DangerIsland

I've been slowly diagnosing my low-boost situation, and I've come to the conclusion that my turbo might be the problem. A lot of people say to turn the compressor by hand and see if it "spins freely" and I wanted to know exactly how freely it's supposed to spin.

If I twist it, it will turn, but it doesn't keep turning after I let go. Should I be able to give it a good twist and have it continue spinning? I talked to Kevin at Majestic Turbo, and he said that it make be "coked up" and need a rebuild. Of course then I get into whether I should rebuild it, or move to a k27, or any other number of options, SFR, some garrett setup, etc. etc. So many options... but that's another topic.

How much should this thing spin by hand?

silicondigital

I can spin mine by hand and it will keep spinning for a second or two until it spins down.
I dont know, its not a very exacting test...

blurry951

I have a brand new To4e on my motor that is not installed yet into my 951 and it does the same that Digital said, spins for a second or two and then stops. Another thing is that the turbine should have very little play moving side to side or in and out, if it has a good deal then your bearings are wearing down or they could be "coked up" with tar-like oil. Hope that helps.

DangerIsland

silicon: that's a lot more than mine will do! I think I need to replace this thing. Now to decide to go with another stock one, or for something bigger and meaner.

blurry: mine didn't have any play in the shaft, it's just not spinning nicely. That would explain why I can get some boost but it takes a lot time to build it up, and drops off very quickly.

silicondigital

Run you 2 bottles of that motor flush stuff subed in for 2 quarts of oil and let if run for 20-30 min or so. freed up an oil pressure relief piston on my 944 N/A Maybe you just have some gunk in the turbo?

DangerIsland

Anyone else have any input on the motor flush idea? Do you have a particular product that you'd recommened, silicondigital? In theory it sounds like a good idea, I don't know how well it will work, but I guess at this point it's worth a try!

silicondigital

Wal-mart sells it its like 2-3$ a bottle. I think its called "Gunk" brand. It says on the bottle 1 bottle for 5 min. i got some cheap 5w-30 oil and put in 4 quarts of that and 2 quarts of the flush stuff and let it run for 20 min or so and revved it a little bit every now and then. Ive done the same in my turbo when i first got it.

blurry951

If your turbine play is minimal then that is a good sign for not having to replace the turbo right away. I don't know what would work well for removing gunked up oil, but best of luck on that.

2+2

Also, you may have a collapsed section in your CAT section or a blocked CAT. By restricting the maximum flow, the boost is also limited.

Perry 951

Try a fresh oil change and a bottle of Rislone. Drive as normal for 100 miles, then change oil and check the turbo again.

Cheaper than a new turbo!

Danno

The other trick is the 1-qt of ATF in the oil to dissolve everything before an oil change. Or maybe you can take the oil-supply line off the turbo and drip some solvents through before your next oil-change.

On my TO4B turbo with ball-bearing center, it spins for about 2 seconds (about 3 revolutions) after I give it a good 'snap' with my fingers. The new TO4E I'm going to be using next spins for about 1-second. And the 200K-mile stock K26/6 I just removed from our test car doesn't spin at all! It stops right where you left it. In fact, it has a bent-axle as you can feel it bind at certain parts of the rotation.

DangerIsland

Thanks Danno. I'm going to go through a bunch of other troubleshooting steps before I decide the turbo is completely shot. I might take the oil line off when I get the intake off this weekend and see if I can put some stuff in there. Even if it was spinning poorly, I would think it could make decent boost, but it aint. It almost sounds like there's an exhaust leak coming from the bottom driver's side but I can't tell for sure... need to test the cat... look for a leak, etc. etc. plus there's an oil leak dripping slowly on the crossover which makes things smell... god this car is a pain in the ***, I haven't even been able to drive it once and feel any real boost. but I love it all the same

Danno

Hey blurry951, please check your TO4E turbo and see how much radial play you have in your compressor wheel! We just check out a car this weekend with a newly rebuilt engine that had a TO4E that wouldn't build any boost. Turned out it may have been spinning a little too freely! There appears to be excessive play in the bearings that allowed the compressor blades to rub on the housing. Not sure if this was an assembly problem, or oil feed, or what... BTW, the turbo water-temp thermoswitch was also broken, so it wasn't getting any water cooling after shutdown except for the first 30-seconds.

tazman

How can I check the thermoswitch? My pump has never ran for more than 30 seconds.

Danno

To really test the thermoswitch, you remove it and put it in a pot of water. Slowly bring to a boil and notice at what temperature the wire makes continuity with the shell of the thermoswitch. Then as the water cools, the temperature where this connection is opened should be lower than the closing temp.

Could also be a bad water-pump relay. Unplug the sensor from the connector. Insert a nail or something into the connector. Ground this against the intake manifold. If the water-pump runs for 30-seconds, the thermoswitch is bad. If the water-pump doens't run when you ground this wire, then either the wire or the relay is bad.

P.S. Your injectors are on the way.