FAILURE OF ENGINE COUPLER TEST & CAUSES.

1)Start with outdrive DOWN , and shift in forward gear.

2)Step on left side blade and force downward (CCW).

3)Watch the engine pulleys when the prop turns.

4)If the engine turns, the coupler is usually good.

5)If the engine does not turn when the prop turns something is broken.

6)If propshaft does not turn with prop, the prop clutch is stripped..

7)If the shaft behind the engine doesn’t turn but the propshaft does your outdrive is broken.

8)If the prop and shaft turn and the shaft behind the motor, but not the engine, your coupler is broken.

9)Before replacement of the coupler, check the following..

10)Look across the boat transom and have a heavy person stand on outdrive and bounce.

11)If the transom flexes it will cause failure and must be repaired before the coupler is changed.

12)If the front motor mount is loose or if the pad where it sits is rotten, alignment will cause failure..

13)If these mounts and transom are good proceed with coupler change.

14)There are several possible couplers most are available aftermarket.

15)The im850 fits all Chevrolet with 3-1/2" bolt pattern on crankshaft.

16)The im598 fits all v-8 Fords.

17)Newer Chevrolet take the triangle coupler (small for 12-1/2 f/w large for 14" f/w).

18)If you do not know the size of the f/w, measure across two holes (10" or 11").

19)The im505 fits newer v-8 Chevrolet engines with 3" bolt pattern to avoid the triangle coupler.

20)The 224 C.I.D. Mercruiser uses two different couplers which are not available aftermarket.

21)When coupler is removed the reason for failure can be determined.

22)There are five possible failures.

23)Rubber in coupler broken in half (Struck under water object).

24)Splines internal in the coupler gone (lack of lube on splines long term) or bad rear alignment (short)

25)Rubber slipping in external shell (underwater object if old, possible flaw if new)

26)Rubber separated from core spline (hit underwater object if old) possible flaw if new.

27)Rubber melted (most common) poor alignment.

28)Only 25 or 26 have chance for warranty if part is new.

29)If melted and transom and mounts are good, Check alignment.

30)Alignment covered in separate section.