HMMWV (not H1) Helical Hubs oil level

[T9000]

As I pulled the tires to rebuild them due to a vibration around 70mph, I decided to also change the geared hub oil.
When I opened the 1” fill plug, a lot of oil started to pour out and ended up being about 30-40% more than the specified 1/2 quart. In the picture the cups are 528ml (0.55 quart) and the fuller cup is already 1/2 quart (473ml):


helical gear is visible thru the fill port

This happened so far on two out of two hubs that I opened and before moving further with the other two, wanted to check with you.

The oil doesn’t look like it has water in it or there is no apparent leak to say that water somehow got inside, however, clearly the facts point that there was a lot more oil inside than 1/2 quart and the question is, how did they put that much in (there is something that appears to be another fill port above the spindle, maybe they used that?)
Do helical gear hubs (which I could not find anything about it in the manuals as new as 2009) require more oil?

 

[springer1981]

Not an expert here and have only had to change my hub oil once and only because it was new to me and I didn't know the condition or maintenance on it.

My thoughts, did you remove the filler plug first? If you did, is that when the excess oil came out? On the other ones I would pull the filler plug first and check the level before draining it. If the level is to the filler plug hole and not excessively over full and coming out then you have the correct level of oil. If it comes gushing out from being overfull then you have something going on. For example, do you have a deep water fording? If so, is it possible that is delivering oil to the portal hubs and overfilling them?

Also that oil does not look good. It shouldn't be black like that unless it is just an optical illusion from camera angle or something. If it is black say due to engine oil in the water forge line or something (just guessing) that could make it black.

Again not an expert and maybe someone else will chime in with more experience.

 

[MarkM]

Oil is dark. You remove the fill plug so air can get in there so the oil will drain out of the dain hole fast. Someone in the past over filled it. I would fill it properly and drive it. I would drive the truck for a while and then hit each of the hubs with a laser temperature gun to make sure they are all running at the same temperature. Obviously if one is running substantially hotter then there is a problem in that hub. Hope this helps.

Mark

 

[blutow]

If oil levels are significantly above the fill plugs, it seems very likely that additional fluid came via in the the vent lines. Does the fluid seem thinner than normal gear oil? It looks thin with the bubbles on the surface in those cups, not typical of gear oil. Maybe contaminated by ATF? Have you checked the level of your transfer case and transmission? From what I've read, a cooler line breach inside the transfer case can fill up the t-case with ATF and then overflow into the vent system (hubs, etc.).

I might be way off base here and I have no experience with this problem, but I can't think of any way for fluid to get above the fill plugs unless it came in through the vent lines.

 

[Action]

They can be overfilled on the bench before installed on chassis.

 

[MarkM]

"They can be overfilled on the bench before installed on chassis."

Good point !

I've delt with the infamous vampire leak and the oil would be much thinner than normal and the tranny would be low. Check your air filter housing to make sure it's dry as mine had a 1/2 qt of tranny fluid in there and it ruined the filter.

Mark

 

[springer1981]

They can be overfilled on the bench before installed on chassis.

That was going to be my next question since it's hard to overfill them on the truck unless you really try.

 

[Retiredwarhorses]

Or as I’ve seen, some fool who filled the hub from the upper halfshaft retaining bolt hole at the top of the GH…
I just did an M1165A1 that had 3 of 4 over filled. Not the first time I’ve seen this.

 

[T9000]

Not an expert here and have only had to change my hub oil once and only because it was new to me and I didn't know the condition or maintenance on it.

My thoughts, did you remove the filler plug first? If you did, is that when the excess oil came out? On the other ones I would pull the filler plug first and check the level before draining it. If the level is to the filler plug hole and not excessively over full and coming out then you have the correct level of oil. If it comes gushing out from being overfull then you have something going on. For example, do you have a deep water forge? If so, is it possible that is delivering oil to the portal hubs and overfilling them?

Also that oil does not look good. It shouldn't be black like that unless it is just an optical illusion from camera angle or something. If it is black say due to engine oil in the water forge line or something (just guessing) that could make it black.

Again not an expert and maybe someone else will chime in with more experience.

Yes, I did remove the fill plug first and that's when the oil started to pour out, from the fill plug,, that's why there is so much oil under the opening.
The truck did have deep water fording originally, but it was removed by GP, I did buy all the deep water fording parts, but didn't install it yet, I installed a regular CDR valve for now.
The engine has no visible blow-by, the oil cap had no oil on it everytime I checked and when I replaced the air canister, the air filter had no oil, the large air intake hose was dry and there was just some very little oil (a light film, nothing large, and thought it was from driving without a CDR valve fpr a few hundred miles) where the CDR valve connects into the air intake. I have some pictures from then, and will double check again to see if anything changed.

Not sure when the hub oil it was last changed, but it's possible that it was sometime in 2012 as that was the date on the oil filter and thought that maybe that's why it was darker green vs. new oil.

Thru what line/ lines would the engine oil get into the hub vent lines? Would it be thru the vent lines that were connected to the deep water fording CDR valve? Or there are other lines?

 

[T9000]

Oil is dark. You remove the fill plug so air can get in there so the oil will drain out of the dain hole fast. Someone in the past over filled it. I would fill it properly and drive it. I would drive the truck for a while and then hit each of the hubs with a laser temperature gun to make sure they are all running at the same temperature. Obviously if one is running substantially hotter then there is a problem in that hub. Hope this helps.

Mark

I thought the oil is dark because it was very old, maybe from 2012, or maybe even factory fill from 2009 as the truck had only 7k miles and maybe they didn't change it. Yes, I do thermal testing using an infrared camera and the hubs look OK, one thing that seems to run hotter is the rear differential. I changed the oil to Lucas 80W90 and now I am switching to Lucas 75W90 synthetic to see if it makes a difference in operating temperature (there is some marginal thermal transfer from the brakes):



Actually I don't know if 75C is too hot, it just seems high to have an almost 50C rise on a let's say 27C ambient. I wasn't pulling anything, it was just the empty truck itself, so I am just getting some data-points for now.

