SoCal Jet Boats
Tech Talk => Engine Mechanical / Electrical => Topic started by: 79charger on August 15, 2009, 06:08:49 AM
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I did a compression test on my bbf and all the cylinders except one came back at 139 -142 psi .The one came back at 119 . I dropped a teaspoon of oil down the cylinder and it rechecked and it came back 150 . There motor isnt smoking and it runs good . Do you gys think it will get me through the season ? The motor was built by harman marine , would that be a good place to have her freshened up ? Thanks
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What does the plug look like? If the engine doesn't show signs of distress I'd run it the rest of the summer.
IMO
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Run some Marvel Mystery Oil in the oil and run it. Recheck the compression after the next trip.
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the plugs are perfect chocolate brown , but now i have a knock in the top end , at idle .So looks like i might have to pull it anyway.
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Is the knock on the same side as the low cylinder? Maybe time for a valve job new seals n what not...I would pull the valve cover and have a look see
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Run some Marvel Mystery Oil in the oil and run it
The magic elixir for old V-8's :thumbup: :thumbup: :thumbup:
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If it knocks I take it apart..... no questions asked.
Good luck which ever way you go.
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If it knocks I take it apart..... no questions asked.
Good luck which ever way you go.
if you need ANY machine work, i highly suggest Dave @ A&D (aka enginedoctor) :thumbup:
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Just out of curiosity I advace my time from 6 degrees btdc to what harman marine recommended 10 degrees btdc last week . I run premium fuel , but i have heard the more you advance the time the more cylinder pressure you create , and i am wondering if thats where the knock i hear is coming from? Is that possible or am i just taking shots in the dark
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I did a compression test on my bbf and all the cylinders except one came back at 139 -142 psi .The one came back at 119 . I dropped a teaspoon of oil down the cylinder and it rechecked and it came back 150 . There motor isnt smoking and it runs good . Do you gys think it will get me through the season ? The motor was built by harman marine , would that be a good place to have her freshened up ? Thanks
Your compression sounds fine, if it's consistent. I wouldn't stress about that.
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Have you ever set the timing on this engine before?
Maybe the timing was set so low because the balancer is slipping and is way advanced when set at spec.
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No , i put in a new distributor so thats the only reason i checked the timing . It sure ran good when i set it to 10degrees but i backed off to 6 for now untill i see a engine builder .
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No , i put in a new distributor so thats the only reason i checked the timing . It sure ran good when i set it to 10degrees but i backed off to 6 for now untill i see a engine builder .
Give Dave a call (714) 879-9671 He will help ya :thumbup:
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I did a compression test on my bbf and all the cylinders except one came back at 139 -142 psi .The one came back at 119 . I dropped a teaspoon of oil down the cylinder and it rechecked and it came back 150 . There motor isnt smoking and it runs good . Do you gys think it will get me through the season ? The motor was built by harman marine , would that be a good place to have her freshened up ? Thanks
Your range of cylinder pressure (119-142 psi) is considered acceptable by most standards, even if only 1 cylinder is on the low side and the other 7 are within 3 psi on the high side.
I would get that "knock" professionaly diagnosed before taking your engine apart mid-season. It could be just a loose rocker arm....or a con rod, or anything in between. In other words, could be fixable without an engine overhaul. If you find that you need an engine we could build you up a longblock lickety-split, pickup in San Fernando valley.
LO
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Well i took it to the engine builder up here in the high desert the only one ....lol . The owners wife i assume wanted me to leave it there and fill out a service form lmao just to hear my motor . She wanted money ....so I told her hey Lady If i leave now and my motor does need work I promise you I wont be bringing it back to you . Her Husband overheard and came out and gave her a nasty look and came out and heard my boat . He said it didnt sound bad , and to try running a heavier oil . I was running 10/30 . So i put In 20 /50 and some marvels oil lastnight and it sounded quieter. Funny my motor only takes 5 quarts of oil ??? Must be the stock pan . Thanks for your help everyone . I guess I will run it until stops .
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unless its a small block i would be suprised...did you check it after you ran it...about another quart is in the oil filter!
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yes i checked it I actually overfilled it a little . Maybe all the oil didnt drain out initially . I let it drain for 2 hours ???? Unless the dipstick is wrong it shows on the full side and oil pressure is good.