GRP151

Why does the Turbo's fail?

35 posts in this topic

Seized turbo perhaps?

 

Waste gate actuator is controlled directly by boost pressure.  Have you not noticed when checking hose that hose connects to outlet side of turbo compressor?

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I see.

So to test the actuator would applying  10 - 30 psi of air pressure be a method for testing it?

I tried revving the motor from the rear with a broom handle to watch the actuator but it doesn't move.

Is it because the engine must detect the vehicle in motion in order to allow it to actuate?

What controls the wastegate?

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Correct me if I'm wrong here, but to my understanding

It seems like this actuator provides a similar function found in small gas lawn mower engine? For example;  it  uses a governor that is controlled by the speed of the motor  from the cooling fins on the flywheel. As the engine speed is increased the throttle is reduced.

 

If that is the case then I would assume....

As the psi increases to a certain point the actuator opens the wastegate valve to allow excessive pressure to escape.

Therefore preventing 'overboost' as many have called it or in what I understand it to be is over pressurized.

Since pressure is measured in psi or kPa etc. etc. that would be the logical understanding for a layman like myself.

 

Once I get the air intake tube off I hope to see the condition of the  impeller.

Perhaps it is seized, free wheeling or the actuator could be at fault?

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Lawnmower engines have a centrifugal speed governor similar in principle to this:

800px-Centrifugal_governor.png

Does not look much like a waste gate actuator does it?

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Im not sure what year lawn mower engine you have but I can assure you the ones here in Canada don't have this contraption that you would call a govenor.

At least the ones that were made in this century.

Nice try!

 

 

2 hours ago, tolsen said:

Lawnmower engines have a centrifugal speed governor similar in principle to this:

800px-Centrifugal_governor.png

Does not look much like a waste gate actuator does it?

 

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The function of the wastegate valve is like you say, to bleed off pressure when it reaches a certain limit. In that respect you are right, although it is much more like an air pressure regulator in function than any sort of governor.

 

A governor of a lawnmower engine cuts fuel/air if the engine exceeds a certain RPM, at least the one like you described, thus limiting engine speed. 

 

The wastegate however isn't limiting boost to slow down the engine. It's limiting boost to keep the stress levels down of all parts exposed to that pressure. If you keep letting the pressure go up, the engine internals will have to withstand high pressure as will the hoses and everything else. 

 

If you were to floor the pedal even with the wastegate being actuated to bleed of excessive pressure thus maintaining a set max pressure, the engine could still rev to destruction. The ECU will be what intervenes prior to that, while the wastegate just did it's part to keep the intake from having too much pressure in it.

 

That photo reminds me of how the older two strokes actuate their exhaust valves. Spring preloaded ramps that have ball bearings in them. Scooter CVT's are similar, as are Sleds CVT's... although those are usually pivoting arms instead. The list is endless.

Edited by DesignerDave
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10 minutes ago, DesignerDave said:

The function of the wastegate valve is like you say, to bleed off pressure when it reaches a certain limit. In that respect you are right, although it is much more like an air pressure regulator in function than any sort of governor.

 

A governor of a lawnmower engine cuts fuel/air if the engine exceeds a certain RPM, at least the one like you described, thus limiting engine speed. 

 

The wastegate however isn't limiting boost to slow down the engine. It's limiting boost to keep the stress levels down of all parts exposed to that pressure. If you keep letting the pressure go up, the engine internals will have to withstand high pressure as will the hoses and everything else. 

 

If you were to floor the pedal even with the wastegate being actuated to bleed of excessive pressure thus maintaining a set max pressure, the engine could still rev to destruction. The ECU will be what intervenes prior to that, while the wastegate just did it's part to keep the intake from having too much pressure in it.

 

That photo reminds me of how the older two strokes actuate their exhaust valves. Spring preloaded ramps that have ball bearings in them. Scooter CVT's are similar, as are Sleds CVT's... although those are usually pivoting arms instead. The list is endless.

 

Thank you DesignerDave!

Your explanation confirms my understanding of the mechanical process that is taking place within the wastegate mechanics.

My example using a small engine govenor was to associate a method that is used to regulate engine speed using air pressure. You are completely accurate in the explanation that it controls the fuel and air if the engine exceeds a certain RPM.

I truely enjoy these forums as it does help motorists like myself under the fundamental mechanics of our little cars.

As simple and obvious are some of the explanations to some, it can add confusion. to novices like myself trying to provide accurate diagnosis to mechanical failures.

 

 

  

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Went to try and start the car and it sounded like the battery was dying. Battery tested full charge.

From what I have been reading It appears that my alternator has seized! Boy that didn't take long!

I was hoping to spray something in the alternator to free it up but I'm not sure what will work without causing damage.

My guess is wd-40 should work, but I'm not sure.

Any suggestions?

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The clearance between the stator and the rotor inside the alternator is almost nil. A build up of rust bridges the gap and seizes the alternator.

Spray HH-2000 oil into the windings from the pulley side but do not overdo the treatment.

You will have to loosen the belt on the alternator and by inserting a socket on the pulley nut work it back and forth using a Breaker Bar for leverage. It should free up.

There's a reason why its called a Breaker bar so go easy!

Breaker Bar, 1/2" Drive W/ 24" Flex Handle

http://www.wurthcanada.com/en/webkit/product_info/productcategories.html

 

http://www.wurthcanada.com/en/webkit/contact/contact.html

Edited by GRP151

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I was able to free my alternator by pushing my car down the driveway while in gear.

 

If my memory serves me correctly this happened to me twice. The second time, I used a 50A battery booster charging the battery while turning the motor over and was successful.

Edited by smartdriver

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