Skip the auto shop - Our mechanics make house calls

Q: Turbo issues with boost

asked by on

My turbo diesel 80 sometimes hit peak boost of 10 psi, which is what i want, but then I can waver or drop to 9 psi with increased throttle. When this occurs there is a faint hiss or psssht of air coming from what i guess is the turbo. Sometimes it even fluctuates between 9-10 psi kind of bouncing making that hissing noise. Could you please give me some idea of what might be happening in the turbo and what needs to be done to fix it?
My car has a manual transmission.

A: Hi thanks for writing in. The Land Cruiser ...

Hi thanks for writing in. The Land Cruiser turbo diesel from that era uses a mechanical waste gate to bypass the exhaust around the turbine when the boost pressure reaches maximum. It should be a quiet and smooth action. It’s possible that you might have an air leak in the intake tract that is allowing the pressure to leak off when it reaches maximum, about the same time the waste gate is opening. The pressure would then drop off suddenly, then the waste gate would close, the pressure shoots back up and the whole cycle happens again. I recommend checking all the clamps and seals on the air intake hoses and particularly the line that goes to the waste gate actuator itself. I’d have a local expert inspect the noise to give you a more precise diagnosis in person. From there, they can move forward with the appropriate repairs.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: My car has a rough idle and water leaking from the tailpipe - 1999 Toyota Land Cruiser

Hello and thank you for contacting YourMechanic. If the smoke is slightly white, it could be burning the fuel too cold. This is an issue with a cylinder misfiring and causing raw fuel to enter the exhaust pipe. Check all...

Q: Coolant leaking, engine might be messed up now

You are correct in not wanting to start the car to avoid any further damage. It sounds like you might have coolant leaking into one of the cylinders due to an engine block failure, resulting in a misfire. What needs...

Q: Cylinder #6 misfire on 4.0 liter SOHC

Hello. Good job on getting the basic tune-up work done! Given the mileage, this engine may have a longer-term issue, namely, accumulated wear on piston rings or a blown head gasket. Both of these can be diagnosed with a compression...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...