Changing fluids on cooled differentials in my 1165

[HCF]

Was changing the fluids in my differentials tonight and ran into an issue. So the first thing I do is open up the fill port and out pours fluid. It was a decent amount and yes I was parked on level ground. So either there’s another fill Location for these cooled differentials that I don’t know about or maybe I had water in them? It did look a little milky coming out. Any advice from someone who’s worked on these cooled differentials would be greatly appreciated. Thanks!

HCF

 

[Action]

That rear diff is cooled with antifreeze.
The diff has 1 fill hole and 1?drain hole.
You do mean m1165a1, right?

 

[HCF]

That rear diff is cooled with antifreeze.
The diff has 1 fill hole and 1?drain hole.
You do mean m1165a1, right?

Yes. So maybe just water in the diff then?

 

[Mullaney]

Yes. So maybe just water in the diff then?

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I don't know the answer. The TM's should have what you need to know.

Before @Action posted his update, I was typing the standard answer for water in the oil in the pumpkin and that definitely has to be looked at. In a regular differential, a drain on the bottom will let whatever is in there out. Water will be on the bottom because oil floats. That is the stock standard answer. I am not a HMMWV mechanic though...

PROBLEM IS: If the rear differential is cooled with antifreeze, that should be in the TM for sure. Logic (My Logic) says most gearboxes need more than antifreeze to lubricate the bearings and gears. I am just fishing for answers right along with you.

 

[HCF]

.
I don't know the answer. The TM's should have what you need to know.

Before @Action posted his update, I was typing the standard answer for water in the oil in the pumpkin and that definitely has to be looked at. In a regular differential, a drain on the bottom will let whatever is in there out. Water will be on the bottom because oil floats. That is the stock standard answer. I am not a HMMWV mechanic though...

PROBLEM IS: If the rear differential is cooled with antifreeze, that should be in the TM for sure. Logic (My Logic) says most gearboxes need more than antifreeze to lubricate the bearings and gears. I am just fishing for answers right along with you.

It definitely takes gear oil (80w90). I assume it has a separate internal reservoir for the coolant.

 

[86humv]

1165a1 has radiator coolant also the transfercase is cooled the same ....There is a small heat exchanger inside cover....so you should not be getting radiator coolant when you open the fill, or drain.....Might have internal leak.

 

[HCF]

1165a1 has radiator coolant also the transfercase is cooled the same ....There is a small heat exchanger inside cover....so you should not be getting radiator coolant when you open the fill, or drain.....Might have internal leak.

No I didn’t have any coolant come out. I just had gear oil come out of the fill port. It was enough to make me wonder if there was another fill point for these cooled differentials. That or maybe water got into the diffs some how? The gear oil did look a little milky.

 

[osteo16]

Contamination through vent line? Although I know nothing about your diff or if it has a vent line, but most do..... any other components have milky fluid (hubs) ???

 

[HCF]

Contamination through vent line? Although I know nothing about your diff or if it has a vent line, but most do..... any other components have milky fluid (hubs) ???

Haven’t gotten to the hubs yet. They’re next.

 

[HCF]

I’m letting it run with the drain port open (obviously not driving it anywhere. Just letting the engine run) Looking to see if any coolant starts getting pumped out. So far nothing so I would hope that means there’s no internal coolant leak.

 

[osteo16]

Well, that might leave vent line contamination.. possibly hubs, transmission and transfer case also... anything interconnected by vent line . No bueno... is this unit new to you ? Have you checked any of the other fluids ??

 

[HCF]

Well, that might leave vent line contamination.. possibly hubs, transmission and transfer case also... anything interconnected by vent line . No bueno... is this unit new to you ? Have you checked any of the other fluids ??

Yes I just got it and am doing my initial fluid changes. So far I’ve done the engine, transmission, transfer case, and rear differential. The diff has been the only fluid that appeared to be cloudy. Planning on doing the front diff and hubs tomorrow so fingers crossed.

 

[Action]

If it had a fording kit, the vent lines were cut.

 

[Retiredwarhorses]

Drain it, refill it, run it, check it…not a big deal.
it’s not uncommon for the cooler loop to fail…you will know when it does.
if it does, just abandon the cooler and loop the glycol lines and be done with it.
Your truck won’t be operating in Iraq loaded to the hilt, so you have no rear diff overheating issues.

 

[HCF]

Drain it, refill it, run it, check it…not a big deal.
it’s not uncommon for the cooler loop to fail…you will know when it does.
if it does, just abandon the cooler and loop the glycol lines and be done with it.
Your truck won’t be operating in Iraq loaded to the hilt, so you have no rear diff overheating issues.

Appreciate the reply! Just curious…what are the symptoms when it fails?

 

[Retiredwarhorses]

Appreciate the reply! Just curious…what are the symptoms when it fails?

Oh, you will know when it fails…

 

[NDT]

Oh, you will know when it fails…

Lemme guess, pressurized antifreeze fills the gear case pushing oil out the vent, overfilling all the other gear cases on the vent circuit, until those are full too, by then it's all antifreeze which I would guess on a USMC vehicle will start to geyser out of the vent stack?

 

[Retiredwarhorses]

Lemme guess, pressurized antifreeze fills the gear case pushing oil out the vent, overfilling all the other gear cases on the vent circuit, until those are full too, by then it's all antifreeze which I would guess on a USMC vehicle will start to geiser out of the vent stack?

In a nut shell….

 

[Mullaney]

In a nut shell….

.
All because of the Sand Box Wars?

Because it was miserably hot over there?
Because the trucks were overloaded with the addition of armor that they weren't designed to carry too?

In some places, Afghanistan is pretty dang cold... Maybe different trucks that had and did not have that feature?


My Commentary:

Maybe next time, we will need heated anti-freeze in the rear axle when we go on our next "mission" to Russia or China or North Korea. Not sure that we need to bother since without total commitment from those people on that swampy hill in Virginia - we just allow our young men and women to die for nothing. AND most of those people on that particular hill have never spent a minute in the military and have no idea...

Off Soap-Box

 

[HCF]

In a nut shell….

Well that just sounds lovely