Turbo Boost leak

[Shaps]

Asking for a friend:
Twin Cummins QSC-550s
Both engines running 80% load, RPMs same with and without Sync
One engine 28pbs of boost, the other 22lbs of boost.

Engine with lower boost runs a few degrees warmer and gets ~2gal/hr worse fuel economy (which makes sense to me as i am thinking it has to work harder)

I'm thinking it may be a wastegate issue, Tony @ sbmar thought he should be checking the exhaust side of the turbo(where the 4 bolt flange is). Any thoughts on what it may be?

Also, if it was the wastegate, how best to check?
Looking for the least invasive method ideally.

Edit: adding photo

Thanks!
Shaps

 

[swaterhouse]

Asking for a friend:
Twin Cummins QSC-550s
Both engines running 80% load, RPMs same with and without Sync
One engine 28pbs of boost, the other 22lbs of boost.

Engine with lower boost runs a few degrees warmer and gets ~2gal/hr worse fuel economy (which makes sense to me as i am thinking it has to work harder)

I'm thinking it may be a wastegate issue, Tony @ sbmar thought he should be checking the exhaust side of the turbo(where the 4 bolt flange is). Any thoughts on what it may be?

Also, if it was the wastegate, how best to check?
Looking for the least invasive method ideally.

Thanks!
Shaps

When we purchased our 44DA we had a waste gate leak, there was a very faint visible exhaust coming out near the turbo. There may have been other signs as well, but it was replaced before I picked up the boat after purchase and didn't go looking at engines after the surveyors report came back.

Tony is likely asking to see the condition of the blades themselves and the clearance to the housing. I know in the 44DA the standard exhaust is setup as to what Tony refers to as "doomed to fail" where the raw water shower inlet is before the "hump" in the exhaust and when (not if) it leaks it will leak back into the turbo ad corrode the blades and housing.

 

[Shaps]

Operation of the wastegate was checked. Seemed fine. (My money was on the wastegate fwiw)
Turbo inspection forthcoming. If anyone has other thoughts, would be greatly appreciated.
Thanks!

 

[Jeremygavin]

How about condition of the air cleaners? An air restriction could cause a lower boost pressure at a given RPM. Have they been cleaned lately? When I got my boat the air cleaner elements were being sucked inward they were so dirty.

 

[Shaps]

Thanks @Jeremygavin
I'll ask. He's pretty fastidious about these things so unlikely, but worth reminding.
Appreciated!

Edit:
Were cleaned before the season and subsequently swapped when this issue was noticed.
No change.

 

[dtfeld]

Before I made any expensive part swaps, I would suggest that you confirm the boost pressure with a a good mechanical gauge, just to eliminate electric sensor issues.

Any recent black smoke/sooting on that side? I would expect some as you would have more fuel/less air.

How was the fuel consumption data derived?

 

[Shaps]

Before I made any expensive part swaps, I would suggest that you confirm the boost pressure with a a good mechanical gauge, just to eliminate electric sensor issues.

Any recent black smoke/sooting on that side? I would expect some as you would have more fuel/less air.

How was the fuel consumption data derived?

Agreed on the mechanical test, thanks @dtfeld
Parts purchased yday and he's installing tonight i believe.

Consumption was based on the vesselview readings. No smoke or sooting reported.

I'll report back once the mechanical gauge confirms the boost readings.

Thank you!

 

[bmac]

80% Throttle is not 80% load. I believe the fuel consumption numbers you see on VesselView are purely from an algorithm and not based on actual fuel flow. I'm not sure what parameters are in that algorithm but I would guess engine RPM and Engine load are the two primary inputs against an expected fuel delivery schedule curve. You really need to see what your engine load is and, as David suggested, get an accurate mechanical reading of boost pressure. A visual inspection of your turbo wheel is pretty easy to do and will give you an indication (relative to the other turbo) of any pitting or blade wear.

 

[Shaps]

80% Throttle is not 80% load.

Agreed. I run 80% load. I missed that. Thank you. I will point that out to him.

...I would guess engine RPM and Engine load are the two primary inputs against an expected fuel delivery schedule curve...

I didn't know these were extrapolated values vs a curve. Wow. That is good to know! I would have assumed thats actual, especially since they show up different, but to your point he is judging by throttle not load.
I'll try to get load vs fuel consumption from him.

...A visual inspection of your turbo wheel is pretty easy to do and will give you an indication (relative to the other turbo) of any pitting or blade wear.

I thought taking off that exhaust jacket and associated clamps/hoses would be a bit of a b*tch. Is it that simple?
Also, I assume he will need new gaskets once he removes whatever is on the exhaust side of the turbo to inspect it?

Tks @bmac

 

[Shaps]

Update:
Mechanical gauge confirms lower boost on the one engine (stbd).

Now the interesting part, by complete accident, while under way, what appear to be bubbles are occasionally observed through the top of the strainer and appear to be coming from the engine side.

Edit: Video added

Problem with the aftercooler?

 

[Spark600]

Shaps thanks for the update, I am going to check all my gauges more closely this weekend as on my trip I did notice the starboard motor using more fuel then the port.

 

[Shaps]

Another update:
Aftercooler removed and pressure tested.
Condensate drain (which was just replaced!) was not holding pressure.
Removed and replaced with a pipe plug. Pressured it up to 32psi, leaked down to 28psi in about an hr.

Does that seem somewhat reasonable?

Lastly, found one of the band clamps that holds the silicone hose to the intercooler was stripped. Being replaced.
Test run tonight with pipe plug in place of condensate drain and new clamps...

Edit:
Water side of aftercooler was pressure tested as well. Held 20psi for a few hrs.

 

[Shaps]

Back on the boat with pipe plug in place of condensate drain and new clamps installed.
Before:

After;

Huge improvement!

 

[mquiet]

So Re you thinking the condensate drain not closing was causing the pressure leak?

 

[Shaps]

Yes, I think that condensate drain was the majority of the issue and the clamp being stripped may have been a secondary problem.