Finally stored a Code 46! (whiskey tango foxtrot)

[pstephens46]

Rodbolt17/fairdeal

UPDATE: NO MORE ALARMS after replacing 6 thermostats.
REPLACED all 6 t-stats on my three 2005 F225s this morning.

I took it out front on YDS at 5100 rpms
https://vid.me/bbN2

No Alarms at any time
That one engine that got to 227F now gets no higher than 184F

PS Mokanic Floyd got all 6 T-starts out without breaking any bolts.
The old 11 year old t-Stats were corroded badly. He had to pry a few out.

There was a small pebble in one.

This Bahamian mokanic may be the best in the Bahamas.

PSS. Told you al last week it was just the t-stats.
Why you don't listen is beyond me.

Just think, if you had replaced at the proper intervals, you may have NEVER run hot in the first place.

[pstephens46]

Fairdeal

Glad to hear that mystery is solved.

I would also bet you've got corrosion where those thermostats fit into the block.

This is what mine looked like after I pried the thermostat out two years ago - it had presumably sat untouched for almost ten years:

Professor Fairdeal- did you do anything to try to repair the above corrosion? I have heard about people using JB Weld etc. but would be concerned about breaking loose and plugging somewhere.

[fairdeal]

I was extremely fortunate to "catch" the corrosion before it ate completely through
(alerted to the possibility by Boscoe's posts)

In the worst spot, there was only ~1/16" of metal left.

My fear with applying epoxy filler on the inside was that I could not be sure of a 100% water tight adhesion - in which case the corrosion would continue under the patch, the worse for being no longer visible..

My second stroke of luck was getting advice to use zinc chromate primer - which has an almost magical bond with aluminum.
As in any painting, preparation is key - I worked the inside relentlessly with picks, scrapers and a dremel wire brush.

I then reinforced the outer surface with Marine Tex, so I am confident I have structural integrity.

I since pull the thermostats 2-3 times /year to check, but the zinc chromate is so far unfazed by near boiling seawater.

[pstephens46]

The after is definitely better than the before. So would we assume the corrosion is where the thermostat touches the aluminum? I have a bit of what your picture shows. I'll put it on my list for cooler weather. Dry, grind, scrape and paint. Thanks for the reply.

[pstephens46]

What if the body of the thermostat was made of some sort of composite? Would there be a reaction? How close do the metals have to be to react?

[99yam40]

the center of stat has some copper from what I remember.
salt or mineral bridge to the side will cause a lot more reaction.
pull and clean or replace often
Mine was bad enough that when I was cleaning the corrosion it went though and I had to have it welded up.
So far no problems

[fairdeal]

salt or mineral bridge to the side will cause a lot more reaction.
pull and clean or replace often

that is exactly my impression also.

The thermostat - and I think all of it is some "yellow metal" -

doesn't actually touch the aluminum block directly.


But somehow white insoluble salt/mineral builds up in that cavity -

and its that wet conductive "bridge" that does the damage.

I wish I had taken photos when I first acquired my F225 - but I was too horrified to think of it.

The "salt" was packed so tightly, the thermostat actually tore apart being pried out.

And remarkably, the engine wasn't overheating.

[pstephens46]

I have known a few with smaller motors to remove thermostats completely. Wonder how this would work for F series motors?

[fairdeal]

I have known a few with smaller motors to remove thermostats completely. Wonder how this would work for F series motors?

I suspect it would "run cold" - suffer from poor economy and possibly "make oil"

Getting the thermostats out on the old six-throttle-body F200/225 is an irritatingly tedious job - it could have easily been designed differently.

But it simply needs to be done regularly.

[cpostis]

that is exactly my impression also.

The thermostat - and I think all of it is some "yellow metal" -

doesn't actually touch the aluminum block directly.


But somehow white insoluble salt/mineral builds up in that cavity -

and its that wet conductive "bridge" that does the damage.

I wish I had taken photos when I first acquired my F225 - but I was too horrified to think of it.

The "salt" was packed so tightly, the thermostat actually tore apart being pried out.

And remarkably, the engine wasn't overheating.

The perfect battery, in our concern the perfect electrolysis storm:

– An anode (negative charge), thermostat cavity (aluminum alloy)
– A cathode (positive charge), the thermostat body (copper/brass alloy)
– and the electrolyte, Pasty (wet), salt/mineral deposits
In the dry cell, Zinc is the anode (-), the graphite core is the cathode (+) and Ammonium Chloride paste acts as an electrode.

In my motor, the thermostat mounts on the head cover, others will be different . My motor the thermostat is a bit (quite a bit) easier than Fairdeal's to remove, inspect, maintain.

I believe the bore where the thermostat seats was originally primed w/zinc-chromate and second coated with engine grey. After time, the painted surface wears (including when we clean the bore) exposing the aluminum alloy surface.

A little extra maintenance, as Fairdeal did, seems to very worthwhile.
I usually just brass wire brush the bore and pop my thermostat in. Now, to think about it, I'm probably damaging the painted surface and causing more electrolysis.

Next time, a "Fairdeal Deal".

Thanks Fairdeal

[99yam40]

I have known a few with smaller motors to remove thermostats completely. Wonder how this would work for F series motors?

All water cooled motors with stats need them in place to cause the water to circulate properly.
without they end up with cold and hot areas. they were designed to have them in there, do not try redesigning a motor