By-Pass return line. Where to put it?

[Neil Womack]

My vehicle will be out of warranty by the end of summer and I'm thinking a by-pass would be perfect.

My supply will come off the oil pressure sending port using a T fitting. The return can go back into the valve cover or the oil pan using a bulkhead fitting or just a T fitting on the drain plug. The drain plug is protected by a steel skid pan.

Any advantages or disadvantages to either return set up?

 

[Bio-T]

Neil,

If this is for you TDI, I would use the Hollow Drain Plug return if you have access to one. A company in Janesville, WI used to make them, but do not at the present is my understanding.

I personally try not to return in the valve cover. Many reasons, one is it has to compete with valve train oil flow, also if it hits any part of the moving parts, oil aeration or mist.
Again just my personal preference is not in the valve train area. A few do, with no problems, but I am a skeptic, if it can mess up, I will own it or do it.

I do have a hollow metric bolt for the engine, but I am not sure if you have any place that goes into the crankcase that it would replace.

The oil pan STHB (Self Tapping Hollow Bolt) would be my other choice if you don't do the drain plug replacement, and the valve cover last choice. Again these are just personal choices.

 

[rugerman1]

Self Tapping Hollow Bolt

 

[cryptokid]

contrary to 59 vetteman, i would think the return of a bypass would be most beneficial in the head area, espically if the return line was t-d off into 4 lines, one for each hot exhaust lobe of a 4 banger dohc. drill the valve cover 4 times, and install 4 90 degree elbows so that the bypass return oil would leak into the cam lobes, and not have any restriction. keep in mind i am not saying to make oil squirters, but mearly oil drippers. the oil would have a cooling effect on the lash adjusters and possibly trickle onto the valves themselves.

i cant imagine this would cause any more areation than what is already going on in some engines, what with oil squiters for pistons and such. my car has 2 oil squirters for each piston.

 

[Bio-T]

quote:

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Originally posted by rugerman1:
Self Tapping Hollow Bolt

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Thanks for the picture Rugerman. Just a note though, this STHB CANNOT be used on aluminum pans, they must be drilled and tapped for 1/8th inch NPT threads. Just to be more specific, you use a 5/16th drill bit and tap with 1/8-27 N.P.T. taper pipe tap.

 

[Bio-T]

Crypto,

Your theory is good in that you want max cooling oil to the lifters. The problem is the bypass flows a quart a minute and putting this extra oil in the cam area with aeration causes flow problems. Also your setup would be a magnet for external oil leaks.

It would take a chapter, but I will try to condense. Oil aeration is a very large problem in auto engines. Engineers design to prevent this. In diesel engines, it can be a disaster, the oil is so aerated, it cannot fire the injectors properly. PSI ranges up to 3000 on HEUI injectors. That is why you see silicon in VOA's, it is an anti-foaming agent. In fact in my diesel engines, both have these injectors plus they use oil scuppers to lube the crank. Yes, both engines have an aeration problem unless a quality oil is used, Schaeffer's, Amsoil, Royal Purple, Delvac I and 1300S, Delo, and many more. In 95 my engine would not run properly on Rotella T. Not enough anti-foaming, had to add Lubrzoil anti-foaming agent. Shell has since cured that problem and Rotella works great, in fact any CI rated oil has the proper additives.

A high revving 4 banger has the same problems. My advice, return the bypass as stated in earlier posts.

 

[Neil Womack]

I figure I won't have enough metal to get very many threads. If I go through the oil pan wall I was thinking of using bulkhead fitting or a through and through drilled and tapped bolt. Where I would use the exturnal bolt threads with a nut and washers to secure fitting to the pan. Then the drilled tapped hole for a hose fitting.

 

[RalphPWood]

I put the clean oil back in the valve cover on my Peugeot 504 diesel. Every thing worked fine until the engine heated up and I started down a long hill. The engine was running very well on Mobil 1. I had to pull off the road and stuff a jacket in the air intake to stop it. I didnt spend too much time wondering what happened all I needed to know is the oil mist was entering the intake.
If I tell people what happened I will get people saying mine worked OK. What if that had happened to a customer.

Ralph

 

[Hajoca]

IMO the cheepest way is to tap into the valve cover cap or oil cap with a rotating hydraulic fitting and let it drip back there.

In my Uncle's BMW I tapped a hole into the oil filter cartridge cap (I like trying the caps because they are cheaper to replace if I Screw Up

) and put on the rotating fitting to it. The bypass filtered oil flows into the oil intake of the oil filter.

Tapping into an aluminumn part is $$$ if it doesn't work.

I took the FRP nylon cap to work so I can borrow a high quality end mill to do the job.

 

[Neil Womack]

Ralph

That is a good point. A run away engine might just ruin my day.

I was originally leaning away from the valve cover return. But my though was the oil would pick up more heat from the head than the designers intended and transfer it to the crankcase.

