Turbo oil pressure

[Mawhitey]

Hi guys, I hope you can help me out here. I have just re installed my refreshed 058 stroker into my A4 and after approx 2k miles the turbo let go. The turbo company stated it was an oil pressure issue. I have an oil pressure gauge fitted and see 60 psi at 3k revs HOT and 20 psi HOT idle, with he feed for that taken from the oil pressure switch port.

Curiosity got the better of me so I hooked up a gauge into the oil feed line and found it to be be less . Using a -4an feed i was looking at 50 PSI at the housing end of the line and a tad over 40 on the turbo end. The feed is a decent size and never been an issue. I run a journal bearing K04-064 from a TFSI car on an adapterplate .

The engine in various formats has always produced about the same oil pressure, but i have never checked the turbo feed. I checked the housing for blockages and iot was all clear, but i note that the feed for the turbo is taken from outside the filter, whereas the switch / sender t is from the outside of the filter.

I don't want to fit the new core without being sure it's ok, but I have nothing to compare to.

Can anyone offer any insight please ??

[Seerlah]

How long was the car down for? And I assume you primed your stroker before starting. If this were the case, did you have turbo off the cinder head when priming? I ask this because you could very much have compromised the bearings too much. Turbo needs to be off cylinder head or spark plug holes open with the chra not spinning (never did the latter, but always the former). The exhaust flow during this time is spinning a dry chra.

I keep the turbo off the cylinder head with a saucer under the drain port of turbo. Once oil comes out the drain, only then do I attach the turbo to the block. Reason being, now you can prime all you want because turbo now 100% has oil flowing through it. And you will be suprised how long it takes for oil to come out when priming. Pumping oil with a starter is much diffetent than the rpm of a starting or running motor. Anyways, if you primed a dry engine with turbo attached that was probably what did it.

[Mawhitey]

She was down for a few months, but I did manually prime the turbo and spin her over with injectors off a bunch of times till i saw pressure on the gauge

[Seerlah]

Not really understanding the process you took. How did you prime the turbo, before starting the engine?

In a nutshell, once bearings are compromised in most cases it is only a matter of time before they let go. I'm trying to figure if this is a compromised bearing issued that revealed itself 2k later or if it is a pressure issue. Because many cars don't see oil pressures we do and turbos don't need much of it anyways. If you can confirm your orifice is not cloggd, then I am leaning towards the chra spinning dry and leading to your current issue.

[Mawhitey]

I primed it by syringing oil into the turbo before connecting the oil feed which was done shortly before the initial engine turn over. I span the engine over about 5 or 6 times with injectors off for about a minute a time, with a minute rest . Oil filter was fitted full too. I do appreciate your comments, i am mainly asking for a sanity check, I cannot afford to nuke another core. Everything from the block oil feed, thru the housing to the oil feed is clear. I have checked, cleaned and blown thru them all

[Seerlah]

What type of fitting do you have on the oil feed inlet of the turbo?

Since turbo is shot (so they say), you can leave it bolted to the block. Place the oil feed to turbo with restrictor being used (fitting, unless one with the casting) into something to catch the oil, and turn the engine by the starter to see how oil comes out the other end of the feed line (basicaly, monitor how oil is being applied to the turbo from whatever rpm th starter turns the motor. If it is ample, I would say you are in the clear.

But with new turbo, prime it like I just mentioned. Don't even trust the oil in the chra it came with. Remove chra from anything that can make it spin. Before starting the car with new turbo, be sure you visually watch at least 3 ounces (not by weight, but equivelant to what 3oz of a 12oz soda can would be) come out of the drain of the turbo before reattaching. Turbos are not cheap, and this paranoia can save you a hefty dollar. Not saying having your bearings run dry is the reason, but recipe I just mentioned can avoid that.

[Mawhitey]

Banjo fitting on turbo currently with 4an pipe

I notice that elsawin says at 3k i need 3 to 5 bar pressure and Bentley states 5 - 7 bar, that's a hefty difference if im expected to make the latter as im at 4 bar. I just need to be sure. WHat GPH or LPM you expect me to push out of turbo line?

[Mawhitey]

I am swapping to an OEM sized pipe to feed my turbo to eliminate the pressure drop there and also looking at replacing my oil cooler with a larger unit than 13 row to reduce pressure drop there too.

I have changed the oil pump and now see a higher overall pressure raising from 60 psi at 3k to 85 at 6k. Still on 5w40 quantum synthetic. I will change to 10-50 full ester based oil once i have eliminated all of the other potential issues.

I do feel the main issue is the pressure drop over the cooler as the oil feed is post cooler/filter and pressure switch is pre

[Seerlah]

Find out manufacturer suggestion for pressure at turbo feed and recommended line size. Once you have that info, test with recommended line size and see if the pressure you have (should be a minimum suggestion spec) is up to par.