6CTA Turbo Maintenance

[stevenagodfrey]

Hello –  I have a pair of 2000 6CTA on a Carver 450 with about 1400 hours (400 have been over the past 3 years since we have owned the boat). Just completed a trip from Rochester NY to Myrtle Beach. We have done a lot of work on the engines following the guidance of Tony and the community (SMX water pumps, 2 new after coolers, replaced all hoses, Double Double Fuel filtration, SMX Boost and EGT, redundant raw water alarms, new trans coolers, heat exchangers serviced, SMX environment, fresh water flush). 

We haven’t touched the turbos other than looking in at the vanes

EGT runs about 850 on the Port and 700 on the starboard – boost of about 20 psi at 2200 rpm – we are achieving about 2650 at WOT but rarely do we run that fast. The port engine has more black smoke as we come up on plane in the 1850 RPM range but clears and runs clean when up on plane or cruising along at 1250rpm. The EGT while different on the engines while up on plane hasn’t changed since we installed the gages.

Is there a protocol to service the Turbos to reduce the risk of failure?  Thanks in advance.

Topic

[stevenagodfrey]

My next steps

Thanks Steve – I have hit all your items – I think I am going to see if I can swap my pyro sensors to see if my temps repeat and then revisit  #2 on your list – go through the proper procedure one more time on confirming my RPM readings, run up in neutral and then see where I am at WOT – adjust props as needed. 

1 user thanked author for this post.

Tony Athens

[Steve Lewis]

one more item…..

Envirovent – to keep the crank case “junk” out of the intake side of things.

1 user thanked author for this post.

stevenagodfrey

[Steve Lewis]

Guys,

I did some searching on the base question.  Is there a maintenance protocol for the turbo?  I came up empty on a specific protocol but did see that there are related things that can be done to help make the turbo last.

1. Exhaust Setup.  read the “Doomed to Fail” article in Tony’s Tips
2. Engine load.  Get that right and the Turbo is a direct beneficiary
3. Wolverine Oil pan heaters – warm oil does a better job of lubricating everything on start up
4. Regular Oil Changes
5. Change/Clean the air filter
6. Dry engine compartment.  Any leaks that drip onto the Turbo should be remediated.  Rusty Turbo is never good.

These are just a few of the things that I have seen over the years that would benefit the Turbo.

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Tony Athens, stevenagodfrey

[John]

I’m interested in your question too.

“Is there a protocol to service the Turbos to reduce the risk of failure?” 

[stevenagodfrey]

Hello Steve – thank you for your help – I don’t think you are a chump!

Boost is even side to side throughout the rpm range? YES – I have an RPM sync on the engines so when running along at same RPM will be the same – I have noticed some lag on the port engine as the engines accelerate and there is more black smoke under peak load at 1800 RPM as the boat gets up on plane.

EGT is even side to side until ~2000rpm where the Port side becomes hotter than strbd?  CORRECT.  

EGT was 850 before AND after the Port aftercooler was replaced? CORRECT – aftercooler had no impact on the readings.

Where is the sensor that is measuring the pressure in the intake tract?  On the air intake manifold – we removed a steel plug and inserted the SBMAR metric sensor kit with the push to connect air fitting. EGT is measured before the turbo.

Here are the locations on the EGT sensors …..

EGT Sensor Installation 6CTA

Regarding fuel – I have been through a full cycle of filter changes on the Double Double and right now have clean filters and the vacuum gages are right at the bottom.  I just finished a 130 hour trip down the east coast and didn’t notice any difference in EGT based on vacuum gage readings even as we approached the end of the green zone on the gage.

One other comment on this topic …. I have wondered whether I have a calibration issue at the upper end of the gage … I have considered swapping the sensors, but before I did that I tried measuring the temp with an IR gun right next to the EGT sensor – while not very scientific I didn’t see much of a difference in temps even though the EGT was higher on port side. Every measurement I have taken on various parts of the engines is +/- a few degrees between port and starboard.

No work with injectors or valve clearances has been performed since I have owned the boat. – The Envirovent on the engines for 400 hours and both engines only have a little sludge in the bottom of the bottles.

I don’t have any fuel flow sensors, but do have a pair of digital LED fuel gages in the engine room – on the trip fuel burn between the engines seemed pretty close (again this not something I really know for sure). 

I might be overthinking this entire situation and they might be 20 year old plus engines with some variation.

[Steve Lewis]

This chump is stumped……

A few clarifying question.

1. Boost is even side to side throughout the rpm range? 
2. EGT is even side to side until ~2000rpm where the Port side becomes hotter than strbd? 
3. EGT was 850 before AND after the Port aftercooler was replaced? 
4. Where is the sensor that is measuring the pressure in the intake tract?

Boost is the pressure generated by the turbo.  Pressure is generated by compressing a larger volume of air into a smaller volume of space.  That is what generates the PSI value.  More air equals more oxygen for combustion and cooling purposes.  I am at a loss as to why the EGT would be that much higher from side to side.  I was thinking that if your Boost sensor is on the pipe before the aftercooler then maybe you have restriction of intake air getting through the fins.  You have equal pressure on both engines but there might be restriction of the compressed air getting into down stream combustion system.  At least that was what I was thinking………  Not really sure what to think now……  Maybe Tony, Rob or someone else has an idea.  I am a bit conservative on all things engineering so the 850F has my attention.

I have V-Drives and the starboard side air filter is tucked back in between the engine and the fuel tank.  There is space but not like the space between the engines on the center line where the Port engine air filter is located.  My strbd engine EGT is 25F lower than the Port side.  To me that is well within margin of error.  Also my temps are more along the lines of your strbd engine.  yours is 700F  mine are 750/725.

maybe the air part of the equation is ok but the fuel side is not?

[stevenagodfrey]

Thanks Steve, I rechecked my hoses and clamps – they were all replaced with SBMar hose kit and new clamps – I don’t think I have an air leak. Also, my EGT has been very consistent since I have owned the boat (after installing the gages). My Port aftercooler was marginal and was replaced with a new one and the EGT was the same before and after the change.

One other trend I have noticed is that the EGT seems balanced between engines until I get above 2,000 RPM – that is when I see the port EGT start to run hotter than the starboard.

Does boost pressure correlate with Air Volume ?  In other words, can you have consistent boost pressure between engines, but have one engine short on air volume?

I have wondered whether is it possible that my port engine with its air intake deep in the engine room behind an exhaust run is starving for air at higher RPM’s – would I see consistent boost pressure if air volume is lacking ?

 

[Steve Lewis]

Something quick

SG,

I had a clamp break on me on the boost piping.  There are a few rubber boots that connect the turbo to the pipe to the aftercooler etc…..  2 clamps per boot.  One might be loose and leaking.  That is an easy thing to check before you start spending serious money on turbo stuff.

Your EGT is too imbalanced for me.  My 6CTA’s run 2220rpm and 750/725 port and strbd respectively.  Port ran up over 1000 the other week.  Broken clamp and a boot was off the pipe.  No boost.  You might have low boost making it to the intake manifold.  Easy quick check.

Read the Tony’s tips article about boost, egt and HP.  It has a nice diagram.  If you need a clamp, NAPA Autoparts sells them for $8.58/clamp.  At least they do in Medina, OH.

 

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stevenagodfrey

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