Boydie Posted February 2, 2014 Share Posted February 2, 2014 As part of my gearbox conversion (ZF4HP22 to R380) I will be upgrading to a disc brake conversion and dumping the very heavy drum brake set up, when I pulled it apart the brake shoes were covered in engine oil - no wonder the bloody thing would'nt hold - this engine oil could only have come from the WABCO vacuum pump. I'm on my third or fourth unit now and they always fail by leaking oil out of the bottom welsh plug due to engine oil getting past the piston and being compressed in the discharge poppet valve, to put it bluntly its a carp design. I've pulled one apart and instead of piston rings it uses a "H" section piston made of some sort of hard plastic which is simply and clearly not up to the task. Replacing the rivets with bolts is only a part solution fix, the material used on the piston seems to be the problem as the skirts wear and break away allowing oil past the piston, this should simply not happen, the old British company (long gone I believe) of Davies & Metcalfe would have produced a far better designed pump - they did it on steam loco's, the XPT and "bendy train sets" and were, engineering wise, far superior to the American Wabco -(Westinghouse American Brake Company). So, do any of you use an electric vacuum pump to replace this piece of turd, if you do have you found them to be reliable, repairable, (the Wabco isnt!) what sort of power -amps/watts- do they use, how big are they, are they noisy (the Wabco accounts for at least 20% of the 300TDi engine noise at idle) and if you use one what make and type do you, would you, recommend ? Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted February 2, 2014 Share Posted February 2, 2014 I don't know about electric vacuum pumps, but how do you equate engine oil getting into the handbrake drum? It's normally EP80 from the transfer box seal. Quote Link to comment Share on other sites More sharing options...
Boydie Posted February 2, 2014 Author Share Posted February 2, 2014 Nope, trust me it was engine oil, for a start it looked like engine oil, it smelt like engine oil and it was the colour of engine oil, the ZF uses ATF (red and distictive smell) and the same goes for the transfer box and EP80, both have a very distictive smell, taking into consideration all the above and that there were no oil leaks from either the two boxes., that and when we came back from our desert trip the Wabco was dripping like a festering sore so I'm up for yet another vacuum pump unless I can come up with any/better electric alternative. I've heard some later models came out with one so just maybe ........................... Quote Link to comment Share on other sites More sharing options...
Nigelw Posted February 2, 2014 Share Posted February 2, 2014 I have been looking at alternators with vac off the back, but surely this would be easy enough to bring into the system of a pulley vac pump? Or maybe you could do an alternator swap for one with a vac unit fitted on the back? Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted February 2, 2014 Share Posted February 2, 2014 I'm still confused as to how engine oil makes its way back to the back of the transfer box, the vacuum pump goes to the servo, and the cruise control if you have it IIRC, how does that affect the hand brake? Quote Link to comment Share on other sites More sharing options...
Nigelw Posted February 3, 2014 Share Posted February 3, 2014 How much constant vacuum do you get from the WABCO units is the first thing to find out as there are a lot out there to choose from and by looking thru some types there are incredible variables in available ranges, from 4" to 22" constant vacuum. Tell me how much you need and I will see what best suits from the catalogue. Quote Link to comment Share on other sites More sharing options...
steve b Posted February 3, 2014 Share Posted February 3, 2014 what about the electric vac pump off an RRC with ABS? iirc they have a tank too to hold a reserve? I too am intrigued how engine oil has found its way inside the HB drum , presumably there is a trail of engine oil underneath all the way back to the HB... An alternator driven vac pump would be my choice , the hassle would be running the oil pressure feed - could be from oil light switch port cheers Steveb Quote Link to comment Share on other sites More sharing options...
Boydie Posted February 3, 2014 Author Share Posted February 3, 2014 There was/is an oil trail from the vac pump, down onto the sump and from there back over the auto gearbox, transfer box and into the brake drum, not much, true, but enough to affect the brake, this is after all the third or fourth time the wabco's I've fiited have leaked out of the lower welsh plug, this indicates that oil is getting past the piston which equates to piston seal failure. I guess I should have checked on oil getting into the park brake the first time I had one fail. As for how much vacuum I need to operate just the brakes, I have no idea, to determine this I'd have to fit a vacuum guage to indicate that and that again would be a real hassle first obtaining one in the right range and pipeing it in to record the vacuum etc.which is why I asked the question. As for one installed on the rear of the alternator, that also leads to problems as most of these, being constantly driven, need an oil supply, again, a real hassle to pipe up and tap into an oil feed, I was hoping that there just might have been an after market unit that I could use that electrically cuts in and out simply to maintain enough vacuum to maintain brake efficiency. I have heard that there are such units available but just how good are they and has anyone had experience with them? Quote Link to comment Share on other sites More sharing options...
