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Subject: Transmission and hydraulics flush

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Charles Hudson    Posted 11-07-2020 at 14:37:03 [URL] [DELETE]        [Reply] [Email]  
  • Transmission and hydraulics flush
  • Repaired leaking rear axle seals as described elsewhere, mounted new tires, tubes and rims, also described elsewhere, and decided now was the time to drain the transmission, hydraulics and differential.

    Pulled the hydraulics (forward plug) first. The fluid appeared clean, a light golden brown. Next the transmission (middle plug). fluid discharged was darker and contained both a gritty sediment and a sort of sludge. I'm attaching a picture for reference.

    Last was the differential, and it too had sludge; I pulled the plug and little water came out but nothing else until I poked my finger into the cavity, at which time sludge and oil came out.

    I think the transmission and differential indicate (beside a lack of maintenance) the formation of deposits that Ford warned about in its specifications for trans /hydraulic oil. Certain additives were the concern.

    My question here is simple: Should I give the cases a flush with some lighter-weight solvent, e.g. kerosene? What is the procedure for dealing with this problem?

    Thanks for your suggestions.


    Tim Daley(MI)    Posted 11-08-2020 at 04:45:59 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Transmission and hydraulics flush
  • I concur with Bruce --- pull the whole pump and clean & rebuild it to do it right. Also, when draining hydraulic oil always go from back to front. Remove the NPT diffy plug first. It has 9/16" square NPT plug on it. The trans and hydraulics are all in the same sump. You need to always put the pertinent info in your post each time like make and model of your tractor. I, and I'm sure many others, don't keep tabs on, let alone remember what each member has, so let the reader know which system you are referencing. There are differences. See the LINK for info on a Ford 9N/2N hydraulic system rebuild. Note the 8N is different - no wishbone bracket, but they explain all that with the 8N control rod.

    Tim Daley(MI)

    Bruce(VA)    Posted 11-07-2020 at 18:51:53 [URL] [DELETE]        [Reply] [Email]  
  • Re: Transmission and hydraulics flush
  • Pull the pump and clean it out.

    Flushing is a waste of time and money.

    Charles Hudson    Posted 11-08-2020 at 07:15:16 [URL] [DELETE]        [Reply] [Email]  
  • Re: Transmission and hydraulics flush
  • Thanks both for your suggestions. I'll look into what it takes to pull and repair the pump. I hear it's a bear.


    BTW: 1949 Ford 8N with front end loader.

    Bruce(VA)    Posted 11-08-2020 at 07:26:18 [URL] [DELETE]        [Reply] [Email]  
  • Re: Transmission and hydraulics flush
  • Repair? If your pump works, there is nothing to repair. You're just cleaning it.

    Resist the temptation to save 5 minutes by parking it nose down in a ditch instead of draining the fluid. The front transmission seal was not designed to be totally immersed in oil. If it's defective, you will fill the bell housing with oil and then you will get to replace the clutch.

    With all of the fluid drained out, block the front wheels & get the rear wheels up at least a foot. (you'll see why soon enough) Remove the 4 bolts holding the PTO shaft in & pull it to the rear & out of the tractor. Loosen all of the bolts. Remove all but 2 corner bolts. Then, carefully remove them. If you are lucky, the pump will drop free (and dump a pint or so of hydraulic fluid down your sleeves). If not, wrestle it free. The pump has 'ears' that fit into the housing; wiggle it a bit & it will drop free. If you have the rear tires a foot or more off of the ground, you will have enough arm room to hold the pump & lower it at the same time. Put it on your work bench & remove the safety valve (p/n 638) and the control arm lever (p/n 643) which will allow you to remove the intake & exhaust valves (p/n's
    640 & 698) Drop all of it in a bucket of diesel (or mineral spirits) or your parts washer & let it soak overnight. Once it has a good soaking, get it on the bench & start blowing it out w/ compressed air. Run cleaning fluid into the hydraulic discharge near the test port & make sure you get a good flow out the small hole in the side of the pump were the control valve fits. I don't see much need to pull it down any further just to clean it. But, I always replace the safety valve (p/n 638, about $25) Reinstalling the pump is harder than pulling it out because you have a gasket to worry about. (no sealer on the gasket) And, you will probably need a helper to guide the control rod into the pump rocker shaft unless you've done this 6 or 7 times before!

    While you have the PTO shaft out, it would be a good time to replace the seal on it. It's got two spring clamps around it. Take your needle nose pliers & remove the one in the front. Then, hang the shaft & bearing housing in your vice & tap the butt end of the shaft; the bearing cap will come off (and the shaft will land on your foot). Then, remove the other spring clip from the other side of the bearing. At this point, remember that you never bought a seal driver & go get a BF socket & drive the seal out. If you have the new style seal, the white side goes out. (open side to the oil) Put some grease on it.

    Contrary to conventional wisdom, not a lot of water gets in the oil from the shifter boot. Of course, if it's bad, replace it, but you get water from the draft control spring & the dipstick. But, most water is just a byproduct of the heating/cooling cycle of the oil. I've seen the pictures of an experiment to test the 'leaky shifter boot' theory. With no shifter boot installed, a lot of water was poured over the transmission cover sitting over a 5 gallon bucket. Result? No water in the bucket.

    You'll need a pump gasket, safety valve, inspection plate gasket(s), PTO seal, PTO gasket, gasket sealer & 5 gallons of fluid to do all of the above.

    Charles Hudson    Posted 11-08-2020 at 18:40:08 [URL] [DELETE]        [Reply] [Email]  
  • Re: Transmission and hydraulics flush
  • Bruce,

    Thanks very much for your response and for 75 Tips; I read all of them. A lot of valuable info and good advice, some of which I actually knew!**

    When I bought the tractor I put a drawbar and bar stays on the rear and have never engaged the height (draft) lever. Never took the PTO cover off, either. In other words, I don't actually know if the pump works. I just use the FEL.

    I already reached out to Just8Ns and asked Derek what I'm gonna need but I'm awfully glad to have the benefit of your experience and insight.

    Thanks again!


    **(#5)I had been adding Alamite CD2, guess no need. (#6) Shell Rotella 15-40; I only run three seasons. (#9) I shut the fuel off when I'm ready to shut down and let the engine die, then turn off the key when it stops.

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