Son of a [bitch tube]!

[Varinn]

I've been having similiar issues to the guy in this thread, crappy cold starts, long cranking to fire on a warm start, and overall poor performance/fuel economy. I've been to a couple different mechanics saying vacuum leaks, but neither of them was willing to smoke test or check for intake leaks before checking everything else first. I've replaced every sensor, and every gasket, hose, ignition and fuel part on the entire engine with new and had only minor improvements so today I met up with Goose and he threw the smoke machine on my car. We immediately found smoke billowing out of the oil return tube on both ends as well as from the brake booster where I always suspected the o-ring to the master cylinder was missing.

Is the intake tube repair as horrid as I have heard? Does anyone have any tips and tricks or should I just take it to a reputable shop and throw a couple hundred at them to be sure the car will run right, with a warranty.


PS: Jlevie is right again. I should have forced a shop to do this test ages ago

[TG Goose]

Smoke was billowing out the top and bottom of the bitch tube.
I love the smoke test, can't believe how well this works as a diagnostic tool, I can't help but keep telling people to listen to the advice about having this test done.

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[jlevie]

Leaks at the oil return (bitch tube) aren't hard to fix, but you will have to remove the intake manifold. Use of a 1/4" drive ratchet, extension, and flex joint makes that easier. But it is mostly done by feel. A helper to hold the tube down against the spring is a plus.

Get new oil return tube o-rings and new intake gaskets.

[Varinn]

The leaks on the intake tube are annoying me, as all of the o-rings were replaced when the engine was dropped in less than 15,000km ago. I might end up just taking it to a shop as I'm reaching a point where I value my time more than the cost of the shop work, or potential do-overs if I were to make a mistake somewhere in the process.

[Todd Black 88]

Do you need that tube? I mean it seriously though. Can it just be plugged at both ends?

Is it just to drain any collected oil in the intake, back to the crankcase?

[bmwguy325is]

I paid a shop and they resealed my tube without pulling the manifold.

[F34R]

Zip tie and slide the compressed spring on the tube. Install then cut and remove the zip tie.

[jeffnhiscars]

Do you need that tube? I mean it seriously though. Can it just be plugged at both ends?

Is it just to drain any collected oil in the intake, back to the crankcase?

Seriously ? The tube is the only way for oil to get back to the pan after lubricating the valve train and the channel that passes through the intake manifold is isolated from the runners.

As for the install..

[kid325e]

Thanks for the pic!

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[Me+SPEED=]

Seriously ? The tube is the only way for oil to get back to the pan after lubricating the valve train and the channel that passes through the intake manifold is isolated from the runners.

As for the install..

Wrong. The engine sits at a angle, there are six oil return passages on the exhaust side. The tube is for crank case gasses.

[Todd Black 88]

Seriously ? The tube is the only way for oil to get back to the pan after lubricating the valve train and the channel that passes through the intake manifold is isolated from the runners.

As for the install..

Wrong. The engine sits at a angle, there are six oil return passages on the exhaust side. The tube is for crank case gasses.

This is what I was wondering.
I know very little about the m20, as my car is a low miler and runs like a top, whereas the s14 has a hose setup similar to this that goes into a separator before going back into the plenum, and tons of guys have disconnected the hose at the plenum.

[jlevie]

Wrong. The engine sits at a angle, there are six oil return passages on the exhaust side. The tube is for crank case gasses.

Actually is does both jobs (as do the oil return passages). At high rpm oil will stack in the head faster than it flows through the return passages, which is when the oil return tube comes into play.

[monsterm20]

Actually is does both jobs (as do the oil return passages). At high rpm oil will stack in the head faster than it flows through the return passages, which is when the oil return tube comes into play.

Theoretically yes but likely no. Every engine has blowbye. No matter what. So there would be an up draft especially at high rpm sufficient enough to prevent most if not all of oil back flow through that passage. It doesn't take much to stop oil from going down thT tube( not to mention the head is tilted away from that tube) Even at idle there could be enough crank case gasses coming up to stop oil. I took my head off last night and there was no oil residue in the tube but oil was clearly present in the oil drain tubes on the other side of the head. So possible sure but very unlikely.

[jlevie]

Well, I have a Paul Poore pan (baffled with mouse traps) on my Spec E30 and the pan has about an extra two quarts of capacity. I'll see a drop in oil press, not dangerously so, under braking at the end of a long straight when the oil in the pan surges forward. A few others have observed the same thing. The most likely explanation is oil stacking in the head from sustained high speed operation. With that much oil in the head at least some of it will be going down the oil return tube.

[Varinn]

The way I see it, is it's there for a reason. It will be repaired in my car, not removed