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Thread: david brown 1494 hydraulic problems

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    david brown 1494 hydraulic problems

    im having hydraulic problems with my db 1494 it takes a while to lift arms and loader when starting from cold,then when it does lift it judders like if there is a lack of oil in back end,checked that its up to mark and looks clean too.Would the filter be blocked in bottom of back end is it a paper element or wire gauze to clean.Maybee theres air in pipes and needs bleeding but how do you do that? I think there is a valve that releases air somewhere on it is this not working? Anyone had similar problems or know what is wrong please? thanks.

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    Senior Member T P's Avatar
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    Post Re: david brown 1494 hydraulic problems

    There are many things that can go awry with the old DB hydraulics. Bearing in mind I am working from a text description rather than a direct observation I would suggest that the most likely causes are:

    In at no 1___ A blocked suction screen, not difficult to clean just drain the oil (if it's a hydrashift AFAIR the long suction screen for the hydrashift pump comes down out with the drain bung otherwise it's just a plain bung for the manual shift job) Then slacken the jubilee clips on the wee rubber flex undo the mounting screws then drop off the large (heavy) circle on the end of the supply pipe to the pump. Sometimes the gasket has really bonded so it needs a good pry but don't let it fall on yer noggin when it lets go! Pull the mesh filter out of the casing (hopefully it's in one piece as they used to have a tendancy to come apart at the bonding but can be rebonded or a secondhand one sourced) Clean filter gauze thoroughly with power washer and airline then clean up mounting faces on the bowl and refit the filter screen after greasing the O ring Refit bowl with a new gasket greased on the side towards the bowl. Refill/change oil. Worth changing the throwaway high pressure filter in the bowl to the rhs at the rear of the tractor at this time too as it keeps the oil going to the valve chest clean to avoid expensive problems. Trust me a filter is buttons compared to a stuffed valve chest never minds trying to find anyone with the special tools to set one up these days. It's more than a decade since I changed a valve chest but I'm sure you would be looking at well on the wrong side of 1500 nowadays to change one and that would likely be recon rather than new. The number one reason for DB's going to the breakers is a malfunctioning valve chest so it ain't clever to try fitting one from a breakers unless you've thoroughly tested the donor tractor as a runner at temperature. You just swop one dud for another.

    No 2 __would be a failing pump shaft seal that is allowing air in when parked and the oil to drain back down the suction pipe so it has to bled itself on starting and hiccups a lot until the air clears. Usually there is a fair bit of wear in the pump bearings too so just fitting a new seal isn't often worthwhile. If there's very little "lift" in the shaft you can get the right sized seal from a decent seal supplier just make sure it's double lipped to keep the dirt out. An original seal kit for the pump theoretically is available but probably unwise as it will be most of the price of the new pump. If the shaft has a lot of "lift" don't waste your time. A new single pump used to be around 150 but the rarer tandems are more like 270-300. Usually a new pump driveshaft and couplings are required too which can leave little change out of 500 for a good repair. Obviously an occasional use model lends itself to the compromise of secondhand parts etc. If you do fit a new shaft and couplings I used to take the shafts to an engineering company who bored a small hole through the centre and then another tapped at 90 degrees for a zerk fitting so the couplings could be greased in situ which vastly extends their life, don't forget about the important O rings and rubber spacer which are missing sometimes. To check for air getting in at the pump shaft seal a good dollop of grease can seal it temporarily for diagnostic purposes but isn't a fix.

    If you have the dual pump variant make sure the modified bracket has been fitted or someone has welded a strip across the angle of the bracket to stop it flexing and scrapping off a new pump when the input shaft breaks. There shouldn't be many tractors around any more with dual pumps and an unmodified mounting bracket but it can be a very expensive mistake to make. The original mounting bracket is fine with the single pump.

    There are a single or pair of air bleed valves (single or dual pump) on the pipe(s) from the pump(s) to the backend beside the relief valves but they never give trouble, they're little more than just a ball bearing and spring with a few bits and bobs that seals a hole when there's oil behind them and bleeds off any fine air bubbles coming from the pump that gathers around the ball bearing back up into the transmission outer casing. They do nothing for big gulps of air/ airlocked pumps. They are extremely unlikely to be at fault.Hope that gives you somewhere to start, the system was very well engineered and long lasting unfortunately it doesn't respond well to neglect, blocked filters or dirty/water contaminated oil but then_what hydraulic system does?
    Links for assemblies:

    http://partstore.caseih.com/us/parts...65466ar1104651

    Suction screen is no 8

    Hydrashift screen no 27

    Normal bung no 6 for manual tranny instead.

    http://partstore.caseih.com/us/parts...65466ar1105014

    High pressure filter is no 2

    Bleed valves are actually nowhere near where they are shown here and are actually sandwiched alongside the relief valves on the high pressure pipes about where the pedals are right underneath the tractor, trust me they aren't your problem:

    http://partstore.caseih.com/us/parts...65466ar1104807

    The pump shaft seal is no 11 here:

    http://partstore.caseih.com/us/parts...65466ar1104736

    There are about a half dozen pump variations especially in the dual pumps where there are single or dual oil inputs so if sourcing a pump take the old one and check carefully the in out galley positions etc.Some dual input pumps can be fitted with a blanking plate others not.

    If you have a single pump the bracket will look like this :

    http://partstore.caseih.com/us/parts...667bi4594520-1

    The later modified bracket for a dual pump (presumably the alternate part number for no 1) should be braced either side to stop the bracket flexing which at best ate the drive splines but more often than not shore off the pump shaft flush with the seal scrap.
    Last edited by T P; 19-09-16 at 09:51 PM.

