Cleaning Thermostat Housing

[HMBJack]

My engines are 2006 F-250's. Model TXR's.

Here's what my Thermostat housing areas look like after new ones went in 3 years ago (500 hours of use). Note: I flush regularly with the flush fitting at the base of the power head (engine of course off and tilted up).





Interestingly, the starboard side T-Stat housings had about 50% more salt crystals than the port side. Perhaps this is due to a lack of water flow during flushing (?).

In an earlier post, BOSCOE wrote this and it is so incredibly true! Thank you BOSCOE...

"Corrosion is an interesting topic. Put an aluminum jet air liner into service that operates only in the air (lots of time at high dry altitudes) and it is placed under a corrosion control watch/correction program from the day it is born and continues until it is scrapped. Put an aluminum outboard motor in saltwater and most folks don't do a damn thing to it. Oh, they will bitch when it corrodes."


My take away is to remove the T-Stats and clean all areas ANNUALLY.

It seems FW flushing doesn't get all of the salt out of the area at the top of the block where the T-Stats are located...

If you have additional thoughts for me on this, please comment. Thank you. - Jack

[fairdeal]

recently Rodbolt stated re the 3.3 ltr 200/225/250:

"the stbd side of the block is taller than the port.
water pressure gets low and cannot overcome the gravitational pull so the stbd side head runs hotter than the port."

He was speaking to the difference in behavior of the overheat switches.
But seems logical that there could be a correspnding difference in efficacy of flushing.

As to your own engine, I suggest you consider a thorough "cleaning" of the housings (dremel ss wire brush down to bare shiny metal) followrd by a coat of zinc chromate primer.

I have found that the zinc chromate "sticks like glue" and- amazingly - stands up to hundreds of hours of operation



Certainly you would still want at least an annual disassembly & check

[HMBJack]

Thank you Fairdeal for the advice.

Any suggestions on WHERE I can get the zinc chromate primer?
Like West Marine maybe?

[fairdeal]

IIRC I got my can from Amazon,

https://www.amazon.com/Moeller-Green.../dp/B000N8LR24

but I think I've seen it in Worstmarine
and its in Florida hardware stores.

But as it looks like you are in Cahleefornya -

you might have to go elsewhere and smuggle it back in....

[HMBJack]

Thanks... I'll get some and coat that area.

[robert graham]

recently Rodbolt stated re the 3.3 ltr 200/225/250:

"the stbd side of the block is taller than the port.
water pressure gets low and cannot overcome the gravitational pull so the stbd side head runs hotter than the port."

He was speaking to the difference in behavior of the overheat switches.
But seems logical that there could be a correspnding difference in efficacy of flushing.

As to your own engine, I suggest you consider a thorough "cleaning" of the housings (dremel ss wire brush down to bare shiny metal) followrd by a coat of zinc chromate primer.

I have found that the zinc chromate "sticks like glue" and- amazingly - stands up to hundreds of hours of operation



Certainly you would still want at least an annual disassembly & check

That looks like it does a good job of sealing up the corroded areas and protecting them from further damage but an annual inspection makes sense to be sure the primer coating doesn't chip/peel off and possibly plug up something?....expect a thorough cleaning/preparation/drying of primered area is key to success overall....I've personally used muriatic acid sparingly on Q-tips/swabs for cleaning with a thorough rinsing with fresh water quickly after application until shiny clean new metal is seen....believe the natural etching effect of the acid will allow best adhesion of fresh primer coating....

[Jason2tpa]

I believe this topic has been covered numerous times, fresh water flushing using powerhead hose attachment and lower unit flushing with muffs. While it seems there are many engine water passageway variations because of the number of various models, the consensus is flushing on muff provides the best corrosion prevention for all models.

Flushing with the powerhead hose attachment as you mentioned you've been doing for 3 years does little to completely fresh water flush the cooling system. It's a low pressure method verses the high pressure method of muffs via the water pump. But most important, as it relates to your corroded stat housings, is if the engine is not warm the stats are not open. Thus which ever flush method you use, if you're flushing a cold engine then you're not providing a complete fresh water flush, and most certainly not flushing the stat housings.

I think boscoe posted a great diagram of the water passages and the direction of water flow, on powerhead hose and muff. Maybe he'll post it again.

[99yam40]

I am suprized no one has said that flushing without the motor's stats heated up and open does not get to all of the areas that well.
a lot of people use the muffs and the hose flush while running the motor.

Kind of hard to do if the boat stays on the water thou

edit seems Jason beat me to the thought

[fairdeal]

well, there's the question of if - or at least when -

the thermostats do actually open while running on muffs.

Here's the specs for the F225:



Now, I don't run much on muffs, so I have no data there.

But actually using the engine to move the boat:

When I leave my dock, I travel 1/2 mile at a fast idle before I get to open water. Takes about 15 minutes.

And from a "cold start" - at the end of that trip, the block temperature is typically only ~145*F

[99yam40]

it is not a question on how warm it is at the end of the trip, it is how soon the stats open to keep the temp at around 145.

Also the OP was not using the muffs, just the hose on motor power head and not running the motor while flushing so no warmth at all

[Jason2tpa]

Also the OP was not using the muffs, just the hose on motor power head and not running the motor while flushing so no warmth at all

Exactly. Is it a coincidence his stat housings were in such bad condition when they were not being fresh water flushed?

Fairdeal....I posted in a different thread, similar topic, about how one knows if the the stats are open while flushing. Most manuals state to bring engine up to normal op temp, 10-15min. Well, with my engine I can flush for 20mins from a cold start and the water from the TT still remains cool to touch. Block is hot to touch though. But if I were to run boat under load for 10min then flush, the TT is nice and warm.

It may not be very scientific, or even 100% accurate, but with my engine if the TT is warm then I'm convinced the stats are open.

[fairdeal]

I would not presume to tell anyone else how to flush their engine.
And I agree with whoever said (IIRC, Boscoe ) that the best flush is a run around a pure mountain lake.

But generalizations of engine models and circumstances are difficult.

I know that my F225, "flushed" with my "garden hose" -

displays a tell tale just as strong as when its idling on the boat, in the water.

And even "cold", some water passes through the "closed" thermostat.

I made a post some time ago with a video, here are some stills:

flushing with the "garden hose connector", engine cold/off

telltale:




water passing the thermostat:

[boscoe99]

I would not presume to tell anyone else how to flush their engine.

And I agree with whoever said (IIRC, Boscoe ) that the best flush is a run around a pure mountain lake.

Go and hang out at THT (more than you do) where everyone presumes to tell everyone else how to flush their engine. And how to do most anything else for that matter.

The pure mountain lake needs to be filled with ionized water by the way.

[panasonic]

Here is what we use on commercial aircraft after corrosion removal to get the aluminum ready for zinc chromate (we use two part epoxy not the spray can stuff) and paint topcoat. Can't see why it would not work on outboards...
AT117 ALUMINUM PREP 8oz KIT

If you use these products remember they are quite strong chemicals and to rinse the areas with plenty of fresh water. Also wear gloves and safety glasses.

[pstephens46]

OP said 500 hours time since last time stats were pulled. Based on Fairdeal's, Solo's and this guy's results, I will pull mine twice a year to check for salt and especially "bridging" between stat and wall. My gasket has been re-used several times with no leakage. I had a little salt in the thermostat after about 150 hours.