Hi guys. Newbie here. Auto machinist/mechanic. These forums are great. Thanks for all the info. I just purchased my first boat. 96 challenger, single 787. I will be rebuilding the engine. I was told that it was fouling plugs, the head is off and the bores look good so from what I have read good chance the crank oil seals are bad. Either way i want to go through the entire boats to reduce the potential issues when its time to enjoy it. I read through the posts on using the oil pump and get the point and want to continue using the oil pump because of the variable feed to the engine based on load/RPM. Sorry... to the question. I understand the pumps seem to wear out after so many hrs? Approx how many? I haven't touched the boat yet so i don't realize what this pump is. Porsche 912 engine rebuild needs to get out of the garage first. Does anyone have and rebuild suggations for the pumps? Pictures? Buy new? Thanks in advance.
787 Ol pump
- Thread starter remeeker
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Volume test....
There are a couple tests to see that the pump is working correctly.
First and easiest....Start engine and run at idle while holding the oil injection pump lever wide open (manually). The engine will begin to run rich and idling irregularly smoking pretty badly. If this happens, it's probably o.k.
There is also a volume (bench) test that is a bit more drawn out. You have to have a way of running it at 1500 rpm for 30 seconds (in the water) or 15 seconds at 3000 rpm (on the trailer) and a graduated cylinder (something calibrated in cc's for up to 1 mil minimum. You should do each port seperately.
The easiest way I know to do it is....On a measured gas tank, (I use a temp 6 gallon portable tank that I have set up for this) add premix of at least 40:1 and start the engine. With the engine at idle, 3000 rpm, pull one of the small oil lines at the manifold, behind the carb. Put it into the graduated cylinder and measure 15 seconds.
At the end of the 15 seconds, you should have 0.71-0.87 mil (71-87cc). You can run for 30 seconds and double the above measurement. I recommend that you run for 30 seconds for 1.42-1.74 mils.
If you are out of those specifications, get a new pump. I hope this helps you out a little..........:cheers:
There are a couple tests to see that the pump is working correctly.
First and easiest....Start engine and run at idle while holding the oil injection pump lever wide open (manually). The engine will begin to run rich and idling irregularly smoking pretty badly. If this happens, it's probably o.k.
There is also a volume (bench) test that is a bit more drawn out. You have to have a way of running it at 1500 rpm for 30 seconds (in the water) or 15 seconds at 3000 rpm (on the trailer) and a graduated cylinder (something calibrated in cc's for up to 1 mil minimum. You should do each port seperately.
The easiest way I know to do it is....On a measured gas tank, (I use a temp 6 gallon portable tank that I have set up for this) add premix of at least 40:1 and start the engine. With the engine at idle, 3000 rpm, pull one of the small oil lines at the manifold, behind the carb. Put it into the graduated cylinder and measure 15 seconds.
At the end of the 15 seconds, you should have 0.71-0.87 mil (71-87cc). You can run for 30 seconds and double the above measurement. I recommend that you run for 30 seconds for 1.42-1.74 mils.
If you are out of those specifications, get a new pump. I hope this helps you out a little..........:cheers:
Thanks for the quick reply guys. Got it on the oil pump test. Are u thinking I should be testing the rotary valve reservoir prior to engine tear down to test the crank seals? Excuse the ignorance. I promise i'll get there once i get me paws on this baby. Thanks again. And Cheers back to u.
http://www.seadooforum.com/images/smilies/new/cheers2.gif:
http://www.seadooforum.com/images/smilies/new/cheers2.gif:
I'm used to answering the questions first, then looking at the big picture.
You should do a pressure test on the rotary chamber to see if the seals are bad. If your fouling plugs as bad as you say, chances are, you've either got bad rotary seals or your VROI pump is set off really bad in the syncro to the carbs.
With your mechanical skills, you should be able to use logic to put together block off plates for doing this procedure. Don't forget to temporally block off the oil supply and vent lines to the chamber. When your ready, pump it up to 5 psi and hold it for 3 minutes. If your pressure bleeds off.....well, you know the answer.......:cheers:
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Thanks guys. Makes sense to me to do the pressure test and will do before tearing it down. I was told it was fouling the plugs every hour or so. Does that sound like carb or crank seals? Either way I will test it. With a boat this old would u expect the seals to be getting hard and close to being ready for a change anyway? anything else u would change because of the birthdays? I want the boat as reliable as possible. I don't mind the work required to do a rebuild or whatever you guys recommend but also don't want to spend money that could go to other goodies. Thanks.
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