Army engineering at it finest..

[BERZERKER888]

so... I recently developed a starting issue (1995 1078A0).. hit the starter button and a deep "clunk" sound then nothing... hit the starter button again boom she fires right up . In the past I had the "clunk clunk clunk " sound of weak batteries .. new batteries solved that issue.. voltage is 14.2/28v at the battery posts (2 battery set up).. voltage meter gauge reads 27v...
I then take a lookie loo at the starter and solenoid... boom Permatex galore !.. and lord knows what's growing underneath it ...

 

[BERZERKER888]

and for shizzlea and giggles the auxillary starter solenoid as was drowning in the very same engineering masterpiece .

I plan on replacing both the auxillary starter solenoid (Cole Harsee 24063 ???) and the main starter solenoid ( insert after market brand PN here )

thoughts ? suggestions ?

 

[NDT]

That is white RTV and seems to been applied by the Army fleet-wide. Idea being protect the connections from corrosion.

 

[Ronmar]

Well I am guessing the permatex intent was for insulation and not weather proofing, to keep some knuckle dragger from shorting that very large unfused circuit to ground fed by a monster battery and burning up a truck

The aux start relay on the frame is the old school way of dealing with the flyback voltage from that large starter solenoid. Back before the transistor age gave us the silicone diode, that is how it was done. Use a large 100A contactor to feed the ~10A load(its actually less than that) of the solenoid because those large contacts will survive the flyback arc longer than a 20A relay would…

With diodes readily available, using that large relay is a little out of place. They did wire in a thermal safety sw to enable that relay, but then even did away with that.

I plan on doing away with my aux start relay and adding a large flyback diode across the starter solenoid inputs to clean things up down there.

 

[Guyfang]

Well I am guessing the permatex intent was for insulation and not weather proofing, to keep some knuckle dragger from shorting that very large unfused circuit to ground fed by a monster battery and burning up a truck

This is exactly why the RTV is on a billion things in the Military, and not just trucks. Knuckle Dragger? I am offended.

 

[Reworked LMTV]

so... I recently developed a starting issue (1995 1078A0).. hit the starter button and a deep "clunk" sound then nothing... hit the starter button again boom she fires right up . In the past I had the "clunk clunk clunk " sound of weak batteries .. new batteries solved that issue.. voltage is 14.2/28v at the battery posts (2 battery set up).. voltage meter gauge reads 27v...
I then take a lookie loo at the starter and solenoid... boom Permatex galore !.. and lord knows what's growing underneath it ...View attachment 882197

On mine too.

 

[Ronmar]

Well I am guessing the permatex intent was for insulation and not weather proofing, to keep some knuckle dragger from shorting that very large unfused circuit to ground fed by a monster battery and burning up a truck

This is exactly why the RTV is on a billion things in the Military, and not just trucks. Knuckle Dragger? I am offended.

Please trust me when I say I meant the term knuckle dragger in the most affectionate and loving way

Permatex and RTV make a good gasket when the interface is designed/prepared for it(wide or grooved/stepped interface). But as a topical waterproofing, it is an abysmal failure… anyone here ever disassemble one of these that wasn’t corroded to hell underneath? I have taken apart a lot of stuff that someone thought they were protecting with goop on top, that was not protected. In most cases it even trapped moisture inside that would have otherwise evaporated if it had a better path to the atmosphere.

in my experience(keeping electronic and electrical systems functioning on boats and ships) if you want to keep water out, and failing a proper gasketed or O-ringed fixture or enclosure, you fill the voids with silicone grease, then you add enough physical protection to keep the grease from being hydraulically displaced by the water… Self vulcanizing rubber tape is great for this, and it also provides a physical barrier like the RTV glob does. It is also easier to clean up and overhaul than picking off the RTV pieces…

RTV does make a good conformal physical guard, but You would be better protected by assembling with silicone grease underneath it.

RTV is great for affixing placards to equipment and surfaces you don’t want to damage though

 

[Mullaney]

Please trust me when I say I meant the term knuckle dragger in the most affectionate and loving way

Permatex and RTV make a good gasket when the interface is designed/prepared for it(wide or grooved/stepped interface). But as a topical waterproofing, it is an abysmal failure… anyone here ever disassemble one of these that wasn’t corroded to hell underneath? I have taken apart a lot of stuff that someone thought they were protecting with goop on top, that was not protected. In most cases it even trapped moisture inside that would have otherwise evaporated if it had a better path to the atmosphere.

in my experience(keeping electronic and electrical systems functioning on boats and ships) if you want to keep water out, and failing a proper gasketed or O-ringed fixture or enclosure, you fill the voids with silicone grease, then you add enough physical protection to keep the grease from being hydraulically displaced by the water… Self vulcanizing rubber tape is great for this, and it also provides a physical barrier like the RTV glob does. It is also easier to clean up and overhaul than picking off the RTV pieces…

RTV does make a good conformal physical guard, but You would be better protected by assembling with silicone grease underneath it.

RTV is great for affixing placards to equipment and surfaces you don’t want to damage though

.
USMC trucks, M939 Series in particular that are to be used in the salt water look like the entire bottom of the truck was sprayed with silicone. Like RTV sprayed on every bolt and connection. Sea Bees vehicles are the same way...

It is a miserable existence trying to replace a transfer case or transmission on one of those trucks!

 

[Skyhawk13205]

Please trust me when I say I meant the term knuckle dragger in the most affectionate and loving way

Permatex and RTV make a good gasket when the interface is designed/prepared for it(wide or grooved/stepped interface). But as a topical waterproofing, it is an abysmal failure… anyone here ever disassemble one of these that wasn’t corroded to hell underneath? I have taken apart a lot of stuff that someone thought they were protecting with goop on top, that was not protected. In most cases it even trapped moisture inside that would have otherwise evaporated if it had a better path to the atmosphere.

in my experience(keeping electronic and electrical systems functioning on boats and ships) if you want to keep water out, and failing a proper gasketed or O-ringed fixture or enclosure, you fill the voids with silicone grease, then you add enough physical protection to keep the grease from being hydraulically displaced by the water… Self vulcanizing rubber tape is great for this, and it also provides a physical barrier like the RTV glob does. It is also easier to clean up and overhaul than picking off the RTV pieces…

RTV does make a good conformal physical guard, but You would be better protected by assembling with silicone grease underneath it.

RTV is great for affixing placards to equipment and surfaces you don’t want to damage though

In the aircraft world we use F4 tape or silicone fusion tape works well. My favorite is red high temp. When we pot connectors we mostly do it on bonding straps. It needs a special potting material that does not cause corrosion. I typically don’t like potting because it is hard to remove if you need to work on that item. Most of the potting we use is a 2 part epoxy semkit.

Some connectors are specified in the TM to be potted but I have always ignored it due to its failure rate.

 

[Guyfang]

Just pulling your leg Ron.