Trim Cylinder End Cap Seal Kit 1100-8M0021648 99638A1 878243A1 for Mercury Mariner
Trim Cylinder End Cap Seal Kit 1100-8M0021648 99638A1 878243A1 for Mercury Mariner
Product Overview
Trim cylinder end cap with a complete seal set for the Mercury and Mariner V6 outboards, the gland that closes the top of the trim ram and holds the oil in. It replaces Mercury 1100-8M0021648, 99638A1, 8M0021648 and 878243A1, it fits the generation 1, 2 and 3 three ram style trim units, and it ships as one assembly in a 150 mm x 180 mm x 10 mm pack at 77 g.
Three ram trim units carry two tilt rams and one trim ram. The cap sits on the ram, the piston rod passes through it, and the seals inside it are what stop the hydraulic oil escaping past the rod. When they let go the trim creeps down, oil shows on the water, and the pump starts to lose pressure.
This is the complete cap, not just the seals. The cap body, the oil seal, the outer O-ring and the inner O-ring all come in the one assembly, so the job is done by removing the old cap and fitting the new one rather than pressing seals out of a corroded housing on the bench.
The cap body is the part that decides whether the job lasts. On an older unit the housing around the seal is usually scored or eaten by salt, and pressing a fresh seal into a damaged bore gives a leak again within a season. Checking the piston rod for pitting at the same time is worth doing, because a rough rod will destroy a new seal whatever cap is fitted.
Fitment is by serial number, not by horsepower alone. Mercury used more than one trim unit across the 135 to 250 HP range and across the Verado, EFI and DFI families, so check the serial number on the engine plate against the table below before ordering.
Specifications
| Specification | Detail |
|---|---|
| Condition | Brand new |
| Type | Trim cylinder end cap with seals |
| Mercury Part Number | 1100-8M0021648 |
| Also Replaces | 99638A1, 8M0021648 |
| Additional Number | 878243A1 |
| Aftermarket Kit Number | FSM024 |
| Fits | Mercury and Mariner 3 ram style trim units, generations 1, 2 and 3 |
| Horse Power Range | 135 HP to 250 HP |
| Ram Style | Three ram trim and tilt unit |
| Seals Supplied | Oil seal, outer O-ring, inner O-ring |
| Quantity | 1 complete end cap assembly |
| Net Weight | 77 g including packaging |
| Pack Size | 150 mm x 180 mm x 10 mm |
| Pack Size In Inches | 5.91 in x 7.09 in x 0.39 in |
| Warranty | 3 year |
OEM Cross Reference
| Brand | Part Numbers |
|---|---|
| Mercury / Mariner | 1100-8M0021648, 8M0021648 |
| Mercury / Mariner | 99638A1, 878243A1 |
| Aftermarket | FSM024 |
Compatible Engines
| Model | Horse Power | Serial Number Range |
|---|---|---|
| Mercury 150 HP | 150 HP | 0G960500 to 0T408999 (cast / removable pump housing) |
| Mercury 150 HP EFI | 150 HP | 0T801000 to 1B226999, 1B227000 and up |
| Mercury 150 HP DFI | 150 HP | 1B227000 to 1B417701, 1B417702 and up |
| Mercury 150 HP Verado | 150 HP | 1B227000 to 1B381711, 0P419487 to 0P464487 |
| Mercury 135 HP DFI | 135 HP | 0T801000 to 1B226999, 1B227000 to 1B417701 |
| Mercury 135 HP Verado | 135 HP | 1B517159 to 2B576734, 0P514869 to 0P593020 |
| Mercury 175 HP EFI | 175 HP | 0T409000 to 0T800999 |
| Mercury 175 HP DFI | 175 HP | 0T801000 to 1B226999, 1B104549 to 1B426560 |
| Mercury 175 HP Verado | 175 HP | 0P419487 to 0P464487, 0P464488 to 0P514869 |
| Mercury 200 HP EFI | 200 HP | 0T750164 to 0T800999, 1B417702 to 1B504988 |
| Mercury 200 HP DFI | 200 HP | 0T801000 to 1B417701, 0T980000 to 1B417701 |
| Mercury 225 HP EFI | 225 HP | 0T409000 to 0T800999 (Marathon / Sea Pro) |
| Mercury 225 HP DFI | 225 HP | 0T599000 to 0T800999, 1B426561 to 1B752546 |
| Mercury 225 HP DFI DTS | 225 HP | 1B417702 to 1B504988 |
| Mercury 250 HP XB | 250 HP | 0G980600 to 0T800999 (cast / removable pump housing) |
| Mercury 250 HP DFI XS | 250 HP | 0T651945 to 0T818042, 0T997974 to 1E000796, 1E000797 to 1E002341 |
| Mercury 250 HP DFI Sport XS | 250 HP | 1E002342 to 1E051823 |
| Mercury 250 HP | 250 HP | 0T801000 to 1B417701 |
| Mercury 110 HP Jet | 110 HP | 1B690542 and up |
What's Included
| Component | Detail | Qty |
|---|---|---|
| End cap body | Trim cylinder end cap, machined housing for the ram | 1 |
| Oil seal | Rod seal that holds the hydraulic oil in | 1 |
| Outer O-ring | 3.1 mm section, 44 mm outside diameter | 1 |
| Inner O-ring | 2.65 mm section, 16 mm inside diameter | 1 |
| Trim oil | Not included, refill with the oil specified for the unit | 0 |
Packing Dimensions
| Measure | Millimetres | Inches |
|---|---|---|
| Pack length | 150 mm | 5.91 in |
| Pack width | 180 mm | 7.09 in |
| Pack height | 10 mm | 0.39 in |
| Weight with packaging | 77 g | 2.72 oz |
Signs The End Cap Needs Replacing
| What You See | What It Means | Action |
|---|---|---|
| Oil film on the water around the outboard | Rod seal weeping | Fit the new cap assembly |
| Trim creeps down overnight | Oil passing the rod seal | Fit the new cap assembly |
| Trim slow or noisy | Low oil from the leak | Fit the cap and refill the unit |
| Water in the trim oil | Seal failed at the cap | Fit the cap and flush the unit |
| Oil running down the ram | Outer O-ring or seal gone | Fit the new cap assembly |
| Cap body corroded or scored | Bore damaged around the seal | Fit the new cap, do not reuse the old body |
Fitting Notes
| Step | Action |
|---|---|
| 1 | Check the engine serial number against the fitment table |
| 2 | Raise and support the outboard before releasing the trim |
| 3 | Clean the ram and the cap area before opening anything |
| 4 | Check the piston rod for pitting or scoring before fitting |
| 5 | Remove the old cap and drain the unit as needed |
| 6 | Lubricate the new seals and fit the assembly squarely |
| 7 | Refill with the specified trim oil and bleed the rams |
| 8 | Cycle the trim several times and check for leaks |
Condition & Warranty
| Item | Detail |
|---|---|
| Condition | Brand new |
| Warranty | 3 year |
| Packaging | Pack, 150 mm x 180 mm x 10 mm |
Before You Buy
- Replaces Mercury 1100-8M0021648, 99638A1, 8M0021648 and 878243A1
- Also listed as aftermarket kit number FSM024
- Complete cap with oil seal, outer O-ring and inner O-ring
- Fits generation 1, 2 and 3 three ram style trim units
- Covers the Mercury and Mariner 135 HP to 250 HP range by serial number
- Check the engine serial number against the fitment table before ordering
- 77 g with packaging, pack 150 mm x 180 mm x 10 mm
- 30-Day Easy Returns
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