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Date:         Tue, 17 Dec 2002 21:56:55 -0600
Reply-To:     Stan Wilder <wilden1@JUNO.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Stan Wilder <wilden1@JUNO.COM>
Subject:      Of Interest to Air Coolers
Comments: cc: wetwesties@yahoogroups.com
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From: Nigel A. Skeet To: Type 2 Listees Date: Friday, 13th December 2002 ! Reply to: naskeet@hotmail.com OR naskeet@yahoo.co.uk

INHIBITING OIL SURGE IN VW FLAT-FOUR ENGINES (AN UNDESIRABLE AND LITTLE RECOGNISED, COMMON PHENOMENON), BY MEANS OF A WINDAGE TRAY, 'WINDAGE-STYLE' PUSHROD TUBES AND/OR OIL-SUMP EXTENSION

Compiled & Written by Nigel A. Skeet

Although unfamiliar to most VW owners, oil surge is a relatively common phenomenon, to which the VW flat-four engine is particularly prone (see Peter Noad, "Pace Notes", VW Motoring, November 1997, pp40~41); resulting from centrifugal effects, which cause the oil to surge out of the crankcase, through the pushrod tubes and into the valve rocker box covers, under conditions of 'high-speed' cornering.

This leads to there being inadequate oil in the crankcase, such that the oil pump pick-up tube is not fully immersed and so sucks up a mixture of oil and air, which does not provide adequate lubrication; yet another reason to ensure that the oil level is always at the maximum mark.

'High speed', is a relative term and in the case of the flat-four engine, oil surge can occur, even under normal driving conditions with a VW 1200 Beetle, as Peter Noad personally discovered. One British owner, of a non-standard VW Beetle, with 1641cc engine, has observed exceedingly low oil pressure (illumination of the oil-pressure warning light, served by the standard 0730 1 0715 BAR oil-pressure switch), as a result of oil surge, when accelerating and/or cornering.

Although not in the same class as a Porsche 911, the 1968~79 VW Type 2, is a remarkably agile vehicle (even without after-market, front & rear anti-roll bars!), when skillfully driven, so it is probably equally prone to oil surge, as the VW Beetles. With the aid of an oil-pressure gauge or high-pressure, oil-pressure switch, one has the option of changing one's driving style in order to avoid oil surge or alternatively, to combat it, by implementing one or more of the recognised engine modifications. These modifications are a supplementary deep sump, a set of 'windage style' pushrod tubes and an oil windage tray.

As the name suggests, the principal purpose of the windage tray, is to prevent windage. Windage is the process whereby air is entrained into the oil, owing to the rotation of the crankshaft and connecting rods, plus to a lesser extent the camshaft; the air being dragged around by the moving surfaces owing to viscous friction. If by chance the oil-sump has been over-filled, then in extreme cases, the oil is whipped-up into a frothy foam. This not only radically reduces the lubricating properties of the oil, but also increases oil temperature and wastes power, hence increasing fuel consumption.

Being a horizontal baffle, which is positioned below the camshaft and just above the surface of the oil, when filled to the maximum, a windage tray also serves the secondary purpose, of limiting the extent to which the oil level can rise at one end of the crankcase (i.e. sump) and fall at the other, so reducing the effects of surge. The windage tray should cover the entire area of the oil reservoir and its edges be a tight fit, to the internal contours of the crankcase.

To allow previously circulated oil, to drain back into the crankcase, it should have a limited area of slots or holes, close to the longitudinal, central axis. Where practical, these slots or holes should ideally have down-turned flanges or spigots In conventional engines with a separate bolt-on oil sump, oil would be further inhibited from sloshing to and fro, by incorporating vertical baffles, arranged longitudinally and transversely. Ideally, the baffles should incorporate one-way valves, to facilitate a rapid return of the oil to the pre-surge level. For a VW flat-four engine, any such vertical baffles, would have to form part of the windage tray. Home-made and proprietory aftermarket windage trays are discussed by Peter Noad, Bill Fisher and A. Graham Bell. Bill Fisher observed that all but the home-made windage trays he had seen (i.e. prior to his book being published in 1970), interfered with the camshaft.

An oil windage tray, with neoprene rubber, edge-sealing strips, is a standard fitment in the VW 411LE & 412LE, plus the VW-Porsche 914-4 engine crankcases. These windage trays can be retro-fitted to the 1972~83 VW 17/18/2000 Type 2 engine, as I have done with my 1911cc, VW 17/1800 Type 2 & 4 hybrid engine; which I photographed for inclusion in my technical book & magazine articles.

