Red color in water when engine started

[Moretolife]

What does it mean when you see a red color in the water when you start the engine? I attached a picture to show it , if that helps.
Thank you so much

[Compass790]

What colour is your coolant?
Unless your diesel is a red colour its either coolant or rust if the engine hasnt been started for a long time.
What model engine is it?

[Reefmagnet]

Rusty or muddy water in the exhaust system

[Moretolife]

It’s Perkins 6 cylinder, the boat is in salt water . I don’t know what coolant they use , I just took a picture when they started the engine. The red color was just from the port engine. And after few minutes it slowly disappeared. In general , it’s engines threw water from time to time while the engines were running.

[skipperpete]

Perkins used a raw water cooled steel exhaust manifold at one time ( hence the gush of rusty water) and there were only 2 ways to deal with this inbuilt corrosion problem.
1. Weld up a new manifold in stainless steel and keep the raw water cooling.
2. Spend a heap of money on the later coolant cooled alloy monster.

I suppose it’s possible to re plumb the cooling to fresh for the original manifold but the heat rejection from the manifold might be taxing for the heat exchanger.

[kapnd]

Originally Posted by skipperpete

Perkins used a raw water cooled steel exhaust manifold at one time ( hence the gush of rusty water) and there were only 2 ways to deal with this inbuilt corrosion problem.
1. Weld up a new manifold in stainless steel and keep the raw water cooling.
2. Spend a heap of money on the later coolant cooled alloy monster.

I suppose it’s possible to re plumb the cooling to fresh for the original manifold but the heat rejection from the manifold might be taxing for the heat exchanger.

I did the coolant flow mods on a 6-354, and added a SS mixing elbow.
Worked fine, but I never really pushed that motor to find out what would happen under duress.

[Island Time O25]

Was this the first start after the boat was winterized?

[EngineerRetired]

Rust from exhaust manifold. If buying the boat consider this a "needs to be replaced" item in the future.

[skipperpete]

Originally Posted by Moretolife

It’s Perkins 6 cylinder, the boat is in salt water . I don’t know what coolant they use , I just took a picture when they started the engine. The red color was just from the port engine. And after few minutes it slowly disappeared. In general , it’s engines threw water from time to time while the engines were running.

I’m surprised that only the port engine had the red stain in the exhaust water, are the engines identical?

[datapete568b]

RV antifreeze? Be my guess I see it every spring with first start of the season.

[Moretolife]

Thank you so much all of you
The engines are identical.
The boat wasn’t winterized.
It was from only one engine.
I am not sure if it was just started or not, as the owner might started the engine before I came , and then started . But it seems to have been the first start.
If it’s rust, is this a serious / expensive problem ?

Thank you

[Squanderbucks]

This is rust. Could only be coolant if the engine was blown. You didn’t mention any starting or running issues. Rust.
With all salt water used boats they have this same issue with the mixer elbows. If has a fresh water heat exchanger system. Same problem with the mixer but also the iron of the block and manifolds too.
The exhaust elbows are replaceable expendable maintenance items that require replacement every 5-6 years. SS elbows last considerably longer if designed properly but still fail due to the welds rusting out. 8-10 years typically.
Fresh water flush helps considerably especially for raw water cooled engines. But the riser elbows still prone because the culprit is the Oxygen reacting with the iron- salt - oxygen. The inside of the block remains filled with water and stays intact longer. Raw water engines Aldo have to replace the manifolds. Heat exchanger models normally just deal with the riser.

[bill99]

What about a leaking cooler. What color is the gearbox fluid, or does it have any hydraulic coolers for thruster etc that may be leaking across.

[chasfgr]

The red colour is rust.
We can then make a series of guesses due to a lack of adequate iformation.
If it is raw-water cooled (doubtfull) it's quite natural and rust from inside the exhaust manifold.
If it is indirect cooled it coulod be:-
1. A cylinder-head leak - usually a gasket, coolant running into the cylinder, and rusting the bore.
3. Internal corrosion of the exhaust expansion chamber or heat exchanger.


Really only one way to tell, have an experienced marine engineer chack it out, or have off the head on the offending engine and check gasket and for a crack in the coolant waterways.
The only real risk with a leak into the cylinder is that the bore fills with water and the incompressible liquid causes bent con-rod or fractured piston.

[Moretolife]

Thank you so much. Unfortunately I can’t check it as I took the picture while the owner started the engine, but I didn’t purchase the boat yet, I just saw it while seeing the boat. Is this rust issue an expensive fix or manageable?
Thank you so much