View Full Version : Turbo not making boost? car runs fine. please help

10-09-2008, 07:51 AM
After doing a whole engine rebuild and also installed AM (after market) exhaust manifold, AM down pipe, Engle valve springs, AM FPR and a bunch of fuel rail mods. I took it for a test drive. It was Ok for the first few times but the last time I test drove it; I was pushing it low to medium.

Then suddenly I lost boost at 15psi, I instinctively thought “Shit one of the intercooler hoses have blown off, now it’s gonna stall cause of a vac leak”. Instead of stalling it drove perfectly, just with no boost. I then stop to the side of the road, opened the hood and noting seemed to be out of place. The only way to describe it now is that it feels exactly like a NA non-turbo car.

After that I just drove it home, trying to get it boosting by giving it a little pedal, but nothing happened.

When I got home I checked:
• Wether the actuator arm disconnected from the wastegate flap, No (I didn’t get to touch/move it because there was no clearance to put my hand through)
• If the gasket blew between head & ex manifold, ex manifold & turbo, turbo & Down pipe, No
• Intercooler piping and hose: all connected
• Vacuum leaks? Seems unlikely, other wise the car wouldn’t start or even idle properly.
• If the car could start from off position; Yes perfectly
• If the gauge reads any vacuum; Yes
• If the turbo has seized: No, turbo fins turns smoothly

• I don’t have any blow off valve or plumb back system
• I have a manual boost controller, but if there was something wrong with that it would just limit me to my base boost
• I didn’t hear any loud cracks, thumps, or bangs when I lost boost on the test drive. So I doubt the turbo ceramic exhaust fins blew.

The car starts and runs fine, I could drive it all day no problem. There is just no boost at all not even a little.

Has any body had this problem? Any help and advice is most appreciated.

Thanks in advance


10-09-2008, 08:49 AM

10-09-2008, 12:10 PM

maybe, thats the next thing i'm gonna check. theres no way to grab hold of the acuator arm/rod cause there is no clearance. What i might do is remove the down pipe and look at the waste gate flap

10-09-2008, 04:23 PM
You won't necessarily hear the end of the world if the ceramic impellers break.
I would suggest checking the exhaust side, which it appears your basically going to do anyways.

10-10-2008, 08:32 AM
Found the problem. Guess what? My ceramic turbine blades blew! How? I think I know why.

About a year ago when my car was up and running I use to boost 20psi every time, everyday and I was never shy to give it the pedal. But just a few days ago when test drove my new setup up there was one major difference, there was no bov(blow off valve) this time. That test drive was to set the manual boost controller, and I remember letting off the pedal at 15-17psi after that the boost never came back up. That was when the ceramic turbine fins blew up.

Reason I didn’t have a blow off valve was because my new ex-manifold was much bigger then the stock which protruded to where my AM(after market) intercooler piping would go. It was also that the aftermarket piping which had a bov welded to it. So for the mean time I had the stock IC back on(eith no bov).>

I think ceramic turbine fins are only good for stock setup. The ceramic turbine blew cause of the build up of pressure in the piping due to not having a bov, which caused the turbine fins to come to a violent halt. The stress from that was enough to crack the ceramic fins.
Ceramic is like glass, once there is a minute crack it will keep slitting till it falls apart.
The ST-185 was much of a beta version2(st165 being beta v1). The ST-205 was perfect. I don’t know why with all the money Toyota had didn’t come up with a perfect gt4 by 1990, at the st185 stage after the ST-165 .
The problems with the ST-185 included:
• The Tvis system
• over bucket Shim system
• Ceramic turbine fin
• Single cone syncros for the gear box
All these problems listed above where redesigned and eliminated in the st-205 gt4. Toyota team Europe also deleted the Tvis from thier rally st185's.


10-10-2008, 08:40 AM
^pure carnage

10-10-2008, 06:18 PM
It was a bomb waiting to go off, if the shock of a non-vented intake was enough to shear it was already ready to go at any time. Probably from going to 20psi, that is WAY above the shaft speed the ct26 is designed for.