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Low oil pressure after landing hard

Old 10-10-2017, 10:54 AM
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Default Low oil pressure after landing hard

35 Fountain, with twin 500 EFIs. 1st. problem - So after catching some serious air the boat came down hard on the right side. So hard it originally sounded like the side window may have cracked. Several miles up river the oil pressure dropped to the point it sounded the alarm and the gauge was reading 20 PSI. I limped into the dock to check it out. Initial it appeared that the oil level was low so I added 1 & 1/2 quarts of oil (VR1 40W) bringing it to the correct level. My boat ramp was only several miles away and we got there with no other problems. 2nd. Because of the low oil pressure alarm I did a complete oil and filter change on both motors. 3rd. Ran the boat last weekend and after about 20 minutes running @ 3800 RPMs the oil pressure started to gradually drop from 38 PSI which has been the norm to 25 PSI. Once again I stopped and checked the oil. It was so clear because of being brand new oil it was extremely hard to see. So after checking it at our next stop I actually added to much. After leaving that stop I decided to just take her back to the trailer. After about 10 minutes the oil pressure started to drop again. Ok fast forward. The motor has been pulled, The oil pan removed. There is no "smoking gun" that would clearly point to the oil pressure or lack there of. Before we tear into the engine is there anything that we might want to check prior to that? I might add that there is only 20+ hours on complete rebuilds. The other motor is running fine at 38/39 PSI on the oil pressure gauge and the low oil pressure on the first motor was verified by a additional mechanical gauge that was added.
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Old 10-10-2017, 11:25 AM
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Tough call!!!!!
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Old 10-10-2017, 12:42 PM
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My best guess is there's a fine crack in the pickup tube that you can't see with the naked eye.
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Old 10-10-2017, 12:47 PM
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Did you check oil temps????

I'm thinking the oil bypass valve may have got jarred in the hard landing and oil is bypassing the cooler
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Old 10-10-2017, 01:52 PM
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I had an oil pressure gauge that was reading low, pulled out the sending unit, cleaned it and haven't had a problem since. I was constantly reading 20psi lower than normal though so doesn't sound like that's your issue but cant hurt to check.
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Old 10-10-2017, 03:35 PM
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I like your riding style. Thumbs up. btw you got some good advice already but before digging to deep throw a mechanical gauge on it even if you just tape it temporarily to top of back seat or where ever.
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Old 10-10-2017, 03:38 PM
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Originally Posted by ben
I had an oil pressure gauge that was reading low, pulled out the sending unit, cleaned it and haven't had a problem since. I was constantly reading 20psi lower than normal though so doesn't sound like that's your issue but cant hurt to check.
How you like your 24? I had one back in 89-92 then went to their 28. The 24 has a Nice slippery fast hull.

Last edited by getrdunn; 10-10-2017 at 03:41 PM.
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Old 10-10-2017, 04:22 PM
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One of the most common bad problems to have is a broken main cap were the bearing starts to turn and you'll loose press. I hope thats not it but it is very common. Cut the oil filter and check for debris . Good luck
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Old 10-10-2017, 04:25 PM
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Bearings all look good? Oil pump, pickup tube and every bypass valve. What you mebbe shoulda done before pulling engine is bypass the oil cooler.
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Old 10-10-2017, 07:46 PM
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Originally Posted by Baja Rooster
My best guess is there's a fine crack in the pickup tube that you can't see with the naked eye.
New oil pump and pick up on order. Thanks Baja Rooster.
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