Ball Bearing Turbo Questions

[No Crust Racing]

Morning gents,

I bought a turbo advertised as S14 and as I understand it 99% of S14s were bush bearing. It was listed as being rebuilt previously but possibly requiring oil seals. This seemd perfect to me as I've wanted to try my hand at a DIY rebuild.

However, I've spent some time cleaning it up and the tag reads 14411-91F00, it has 6 bolt housings, and has the cast divider between the wastegate port and turbine exhaust flow which appears to indicate it's a Ball Bearing Unit from an S15.

I understand that BBs cannot just be rebuilt in the same way standard bush bearing turbo's can, as in DIY?

I note that the oil feed line did not have a restrictor in it, I thought that BBs should have a restrictor?

The turbo spins OK and the blades are in very good condition, there is no free play in any direction, up/down/left/right in/out. I noticed that there was oily residue on the inlet snout and on the outlet of the comp housing as well as around the oil feed line fitting.

I'm wondering two things, does this indicate the oil seals are blown? Is it possible that too much pressure from the oil feed (no resitrictor) was forcing oil past the seals and that it could run fine with the right pressure?

Is there any way for me to inspect it myself to determine if it's really stuffed? Can just oil seals be replaced or does it require an entire cartridge?

Cheers

[GTScotT]

Generally if the oil seals go you will see an oily residue on the rear wheel and in the rear housing.

Oil in the comp cover is normally blowby from the rocker covers.

Personally I would not DIY rebuild either the BB or bush turbo in this case.

[No Crust Racing]

I was thinking the same thing in so far as if it blows there's usually oil in the turbine housing, however a lot of other resources, granted just google searches, indicate oil in the comp intake out outlet pipes is also sign of blown oil seals. Any thoughts on my restrictor theory?

If I remove the housings is there anything in particular that would be a dead giveaway? I don't want to go ahead and fit it just to have to pull it off again.

[No Crust Racing]

I've been having a word to a few turbo places. They had the following to say.

3an lines can use a restrictor inline and should do so. Some T28 BB's have a restrictor in the oil feed port from factory though. A restrictor should be used if the turbo smokes a but on idle (as the seals are dynamic).

Oil in the inlet snout and outlet pipe on the comp side is fairly normal and does not warrant a rebuild unless the comp blades are damaged or there's excessive binding or contact with the housings at all. Usually this is just breathed in from the PCV system.

So at this stage I might just bolt it on and see what happens, for the price I paid, it's worth having a go as if it's good it'll be the cheapest working BB in bloody history.

[GTScotT]

Haha sounds like a plan. Honestly Ive had them smoke till a restrictor was used and were fine thereafter.

If you buy a braided hose for it the hose should come pre restricted, just get it made at pirtek and tell them it needs to have a restrictor inline. They will work out the rest I guess.

You can also buy one of the Kando feed lines on ebay, probably cheaper and you know its for a BB.

[No Crust Racing]

I've got a braided kit for it, I'll just get a restrictor for it as a safety measure.

Fingers crossed it stays in one piece on it's first spool...