Mess under the intake? Read this!

[Simon S]

sweet jesus !!

[unevolved]

Although I must say, unless you've ever worked on an RX7, you haven't seen a TRUE "mess under the intake."



Commonly known as "the rat's nest."

[Ryann]

Hey hey.. I did it for three reasons..

I know, man. Everything you've done to your car has been done impeccably.

I first read about 'the mess' on m42 club and actually removed my manifolds with every intention of following suit. Once I laid eyes on mine and saw what minor vacuum leakage issues it actually had I decided to delete the TB heater, replace all the air hoses, and call it good.

People make it sound like TMUTI is some kind of mandatory m42 procedure.. I'm sure on some clapped out neglected cars it's a leaky nightmare under there. I must point out though that I maintain a 270k+ '91 318i with all the original 'mess' and it's just now beginning to develope some vac leaks at the 4-way fittings, still with no coolant leaks.

[Simon S]

Because bandwagon.

Hey hey.. I did it for three reasons:
1. Heater plate is not necessary
2. Thirteen eliminated junction points
3. I like shit simple

All parts I used were OE with exception of some hoses.

Where do fuel lines come into play?

There are two, short sections of fuel line that are cheap and easy to replace “while you’re in there”. If they haven’t been replaced by now, then they are old with countless heat/cold cycles on them per engine proximity. To not replace them is an invitation to engine fire.

With the seafoam if I disconnect the vacuum hose to the brake booster and apply seafoam there will that work?

You’ll want to use the skinny vacuum hose that runs from the throttle body to the fuel pressure regulator.



The brake booster vacuum hose line is only open to one runner – for one cylinder.

And its 1/3 in the intake 1/3 in the oil and 1/3 in the gas right?

I have no clue but would also like to know.

The formula is what you choose. Via intake is theoretically best for compression chambers and valve seats. Via oil is meant as a flush (change it out with fresh oil w/in ~200 miles). Via gas is meant to keep fuel tank, pump, lines, and injectors clean/dry/water-free to my understanding.

Fwiw, I ran two whole cans through the intake using 1/3-can intervals. This was done just prior to pulling the head for inspection. It wasn’t like the chambers and piston-tops were magically clean. They had plenty of soot on them..

[Ryann]

Then why do most people, even people like Simon S, use this method? It's not because they're too lazy/unskilled, I can tell you that much.

Because bandwagon.

[unevolved]

For me, it's because I've got massive meathooks, not dainty little girl hands. I can't reach in there to reattach the coolant lines, so out they came.

[Vivek]

Then why do most people, even people like Simon S, use this method? It's not because they're too lazy/unskilled, I can tell you that much.

[Ryann]

^^ dude your comment is a little rediculous. NO its not next to impossible to replace everything back to stock. I did it and I dont consider myself a expert mechanic. only benefit I see is ease of maintenance and possibly cheaper to not have to replace all hoses. Otherwise theres no difference

I agree with this 100%. While it may be cheaper to driveway engineer a simplification of everything with shit you found at Home Depot, the stock setup is easy to replace and really not that messy once you've revamped it and know what you're looking at.

Also, the notion that stuff under the intake is 'inaccessible' on an m42 seems odd to me. It's probably the easiest intake manifold I've ever removed.

[unevolved]

Just did this last night. Used some parts from a Miata PCV system to make the bypass from the plastic junction to the head, 1/2" heater hose from the valve cover to the throttle body, and 5/8" heater hose from the ICV to the intake.

This should be stickied.

[Chrisv006]

Your the man, saved me a trip :-)

[brent5631]

3 ft of 19/32 vacumn hose
1ft 5/8 heater hose (to make the bypass form the plastic junction to head)
3ft 5/16 fuel injection hose

Thats what I used. You'll need more heater hose if eplacing lines to the heater core.

[Chrisv006]

Can anyone post the coolant / vacuum hose sizes needed? Would be super helpful. Ordering the rest of the parts tonight.

[///M42 sport]

^^ dude your comment is a little rediculous. NO its not next to impossible to replace everything back to stock. I did it and I dont consider myself a expert mechanic. only benefit I see is ease of maintenance and possibly cheaper to not have to replace all hoses. Otherwise theres no difference

[Vivek]

any benefit to this?

If you take it apart to fix the vacuum leaks, you'll soon realize that it's all but impossible to put it back together the way that they did it originally.

[oldmann]

any benefit to this?

It is to eliminate all the extra failure points, and possible leaks in nearly inacessible locations.