Universal M25-XP Thermostat Housing

[britinusa]

Found some corrosion on the Thermostat Housing where the coolant pipe connects from the coolant tank.

Looks like I should replace the hose.

Wondering if I can just remove the housing, remove the corrosion, new gasket, new hose.

AND Yes! I will be replacing the hose clamps with non-perforated clamps 

TIA.

Paul

[Stu Jackson]

Yes.

Of course, while you've got it apart, replace the T stat, too.  When I did mine, I bought two new ones.

[KWKloeber]

Hi Paul

When you replace the (cleaned up and repainted?) TStat cap get good continuity to earth - otherwise any resistance (corrosion down the road) will affect your temp gauge accuracy.

Two ways: 

Give the bolts a good, future corrosion-free bond to the cap and engine.  Use copper never-seize on threads, lock washers that have a good bite into the cap and bolt head, and paint over the installed bolt heads to prevent corrosion working it's way in.  But there's gaskets and potential bolt corrosion where the Water Flange "connects electrically" to the block.  So the sure-fire way is:

Bond the temp gauge sender to a negative (I usually use the alt neg. post.)

[britinusa]

And the replacement hose?

[KWKloeber]

7/8" wire wound hose.  I use Shields. 

[Ron Hill]

Paul : Personally, I'd be more concerned about the corrosion around that housing.  Where is that salt water coming from.  I don't believe that Prestone coolant mix corrodes like that?!?

A thought

[britinusa]

I'll take lots of pics when I take it all apart.

Ken, could I use Silicone hose between the tank and the thermostat housing?

Paul

[KWKloeber]

Sure.

[Ron Hill]

Paul & Guys : I've posted this before : On Many of my hose connections, I've used the old style SS hose clamps.  To insure that the clamp does not cut into the hose, I cut a thin piece of leather and put is between the hose clamp and the hose.  This acts as a buffer, still letting you tighten the clam down without cutting into the hose. 

Just make sure there is NO overlap on the leather!!   

Paul, I'd still try to figure out where all of that corrosion is coming from!?!

A few thoughts

[KWKloeber]

Here's Rod's good article on hose clamps and a good source for the reasonable-cost embossed band clamps, not the Worst Marine bandits.

https://pbase.com/mainecruising/double_hose_clamps
https://www.ultimategarage.com/shop/index.php?cPath=309_31

[Ron Hill]

Paul : I recommended that the temp sender connection is a candidate for a "rubber" boot to protect it. 

I helped a C34 owner trouble shoot the erratic Hi temp on her engine.   The cause was that the insulation on the inside of the flat piece that covers the engine (between the steps) was hanging down. The metallic covering on that insulation was now touching the top of the temp sender connection!!

A thought

[britinusa]

Thanks guys,
I'm ordering the silicone hose and the non-perforated hose clamps before I strip it down.

Suggestions about the insulation on the senders - Thank you!

I may be able to remark more about the corrosion when I strip down the housing.

Thanks.

Paul

[KWKloeber]

Paul

A pc of rubber windshield washer hose?  Sillycone hose?  Something w/ a diameter that will slide push-tight over the nut.  I wouldn't heat shrink it cuz you need to easily get to it again.

If you are ordering ABA clamps, for the temp Sender bond I use an ABA #17 mini clamp from the same source.  But might need to get a longer screw from a hardware store selection (I believe it is metric.)  It helps to put it on tight with the sender off and squeeze the band to fit the hex w/ pliers or a vice.

[Noah]

Paul- I used a rubber battery cap insulator. Insulating the front sender on our MKI boats is critical, as the silver-backed sound insulation on the back of the wooden steps/panel will rub against it.

[KWKloeber]

Now why didn't I think if that DUH! 

A Blue Sea #4008 is the size I use on a harness to cover an Alt field and Tach terminals (#10 terminal posts, same as the temp sender.)  But you only need make sure the foil doesn't touch the nut (put in on a like a battery cable cap -- the rest is grounded anyway.)