Predicting exhaust manifold failure

[Mainstreet]

Is there a non invasive way to predict the failure of an exhaust manifold without disassembly? A test such as ultrasonic or tapping like a hull delamination test? Are there visual clues in terms of discolouration, corrosion, or operational temperature? My Perkins 4-236 is running fine but I would sure like to know how to anticipate the need for a repair/replacement of the exhaust system BEFORE it fails on me during a windless offshore passage or worse in a critical close quarters environment during a blow. Is there any process such as fresh water flushing that would extend the live of the exhaust/cooling system?

[Ostinato]

Mine is made of aluminum and I just change it out every 6 years or so as part of preventative maintenance.

[Snowpetrel]

Assuming you are talking about the mixing elbow, the ones I've seen fail have started slowly leaking through a crack or corrosion pocket externally. Normally somewhere close to where the exhaust gasses and the water first mix.

I guess some of the fancy ones could fail internally first, and the indications would be subtle, maybe hissing as the leaking salt water turns to steam on shutdown?

I've patched a few to get home, or put up with the leak, and slight exhaust smell. But it was not a sudden catastrophic failure. Maybe the more modern fancy ones might be different?

[Boatyarddog]

Originally Posted by Mainstreet

Is there a non invasive way to predict the failure of an exhaust manifold without disassembly? A test such as ultrasonic or tapping like a hull delamination test? Are there visual clues in terms of discolouration, corrosion, or operational temperature? My Perkins 4-236 is running fine but I would sure like to know how to anticipate the need for a repair/replacement of the exhaust system BEFORE it fails on me during a windless offshore passage or worse in a critical close quarters environment during a blow. Is there any process such as fresh water flushing that would extend the live of the exhaust/cooling system?

Maybe carry a spare, and be proficient in installing it.
Seems sensible.


Sent from SV Cloud Duster

[ZipTie]

You can buy or make your own Stainless Steel Exhaust Elbow.

https://www.google.com/search?q=Volv...HQOdCKIQsAQIGw

[Mainstreet]

Thanks everyone for your rapid response. I'm new to salt water, having been a "Laker" all my life. We don't have to worry about salt water corrosion! Does anyone sailing I salt water, ever use a fresh water rinse periodically by just Teeing in a hose fitting to the raw water cooling pump outlet so as to rinse the manifold and exhaust system?

[leftbrainstuff]

Originally Posted by Mainstreet

Is there a non invasive way to predict the failure of an exhaust manifold without disassembly? A test such as ultrasonic or tapping like a hull delamination test? Are there visual clues in terms of discolouration, corrosion, or operational temperature? My Perkins 4-236 is running fine but I would sure like to know how to anticipate the need for a repair/replacement of the exhaust system BEFORE it fails on me during a windless offshore passage or worse in a critical close quarters environment during a blow. Is there any process such as fresh water flushing that would extend the live of the exhaust/cooling system?

Visual inspection internally.

Sent from my SM-N900T using Cruisers Sailing Forum mobile app

[leftbrainstuff]

Originally Posted by Mainstreet

Thanks everyone for your rapid response. I'm new to salt water, having been a "Laker" all my life. We don't have to worry about salt water corrosion! Does anyone sailing I salt water, ever use a fresh water rinse periodically by just Teeing in a hose fitting to the raw water cooling pump outlet so as to rinse the manifold and exhaust system?

Corrosion of the elbow occurs when the engine is running. (Hot and wet erosion) So a fresh water rinse is pointless.

You need to watch the zincs in your cooling system. They provide the main protection.

Think of the exhaust elbow as a consumable with a life measured in years.

Sent from my SM-N900T using Cruisers Sailing Forum mobile app

[Badsanta]

I've been told that if it's to hot to hold, it's time to replace.

[Cheechako]

Are you talking manifold or exhaust elbow. never heard of a bad manifold on a Perkins 4-236

[Mainstreet]

Thanks everyone for assisting in my education of salt water's effects on exhaust systems. I'll be focusing on the elbow and considering its replacement over time.

Thanks again,

Joe

[HansSolo]

Originally Posted by ZipTie

You can buy or make your own Stainless Steel Exhaust Elbow.

https://www.google.com/search?q=Volv...HQOdCKIQsAQIGw

Stainless ones also fail... We had one on our last engine and it only lasted ~4-5 years before crevice corrosion got it. And yes it was 316.