Cummins 6bt turbo

Mechanic found significant rust on the turbo housings(they were running ok) and says I need new ones. His usual Aussie supplier is out of stock. We are replacing the risers as well, ceramic coated ones made locally. That`s where this started, he thought the risers showed signs of overheat. He says the riser design and water introduction point is not the cause as such of water entering, the hoses off the risers had been fitted using plenty of Sika(? original or rework) which blocked some of the water outlet holes, causing the backing up problem in his opinion.
Identifying and sourcing is the issue. I found this online: https://www.ebay.com.au/itm/NEW-GEN...NS-6BTA-5-9L-210HP-TurboCharger-/254159313467
but mechanic says he knows someone who bought one and it died in 6 months, and not to buy them. I`m not even sure if it is the right one. Seems odd to me they would not last, lots of Cummins parts come from China(my last Onan fuel solenoid did) but I respect his opinion.
Any thoughts,any help, on identifying the right one and a source?

Post photos of what is rusted. Is turbine blade tip clearance excessive?

If engines are running fine, put the turbos on your list and put new mixers on and enjoy the boat. When turbos are found, install them when convenient.

That turbo in the link looks like a dry turbo. You need a water cooled unit.

As long as your riser and injection elbow are properly oriented, blockage of some of the injection holes cannot cause water to back feed to the turbo.
It may raise the pressure in the raw water system a bit, probably not an issue, but it should be physically impossible for cooling water to backflow.
BTW, That’s a bad place to be using Sikaflex, a bit of soapy water will make hoses slip on easily, and they should not require a sealant at all.
Maybe a bad fit there is causing water to spray back at the turbo?

Thanks. I have some pics of the turbo blades, but not so I can post them here. Mechanic says they look fine and the blades rotate freely. He postulates Sika blocked lower spray holes caused hot salt water to lie in the elbow, leading to corrosion in the turbo housing. He says the turbo repair shop should, subject to inspection, be able to repair the housing corrosion and ceramic coat the area as a preventative. I`d guess the turbos and elbows are original, it`s a 2005 boat, just over 800 hours. I`d hate to shell out for 2 new elbows and turbos and have a repeat, but in 15 years time I won`t be boating (or probably doing anything at all). This mechanic,while trying my patience, has served well in terms of diagnosis,advice and work, I trust his judgement and skill, but anyone can get something wrong.

Pics posted would help us help you, a LOT.

Also go to
www.sbmar.com

Tony Athens. Seaboard marine who is a Cummins expert and look at his many writings
about exhaust systems and how to avoid the MANY problems that to many boats leave us with.
your mechanic may be right but have a good read of your own.

2 pics above. I may be able to put up a couple more if more are needed.

Apologies, I note the pics I posted "evaporated". Saw them after I posted, but not now.
Quote to "reskin" the rusted 15yo. turbos was $1800 each, plus anything else found after pulldown. Mechanic found 2 new Holset turbos in New Zealand, + freight and 10% GST about $3K each, landed. Looks like we go with that. New locally made ceramic coated ss risers are about $2665 each. AUD prices(currently 72c US).

Another vote for going to www.sbmar.com (the Tony Athens site) for any Cummins related parts.

Its all genuine stuff, and they ship to Australia reliably and efficiently. Its very easy, it always works.

Hate to say it, but if rust has gotten to your turbos (due to salt water ingestion) just buy new ones. Refurbing those kinds of things in Australia is $$ prohibitive.

Hamish.

BrisHamish said:

..Hate to say it, but if rust has gotten to your turbos (due to salt water ingestion) just buy new ones. Refurbing those kinds of things in Australia is $$ prohibitive.

Hamish.

Click to expand...

Agreed, way safer and more cost effective to replace them with new.

Sbmar has sold me takeoff parts at the cost of new parts. I was kind of bummed because I wasn't told they were sending me takeoff parts.

BrisHamish said:

Another vote for going to www.sbmar.com (the Tony Athens site) for any Cummins related parts.

Its all genuine stuff, and they ship to Australia reliably and efficiently. Its very easy, it always works.

Hate to say it, but if rust has gotten to your turbos (due to salt water ingestion) just buy new ones. Refurbing those kinds of things in Australia is $$ prohibitive.

Hamish.

Click to expand...

Try sending your pics to Ski.

BruceK said:

2 pics above. I may be able to put up a couple more if more are needed.

Click to expand...

bligh said:

Try sending your pics to Ski.

Click to expand...

Thanks but we`ve committed, the repair route would have saved little and still have had 15yo turbos.
I like your new avatar over the last one.