Tapping oil pump cover for turbo oil return

**Judo** · 17th July 2013, 10:55 AM

Agree it's a good solution Brian (although having it above oil level might be tricky on a wingless sump?), but my aim is for a solution that I can implement without a welder. Also, I have just finished putting my new sump on. No way I want to take it off again if I can help it!

Here is some further info on the side covers.

Behind the silver breather cover.

The cover itself, which shows the best spot is at either end, or you will no doubt be spraying oil into the breather outlet. I don't own a caliper to measure the thickness exactly, but the cover seems to be just thick enough to safely tap considering there won't be any great force applied to it. It is aluminium (or potentially an alloy, but it's not magnetic at least).

With most stuff I'm doing, it's the first time! I'm assuming these are push rods for the tappets in the top cover? Would oil drain down here during operation?

This is what is seen down the centre hole. Oil pump gears, but also plenty of space for drainage.

To the left of the breather cover is also this cover/plate. Holding it in my hand it feels much heaver than the other one and is made from steel. I would say similar thickness, but if the hose routing suits, this will be my choice for tapping.

Behind it is identical except down the centre hole there is no oil pump gear. Looks like a shaft goes past there, but again, plenty of space for oil to drain.

Unless anyone sees issues with the above, I would say these provide a lot of simple options for drain location and sizes.

**steveG** · 17th July 2013, 11:28 AM

Forward cover is just thin steel (1.6mm or less) and too thin to tap (but would be fine with a tube brazed/welded in.
Rear alloy cover is definitely thicker and should be OK to tap but I wouldn't be keen for a large diameter fitting.
Avoiding welding, my advice would be to stick with the tried and true method of tapping the oil pump cover and make sure you keep the internal diameter of any fittings as large as possible. Use a slight reducer between the fitting and the drain tube from your turbo if you have to.

Steve

**Judo** · 17th July 2013, 11:53 AM

You don't think going from 5/8" on the turbo to 1/4" ID at the other end is too much? Seems like a big reduction...

**steveG** · 17th July 2013, 12:29 PM

I'm sure that I got bigger than 1/4" into mine. Think I drilled the internal diameter hole all the way through, and then put the tapping drill for the thread in just deep enough to be able to tap a secure thread.

Here's another idea that I haven't looked into in detail. What about fitting a bolt on flange like this - either to the oil pump cover, or possibly onto one of the tappet covers.

Steve

Adrian18 · 17th July 2013, 01:40 PM

As said before mines in the alloy cover I put it as far as possible away from the breather hole and low down never had a prob with oil ...I drilled and tapped 5/8 or so hole ... cheers

**Judo** · 17th July 2013, 02:02 PM

Originally Posted by steveG

I'm sure that I got bigger than 1/4" into mine. Think I drilled the internal diameter hole all the way through, and then put the tapping drill for the thread in just deep enough to be able to tap a secure thread.

Here's another idea that I haven't looked into in detail. What about fitting a bolt on flange like this - either to the oil pump cover, or possibly onto one of the tappet covers.

Steve

Brilliant idea Steve. Cheaper too, as I don't need to purchase the rather expensive drill bit and tap for 1/2" NPT.

HOWEVER, neither of those cover plates have a flat surface that size. The black steel cover has a curved face. Sealed with RTV silicone might be enough to deal with the curve, but could result in a leak...

**steveG** · 17th July 2013, 03:07 PM

Ebay is your friend for taps - either NPT or BSP in 1/2" can be had for around $15.

Although I said I wasn't keen on tapping a large hole in the alloy tappet cover, since Adrian18's is working fine just run with that.

Just careful you don't end up in the situation that I did with looking at each problem in isolation, then having to re-do things to solve the next issue. Think about where you're going to run all your provent, exhaust, and intercooler

plumbing before committing to anything.
You might find that getting a tube welded into the sump becomes an attractive option....

Steve

**Bush65** · 17th July 2013, 04:36 PM

Another option is to replace one of the covers with a flat steel plate of 5 to 10 mm thickness.

**Ancient Mariner** · 17th July 2013, 05:39 PM

Originally Posted by steveG

Forward cover is just thin steel (1.6mm or less) and too thin to tap (but would be fine with a tube brazed/welded in.
Rear alloy cover is definitely thicker and should be OK to tap but I wouldn't be keen for a large diameter fitting.
Avoiding welding, my advice would be to stick with the tried and true method of tapping the oil pump cover and make sure you keep the internal diameter of any fittings as large as possible. Use a slight reducer between the fitting and the drain tube from your turbo if you have to.

Steve

Just measured the steel cover in the boat 3.2mm or .125" thick good enough to tap and if unsure Locktite a backnut on .A better solution would be a SS socketwith a birdmouth cut to go over the rounded section TIG welded on as any vertical angle will drain better

AM

Adrian18 · 17th July 2013, 05:42 PM

Here's my set up the black rubber is the turbo oil dump the shiny pipe is the crank vent I re routed it to the intake side after turboing

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