Boydie Posted February 3, 2014 Author Share Posted February 3, 2014 Nigelw, the problem with the alternators with a vacuum pump on the rear is that the vacuum pump would be less than 10-15mm off the exhaust manifold, my EGT guage normally in top gear cruising at 110 KPH runs at 500 degrees Centigrade for 90% of the time and anything up to 700C if pushed hard up a hill , I dont think that this level of radiant heat would be good for any vacuum pump. Quote Link to comment Share on other sites More sharing options...
TSD Posted February 4, 2014 Share Posted February 4, 2014 The vacuum pump on a TGV is on the back of the alternator. Mine hasn't given any trouble over the past 200k miles, and it doesn't have an oil feed as far as I recall. Then again, I don't recall ever needing to replace the vac pump on any of my 200 or 300 tdis either, so maybe my memory is failing. Quote Link to comment Share on other sites More sharing options...
Boydie Posted February 5, 2014 Author Share Posted February 5, 2014 Okay forgive my ignorance but TGV ???? and does this nessesitate buying a new alternator? and I know I'm a bit weird and annaly retentive but vacuum pump aside I can honestly clain to be able to park my disco over white butchers paper and reveal not a single oil leak. Quote Link to comment Share on other sites More sharing options...
TSD Posted February 5, 2014 Share Posted February 5, 2014 TGV - 2.8L VNT version of the 300tdi built by MWM/International in Brazil/Argentina. They also built a 2.5L wastegate version. Yes, it's a new alternator, and on the 2,8 it mounts slightly further outboard than on the 300tdi, though I can't remember why off the top of my head, but I can't see any reason not use put one onto a tdi except :- 1. Unusual bosch alternator outside South America, so probably not cheap - though bearings/brushes etc are standard bosch parts so easy to overhaul. 2. Unusual number of poles, so will make your rev counter read funny. How about some of the Ford Transit units? Don't know how sourceable they would be down there of course, but that's where I planned to start looking if my TGV one ever gave trouble. Quote Link to comment Share on other sites More sharing options...
Nigelw Posted February 5, 2014 Share Posted February 5, 2014 The vacuum pump can be easily heat shielded from the manifild with some creative tin work. Wonder about the lack of oil feed on your TGV TSD???? Quote Link to comment Share on other sites More sharing options...
TSD Posted February 5, 2014 Share Posted February 5, 2014 I did say 'as far as I recall' Looking at the parts catalogues, the 2.5 manual shows what looks like an oil feed pipe that isn't explicitly shown in the 2.8 catalogue. It looks (from the 2.5 parts catalogue) that it takes a feed from the turbo oil pipe, and dumps into the sump, but I'd have to get under the bonnet in daylight to confirm exactly how it's done. This is the 2.5 parts catalogue drawing... Quote Link to comment Share on other sites More sharing options...
Boydie Posted February 6, 2014 Author Share Posted February 6, 2014 No, the above TGV is far too complicated conversion wise and parts wise, here in good old Oz obtaining them would be a nightmare. I have heard of an electric vacuum pump and of someone fitting one, I'll meet up with him on Saturday and get the info on it, from conversations I've had with others I am led to believe it has/includes a remote sensor in the vacuum line that operates it's switching relay so it only runs when there is a demand for constant vacuum, ie, constant baraking in traffic but if the brakes are not being used, as on a long flat road ot motorway it is off for most of the time. It's self contained and like your average air pump compressor only relies on a small amount of contained grease/oil to maintain lubrication of the rotating parts & piston. I'll let you know on Monday. Quote Link to comment Share on other sites More sharing options...
