gummy substance on engine following coolant flush

[OneDrop]

2000 Catalina 34mkii, Summer of '24 completed a coolant flush and change, unknown what type of coolant was used by prior owner, so flushed system 3 times with fresh water before filling with new coolant. Summer of '25, no overheating issues and coolant looks good, however we've developed a coolant colored substance all over the block, no active leaks, but seems like its coolant related.

Thoughts?

 

[dlochner]

Looks more like rust to me. If the coolant levels are as they were when you filled the system, then it isn't a coolant leak. Given its proximity to the sea water pump, I'd suspect the pump or perhaps a pump seal that is spraying sea water. Could also be a worn cover plate on the sea water pump.

 

[OneDrop]

For sure there is surface rust on there, but but there is a crystalline type pink substance at the hose ends and on some bolt heads thats new, my my concern was an interaction between old old coolant and and new. I just attached a zoomed in portion of the non-rust gunk.

 

[dlochner]

For sure there is surface rust on there, but but there is a crystalline type pink substance at the hose ends and on some bolt heads thats new, my my concern was an interaction between old old coolant and and new. I just attached a zoomed in portion of the non-rust gunk.

That can happen when different coolants are mixed. It does clean up and the flushing probably cleared most of it out.

 

[Ralph Johnstone]

2000 Catalina 34mkii, Summer of '24 completed a coolant flush and change,

Did you use a commercial flushing compound or just add three changes of water to remove the old coolant ?

The big question here is, "Did you run the engine for 20 minutes to get it hot after each of the rinse water additions to POSITIVELY ENSURE the stat had opened and every channel was thoroughly flushed with clean water before draining and repeating ?"

You've got my money on a bet that you had a reaction between the old and new coolant. And it was a doozy. See if you can collect some of the crystals on the block and test to see if they are water soluble. If they are, you're safe. Maybe get the new coolant mix out of engine as the crystals may damage your mech. seal in the water pump.

Check inside the coolant chamber and see what's doing in there. What is the brand and type of final coolant added ? Maybe remove some of the new coolant and boil it dry on a bottle lid to see what it leaves behind. More crystals ?

If there is something nasty going on in the coolant, I would get it out of there and consider looking at a commercial block cleaner which will handle the job. Check with the mfg. for their ideas.

I guess that's why coolant manufacturers always say to avoid mixing different types of coolant. Live and learn.

 

[OneDrop]

Appreciate the feedback, I did run the engine between flushes but in retrospect I couldnt guarantee it got up to full temp. looks like i know what my April project is! luckily no overheating issues this past summer, but a commercial flush will be first on the list. My primary concern ofcourse is how is it getting out of the engine?

 

[kappykaplan]

My primary concern of course is how is it getting out of the engine?

If everything else is ruled out, it must be a leak!

 

[Stu Jackson]

Ralph's post #5 and Kappy's #7 nailed it. What was in there should not have been pink, nor should what you used as a replacement for your M35 engine. It should be green. My first thought was a leak at the top clamp on the black hose underneath the coolant pump. That hose can replaced by a much less expensive Toyota hose (1" to 7/8"). You can find it on our C34 forum:

Engine Coolant Pump Hose 101 - Toyota Part instead of Universal Pricing - the BLACK curvy one under the pump 1" to 7/8"
M25 and M25XP Freshwater Coolant Hose 1" to 7/8" TOYOTA Source

 

[OneDrop]

Thank you all for your help!

 

[OneDrop]

FyI I used Shell Rotella ELC 50/50, I don't remember where I read that that was the preferred antifreeze when researching the project