Tapping oil pump cover for turbo oil return

**Judo** · 14th July 2013, 01:36 PM

The turbo oil return hose is 5/8" ID and because it shouldn't be joined to the vac pump return (high volume of oil?), I'm planning to tap the oil pump cover like others have done. I was thinking 1/2" NPT would be best as it's only a small step down from 5/8", however it appears 1/2" NPT is almost an 18mm hole to give 1/2" ID? Surely 1/2" NPT doesn't fit? If I can go smaller than 1/2" from the 5/8" hose, then how small can I go? What size did you guys tap?

This is an 18mm spanner. Clearly I can't drill a hole that big!

**Judo** · 14th July 2013, 01:47 PM

P.S. While I'm here.... The oil feed is obviously on top and the return on the bottom of the turbo, but both are at about 45*. Any problems with that angle??

**Bush65** · 14th July 2013, 02:14 PM

Originally Posted by Judo

P.S. While I'm here.... The oil feed is obviously on top and the return on the bottom of the turbo, but both are at about 45*. Any problems with that angle??

Yes, you need to rotate the turbine housing. IIRC you can be out about 5*, but nowhere near 45*.

Remove the housing before trying to rotate it as some have a dowel pin that has to be removed before they can turn.

**bee utey** · 14th July 2013, 03:25 PM

A 3/8 NPT or BSP by 5/8 steel hose nipple would be my choice as the ID could be drilled to about 13-14mm without risk. 3/8NPT is around 17mm OD max. Ford used to list one that I bought for a range of jobs, can't remember the part number now.

Failing that I'd be looking for an old steel 5/8" heater pipe end and either pressing (or silver soldering) that into the cover, the same way Ford V8 water pumps used to be done.

Adrian18 · 14th July 2013, 03:30 PM

I didn't like drilling in to that oil pump plate so I went in beside the breather in the aluminum cover plate easy

**Judo** · 14th July 2013, 03:38 PM

Originally Posted by Adrian18

I didn't like drilling in to that oil pump plate so I went in beside the breather in the aluminum cover plate easy

All of a sudden this is sounding easier... I might take the breather cover plate off and check the thickness then make my choice...

**flagg** · 14th July 2013, 06:03 PM

I looked at the cover too, but didn't think it was thick enough for a tap and I didn't want any oil from the drain getting into the breather..

**Judo** · 14th July 2013, 06:27 PM

Originally Posted by flagg

I looked at the cover too, but didn't think it was thick enough for a tap and I didn't want any oil from the drain getting into the breather..

Well true, but I can't imagine I'll have more oil in my breather than Dougal. Sounded like he had some air in his oil breather.

Did you tap a 1/4" or bigger? Is your turbo oil return 5/8" or smaller? I have a feeling mine might be bigger than most...

**Judo** · 14th July 2013, 06:30 PM

P.S. This is my reference to Dougal's provent.

http://www.aulro.com/afvb/isuzu-land...on-dr-ben.html

**flagg** · 14th July 2013, 06:50 PM

1/4, with 8an drain. I had to put 45deg elbows in both ends to get around the breather but it drains fine.

Note that the oil requirements for mine may differ from yours. borgwarner vs garret etc.

Yes I read and re read that thread many times.. My Provent is mounted high up, with the check valve and I have a 90deg elbow in the breather before the Provent.. No oil in it.. Just mist residue. Seems to be doing what it should.

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