TSD Posted February 6, 2014 Share Posted February 6, 2014 No, the above TGV is far too complicated conversion wise and parts wise, here in good old Oz obtaining them would be a nightmare. http://www.davisperformance.com/parts.html#tdi2.8 Quote Link to comment Share on other sites More sharing options...
simonr Posted February 6, 2014 Share Posted February 6, 2014 For my Electric Freelander, I looked high & low for a decent vacuum pump (as an eleccy motor does not produce much vacuum, nor has the facility to drive a mechanical one). Initially, I made my own out of a Series 2 Diesel fan belt driven pump driven by the motor from a 12v car cooling fan. This worked fine - but was very noisy! In a Series 2 Diesel you wouldn't notice it, but in an EV it was very loud! I've since replaced it with a Vacuum pump from an Audi TT (also used in several other makes of cars) similar to this one: http://www.ebay.co.uk/itm/AUDI-TT-8N3-ELECTRIC-BRAKE-ASSIST-VACUUM-PUMP-1J0612181B-1J0612181-B-/251363152453?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item3a86695245 It has both been reliable, low cost and best of all from my POV, it's near silent! Si Quote Link to comment Share on other sites More sharing options...
Boydie Posted February 7, 2014 Author Share Posted February 7, 2014 Thank you, I"ll look one up, Audi's are fairly common in Oz. Quote Link to comment Share on other sites More sharing options...
Boydie Posted February 15, 2014 Author Share Posted February 15, 2014 Hi guys, I got one on EBay, it seems that these are failrly common as a fixture on hot rods etc. that dont have sufficient suction at the manifold to operate their assisted brake system, the little doozie I have is machined from alloy billet of aircraft quality, has a built-in vacuum pressure switch and supplies 22" of mercury suction, the beauty of it is it has a diaphram and not a piston and therefore no need for lubrication, only draws 5 amps when running - which isnt often unless I'm in traffic - and is silent and best of all goodbye Wabco - the blanking plate on the cylinder block looks very nice When I fitted it I found I have assisted brakes by the time the glow plug light has gone off, very fast! - its wired to the same circuit as the fuel valve. Quote Link to comment Share on other sites More sharing options...
Inigo Posted April 8, 2015 Share Posted April 8, 2015 Do you have any details on the pump you bought? I'm trying to track down something similar and not having a lot of luck. Quote Link to comment Share on other sites More sharing options...
Boydie Posted April 9, 2015 Author Share Posted April 9, 2015 Inigo, I'm not having too much luck in pasting the EBay address over to this page, if you know how I can give you the address and item number Quote Link to comment Share on other sites More sharing options...
Nigelw Posted April 9, 2015 Share Posted April 9, 2015 Do you have any details on the pump you bought? I'm trying to track down something similar and not having a lot of luck.This will suit your needs Inigohttp://www.ebay.co.uk/itm/AUDI-A4-S4-A5-S5-A6-S6-A8-S8-ELECTRIC-VACUUM-PUMP-8E0927317F-/281628806025?pt=LH_DefaultDomain_3&hash=item4192628b89 Quote Link to comment Share on other sites More sharing options...
Inigo Posted April 13, 2015 Share Posted April 13, 2015 Thank you both. Found a similar one to that listing on German ebay that came with a bracket (that I can modify to fit). It seems to have decent rubber mountings to reduce vibration and noise. I see that Hella make a range of vacuum pumps that look very similar to the Audi one, but Hella said they don't supply direct to end users. I did find that Summit racing sold them all though. Is the one linked man enough to be used on its own, some descriptions suggest it is suitable for use to assist or improve brake vacuum. Should I be thinking of adding some sort of vacuum reservoir, or would that be overkill? Quote Link to comment Share on other sites More sharing options...
simonr Posted April 13, 2015 Share Posted April 13, 2015 I used the one pictured in my Electric Vehicle as the sole source of vacuum. So long as you keep the hoses short (mount the pump close to the servo), I found it was enough for it to switch on with the brake light! It gives the pedal a different feel but it works just fine. Si Quote Link to comment Share on other sites More sharing options...
Inigo Posted April 13, 2015 Share Posted April 13, 2015 Does yours have a built in vacuum pressure switch? I have an external one, and was going to figure out how to connect them up on the bench, but it maybe surplus to requirements. Quote Link to comment Share on other sites More sharing options...
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