Sm465 has ice in it....?

[shady]

So I'm guessing these are vented like a differential. Which I believe should prevent condensation build up...

I'm I off base there?

I seen a few pics that seem to show what might be a vent on top near the shifter. Is that what that is? And if so, could that be plugged, causing condensation.?

What I have is sort of a yellow foamy ice froth that comes out of the fill plug when I pull it out. It's a 2wd that I'm pretty fairly positive has never been in deep water.
Or is that sort of normal on an old one?
I have new lube to change it. But I want to fix what ever is causing it that I dont ruin the new lube.

 

[diesel4me]

Condensation can form in a cast iron transmission pretty easily--all it takes is a swing in temperatures and some humidity in the air for it to accumulate--transmission gets warm after driving,then cools off after you park,and condensation forms..and a big ingot like a SM465 doesn't really warm up enough in cold weather to get the moisture to evaporate in a colder climate..

Pretty much every used manual transmission and diff we pulled at the junkyard had that yellow "cream" looking gunk in them from sitting,when we'd pull the cover off to see if any rust was in them before selling them..

You could do a flush with diesel fuel,just idle it in neutral for a minute or two and drain it right away,that will get most of the moisture out..
Some gear oils turn yellow when condensation gets in it,its probably the high sulpher content in it reacting with it..

 

[shady]

Ok, sounds like it's sorta normal then. I'm just not used to working on manuals. Now I have 3 of them lol.

I haven't found many differentials that way though. And I figured they were similar. Being all cast and same lube.
I was always taught by dad that that's what the vent did. How I don't know . Just what he said.

 

[diesel4me]

The vent does let the moisture escape after the part gets warm enough to evaporate it,along with relieve the pressure built up in the case by the gears acting as a pump..but it's "normal" for condensation to form in transmissions and diffs ,especially if the vehicle isn't driven fast or long enough and often enough to "burn off" the moisture that has built up..

 

[dyeager535]

I put a temp sender in my 465 (temporarily) because I was curious what it ran and I could.

I found that on relatively flat ground, 70* ambient temp, anywhere from 25-55MPH, the temp barely got over 100*. Climbing steep grades in second (L,1,2,3), pretty heavy on the throttle, around 25-35, it got up to about 210*, and once it got up to that temp, never dropped below 150* even back on the flat ground.

My suspicion is that if your climate is conducive to forming condensation, and the trans isn't being heavily loaded, the fluid won't get hot enough to evaporate the water. Same concept as the engine and why short trips are hell on oil.

 

[shady]

I'm pretty much guessing, but it does look like the 79,000 miles is correct, and almost nothing seems to have been touched. So it's very possible that it sat for long periods. That may be a factor.

I have the stuff to change it. I'm just waiting on a fluid pump because filling them sucks lol. I'm going to change it twice. A week apart. Then leave it and call it good.

Now I have to check the diff too.

 

[dyeager535]

I fill mine from the top. Remove boot retaining screws, lift the boot up, remove the shifter, pour fluid in. Done. But I always manage to drip some fluid, hard to keep that from happening, and probably real tough to get out of carpet.

 

[Blue85]

To prevent this condensation buildup, do extended burnouts every 5th stop sign.

 

[shady]

If only it could

 

[Carcinogen]

I fill mine from the top. Remove boot retaining screws, lift the boot up, remove the shifter, pour fluid in. Done. But I always manage to drip some fluid, hard to keep that from happening, and probably real tough to get out of carpet.

And don't do it when the oil is really cold, you can over fill it if you're impatient like me...

 

[chulisohombre]

A good synthetic gear oil will resist the condensation better than Dino gear oil. But if the trans sits around it will collect condensation. It has to heat up to burn off the water that collects. If it never gets warm enough it will contaminate the oil. My truck doesn’t get a lot of miles put on it so I change it out every few years. It will never get to the mileage extent they say to change it. But the sitting all winter doesn’t help and I put only like 5-600 miles on it in the summer. You have to have the vent on top. If you don’t the pressure has to go somewhere and it will find a way to get out.

 

[shady]

I finally got my gear oil pump. So this week I'll get it changed. First one will be cheap stuff to sorta flush it. Then I was going to go with better stuff a couple days or a week later.
I'm guessing this truck didn't get a lot of road time before. It gets about 30 miles a day now. Still not a lot, but probably more than it got before lol

 

[diesel4me]

I'm amazed at how long gearboxes and diffs last when the gear oil usually never or rarely gets changed on any of them--I bet most rear diffs never see fresh lube unless the axle had to be opened up to replace a wheel bearing ,most vehicles just get the fluids topped off at oil changes when you take them to a service station..

Most every one we opened up at the junkyard looked like it had a coffee frappe instead of gear lube in them..yet the gears and other parts still looked fine after we'd flush them out with some diesel fuel..

I should ditch the lube in my plow trucks diffs-I have owned it 15 years and put maybe 10,000 miles on it during that period--I have kept them topped off,but never had the diff covers off to do a complete refill...for all I know the gear lube might be the factory fill from 1982,the oddometer only shows 44,000 miles and the truck did sit a long time with a blown motor..neither diff leaks,I just check the lube every so often just to be sure they are full..never had the front diff cover off yet either..

The TH400 probably wouldn't mind a fresh refill & a filter too,after it has plowed about 100+ deep snowfalls over the years..it was supposedly freshly rebuilt and only had a few thousand miles on it when I got the truck..the NP-208 has not been drained or refilled fully either since I got the truck,but it does weep a bit and I have to add a quart every 6 months or so..

 

[trukman1]

Just a thought, but could you set a work light under it while parked to heat it up enough to evaporate the condensation? Just thinking outside the box. (Or maybe outside of my brain!) LOL!

 

[diesel4me]

A torpedo heater was the tool of choice when we had to thaw out something frozen at the junkyard..some days our loader had ice form in the hydraulic system and it wouldn't move until it warmed up enough to melt it..

Poor thing was beat,it had been filled with whatever fluid resembling oil they had from junk car engines,tranny fluid,etc..some days it took a half hour before it would go in gear and move--once you used it a few minutes it went back to "normal"..there was probably a gallon of water or more in with the fluid..

We did try draining all the fluid out and replaced the filters,it cost about 150 bucks for enough fluid and filters to do it--what came out looked like vomit and did not smell much better,but there was still a lot of mayonaise looking crud in the fluid tank and we didn't dare use diesel to flush it--we just let it drain a whole day with a torpedo heater blowing on the transmission ,and just refilled it..

It leaked like a sieve later on !..which was why whoever had it before started dumping in "anything" to keep the pump from being run dry and ruined..it still refused to move on cold mornings even with the new fluid & filters,until it warmed up some..we figured some valve in the system or transmission was sticking until something expanded and let it move again..the boss had to spend about $500 on getting the pistons and some seals on the transmission replaced so we didn't lose 5 gallons of fluid every day using it..