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Old 05-14-2018, 08:51 PM
valovic valovic is offline
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Question Whine and slight loss of power

I'm a new owner of a 96 prostar 205. It has the 350 LT1 motor in it. I rebuilt the engine last winter where the old block had cracked due to improper winterization from the previous owner.
I have been out on the water with it a few times, and it runs great for about 45 minutes, and then I get a whine out of the area of the transmission. It sounds just like a blower fan or the bilge pump, but you can hear it over the engine. If you drive it, there is no problem up to 30 mph. After that, if you push farther into the throttle there is some loss of power and it really does not do anything more. Does not rev any higher either.
If you bring it back down to 30 or lower it is back to normal. The whine is there until it cools off.
Any suggestions on what to address with the whine and loss of power.
Oil pressure and engine temps are fine and don't climb during this time.
oil is clean.
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Old 05-14-2018, 10:05 PM
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mikeg205 mikeg205 is offline
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can you post a video? how many rpms are you turning at 30mph
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Old 05-14-2018, 10:15 PM
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CruisinGA CruisinGA is offline
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Might be fuel pump whining. Check gas tank vents, if plugged tank might be pulling a vacuum and causing pump to work harder and eventually not keep up.

Easy way to check is run with loose gas cap for a short time being careful to not get water in the tank.
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Old 05-14-2018, 10:40 PM
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Quote:
Originally Posted by CruisinGA View Post
Might be fuel pump whining. Check gas tank vents, if plugged tank might be pulling a vacuum and causing pump to work harder and eventually not keep up.

Easy way to check is run with loose gas cap for a short time being careful to not get water in the tank.
^^^^ It sounds like your fuel pump (by the transmission) is telling you there is a problem.
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Old 05-15-2018, 07:34 PM
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André André is offline
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Clogged inlet screen at the pump.
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Old 05-15-2018, 08:56 PM
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Check your transmission fluid? I have a 1992 Prostar 190, and there would be a slip, then loss of power. I'd back off, and then up until a certain RPM would be fine, then slip again. Constant whine at that point.

Tranny fluid was a quart low. Some are 2 qt. trannies, some are three qt. trannies. Check the level while the engine is hot, and immediately after you shut it off.

Same exact thing was happening to me, took me a week to figure it out. Also, make sure the fluid is the same color that comes out of the bottle. If it's dirty, or has bubbles in it you may have other issues like a seal, etc. Bubbles mean air, not good. These trannies rely on pressure.

Hope this helps, that was my issue.
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Old 05-16-2018, 08:22 PM
valovic valovic is offline
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Thanks, I'll get a video this weekend.
I don't think it is the fuel pump. I can do 40+ when it is cool or within the first 30 minutes of driving. I did loosen the gas cap and made no difference.
After it gets hot, the whine never goes away until it is cool again, it is there even at idle. I'll replace the fluid and see how it goes.
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Old 05-16-2018, 08:30 PM
valovic valovic is offline
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and am I OK Using Dextron II or is there something better?
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Old 05-21-2018, 06:51 PM
valovic valovic is offline
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I took the oil cooler off and it was clear. drained the oil and it looked fine. There was one supply hose, the one off the top of the transmission that has a kink in it. Not that bad, but that could be restricting some flow. I'm going to replace it with a longer hose and route it better.
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Old 05-22-2018, 04:21 PM
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Quote:
Originally Posted by valovic View Post
I took the oil cooler off and it was clear. drained the oil and it looked fine. There was one supply hose, the one off the top of the transmission that has a kink in it. Not that bad, but that could be restricting some flow. I'm going to replace it with a longer hose and route it better.
Wouldn't cause loss of power...
Checking fuel pressure will help a lot in troobleshoothing what's happening.Help us help yourself!
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