WTB: L18 crankcase breather tube

[Silky_Johnson]

I'm pretty sure I have a JDM L18 in my goon. It's set up with dual mikuni phh40's. The car has smelled like gas since I've owned it, and I'm finally fet up with it.

 

I have narrowed down "gassy" smells to the cam cover breather tube which has a filthy air filter on it and gassy fumes that come pouring out. After doing some research, it seems like the culprit is the PCV system? I was looking for the crankcase breather tube, but alas, there was none to be found -- just a hole in the block.

 

So I need a breather tube for the crankcase. It's not the L16 type that sticks straight out -- it looks like it would be the L20B setup. I'm not entirely sure where the hose will go after that? Does the crank run to a PCV valve on the intake manifold? Are Mikuni manifolds set up that way?

 

First step is the tube/pipe. Anybody have one laying around in the Portland area?

 

 

[ryknot]

Yes, the crankcase breather would go to your pcv valve (if you gots one). I did away with mine and mounted a small K&N filter on the end of the tube coming from the block. I dont know if your manifold has provisions for a pvc valve, it would just be a threaded female port anywhere on your manifold providing vaccuum - pics might help -

[Silky_Johnson]

I think I found out where the PCV valve would go (if I had one). I'm not set up for pics yet, but I found pictures on another thread posted by DOnatello. http://community.ratsun.net/topic/38898-what-carbs/page__st__20 He's got the same manifold, and it looks like he's got a hose running from the crankcase to the #4 cylinder. My manifold has a bolt in that spot right now, so I would have to get a valve in there. That's the easy part.

 

I still need the breather tube. Anybody in the Portland area? On DOnatello's engine, the hole for the breather is straight out. The hole on my L18 is straight up. It's like it's sitting on top of that little shelf. I'll see if I can take some pictures, bu I doubt it's going to do any good, because I could barely get a finger in there with the exhaust manifold bolted up, much less take any meaningful pictures. The car is my daily driver, so I need to leave it built between projects.

[datzenmike]

If the hole for the PCV valve it will be centrally located so the fumes are (more or less0 evenly distributed to the cylinders. You will have to make up something to get the fumes there from the block. The valve cover breather hose should also be connected to the air filter housing so the fumes get sucked down the carbs.

 

ryknot the crankcase breather should always be connected to a PCV valve. Using manifold vacuum, it will draw warm moist gas and water vapors and blow-by combustion gasses back into the motor and burn them. If left, these gasses will condense like sweat on the inside if the block when the motor cools down and contaminate the oil. The PCV keeps your engine cleaner and extends oil changes. It also prevents the bad gas smells.

[banzai510(hainz)]

Bruno.

I have a 40mm set up also and just open vent mycrank case. Since mine is a l16 block I have just the tube sticking straight out.

If the very late L16/18/20 its just a up then 90 deg bend and then I cut it off and open vent that also if running Mikuni/wber DCOES.

 

Now Mikuni ,the short mikuni manifolds had a small hole on each runner to hook up then go to a PCV valve. I have a Toyota 20R set up and that the way to run it(its just hoses in pararrell to a PVC valve then you route to Crank case. FUNKY!!!!!!!!!But I have never seen it on here on any Datsun I have seen.

 

Now if you got alot of gas smell I would ck your oil and see if there is gas in it also. It could be a BAD mechanical fuel pump the diapphram has a hols and soem gas is getting by.

 

also maybe the gas smell is comming from the back.

 

If motor is stinky from the crank case vent. esp at idle. then its just nastly blow by and youll need to rebuild the motor.

 

I have 510 that run open vent and they are naturally more stinky but not that bad considereing a 40 year old rig with a open crank case.

But if running stock Yes I would run the crank case and PVC valve like in stock set up.

Howeever alot of sidedraft manifolds are basic and not set up to run that way .

 

 

ck the jets to make sure they didnt back out and flooding it out.

