Too low drive pressure in turbo?

BiodieselPower

BiodieselPower

New member
I have had SEVERAL single turbo issues in the last two years. Here are the turbos i have been through...366, two 363's, 463, 467, and now another 467 on a completely different motor and truck. 12 valve P pumped trucks with full cuts/no fuel plates... 5X14's and then 5X20's at one point. The deal im having is the thrust bearing tends to go out on the front side. Also on both trucks they always have less drive pressure than boost. At max throttle high RPM it usually gets to about 1:1. Then shift from 3-4th gear drive pressure wil drop 10-15psi and slowy climb back to 1:1. Under moderate throttle drive is half (10 drive, 20 boost) and low throttle it may be 1:3 ( 3 drive 9 boost)

Has anyone else experiened this? It has happened on both my trucks and im having a hell of a time keeping a charger together for more than 1000-8000 or so miles. And the last charger that went i had a fuel plate in and max boost was hitting 40psi on a 467, the thing only lasted 1500 miles(1000 miles towing)

And yes Ive checked for boost leaks and oil pressure(AN 6 lines)
 
lack of oil pressure would wipe out journals. all the turboes listed are horrible choices for towing. with the exception of the 363's depending on the turbine side.

the only thing that makes sense right now is to ask if all these turbo's were waste gated?
because they are crappy sizes for towing they are all gonna surge like hell. there is no way around it. when they do this the compressor side gets the advantage over the turbine and wears backwards. i cant explain your drive/boost pressure reading though.
were these turbo's all non gated chargers???? its obviously not truck related and the problem follows the chargers.
 
The compressor side is being slammed against the thrust bearing when you shift under higher boost levels. Even if it doesn't get to the point that it surges, it's still hard on the thrust bearings. Easiest cure is a steel thrust bearing.

I used to go through bronze thrust bearings in weeks sometimes (100psi+ drive pressure), the current steel one has been in there for 1 1/2 years.
 
Drothgeb said:
The compressor side is being slammed against the thrust bearing when you shift under higher boost levels. Even if it doesn't get to the point that it surges, it's still hard on the thrust bearings. Easiest cure is a steel thrust bearing.

I used to go through bronze thrust bearings in weeks sometimes (100psi+ drive pressure), the current steel one has been in there for 1 1/2 years.
Click to expand...

Where did you get the steel thrust bearing?

Sent from my DROID RAZR using Tapatalk 2
 
homewrecker said:
Where did you get the steel thrust bearing?

Sent from my DROID RAZR using Tapatalk 2
Click to expand...

I couldn't find anybody that would sell me one. But there's a local turbo guy, "Tims Turbos" that can install them as part of a rebuild. That was a while back though, maybe someone sells them now.

Don't waste your money on the 360 degree bronze ones either, they don't last much longer than the 270 degree ones.
 
I have used two different kinds of oils. Co-op and rotella oil...about half the turbos failed on each.

Oil presssure feeding the turbo through AN 6 line was still 60PSI

All the chargers were non gated.

Jonny at stainless told me he has still seen the steel ones fail. But maybe they are worth trying?

And the only reason I went to a single charger was to sled pull...
 
reply

I'll go with Turbo2332's suggestion, surge seems to be the most obvious killer.
Going by your pressure ratio figures I would also check the pressure lines to your gauges as it sounds like they could have been switched over inadvertently. Are you running name brand turbo's or using an aftermarket brand?
 
Try a synthetic oil, or semi synthetic.
I have been using mystic 15/50 for a while, and none of my turbos have loosened up at all, though with twins there is no surge, just chuffing if i let it happen..
Forcedperformance.com has a great article about engine oil needed to make turbos bearings and thrust surfaces survive.
 
BiodieselPower said:
I have used two different kinds of oils. Co-op and rotella oil...about half the turbos failed on each.

Oil presssure feeding the turbo through AN 6 line was still 60PSI

All the chargers were non gated.

Jonny at stainless told me he has still seen the steel ones fail. But maybe they are worth trying?

And the only reason I went to a single charger was to sled pull...
Click to expand...

Nothing last forever. But there's big difference between bronze and steel.

I run Amsoil with zinc additive.
 
Last edited:
all of our rebuild kits (doesn't matter the brand) come with bronze bearings. i do however see steel thrust bearing very often in genuine MACK s300 and s400 turbos. I save the undamaged steel bearings if you would like one.
 
What timing are you running, advancing timing will lower boost pressure. Your boost to drive pressure seems odd from what I've experienced running similar turbos.
 
jasonc said:
What timing are you running, advancing timing will lower boost pressure. Your boost to drive pressure seems odd from what I've experienced running similar turbos.
Click to expand...

I agree, I bet you have a leak to you DP gauge. I have only seen 1:1 or less than in very small RPM windows and load situations. Have any actual pressures to compare with?
 
just because i guess. because all of the turbos he has ran have experienced the same death and all the turbos he has ran do not have gates. something needs to be played with. I wouldn't gate an s4 but the s3's definitely, on such a rig. i have no idea how he is getting energy from nothing. but if he is making 50 psi of boost and surging the hell out of the charger when it shifts, it would be very beneficial to dial the pressures down so the surging even is much less violent.
 
Extended Power said:
If his drive to boost is lower than 1:1, why would he need a gate?

I can't see how he can have 3psi drive, and 9psi boost...like mentioned...lines got switched maybe.
Click to expand...

I don't see that either my s400's have always needed the drive to be a little over boost typically 5 to 10 psi. My guess is the drive pressure is not reading accurately for some reason.

Is your compressor surging when you shift gears?
 
You must log in or register to reply here.
Back
Top