Thread: Isuzu Engine Swops for Dummies

Originally Posted by steveG

Bugger
Any idea what was causing the leak? There's not much to go wrong with the seals I wouldn't think unless one got damaged during assembly.
Its not a case of the drain being too small and causing the oil to back up inside the turbo like JC has reported in the past is it? Or too much oil supply (IIRC its a 1.6mm restriction that the journal bearing turbos need)?

Anyway, if that's the only thing left to sort out before its back on the road you're almost there!!

Steve

Turbo has new seals in it so shouldn't have a problem there. I just think the oil couldn't get away quick enough, and/or to much oil pressure.?. Interesting about the restricter though, better look into this one.

Originally Posted by Vern

Turbo has new seals in it so shouldn't have a problem there. I just think the oil couldn't get away quick enough, and/or to much oil pressure.?. Interesting about the restricter though, better look into this one.

I can't find the source of that restrictor size, and Garrett are saying in this info that a restrictor isn't necessary unless oil pressure is excessive: http://www.turbobygarrett.com/turbob...timization.pdf
There's some other good reading in there.

What size is the drain fitting back into the oil pump cover?

Steve

Originally Posted by Vern

Jc, it runs back to that cover plate thingy below the side plate
(Oil pump drive cover perhaps)??, enlarged the fitting and seems to be OK, but has the pro vent drain it'd into it as well.

mmm, i'd remove the provent return and try it.

jc

Originally Posted by steveG

I can't find the source of that restrictor size, and Garrett are saying in this info that a restrictor isn't necessary unless oil pressure is excessive: http://www.turbobygarrett.com/turbob...timization.pdf
There's some other good reading in there.

What size is the drain fitting back into the oil pump cover?

Steve

At a guess, half inch

Originally Posted by Vern

At a guess, half inch

Mine is only 3/8 BSP, and has no problems so if its at least that big it should be fine.
I'm assuming its a nice straight run from turbo straight down into the fitting on the oil pump cover? No hose loops or nasty angled fittings etc?

Any chance the small breather from the rocker cover is plumbed into the inlet manifold (pressurising the sump) as was the problem in this thread: http://www.aulro.com/afvb/isuzu-land...uestion-2.html

Steve

Originally Posted by steveG

Mine is only 3/8 BSP, and has no problems so if its at least that big it should be fine.
I'm assuming its a nice straight run from turbo straight down into the fitting on the oil pump cover? No hose loops or nasty angled fittings etc?

Any chance the small breather from the rocker cover is plumbed into the inlet manifold (pressurising the sump) as was the problem in this thread: http://www.aulro.com/afvb/isuzu-land...uestion-2.html

Steve

From what I gathered, the turbo should be able to handle the 4BD1 oil pressure without being restricted, so should be okay there. I think the issue was with the oil return, bored it out and it's looking okay - certainly not getting the pints of oil shooting through the turbo that I got earlier. Getting a very, very slight film on the exhaust side of things but it looks to be residue that is being forced out - barely enough to put a smudge on a white cloth. I'll keep an eye on it, and but my bet would be that once the residue blows through, it'll be good.

Originally Posted by justinc

mike, how have you done the return line from the turbo oil feed? it needs to be on its own back to the sump not tee'd in to the alternator return.

jc

sorry - on tablet pc so didn't see this earlier. Tapped into the cover plate as per your thread from a while back, 1/2" line from turbo with provent drain tee'd into it. Seems to be good now, as per above post.

A turbo spitting oil is never the seals. It's either too much oil supply pressure or too high crankcase pressure. If you are that close that a rebuild kit made the difference, I would suspect you could be pushed back into problems quite easily.
Stock the 4BD1T has a turbo oil supply line maybe 70cm long which through internal friction drops the turbo oil supply pressure and flow to managable limits.
What is your breather setup?