KAD 300A Turbo Issues

Greetings all,

Recently I picked up a 2002 Pursuit with a 2002 Volvo penta KAD300A turbo diesel (460hrs) and am having some issues with the turbocharger.
At 1500 rpm the supercharger kicks in and then disengages at about 2700-2750rpm where the turbocharger should kick in. Between 2750-2950 the supercharger disengages and re-engages (when pressure drops to much). The boat surges as the pressure fluctuates. If we accelerate to 3100-3200 turbo runs fine and supercharger remains disengaged. WOT is 3650-3690 and turbo is smooth.
She also seems to be burning a small quantity of oil; blueish smoke at lower rpms. Potentially in the turbo?

Any thoughts to what is happening?

So far have:
-pulled the exhaust elbow looks good; minimal scaling
-compressor wheel clean with acceptable gap around between the housing
-turbine looks slightly sooty and ends to blade are NOT linear like compressor wheel; as though the turbine blade is made to fit inside the flange on the turbine housing
-turbine housing inside has some scaling where exhaust elbow is attached; nothing terrible

My gut is afraid that the turbo is shot...!?!
Should the turbine + turbine housing be replaced, rebuilt or purchase all new turbocharger ($$$$$)?

Any experience running Rotella's T-6 heavy duty synthetic oil in these (5w40)? Run that oil in all the trucks and equipment

Other than that she runs smooth!
Any insight would be greatly appreciated!

Thank you
Chris
Miller

What you are experiencing is usually a sign of low turbo boost. Typically this is caused by excess tip clearance in the exhaust side of the Turbo. It can however also be a leaking joint in the turbo to manifold connection, or a leaky manifold gasket etc. Here in New Zealand there are people who make a business of machining out the Volvo turbo exhaust housings and fitting CNC machined inserts to fix the tip clearance problems. Typically US$400 - $800 exchange rather than the $1000's that Volvo will want for a replacement turbo. You may find someone doing similar where you live. You may also find a turbo service guy who could supply and fit a new housing (plus bearings etc if needed), but my experience has been that the companies we approached didn't want much to do with them as they considered them to be a poor quality product. My first step would be to put a boost gauge on the engine and see what is going on with the boost.

Thank you for the insight!
What is the clearance supposed to be on the exhaust side? I have a feeling that it is excessive given my feeler gauge goes to .024" and it was a little loose.
If this is the case does the housing have to be machined prior to installing a new turbine?

I am definitely interested in hearing more about your machined housing. Though I have a feeling the bearings should as be replaced.
Would you suggest having the turbo rebuild (can I locate parts?) or total replacement


Chris

aliboy said:

What you are experiencing is usually a sign of low turbo boost. Typically this is caused by excess tip clearance in the exhaust side of the Turbo. It can however also be a leaking joint in the turbo to manifold connection, or a leaky manifold gasket etc. Here in New Zealand there are people who make a business of machining out the Volvo turbo exhaust housings and fitting CNC machined inserts to fix the tip clearance problems. Typically US$400 - $800 exchange rather than the $1000's that Volvo will want for a replacement turbo. You may find someone doing similar where you live. You may also find a turbo service guy who could supply and fit a new housing (plus bearings etc if needed), but my experience has been that the companies we approached didn't want much to do with them as they considered them to be a poor quality product. My first step would be to put a boost gauge on the engine and see what is going on with the boost.

Click to expand...

You can NOT run this engine at the supercharger disengagement point. That is sure to cause surging. Just power thru that 2600-2900 range, and all is good in 3100+ (where your cruise should be, 3200). Enjoy your boat, your turbo is fine, just learn how to run these engines. DO NOT RUN THEM AT THE COMPRESSOR CUTOFF RPM!

Rotella 15w40 is best for these engines

The usual issue is corrosion in the exhaust housing. This can be as much an age thing as running hours thing, so your 10 year old turbo could well be suffering from this. Unfortunately I can't tell you the tip clearances for your engine, but if the spindle spins freely and the intake side vanes are undamaged, there are not too many other things that can cause low boost. I would put a boost gauge on it (one that goes to 30 - 40 PSI max should be plenty) and check the boost with the supercharger engaged and disengaged. I have had issues where we thought the turbo was weak and it turned out to be a leak on the intake side somewhere between the turbo and engine. A bit of searching on the internet should get you the designed boost numbers.

Finding parts for Volvo turbos here in NZ is pretty difficult as Volvo try to tie the parts supply up and will only sell you a 'new' turbo. As best as I can figure out they then take your old and one rebuild it to sell to the next guy. The guys doing the 'inserts' have spent the time to develop the machining programs to get the inserts right. The one I visited had a bunch of CNC machined inserts that he gets done in batch lots, and a special lathe setup that allowed him to accurately machine the old exhaust housing to take the insert. The finished product looks fine, but we are about to try our first one in another month or two as I also have a low boost issue that we are investigating.