 

[springer1981]

Thru what line/ lines would the engine oil get into the hub vent lines? Would it be thru the vent lines that were connected to the deep water fording CDR valve? Or there are other lines?

I don't have the the Fording kit myself but I have read others talk about overfilling something and it getting fluid in the Fording Line. I think it was ATF from the power steering? But I suppose if that is a possibility there may be other possibilities that could allow other oils in the lines. Again, no experience and just thinking out loud as to possibilities.

 

[T9000]

I don't have the the Fording kit myself but I have read others talk about overfilling something and it getting fluid in the Fording Line. I think it was ATF from the power steering? But I suppose if that is a possibility there may be other possibilities that could allow other oils in the lines. Again, no experience and just thinking out loud as to possibilities.

I understand and appreciate your feedback, I don't have much experience myself. On my truck the power steering line is not connected to the rest of the vent system and it is routed by itself to the top of the air intake stack, it was built like that from the factory, maybe to solve exactly what you described:



When I replaced some of the fuel lines, the vent line by the fuel pump broke and I used high temperature silicone tape to temporarily fix it.
I will open it to see if there are any oil traces inside.

 

[MarkM]

The Vampire problem comes from the internal transfer case cooling tube. When that fails then transmission fluid fills up the transfer case and pushes fluid out the breather/fording lines and the fun begins.

I first found out I had a problem as the air filter housing was leaking a little transmission fluid out the weep hole.

150 degrees Fahrenheit is not overly hot for a heated rear end. The synthetic oil will help with it a bit but if it were my truck I would let it be.

Mark

 

[T9000]

If oil levels are significantly above the fill plugs, it seems very likely that additional fluid came via in the the vent lines. Does the fluid seem thinner than normal gear oil? It looks thin with the bubbles on the surface in those cups, not typical of gear oil. Maybe contaminated by ATF? Have you checked the level of your transfer case and transmission? From what I've read, a cooler line breach inside the transfer case can fill up the t-case with ATF and then overflow into the vent system (hubs, etc.).

I might be way off base here and I have no experience with this problem, but I can't think of any way for fluid to get above the fill plugs unless it came in through the vent lines.

I didn't check the transfer case level yet and will do. The transmission oil level looks good, It hasn't changed since I replaced it and the original oil was very clear.

 

[Mullaney]

I just read a useful article with a comment from @Retiredwarhorses that might shed some light on your overfilled hub question... Especially if you happen to have a REV A truck. If the fluid you have smells like power steering fluid - the extra fluid could be coming from the rear differential cooler.

REV A rear diff cooler is PS fluid
REV B Tcase and rear differential are Glycol cooled.

I didn't see which hubs (front or rear) you drained. Might be that my suggestion is nothing but at least now you have a little more information now...

 

[T9000]

I just read a useful article with a comment from @Retiredwarhorses that might shed some light on your overfilled hub question... Especially if you happen to have a REV A truck. If the fluid you have smells like power steering fluid - the extra fluid could be coming from the rear differential cooler.

REV A rear diff cooler is PS fluid
REV B Tcase and rear differential are Glycol cooled.

I didn't see which hubs (front or rear) you drained. Might be that my suggestion is nothing but at least now you have a little more information now...

I should have mentioned that it was the two rear hubs, so your theory could be correct, The oil smells like gear oil, it's easy to tell, but also I am not sure how the steering oil smells like, as I haven't replaced it yet, it looks clear and has the right level (but I think you are saying that the same type of steering oil it is running in the oil cooler?).
How could I tell if I have a REV A or REB B truck? I thought there was only one REV, which are the trucks made in 2008 and later, with serial numbers above 300,000?

 

[Mullaney]

I should have mentioned that it was the two rear hubs, so your theory could be correct, The oil smalls like gear oil, it's easy to tell, but also I not sure how the steering oil smells like as I haven't replaced it yet, it looks clear and has the right level (but I think you are saying that the same tyoe of steering oil it is running in the oil cooler?).
How could I tell if I have a REV A or REB B truck? I thought there was only one REV, which are the trucks made in 2008 and later, with serial numbers above 300,000?

Steve (RetiredWarhorses) has so much more experience on this than me, but serials 300,000 up are REV B for sure. I don't know exactly where the REV A trucks started, but the 200,000 serials and with dates back in 2005 had the "enhancements" for heat in the big sandbox.

 

[T9000]

Steve (RetiredWarhorses) has so much more experience on this than me, but serials 300,000 up are REV B for sure. I don't know exactly where the REV A trucks started, but the 200,000 serials and with dates back in 2005 had the "enhancements" for heat in the big sandbox.

Ok, I think I understand. From what I read, it sounds like the ECVs were the first level of recent upgrades part of the MECV program (perhaps that's what others call REV A) and then later on serial numbers above 300,000 it was the Reliability Enhanced Vehicle (like mine) which it sounds like it also called REV B.

 

[98G]

Or as I’ve seen, some fool who filled the hub from the upper halfshaft retaining bolt hole at the top of the GH…
I just did an M1165A1 that had 3 of 4 over filled. Not the first time I’ve seen this.

Speaking from experience, this is a real temptation....

 

[blutow]

Speaking from experience, this is a real temptation....

If I had to put $ on a theory for the overfill, that's the horse I'd bet on. Bench fill is possible also, but seems less likely. The vent lines are probably a long shot if the fluid doesn't look thin and the transmission fluid level hasn't changed.