If a windage tray is being fitted to a VW Type 4 engine, equipped with carburettors and associated mechanical fuel pump, provision must be made, for oil lubricating the fuel-pump pushrod, to escape back into the crankcase. Tom Wilson's book (see pages 72, 74 & 123), both documents and illustrates the windage tray, but no mention is made of it, in the Haynes manual for the VW 411 & 412 and so far, I have not seen it mentioned in any other books!

A few years ago, whilst on a desk-top publishing course, I prepared an illustrated sheet, showing my VW 411LE windage tray, positioned in one half of the crankcase, together with the camshaft gear, which had been modified, by cutting two 0.090 inch wide grooves, to the depth of the gear teeth. Regretably, I neither possess an Internet website (my local public library, is my only access to Internet & e-mail facilities!) nor have any present means of scanning, my illustrated sheet or photographs, to send as e-mail attachments. However, I can send photocopies by snail mail, if desired.

According to Bill Fisher's book (see pages 99 & 107), this grooving modification, is attributable to Gene Berg (that icon of Southern Californian, VW air-cooled engine tuning!), which is said to reduce the internal pressure and excessive oil mist (hence reducing crankcase breather emissions!) inside the crankcase, plus recovering a little of the power, used to squeeze the oil between the gear teeth.

Keith Seume advocates substituting windage style pushrod tubes, which also inhibit oil surge. These are characterised by a longer section of tube, which extends further into the crankcase. Bill Fisher suggests supplementing the standard pushrod tubes, of the VW 12/13/15/16000 Type 1, 2 & 3 engines, with inch (i.e 19 mm) long sections of pushrod tube, to obtain the advantages of the windage style pushrod tubes. One end of the short tube section, is peened over to form a lip, so that it is held in position by the pushrod tube seal. He states that this simple modification, is commonly used in Formula Vees

Priced at US$ 39799 in October 1997, windage style pushrod tubes (stock No. 46-8531), for the VW 12/13/15/16000 Type 1, 2 & 3 engines, made from stainless steel (a useful bonus, as the original factory fitted components are prone to rusting) are available by mail-order from Car Custom Inc., in California, USA. I am not aware of any off-the-shelf, windage style pushrod tubes, for the VW Type 4 engines and owing to the form of the pushrod tube seals and crankcase design, it would not be practical to supplement the standard pushrod tubes, as suggested in Bill Fisher's book (see page 98). However, it might be possible to extend the standard VW Type 4 pushrod tubes, by welding or brazing on, an extra length of tube.

Fitting a supplementary oil-sump beneath the engine crankcase, in conjunction with an extended oil pick-up tube, overcomes the problem of inadequate oil supply, associated with oil surge. Although oil surge can still occur within the crankcase, the oil does not surge out of the supplementary sump and hence the extended oil pick-up tube remains fully immersed in the oil.

Supplementary oil-sumps, of 175, 375 & 470 US quart capacities (note 1 US quart = 079464 litres) are available for VW 12/13/15/1600 Type 1, 2 & 3 engines, from Gene Berg (reputedly pioneered by him) Unique Supply, So. Cal. Imports, Kustom 1 Warehouse, Performance Express and other suppliers; including some in Great Britain. I believe there is also a SCAT branded, 175 US quart capacity, supplementary oil-sump available, for the VW 17/18/2000 Type 2 & 4 engines, but from what sources, I don't know! If anyone knows, please tell me?

REFERENCES

Peter Noad, "Pace Notes", VW Motoring, November 1997, pp40~41

Tom Wilson, "How to Rebuild Your Volkswagen Air-cooled Engine", HP Books, 1987, pp72, 74 & 123.

Bill Fisher, "How to Hot Rod Volkswagen Engines", HP Books, 1970, pp96~99 & 107.

Keith Seume, "Aircooled VW Engine Interchange Manual the Users' Guide to Original & Aftermarket Parts for Tuning", Bay View Books, 1996.

A. Graham Bell, "Performance Tuning in Theory & Practice", Haynes Publishing, 1981, pp191~192.

J. H. Haynes & K. F. Kinchin, "VW 411 & 412, Owners' Workshop Manual; 1679cc & 1795cc; 1968 to 1975", Haynes Publishing, 1988. Everything you'll ever need on one web page from News and Sport to Email and Music Charts


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