Stumped about turbo

[gsx rated98]

Ok, i picked up a 1G earlier this week, drove it and no boost, on blown turbo, no biggie i have a spare 14b sitting around.
Well, i havent gotten around to swaping the two out yet, but im cleaning the car up today, and i just wanna check the turbo for shaft play, and the shaft isnt moving, and it spins fine. Now i know the signs for a blown turbo is shaft play, or no spinning, or blue smoke comming out the exhaust, these are three things i dont have.

To give a little idea about the car, its a 90 AWD, 100% stock with 147k miles. So for the hell of it i remove the heat sheild from the exhaust mani, and low and behold, there is a 3"+ crack between runners 2 and 3 (i know the 1G Mani is known for it). Now im in the process of finding a 2G mani, and im still going to swap the turbos out.

What im curious is, will a crack in the exhaust mani be big enough for me to get no boost? The stock boost gauge (not sure how reliable 1Gs are, i know my 2G aint worth a damn) does go up to 3 - 4 lbs now and then, but dont really hold it, plus i havent really gotten on the car hard. Vacuum in the car seems ok (again watching the boost gauge). Main question is, do i need to be looking else where for issues? No, i have not done a complete look over of the engine and all its hoses, im sure much is to be replaced.

Thanks in Advance,
Jerry

 

[25psilaser]

I had a gsx that did the same thing, it was the exaust housing it was cracked so bad that it would not boost, its like having no wastegate flapper on there. Hope this helps you just my input,also check the cat.

 

[Quasimondo]

You can pull the exhaust housing off without pulling the rest of the turbo out if you unbolt the manifold, the downpipe, and the ring clamp. You might still need to seperate the manifold from the exhaust housing, but once you get it pulled you can check for cracks around the wastegate area. Mine was bad enough that I wouldn't hit full boost until 5K.

 

[oldman]

1. Yes large exhaust leaks before the turbo can definitely effect boost, severity depend on how bad the leaks are. It can also effect the o2 sensor reading.

2. Make sure the actuator arm is connected to the wastegate door.

3. Do a REAL boost leak test.

Good luck.