 

the vent on the valve cover? I just route a hose down under neath to keep the oil spray hitting the fire wall.

 

I hear wagoons have a different gas vent system so maybe that can be looked in to . Im not a wagoon expert.

Datto510(Eric) on here had one and PM him he might know.

[Silky_Johnson]

Thanks Mike and Hainz. I had a feeling you guys would eventually chime in.

 

I have narrowed down the smell to primarily the valve cover vent. There doesn't seem to be any gas in the oil, and I've never had problems with the wagon gas tank venting into the car. I'm getting quite a bit of blow by (a lot), so it would seem I'm looking at a rebuild? Are we talking top end rebuild? Bottom end? I've also got a considerable amount of valve train noise. Lash is set to spec, and I have an L20B (U20 is stamped on it)) cam, so I'm pretty sure I can rule out adjustment issues or a wild cam. I was planning on eventually rebuilding the head anyway. I figure while I'm at it I should swap in an L20B block for a little extra torque? I'd rather not rev to 3000 or 4000 RPMs to drive uphill. The screamer's fun, but not as practical.

 

Since this is in the parts wanted section, is anybody looking to unload a good, tight L20B? I'll do the timing chain and gaskets and such, but I'd rather not mess around with crank and pistons unless absolutely necessary.

 

By the way. How do I change my name on here? Bruno sucks.

[datzenmike]

I think I can change the user name what one do you want?

[Silky_Johnson]

Could you make me "Silky_Johnson"? That's also my dirt biking name...

 

As "payment" for changing my name, I'll post some oics soon so you know who to look for at Canby.

[banzai510(hainz)]

I adjust my lash to .006 in .008 cold. to try to get the valves less noisey

try that.

 

while at idle stick your head down by the exhaust and that crank case vent should be blowing air out. It will be the most sticnk at idle as more positve pressure is right at idle. when you increeas the spped the crank will then start to suck in.

I cant remember for the valve cover what it does. But assume its pressured the same thru the front cover housing

 

 

what I do is at night shine a flashlite across the engine bay from the drivers fender across the other side going above the motor into the night. at idle if there is blow by youlls see the smoke reflect back.

 

Kinda like a cig at night with a light on it.

[Silky_Johnson]

Thanks for the input Hainz. So if I'm hearing you correctly, adjust the lash cold to .006 and .008, and by doing so I'm not going to be ruining my engine? I'll give it a try. Likewise I'll do some more investigative work with the vents/blow by. And FYI, thanks to this forum, I am now running Wix filters and Valvoline VR-1 20-50.

 

Thanks for the name change, Mike. I've got a few oics posted on the GOONS check in now.

 

Speaking of oics, here's a picture of my manifold:

 

 

My guess is that the allen bolts in between each runner is what I could potentially hook up the breather to? If I can get a breather tube, I suppose I could hook up a "Y" and spilt the hose to both locations.

 

Speaking of breather tube, here's what I'm working with on the engine side:

 

 

Anybody? Breather tube? I'll pay good money to get this working right, and I'll even pay for shipping.

[banzai510(hainz)]

Somebody has a breather tube close they just being lazy to get you one right now.

 

I would just get the tube and cut it a few inches out.

 

 

I guess you could Y splices it like you say but if its real stinky Im thinking a motor rebuild Or make a aircleaner assemble thayt sucks up the stink.

 

Sidedrafts are naturally stinky anyways.But if its bothing you then work on it. Im not sure if the Y splice to a PCV valve will work

 

Imyself do my lash at about .006 and .008 .007 or .009 what ever feeler gauges I can find at the time.

 

Per spec is OK but just try it closer. My Schneider specs say .006 .008 anyways so dont be scared of doind it. It might not even fix your proplem anyway.

[Silky_Johnson]

Bump. I still need an L20B style crankcase breather tube. Willing to pay $$.

[tdaaj]

got one, $15 shipped.

[Silky_Johnson]

got one, $15 shipped.

 

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