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    Re: david brown 1494 hydraulic problems

    Thanks tp for the advice will have to try these things to see if I can get it sorted in next few days will let you know the problem when sorted .

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    Re: david brown 1494 hydraulic problems

    just sorted the pro blem it was blocked suction filter cleaned it and new pressure filter fitted filled with oil and worked straight away.The loader now lifts in half the time a lot faster. Thanks for the information very much appreciated .

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    Re: david brown 1494 hydraulic problems

    Big smiles all round that it was a cheap fix, filters are the cheapest parts you can ever buy.Another piece of information to consider is that there three separate oil supplies in the backend of a 1494.The main one that you drained and then two smaller ones in each of the reduction hubs. Each hub holds just over a gallon and it's critical as the wet brakes run in it.it needs to be changed at the recommended intervals as it gets very dirty with brake filings. Also any leaks in the hubs soon lose the gallon of oil. Never overgrease the nipple at the wheel as doing so pushes the outer halfshaft oil seal into the hub and starts a big leak at the wheel.in order to fix this it is necessary to dismantle the hub by taking off the big plate and I think a big nut inside then remove the ring of bolts from the seal flange and pull out the half shaft. You can either reseat the seal and re-assemble or at that stage fit a new seal and adjust the shims to rest the bearings so there's no lift in the shaft. Moral of the story is change the gallon or so of hub oil regularly and no more than a couple of strokes of the grease gun once a year in the grease nipple at the wheel (for those who ever noticed it) It is also critically important to monitor the pair of handbrake cables for sticking, the early 90's had grease nipples on the cables and provided they were greased they were eternal. The 94's and all the replacement cables had no grease nipples and were prone to seizing especially if the rear window or top half of the cab were missing as water got down the cable below the handbrake lever. If a cable seized and didn't release the brake properly it inevitably destroyed the plates in the hub . As is always the case a little bit of observation and care saves Handbrake cables used to be about 50 pair but the life expectancy got worse with cheaper manufacturing when case took over. No doubt they were tendered out to a price instead of made to a decent standard. The oil drains (best when warm) from 2 locations in each hub a small bung 20 and a large bung 21. if neglected the hole at 20 can be silted up and need a poke. If neglected change oil then change again after some roadwork to flush the system. The grease nipple you don't want to overgrease is no 16.

    http://partstore.caseih.com/us/parts...65466ar1049768

    I saw far too many tractors destroyed for lack of a gallon of oil in a hub. Once the bungs are in you just refill with good wet brake transmission oil through bung 30 till it starts to spill out. A good time to adjust the brakes through I thing through bung 30 too (need to check as the hub is slightly different between 14 and 15/16 models). Do not pull up the brakes unless the handbrake cable release properly.

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    Re: david brown 1494 hydraulic problems

    Hi All,

    I'm having the same issue with my lift and loader on my 1494. When started from cold it takes about a minute before the lift and loader will respond. There was a troublesome leak from the 3 way valve which was solved by worn O-rings. I also changed both filters and the oil to see if that would work but no joy. Has anyone got any more suggestions as to what it might be?

    Regards,
    James

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    Senior Member T P's Avatar
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    Re: david brown 1494 hydraulic problems

    That sounds like "No2" .The pump is losing the prime while parked and having to bleed itself on starting. Try the grease trick around the seal to see if that helps. If it does you're looking at a new seal or a new pump. If the old pump is badly worn a seal will not last long.

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    Re: david brown 1494 hydraulic problems

    Quote Originally Posted by burkejames142 View Post
    Hi All,

    I'm having the same issue with my lift and loader on my 1494. When started from cold it takes about a minute before the lift and loader will respond. There was a troublesome leak from the 3 way valve which was solved by worn O-rings. I also changed both filters and the oil to see if that would work but no joy. Has anyone got any more suggestions as to what it might be?

    Regards,
    James
    Not wishing to step on TP's territory coz he has vastly more experience than me, my experience was with an MF168 which developed slow 3 pl lift, but the loader seemed normal. the linkage would come good after a couple of minutes.

    Turned out to be crap (!) rather like cheese which was coating the inlet strainer for both pumps. I strongly suspect it was either a fungus or bacterial growth, prompted by moisture in the transmission due to irregular use of the tractor. Searched diligently for a material which would kill the infection without harming the new oil, without success. In the end I had to pull the lift cover and suck the stuff out with a vacuum cleaner. A year on, all seems well.

    JV
    Agtronix - the home of the Weedswiper

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    Re: david brown 1494 hydraulic problems

    Quote Originally Posted by T P View Post
    That sounds like "No2" .The pump is losing the prime while parked and having to bleed itself on starting. Try the grease trick around the seal to see if that helps. If it does you're looking at a new seal or a new pump. If the old pump is badly worn a seal will not last long.

    Thanks for your response. I will put some grease around the seal and see does it sort the problem. I currently have it parked on an incline with the nose of the tractor facing down to see if it will airlock it here.

    On a side note, the three way valve at the back of the tractor is leaking literally a drop of oil when parked. Do you think this might be the cause of air getting into the system?

    Regards

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    Senior Member T P's Avatar
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    Re: david brown 1494 hydraulic problems

    Quote Originally Posted by burkejames142 View Post
    Thanks for your response. I will put some grease around the seal and see does it sort the problem. I currently have it parked on an incline with the nose of the tractor facing down to see if it will airlock it here.

    On a side note, the three way valve at the back of the tractor is leaking literally a drop of oil when parked. Do you think this might be the cause of air getting into the system?

    Regards
    No

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