14b Oil Pressure- Too Much?

[tec_41]

I was on the verge of completing my 420a turbo build last night and went to start it for the first time. Started up fine after priming once, then started a second time a few minutes later. After a few seconds it just started spitting oil out the exhaust housing, heavily. I then started trying to research if I was putting too much oil pressure through a 14b since 4g63's run the feed off the head. I'm using the stock oil pressure sensor hole on the back of my block and a -4an braided hose.

Is it possible that I blew the seal out of whack by sending too much oil pressure into it? I want to think this because it started once just fine then the second time I started it the thing just puked.

 

[JusMX141]

Too much pressure is likely to give you a smokeshow more a wide open throttle or after letting off from a pull. Idle oil pressure shouldn't exceed the max pressure the turbo can handle.

Although you are correct- the TD05H center housing has a very light thirst for oil, and can easily be overoiled if you're not careful. If you suspect oil pressures to be too high, you'll want to use a restrictor in the oil feed line.

 

[tec_41]

Okay thanks for the reply. I'll be ripping into it later to see exactly what went wrong. But is a restrictor made for the 14b or would the threads be the same as something like this- OBX TURBO OIL FEED RESTRICTOR FITTING -4AN GT28R GT28RS:eBay Motors (item 220456368205 end time Jul-29-09 20:28:31 PDT)

 

[JusMX141]

A GT center housing's inlet thread is 1/4" tube, so this restrictor will not work on a MHI turbo.

Honestly, the best way to incorporate a restrictor would be to somehow use a piece of the OEM oil feed line and join it to your oil feed setup. The banjo fitting at the turbo on the OEM oil feed line from the head on a 1G has a restrictor built into it.

If not you're going to need to get creative...perhaps install the restrictor where the line comes out of the block? Also be sure your oil drain is free of kinks and does not drain into the bottom of the pan where there is always oil.

 

[tec_41]

A GT center housing's inlet thread is 1/4" tube, so this restrictor will not work on a MHI turbo.

Honestly, the best way to incorporate a restrictor would be to somehow use a piece of the OEM oil feed line and join it to your oil feed setup. The banjo fitting at the turbo on the OEM oil feed line from the head on a 1G has a restrictor built into it.

If not you're going to need to get creative...perhaps install the restrictor where the line comes out of the block? Also be sure your oil drain is free of kinks and does not drain into the bottom of the pan where there is always oil.

Durrr, didn't even think about that. I believe it's a 1/4" outlet coming out of the block. Also, my drain is a-okay and tapped at the top of the pan.

On a side note, I tore apart the turbo today expecting to see something totally obvious, like a blown seal or whatever. But everything looked new, rebuilt, and well in tact. The only bad thing I found was this cracked plate. Would it hinder anything?-

 

[JusMX141]

That's just a heat shield....they can sustain some serious damage before they're useless. I have piles of good used ones as well as some new ones here at the shop if you're really concerned.

Look how wet the heat shield is! That thing was obviously pumping oil past the turbine seal and into the exhaust system.

 

[tec_41]

Ah, okay thanks...Yeah it was leaking heavily out of the exhaust housing. I bought it from a guy who said it was rebuilt, which I don't doubt. It came apart easily and all the internals appear to be in good condition. If it were pouring out into the exhaust, it'd be the small metal seal the goes around the top of the shaft correct?

I have a plan of attack. I'm going to make a restrictor following this little write up- http://www.sr20-forum.com/forced-induction-turbo/2357-how-make-oil-restrictor-less-then-10-a.html

I'll put it on the back of my block then throw the turbo back together and try it again. On a cold startup I typically get 70+ psi of oil pressure so I guess my theory right now is that I was blowing oil by the seal due to excesive pressure. Hopefully with the restrictor in I'll knock down that pressure at the turbo and it will seal properly.

Any idea what size I should drill for the restrictor for a 14b?

 

[JusMX141]

I would recommend a .0625" (1/16") restrictor for such excessive pressure. I believe the hole in the 1G feed line from the head is around .078" (5/64"), but your source has much more pressure than the head of a 4G63 provides.

 

[tec_41]

Okay that's what I'll use then. You've been a great help, thanks

My plan of attack failed. I made the restrictor which worked well, then I reassembled the turbo making sure everything sealed right. Apparently it did not, it still was leaking oil (though it wasn't as bad). It seems like when I rev it up a little the oil doesn't leak, then after idling maybe 10 seconds after giving it gas it will start to leak again out the exhaust housing. So this pretty much has to narrow it down to a bad seal, right?

 

[JusMX141]

Sometimes it's too little too late when it comes to giving proper oil pressure to a turbo that has recently been overoiled. Occasionally you can save them, but more often than not a rebuild (or at least new seals and journal bearings) is in order to bring it back to 100%.