guess I'll wait until I have a decent intake manifold in hand before putting more thought into that one.

[IPreferDIY]

I managed to score a PI intake manifold in decent shape from a 2011 CVPI with only ~66,000km (~41,000 miles). Things didn't look all that great between the plastic and the aluminum crossover, but the plastic is still intact and the aluminum can be cleaned up, so overall it'll make a suitable candidate to see if partially filling in the o-ring grooves with JB Weld and using RTV provides better longevity than using o-rings. It seems clear to me that even on new ones, that area is a failure waiting to happen. While I'm at it, I'll try putting a heater hose nipple at the back on the driver's side. The plastic seems thin there, but it seems do-able with JB Weld in the threads and on both sides.

[IPreferDIY]

Disassembled and preliminarily cleaned my PI intake manifold. The 'o-rings' between the aluminum and plastic are actually 1/4" high (just like the seal between the top of the intake manifold and the plenum), but I'll continue to call them "o-rings". There was a lot of particulate matter in the o-ring grooves, and the aluminum on both sides of the o-rings is showing significant corrosion. I have to wonder if the o-rings are maybe water-tight but not gas-tight, such that just enough gas gets out to mess up the aluminum.

I definitely don't want to rely on the o-rings. Someone on CVN used RTV as a supplement to the o-rings, but I'm inclined to partially fill in the grooves with JB Weld and then use RTV as a gasket-maker. Details and pics to follow (eventually).

[IPreferDIY]

Here are some pics of the aluminum crossover and plastic interfaces before I do any work on them:



There must be some kind of funky chemistry going on.

The o-ring grooves are about 0.225" deep, leaving about 0.135" on the bottoms.

The thickness at the driver's side rear where it would be ideal to put a heater hose nipple is somewhere around 0.125". It would seem that putting a nipple in material that thin would just be asking for trouble, but I might just be nutty enough to try it.

For those who've had their hands on a new Ford PI intake manifold, was the gasket surface for the ports perfectly flat? I can feel my air ports bulging out around the edges. I can also see indentations where the plastic part of the gaskets were sitting. For each row of ports, the ends also bow up a bit. Since the torque sequence starts in the middle and goes outwards, I'm guessing there would be enough flex in the plastic for it to end up straight enough. The bowing would definitely be a problem for an all-metal unit.

The ID for the plastic heater hose nipple is about 0.600". I'm going to look into the possibility of inserting a sleeve for reinforcement. I have my doubts about making that work, but if it would, it would also be a way to reduce the coolant flow to the heater core for those who've had issues with too much pressure there.

Any insights and suggestions would be appreciated.