John431 Posted October 21, 2020 Report Share Posted October 21, 2020 Hi all...question. I want to change rear diff fluid and put in some redline 75w90 My question is...I dont see a drain plug...does anybody know the procedure/how this is done ? Thanks ! John Quote Link to comment Share on other sites More sharing options...
Jerry Roberts Posted October 21, 2020 Report Share Posted October 21, 2020 If it doesn't have a drain plug you will have to use a suction gun . I haven't seen one without a drain plug though . Quote Link to comment Share on other sites More sharing options...
John431 Posted October 23, 2020 Author Report Share Posted October 23, 2020 Hi all, update: the differential does not have a "drain"plug only a fill plug. So any fluid would have to be sucked out I was lucky mine was pretty much empty ? So with some Redline all is quiet now ! Thanks to all for comments/advice.. Happy motoring !!! : ) 1 Quote Link to comment Share on other sites More sharing options...
Sniper Posted October 23, 2020 Report Share Posted October 23, 2020 I pull the axle shafts and the driveshaft. then crack the third member loose to let the fluid drain into the pan you have below it. Once it's done pull the third member and inspect/clean out the housing. That will tell you a lot and will allow you to inspect the gears for any issues. Seal it up and fill it up. Yes it's tedious but especially on a new to me vehicle it's sort of mandatory for me. This will also allow you to inspect the axle shaft bearings though you will likely need, at a minimum, outer seals for the shafts and a carrier gasket. Probably wouldn't hurt to put in new inner seals too. Quote Link to comment Share on other sites More sharing options...
Merle Coggins Posted October 23, 2020 Report Share Posted October 23, 2020 In some cased you can remove one of the bottom differential mounting studs to drain the oil. Quote Link to comment Share on other sites More sharing options...
soth122003 Posted October 23, 2020 Report Share Posted October 23, 2020 Hey John, On my P-15, I didn't think I had a drain plug either. Turned out it was covered by dirt. Not a lot but enough to cover the plug. Scrape a little bit at the backside area at the 5:00 position just above the bolt holding the diff together. It has a square hole in it instead of a hex to remove the plug. Had to dig mine out to get a rachet in there to remove it. Joe Lee 1 Quote Link to comment Share on other sites More sharing options...
Adam H P15 D30 Posted October 23, 2020 Report Share Posted October 23, 2020 Yes, my 49 also had a small drain plug. Lots of scraping on the the housing to find it but it's there. Quote Link to comment Share on other sites More sharing options...
John431 Posted October 25, 2020 Author Report Share Posted October 25, 2020 Thanks everybody! Although diff fluid change is complete...I'm going to take a closer look..."just because" : ) Thanks ! John Quote Link to comment Share on other sites More sharing options...
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