 

[mangusta1969]

I just installed an Oilguard bypass filter on a BMW 6 cylinder motor. I was going to use a hollow oil drain plug for the return, but became a little reluctant to do this as I examined things in more detail. The car is lowered and there is not a large amount of clearance to avoid road debris hurting the flexible oil return line when it is mounted low for the return line through the hollow drain plug.

As I was puzzling out what to do, I noticed that the BMW oil dipstick tube was a perfect interference fit for the flexible rubber oil return line. So I pulled the dipstick out, fabricated some more positive retention device (with hose clamps) to ensure the return hose could not come out and am using the oil dipstick tube as a return oil path to the aluminum pan.

It is a little bit of a hassle to check the oil level, but I can do it in about 2 minutes and I have absolutely no worries about trashing the engine due to some road debris problems. This would not be too good a solution for a car that burned a lot of oil and required frequent oil level checks.

I can already "feel" my oil getting cleaner, but I am running some before and after oil analyses to verify what is going on with the bypass filter installed.

 

[Neil Womack]

mangusta

That is an interesting idea. I believe my VW dipstick tube is threaded into the block.

The pipe fitter in me is starting mull over the possibilities.

 

[mangusta1969]

Something I forgot to mention about my BMW setup:

A side benefit of my interference fit oil dipstick return is that (with the engine off ) I can just pull the return line out of the dipstick tube and put the line in an oil analysis container. When I start and briefly run the engine, I can both verify the bypass filter oil flow rate and obtain a clean oil analysis sample.

 

[rob-the-oil-nut]

Perhaps a tad

but when mine was installed on my previous car, it was returned to a hole that had been drilled in the valve cover. Made sense at the time, to me and the mechanic.
There was a reference to the oil beccoming a "mist"....Hehehehe, well there's also a hurricane of wind going on between the breather and the PCV and all this stuff went out the tailpipe. $80 worth of oil (2 fills, one TO work and one FROM work. 8-10 quarts) out the tailpipe in 40 km. Smoked like a skeeter truck.
That was 16 months ago and NOW I can laugh about it...a bit anyhow

 

[Neil Womack]

Rob

I've ruled out using the valve cover as VW TDIs already have an oil carry over problem. The CCV oil mist combines with soot from the ERG and clog the intake manifold and intercooler.

Looks like the smart money is on the oil pan.

And if I screw it up a new oil pan is just $89.00 plus shipping and handling.

 

[bron32]

I have a 91 vw diesel jetta. I installed the
frantz filter,and installed the return line to
the oil filter cap. VW has a plastic cover over
cam and lifters to prevent misting.

It worked good except for the oil misting. The
oil cap is at opposite end of the pvc breather.
but it still sucked oil into the intake.

I solved this problem by disconnecting the breather from the intake and installing a hose,
running it down beside the front tire.

Bron32
Bron32

 

[Gary Allan]

quote:

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I solved this problem by disconnecting the breather from the intake and installing a hose,
running it down beside the front tire.

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Without a filter attached to it?

 

[Tim]

quote:

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Originally posted by Gary Allan:

quote:

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I solved this problem by disconnecting the breather from the intake and installing a hose,
running it down beside the front tire.

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Without a filter attached to it?

---

This common modification to VW diesels is called the "Elephant Hose" mod. Because of the positive pressure at the valve cover, most folks don't worry about a filter. I would worry about crud being drawn in during cool-down.

They also tend to freeze up in the winter because of all the water from condensation. I have an oil water separator and get mostly water out of it below 60 degrees F ambient.

BTW - I have my bypass returning to the valve cover just below the oil filler cap and do not seem to have any issue with excessive oil being drawn through the CCV. As someone mentioned, we are talking opposite ends of the cover. My bypass has been in place 27,000 miles.


Tim

 

[Mike_dup1]

fyi

Amsoil has these self-tapping hollow bolts, PN BP-40 ($1.50) and PN BP-41 ($0.70) for the Sealing gasket for same; + your state sales taxes. Its going to cost you $5.45 for S&H of 1-3 lbs.

You could try a hardware store that has a big supply of fasteners, might get lucky and find something similar.
Parts List

 

[alloy]

Neil,

You didn't say what type of vheicle you have, but I'm in the process of planning a bypass install on my 87 camaro IROC-Z. The car sits low from the factory and I considered using the self tapping bolt in my oil pan or drilling and tapping my drian plug for a return line. But I'm just not comfortable with the possibility of leaks from the self tapping bolt, or an oil line in harms way with such a low car. I also think that putting an extra quart of oil in the upper valve train isn't a good idea, nor is returning it to the lifter valley area and having it drip onto the spinning crank and rods making the oil rings work harder to control oil splash.

After much thought I realized my car has an electric fuel pump in the fuel tank, and the engine (305 Tuned Port Injection V8) still has the mechinical fuel pump provision on the block. It's just capped off by a block off plate. My plan is to pull that plate off and drill and tap it for a return line. This will return the oil directly to the crankcase below the spinning crank/rods, and if it leaks it's no big deal to pull it off and repair or replace the block off plate.