MadModder
The Craftmans Shop => New from Old => Topic started by: awemawson on June 05, 2018, 12:39:45 PM
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For the past eleven years my 2.2 kW Hydrovane compressor has given loyal service, rewarded by the occasional oil and filter change. Although it is on 24/7 it doesn't get heavy use - in fact in those eleven years it has only run for 268 hours. It wasn't new when I got it and I fitted the hours meter pretty soon after I got it.
Recently I've noticed that it is pumping up rather more often than it has been, and a splurge of oil has been dripping out of the oil cooler onto the tank. Speaking to the chap I bought it from (amazingly he is still in business!) it should pump it's 50 litre tank up from discharged in two and a half minutes. I tried it yesterday and it took three and a half minutes, and today it wouldn't ever get there poor thing.
Received wisdom it that it's probably the rear air / oil seal. So today I dismantled to check and order parts.
The air vane compressor hangs off the motor, so, a bit of dismantling and sure enough lots of evidence that indeed this is the problem (or certainly A problem!)
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This is where the fun started - just need to remove two counter sink 6 mm x 20 mm socket cap screws and pull the old seal out. One was fine, but the other had rounded off faces to it's hex socket, and no way would an allen key turn it.
I tried all the tricks I know:
- grind the end of the key to raise a burr
- peen the socket with a pin punch to close it up
- heat the screw cap with a red hot bar
etc etc and nothing worked - nothing for it but to drill it out :bang:
Now due to the nature of the beast this meant using a hand held drill - not nice in a situation where precision is called for. Now M6 tapping drill is 5 mm so theoretically if I can manage to drill 5 mm then I can re-tap which should dislodge the remains of the thread. Fortunately the screw was not high tensile - which is probably why it had been rounded in the first place, and also fortunately with socket cap screws you have a good chance of getting a pretty well centred drill to start with.
I selected a drill that just fitted inside the rounded hex, drilled all the way through, then worked up in 0.1 mm steps until I got to 5 mm at which point the top of the countersink came off releasing the oil seal.
A careful clean up, and an M6 tap produced an acceptable if not perfect thread. :thumbup:
OK pull the oil seal, but first clean up the shaft as there is a bit of surface rust. Now we can order parts.
The seal itself is actually a double seal with lips facing both ways, as not only does it seal against air pressure and oil, under some circumstances it has to seal against vacuum or 'suck'
20 mm shaft - the seal is £80 :bugeye: :bugeye: I was advised that the best way to buy it was as part of a 'Top Up' kit that had the seal, all the oil rings and gaskets, and various shims and bits. What with the Top Up kit and a filter / oil change kit I have no change out of £140 :bugeye:
Bits on order - should arrive later in the week, meanwhile no air to any of the workshops :(
. . . it's amazing how often today I've reached for a blow off gun, forgetting there is no air !!
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Very neat job, managing to get that reluctant screw out.
Now you've shown how to do it, my excuses are rapidly diminishing for ignoring the noises my Hydrovane is making.
Pete
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It ain't fixed yet Pete, this may not be the only problem - but the only way to find out is to pack it with expensive bits and put it back together :med:
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This is going off topic but is still to do with repairs.
On Sunday I sold my Raglan Mk 1 lathe, I felt it was worth £200 but I only got £125. None the less I was happy to get that money. In the meantime my Land Rover blew a top hose. It cost me £157 to be fixed. How the f**k do I make any progress in this world? I know that if I had not sold the lathe I would be in deep ****, but for a short time I was dreaming of what I could do with my new found riches. Ah, such is life!
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That's a mighty expensive top hose Norman - do I recall that you have a Discovery? They are far cheaper than that on eBay :bugeye:
If it's any consolation my Hyster H2.5HL Fork Lift forward clutch failed a couple of weeks ago. Parts just over £1000 and labour (including collection and delivery - it weighs about 3 tons) another £1000. OK the parts included both forward and reverse clutch packs, brake shoes, brake cables and an exhaust.
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I won't be going back to that garage with my Discovery. A top hose should only cost £35 plus fitting. My nearest Landrover dealer is 50 miles away. C'est la vie!
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This is where the fun started - just need to remove two counter sink 6 mm x 20 mm socket cap screws and pull the old seal out. One was fine, but the other had rounded off faces to it's hex socket, and no way would an allen key turn off one because the socket rounded.
I wouldn't use either countersunk or button headed socket screws out of choice. The sockets are one size down and shallower than their normal socket head counterparts.
I once used M6 countersunk socket screws on the bearing cap of a milling spindle I'd built. I did a trial assembly and a couple of minutes later tried to take it apart and couldn't believe that one wouldn't budge and the socket rounded - I too had to drill the head off.
Many's the time I've had to use a hacksaw to put a screwdriver slot in a button headed socket screw to get it out.
Torx heads are a different matter - a pity they're not as easy to find.
Phil.
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Hi Andrew
Just curious do you use a synthetic oil in your machine.
Great piece of machinery and quiet running and with regular some what expensive servicing will give many years of use.
Eric
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I don't know what the oil specification is Eric, as I have always bought a 'service kit' - the remains of the oil is still on the shelf from last time in an anonymous red bottle and is red coloured.
Just taken delivery of those expensive bits - impressive fast delivery but I'll have to curb my enthusiasm as we have company for lunch.
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. . . what is less impressive is that they have forgotten to put the oil in the parcel :bang:
OK in post tonight so maybe tomorrow :scratch:
(The oil in the picture below is the remnants from my last service on this machine)
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Lots of counter sink 6 mm screws on modern motor cycles Andrew, what i do is hammer in the next size up Torx and unscrew,
next failed yet i buy the cheap torx sets from fleabay.
Lyn.
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Torx bits are my go-to method also :beer: Haven't had to drill one for ages...
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Sorry that happened to you Norman.
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The oil arrived today, so I put it all back together - no pictures as there seems little point - just look above in reverse :ddb:
The expensive seal looks all fine and dandy, but in essence all it is is a pair of seals mounted back to back in a housing - if I could find suitable seals I could refurbish the old one but they are not a standard size, having a 20 mm bore and a 31.5 mm o/d. However the housing is 35 mm o/d, and 20 mm bore x 35 mm o/d is a standard so I expect originally they didn't use a housing :scratch:
So what was the result ?
Well initially, horror of horrors I had oil leaking from the new seal :bang: First inflation of the tank quite a big leak. Second and third inflation's the leak was very considerably reduced, and by the forth inflation there was no leak.
I can only assume that the new seal has bedded in to the slightly worn seal surfaces on the shaft. Interestingly it was only leaking when rotating, and not at all with the shaft stationary.
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Is it definitely a metric size, Andrew? It's very close to 3/4" x 1-1/4"
Several thicknesses available here - https://www.bearingsrus.co.uk/sealing-products/oil-seal/imperial-oil-seals?p=3
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The shaft is bang on 20 mm
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Oh well, it was worth a try.
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Years ago when trying to replace a seal that took a few tries I was told to wrap a oiled piece of paper around the shaft to slide the seal down.
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Tom,
I remembered you mentioning that when I rebuilt that tractor rear wheel trumpet, I looked up the thread, and tried it on this shaft to protect the seal from the keyway. However in practise I found that I could not get the seal over the well oiled paper - (I was using a single wrap of 80 gsm copy paper)
So instead I compressed the seal against the shaft opposite to the keyway to give the bit at most risk a better chance.
Maybe I should have used cigarette paper, but I think it would be too weak - the seal is very tight on the shaft despite copious lubrication as I installed it.
The good news is that I've performed numerous deflate / reinflate cycles and had no more leaks - phew