Check Valve 21-8781051
- Guaranteed fitment for 376 different models
- This is an OEM part manufactured by Mercury Marine
- Flat rate shipping starting at $4.95
- 30 day return policy
Product Description
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20 Product Reviews
Mercury Optimax 150
- Repair Difficulty
- Medium
- Repair Time
- 1 to 2 hours
Problem fixed: Oil tank would not fill
Check valve was bad
200 hp mercury
- Repair Difficulty
- Easy
- Repair Time
- 30 to 60 mins
Problem fixed: Lot of smoke start up
Replaced oil air pressure check valve
Mercury 135hp Black Max
Mercury Outboard 175 V6
- Repair Difficulty
- Medium
- Repair Time
- More than 4 hours
Problem fixed: Excessive smoke.
Compression is good 120 all around. Replaced old check valves for fuel/oil lines. Didn’t fix problem. I’m now going to look for air leaks in fuel lines which can cause excessive smoke.
150 Mercury
- Repair Difficulty
- Easy
- Repair Time
- Less than 30 mins
Problem fixed: No oil pressure in reserve tank
Replaced the check valve on the engine leading to the remote oil tank. Problem solved
200 mercury
1985 Mercury Black Max 150 hp Long Shaft
- Repair Difficulty
- Easy
- Repair Time
- 30 to 60 mins
Problem fixed: On-going low oil alarm periodically going off.
Have been working to solve this on-going low oil alarm issue and have slowly (hoping) to finally be resolving the issue here's how; 1) replaced the control module due to water getting into it causing a 'false' alarm. Bought a 'used' one on ebay for $85. Works great. Temporary alarm fix. 2) bought a new on-motor sensor cap for the remote oil tank due to a crack on the cap causing loss of pressure and the oil level dropping setting off the alarm. Temporary alarm fix. 3) Replaced the two oil feed lines to the main tank; both had cracks at the fitting at the tank. Replaced the hoses. Temporary alarm fix. 4) checked the 2 p.s.i. check valve which the 'pressure' hose is connected to at the crankcase; I could blow air in both directions, which I shouldn't; loosing pressure in the remote reservoir at low speed. Oil is unable to be fed up to the engine reservoir with steady pressure due to the leaky check valve....I think. Ordered the new valve from Crowley and will report back if this finally solves the on-going issue. 5) if this doesn't solve it I will disconnect the whole system and run pre-mix 50:50.
mercury 225
- Repair Difficulty
- Hard
- Repair Time
- 2 to 4 hours
Problem fixed: oil tank not being filled when engine is running
we requested the part via normal post and never received it. When we contacted Crowley they reimbursed our previous purchase and resend it via priority post. great service!
Mercury XR6
- Repair Difficulty
- Easy
- Repair Time
- Less than 30 mins
Problem fixed: Loss of oil to cowl resevoir
Noticed my boat was pulling off the cowl tank rather than the reserve tank. Replaced the 1 way check valve after I blew through it both ways. Fixed the problem quick and easy!
Mercury 240 Jet
- Repair Difficulty
- Easy
- Repair Time
- Less than 30 mins
Problem fixed: Oil not flowing from reservoir to engine mounted tank
Crankcase check valve not working. Replaced check valve and it is working now.
Customers Also purchased
Supersession Chain
| Name | SKU | Superceding SKU |
|---|---|---|
| Check Valve VIEWING THIS PRODUCT | 8781051 | CURRENT |
| Crankcase CHECK VALVE | 878105 | 8781051 |
| Crankcase CHECK VALVE | 432783 | 878105 |
| DRAIN FITTING | 432781 | 432783 |
| CHECK VALVE FITTING (CRANKCASE) | 43278 | 432781 |