Wanted: 350 MAG MPI Motor for 2001 2300V

[Thegerman618]

This is all very interesting... with information I’ve never heard before. Tomorrow I’ll be acid washing the hull, and I’ll check on prop info, as well as do my best to get a compression check.

So, the loss of a low pressure fuel pump can affect oil pressure?


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they shouldn't be related, fuel and oil pressure however i had the same symptoms. Loss of Fuel pressure showed a loss in oil pressure as well, when i ran the boat empty (no ballast) and a few people it would run fine, it was when i put a huge load on the motor with full ballast when the boat really started to show that i had a problem, backfiring, slight miss, etc. but if i pulled back to idle would run just fine (with lower than normal oil pressure).

[Djimax]

they shouldn't be related, fuel and oil pressure however i had the same symptoms. Loss of Fuel pressure showed a loss in oil pressure as well, when i ran the boat empty (no ballast) and a few people it would run fine, it was when i put a huge load on the motor with full ballast when the boat really started to show that i had a problem, backfiring, slight miss, etc. but if i pulled back to idle would run just fine (with lower than normal oil pressure).

I don’t feel I’m experiencing this. The motor runs fine, it just doesn’t get into the upper limits of its potential rpm. It doesn’t misfire or backfire. But very interesting!


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[Djimax]

The v drive is blue.


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[chpthril]

Ok, so a 4-blade would be the ideal # of blades, but the dia and pitch can still play a factor in reaching the correct RPM range.

Also, does the throttle actually open the throttle body all the way?

[Djimax]

Ok, so a 4-blade would be the ideal # of blades, but the dia and pitch can still play a factor in reaching the correct RPM range.

Also, does the throttle actually open the throttle body all the way?

I’m... not sure. I’ll have to check. Also, my prop is 4 blade, but I don’t know pitch or diameter. I’ll investigate lol.

So, is my theory about needing to rebuild the motor because of the drop in oil pressure inaccurate? Granted, I’d love to not have to rebuild, but I’m also still concerned about this.


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[chpthril]

Regarding the oil pressure. Low oil level could cause your scenario as a thought, since its using oil. A rich running engine can thin the oil, creating oil pressure issues. Without seeing the oil pressure issue on an old school manual pressure gauge, I would not draw any conclusions of a rebuild.

[Djimax]

Regarding the oil pressure. Low oil level could cause your scenario as a thought, since its using oil. A rich running engine can thin the oil, creating oil pressure issues. Without seeing the oil pressure issue on an old school manual pressure gauge, I would not draw any conclusions of a rebuild.

I check oil level regularly. Even when topped off, I experience the oil pressure issue. I’ll see if I can check AFR on the motor as well.


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[boatwakes]

We had a similar issue with a customer's boat last year. His engine would burn oil and the loss of oil pressure was a head scratcher. We determined the rings were shot on the motor but the oil pressure issue turned out to be this:

On the block at the oil filter adapter and/or the oil filter (if it's not remote and instead block mounted) the threaded adapter TO the engine block has a bypass in it. We pulled the adapter on our customer's boat and found the bypass was broken. The close off piece had shattered and was allowing oil to circulate without going through the oil galleries immediately after the filter. $20 later the problem was solved except the rings were already bad. Rebuilt the engine and off they went.

[boatwakes]

Are you carbureted or EFI?

[Djimax]

We had a similar issue with a customer's boat last year. His engine would burn oil and the loss of oil pressure was a head scratcher. We determined the rings were shot on the motor but the oil pressure issue turned out to be this:

On the block at the oil filter adapter and/or the oil filter (if it's not remote and instead block mounted) the threaded adapter TO the engine block has a bypass in it. We pulled the adapter on our customer's boat and found the bypass was broken. The close off piece had shattered and was allowing oil to circulate without going through the oil galleries immediately after the filter. $20 later the problem was solved except the rings were already bad. Rebuilt the engine and off they went.

My best friend mentioned it could be this! I will 100% look into this. But, could this explain the loss of power as well? I’ll try and do a compression test today. I’ll also have answers on prop size (although, not sure how to measure pitch). And to answer your question, I’m EFI.


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[chpthril]

Prop info will be stamped around the hub where the nut is. 3 or 4 digit part #, dia and pitch like DD.D x PP.P

[Djimax]

I know I need a new prop too, because mine is pretty bad. Did a compression test. 6 of the 8 cylinders came up at 110-120psi. However, one came up at 50, and the adjacent came up at 100. Head gasket maybe? This could explain the loss of power, but still not sure about the oil issue. Where would I find this bypass, and what does it look like?


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[chpthril]

That hole with 50 psi is definitely an issue. Could be rings/piston, cam, valves or gasket. A leak down test will tell more about where the compression is going. That 100 psi is a little low in comparison.

All the others are low. Was the engine cold? Throttle closed? Battery weak?

Did you find the dia and pitch stamped in the hub of the prop?

[Djimax]

That hole with 50 psi is definitely an issue. Could be rings/piston, cam, valves or gasket. A leak down test will tell more about where the compression is going. That 100 psi is a little low in comparison.

All the others are low. Was the engine cold? Throttle closed? Battery weak?

Did you find the dia and pitch stamped in the hub of the prop?

Yeah, that 50 makes my stomach turn. The 100 is right next to it... could be HG? Yes, the motor was cold, I heard a warm motor would read closer to 165. Is that correct? I took pics of anything on the prop that looked stamped in... unless I missed something? I can check again tomorrow. There was a number on the prop, 1399. Not sure if that’s important? I’ll try to get a leak-down done as soon as possible.

All this.. and still no answer for the oil pressure drop. That’s on my mind as well...


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[chpthril]

If the gasket was breached between the 2 cylinders, id expect the 2 to have nearly the same compression.

Google could not find an OJ prop model 1399. Their site does not have a search function for props, that I can find. They usually stamp those numbers on the face of the hub where the nut is.