Austin Seven Failures and How To Avoid Them
PART 1 - THE SEVEN ENGINE
Click here for part 2 - Transmission
Click here for Part 3 - Lubrication
BROKEN CRANK
* Crack Test
* Line Bore 3 Bearing
* Fit Phoenix
LOOSE FLYWHEEL
* Riding On Key
* Fit Out Of Engine To Ensure Oil Thrower Clearances etc.
* Lap Onto Taper
* Really Tight – Use Impact Driver with a 3/4" socket/bar on flywheel. Think about Loctite
OIL PUMP
* Vanes: Flats go on bottom
* Check pressure release is clean & not rooved
* Check springs
* Make sure gear on very small key
* Loctite gear nut
Front bearing lip broken
* careless bearing removal
* trying to fit wrong bearings
* inspect carefully for cracks
* replace ring – Vince does them.
Split cam followerS
* difficult fault – misfires at high speed –sticks in guide
* check before fitting
* avoid over tightening (& under tightening!)
Sheared studs
* what made of ? – EN36? Dave Cochrane uses EN16t
* beware cheap
* leave good original alone
* use Studlock
* avoid over tightening
* helicoil if slack
Front camshaft bearing
* replace peg with 5/16 bolt with washer (tap bearing in situ)
* can use socket headed screw
Head gasket
* flat surfaces
* no corrosion
* assemble with grease smeared on
* ensure correct gasket (HE or LC)
* can be either way up (usually seam up)
* torque to 20 ft lbs in correct sequence
Oil leak rear main
* modern lip seal on smooth surface or use speedy sleeve repair
* worn out Quickthread
* loose rear main
* oil thrower missing/ wrong way round /not crimped
* oil return hole not lined up in carrier
* three different flywheel boss sizes (so use lip seal!)
* make sure seal casting is drilled correctly
Overfilling the rear axle can result in oil contaminated brake shoes and using the recommended ⅔ pint in a worn chummy gearbox can result in oil on the clutch linings. Phil stressed the importance of always knowing how much oil there is in your rear axle/gearbox so it is important to drain the oil completely and inspect and measure it in an accurate gradu-ated measure. This gives early indication of axle/gearbox damage and/or leaking. When doing intermediate checks between oil changes you can make up a hook to check the correct depth from the filler orifice corre-sponding to your chosen capacity but the car has to be on all its wheels on level ground so it's more accurate to always drain and refill.
Vince Leek recommends a maximum of ˝ pint in a chummy rear axle and Phil said that in line with many Austineers Phil uses a maximum of ˝ pint in his worn chummy gearbox (and as a personal choice uses about 10cc of Gear Molyslip in his gearbox and also his back axle. Note: Gear Molyslip should not be used in a synchro box.
Split crankcase due TO little end bolt
* use new HT bolt with spring lockwasher & Loctite
* use internal stainless shakeproof
* loose bolts split 1 in 12 conrods
blocked oil jets
* change oil regularly
* beware multigrade detergent oil unless oilways scoured out
* use monograde oil
* use oil filter if doing high miles
Broken top water manifold bolt
* use stainless stud
* inspect carefully – make sure not cracked strap (use nut under?)
* tighten carefully
Broken side manifold bolts
* same as top
* when repairing do not drill/tap into bore
* use hacksaw blade as drill stop
Cracked block
* watch out for sludge around bottom of bores
* watch out base of no. 4 bore can be thin when sleeved
* change block if cracked from centre stud
GENERAL
Head nuts torqued to 20 - 25 ft lbs. Seal stud threads with Red Hematite etc. to prevent leaks
Camshaft end-float is best adjusted on the bench (if the engine is dismantled)
Machining of later flywheel to take earlier ring gear (the early rare 1 5/16 flywheel can be used if you can find one)
There are several sizes of rear oilseal scrolls and cam shaft bearings - make sure you have the right ones!An Engine Fault Tracing Chart is located on the DA7C website. Under ‘Technical’ select ‘Engine’ then ‘Tracing Engine Faults’.Ruby with clickety click sound on overrun and popping. - Weak mixture or leaky manifold gasket.
Will flat cam followers and a sports cam give much performance improvement. - flat cam followers and a fast road cam would give more torque and top speed. The next level is a full race cam and this would give poor tick-over. Paul Bonewell can provide re-profiled cams or can re-profile your own.
What is the normal tick-over speed. - The general view was that 500rpm is about right.
What the ideal length is for an exhaust system for an RP. The correct length of exhaust for an RP Saloon is 52” from the manifold to the end of the tail pipe. This provides greatest efficiency and prevents unpleasant resonance.
What oils are recommended? - Avoid EP oils with
high sulphur content because they attack and corrode phosphor bronze bushes and
brass bearing cages .
Oils for old engines require high levels of zinc and
phosphates to cope with the rubbing forces in plain bearings and cams and
followers etc.
Guy Butcher then wrote to classic car oil manufacturers and
the only one that helped and supported him was Morris Lubricants who made the
following recommendations :
For Engines: Morris Lubricants Golden Film SAE
15w50 Classic Motor-sport Mineral Engine Oil.
For Gearboxes: Morris
Lubricants Lodexol 80W-90 Mineral Gear Oil API GL-4.
For Rear Axles: Morris
Lubricants Golden Film AG 140 Gear Oil
These products are available from
Blillov Ltd. via eBay and from The Motor-ist Centre in New Milton.
I hope you find this useful, Phil Whitter