“SUN” SERVICE STATION

Sun (Auckland), Volume IV, Issue 970, 13 May 1930, Page 6

“SUN” SERVICE STATION

THE 'Motordom' section or The Sun includes in its service to readers a A Queries and Answers Department, the object of which is to give accurate Information regarding mechanical and touring subjects. Whatever the particular puzzle may be in either diagnosing irritating or motoring information of any kind. “Headlight* will endeavour to help or refer the point to men who are recognised automobile experts in their respective lines. All communications must Oe accompanied oy the inquirer's name arid address (not for publication}, and sent to THE SUN m ‘Service Station MotordomTUß SUN Auckland. Answers will appear weekly in thi«= column

“Puzzled.” —1 have a 192 S Trojan that has done nearly 25,000 miles, and the dynamo has given no trouble until 10 days ago, when the output as shown on the ampmeter suddenly increased for a day or two then decreased to zero. I examined fuse block, wiring, etc., and found all O.K. there. Took out the dynamo and found that about twothirds of the circumference of the commutator had a thin film of what looked like carbon spread over it, the other third being bright and shiny. I cleaned it with fine sand paper and on the next run found the dynamo charging O.K. After about three days’ running the output gradually decreased and an examination showed much the same deposit as before except that the black part started suddenly in a straight line and ended as suddenly. (2) While the dynamo wasn’t charging I was afraid of running my battery down while doing daylight running, as there is no magneto on the Trojan, but found that the ampmeter needle remained at zero. (a) The trouble with the black deposit on the commutator Is due almost certainly to a fault in wiring which has just made its appearance. It should be taken to an electrical expert. (b) If you were using the car, and nothing going from the battery to the dynamo, the ampmeter should show a discharge, and if it didn’t do so the trouble is with the ampmeter or needle. H.H.—Knowing the great service the S.S.S. gives, I would be much obliged if you could help me out. I have a “Chev..” which lately developed a knock. To cure this the following adjustments have been made: Play taken up in main bearings and big ends, set new gudgeon pins, decarbonised and valves ground, without curing the trouble. This knock does not occur until the speedo registers 25 miles an hour. With the car standing and pulling against the hand brake there is no knock. The knock can be stopped by retarding spark fully. Otherwise the car pulls and runs O.K. Is it the timing which requires attention? There is about 3-16 end play in the crankshaft, but as the above adjustments have been done by a service station, it should not be that. Presuming that the work carried out on this car has been done in a workmanlike manner, the knock points to piston slap. However, the same knock may be caused through the end play in the camshaft, which is certainly excessive. but, of course, not so exces-

sive to be dangerous, or likely to cause trouble. I presume that when the work was carried out on the bearings they were only tightened up, but in order to make a thorough job of bearings—particularly raaiij bearings they should be removed, properly scraped and fitted. It is impossible to make a first-class job of main without completely removing the engine from the chassis. If this has not been done, it is possible that the knock may be in the main bearings. A.F.—Could you find out for me the size of the tyres on the 1925 Reo. Thirty-two by Six “Driver.”—Will you please advise through the S.S.S. how I can take up the slack in the chain-drive from crankshaft to generator of 1924 Dodge; also, show how much slack to allow? * * * To adjust starter generator chain: Remove chain inspection cover over sprocket end of starter generator. Loosen starter strap clamp bolt and lock nuts and turn “V” block stud until blocks are well clear of starter. The strap and block should be very loose while the adjustment is being made to avoid throwing sprockets out of alignment. Straighten tongues on large circular lock washer to release castlehead lock nut on starter. Back off lock nut two or three turns. Loosen set screw that locks eccentric adjusting ring in crank-case, that is the exterior screw adjacent to generator chain inspection cover. Drive eccentric round until proper adjustment of chain is secured which should give half an inch of free up and down movement of chain midway between sprockets. This can be determined by inserting the fingers round the small sprocket after the inspection cover has been removed. A correctly adjusted chain will run without noise, providing, of course, it has not been run previously for any length of time out of adjustment. In consolidating the adjustment, carry out the following operations in the order mentioned: Tighten set screw locking eccentric ring in chank-case, then castelated lock nut on starter, and turn down tongues on lock washer to lock it in position. Adjust “V” block firmly against starter. This adjustment is important, and the block should be firmly enough against the starter to hold it in position, but not enough to force it out of alignment. Tighten lock nuts on “V” block stud, tighten starter clamp bolt, replacing chain inspection cover, renewing gasket if necessary.