Pumping out the Rear Diff, not removing the cover.

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My 92 S-10 just hit 30K miles (yep, no typo, 30K), so working my way around complete fluid exchange on the vehicle. The Power Steering is the only factory fill left. Like many rear diffs, there is not a drain plug, and I **really** didn't want to mess with removing the cover, gasket scraping, etc. I know, its not **that** big a job, but its not leaking, and I want to keep it that way.....I've had lousy luck in the past when removing pans, valve covers, etc, and fighting leaks after. So, I bought a cheap suction pump, a gallon of Super Tech 80W-90, plus a quart squeeze bottle of the same gear oil (saved a few bucks doing it that way, just keep refilling the squeeze bottle). Removed the fill plug, added some gear oil so see how low it was, maybe 1/4 quart....not bad for 17 years, IMO. I drove around a bit to warm things up, then was able to pump out just under 2 quarts after fishing the hose as deep into the diff as I could. I then filled it, and plan on repeating this procedure after a few hundred miles. This should give me a good majority of oil replacement. Not sure of total capacity, but can't be much over 2.5-3 quarts, give or take, so looks like I got a good majority pumped out removing 2 qts. So, any real disadvantages to doing it this way (besides not being able to inspect the diff gears, but I'm not experiencing any problems with it), because if I had a drain plug, which some diffs have, it would be about the same thing, right? I still would not be able to inspect, or wipe the cover off, clean sludge out, etc. Pump cost: about $7 at Wally World, not too much more than a gasket and RTV. So, my question is, why don't more people use a suction pump, it seems to me a way easier way to change or refresh the rear diff oil. PS: The Haynes manual for the S-10 4WD version says using a suction pump is the only practical way to change the front diff oil. I have to take their word, since I have 2WD.
 
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Many use suction pumps. I find that fluid extractors can make maintenance for the backyard do-it-yourselfer easier and timely.
 
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I syphoned the rear end on a motorhome. Got nearly all of the 4 qts out. Somehow got a little on my lip--pretty nasty tasting!
 
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 Originally Posted By: TallPaul
I syphoned the rear end on a motorhome. Got nearly all of the 4 qts out. Somehow got a little on my lip--pretty nasty tasting!
You work on your cars a lot yourself, you should buy a fluid extractor. Otherwise, all kinds of nasty stubs may be in your stomach.
 

KilgoreBass

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 Originally Posted By: panthermike
Where do most get their suction pumps?
The pump I got at WM isn't a dedicated suction pump (the type that looks like a grease gun), it can also be used to inflate things. I think this makes the oil extraction easier, as I didn't have to keep sucking and removing the hose to empty the pump, once it was hooked up, just keep working the pump. here's a link to what I used, but it was only about $7 at WM, not $30!!!! http://www.autoparts2020.com/rsdev/part_detail.jsp?PART_HDR_ID=22012
 

Bill in Utah

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 Originally Posted By: panthermike
Where do most get their suction pumps?
Not the model I have but I have used this one with excellent results! Oil suction tank I've used mine quite a bit. It works well for most anything. Engine oil, diffs, transfer case, power steering systems, brakes, coolant tanks, windshield washer and much more. I've actually measured a engine oil change using a pan vs my pump and got more fluid using the dipstick since it gets ALL the fluid out of the pan where the drain plug gets most of it. Take care, bill PS: This is the model I have --> Oil change pump
 
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one downside is that you wont get all of the metal particals out from wear and breakin. some diffs have a magnet that holds them....
 
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Due to the age of the vehicle and the fact its never been serviced in over 16 yrs you should remove the cover and service it that way. Differentials generate of lot of wear metal in the first few thousand miles of operation. Just sucking out the fluid will not clean out the axle cavity and therefore lots of debris and sludge could be left in there to mix with the new fluid. You just will never know unless you do a visual inspection. IMO suction method is not the best way to go.
 
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After you have removed the diff cover once, you will realize this is anot a big job at all. As others said you can clean out the metal, and let the oil drain overnight. Clean the cover and the diff with a rag and Varsol. Apply RTV sealant to the diff and install cover. Let it cure overnight if you can. It will not leak.
 
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If only they built cars right there would be a drain plug at the very bottom. Then all you would need is a flushing oil to clean her out. How about a flushing oil on a mini power washer, something the consistency of say MMO. Yeah, I have a suction pump got at a garage sale, use for power steering mostly. Don't think I had it for the rear end syphon. I noticed that it is much harder to suction cold PS fluid than hot. Interesting as it's not especially thick to begin with.
 
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 Originally Posted By: Mike_dup1
Due to the age of the vehicle and the fact its never been serviced in over 16 yrs you should remove the cover and service it that way. Differentials generate of lot of wear metal in the first few thousand miles of operation. Just sucking out the fluid will not clean out the axle cavity and therefore lots of debris and sludge could be left in there to mix with the new fluid. You just will never know unless you do a visual inspection. IMO suction method is not the best way to go.
I agree with this. You just can't get the junk out with an extractor, it needs to be drained and cleaned.
 
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If you remove the cover once and clean the magnet, most of the wear is in the initial phase of 10K miles. after that there isnt much wear, look at the Amsoil paper on gear lubes and the amount of wear. Moral of that paper was to change the initial fill early after 5-10k miles. So if you remove the cover and clean the magnet and change the fluid the 1st time your probably pretty good and you could then on subsequent changes just suction it out and refill. That is what I do.
 
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Most of the housings I have seen can be drilled and tapped for a plug. Sometimes there is even a "legacy" boss where a drain plug used to be fitted. Do this the first time you have the cover off, use a magnetic drain plug and you are set for good service from then on. I concur. That first drain should be done with the cover off so you can remove break-in contaminants and clean the magnet (if fitted). If no magnet is fitted, you can add one.
 
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OTOH, My '84 F150 went about 300,000 miles (me and second owner) with the original rear end fluid and no problems, though it rarely hauled any kind of load.
 

KilgoreBass

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To tell the truth, if I wasn't reading posts on this site, I probably would not have even bothered pumping out the old fluid. This is a straight gear diff, no limited slip concerns or anything..... Guess when I get a chance I will remove the cover, since I want to paint it as well, but for now a pump-out and replacement of the oil will have to do, and not real worried, since the truck gets only like 2K miles a year. BTW, didn't see my original point really addressed, would people still remove the rear diff cover if they all had drain plugs? Maybe the lack of drain plugs has just ingrained this "habit" in people?? (like having to drop the AT pan if no drain plug) Has anyone removed the diff cover after a few 10K miles on a factory fill, and seen chunks of metal in there that would evade a good suctioning or gravity drain, saying to themselves "glad there wasn't a drain plug, and I was forced to pull the cover"???
 
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I'd pull the cover, even if there was a drain plug. It's really not that time consuming.
 
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If there wasn't a magnet and I had drain plugs, I see no point in pulling the cover. If there was a magnet, then at least that first time. After than maybe every other or every third time.
 
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 Originally Posted By: KilgoreBass
 Originally Posted By: panthermike
Where do most get their suction pumps?
The pump I got at WM isn't a dedicated suction pump (the type that looks like a grease gun), it can also be used to inflate things. I think this makes the oil extraction easier, as I didn't have to keep sucking and removing the hose to empty the pump, once it was hooked up, just keep working the pump. here's a link to what I used, but it was only about $7 at WM, not $30!!!! http://www.autoparts2020.com/rsdev/part_detail.jsp?PART_HDR_ID=22012
Thanks for the reply, I've seen that at Walmart. And thanks Bill, that looks like a quality pump.
 
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