Re: My 1990 Thundercraft 1506 rebuild + background
decided to work out some problems I've been having with the boat before trying to launch it today. for the first time in forever it either wasnt 120*+ outside or raining so I went at it with water and sweat towel in hand.
decided to test the oil pump to see if it was working.
I have a 10 gallon gas tank that is full. I added tcw2 to it (1-quart) which is a bit richer than 50:1 as per the manual but I'd rather be rich at this point.
I popped off the oil pump outlet and plugged the inlet to the fuel pump and cranked up the engine. yay! first time I've seen oil smoke in the exhaust. I ran it about a minute and saw no oil come out of the pump outlet (hose was dry actually).
I shut it down because apparently my water pump decided to crap out on me (sigh). anyway, I checked the procedure afterwards in the service manual which mirrored what I did except it said to run the engine for 15 minutes and look to see if oil output is around 25cc...did not feel comfortable with that obviously.
I didnt see any oil during that small amount of time and it started to erk me somewhat.
also, because recently the engine would crank and run a quick minute and then shut off. I decided to empty the carbs before pumping up with the tank mix and the top two carbs had clean gas. the bottom one had what looked like oil/water/gas in it? any ideas how this happened? I'm sure this was causing the bogging. I think maybe water may be sitting in the plastic intake box and getting sucked in the carb but had no idea how to test for this.
by the way, after draining all the carbs and pumping with the gas/oil tank mix. it fired right up and purred (except for no water pee and no oil from outlet).
so then, I pulled the carb cover off and at least I know the gasket is sealing properly without the bottom two bolts lol.
bunch of oil poured out the bottom and you can see some still in there.
my thoughts: I know the oil reservoir cap is leaking and I have had the motor tilted up for a couple days several times while dealing with lower unit issues.
I've seen oil down in the splashwell actually as well. I'm thinking its dripping while trimmed up from the oil cap and inside the carb box and collecting in the bottom then getting sucked into the lower carb. though how it gets in the bowl is beyond me unless when its overflowed it back syphons down the jet into the bowl as it probably submerges that area due to the engine still being tilted slightly forward even when down due to grond clearance issues.
at this point I'm really hot and sweaty to the point there isnt any part of me or my clothes that are dry even though it hasnt rained in day. But the weather gods smiled on me by abating the 110* heat with a thunderstorm about 8 miles away which lowered the temp outside and hid the sun. so I downed two glasses of water, tossed on a fresh shirt and went back at it.
I completely cleaned off the carb box with brake parts cleaner and some towels. dry and squeeky clean. why? because I raised the foot just enough to pull the foot and without getting the oil tank level up enough to the cap so it couldnt leak.
I then took the water pump housing off and the impeller was in great shape? the hell? oh, duh...forgot to put the impeller keyway back in :facepalm: driveshaft was just freewheeling the impeller. found it on the shop bench under a dirty rag
put it in, put the foot back on the boat 25 minutes later and lowered it to ground level. hooked up the muffs after I bypassed the oil pump again and this time I put a cut open beer can as a container to see if 25cc of fluid would come out during the 15 minute run time.
I cranked it up and it idled nicely. nice huge pee stream rawr! approximately 700rpm idle, 8 psi water pressure, water temp was around 130-150* entire time. I can still hear the "grinding" noise inside the head which at this point I'm almost positive is a galled roller bearing. I got oil in the can but cant tell if its ~25cc. doesnt quite look like it to me but I could be wrong. looks to be about half of that (I'm a microbiologist by profession and I've used countless 25cc pipets and this just doesnt look like that to me). I am saving it though and will grab a pipet and manual pipetter from work week after next (leaving town tomorrow morning for the week) and I will check it myself.
so is the pump weak or would you run it or replace it, or is it fine and I'm just trying to see things?
video for support (the buzz at the end was a friend calling in haha). you can also hear the grinding noise I'm concerned about pretty well when I go in for the close-up on the oil pump "can" on the side of the engine.
also, after I cut it off. I opened up the carb cover again and there is fresh oil in there. it formed a small pool at the bottom in the same place as the previous pic and there was a "stream" going from the top of the first carb down to the last carb before forming the pool at the bottom. anyone have a clue what is causing this? its hard to see in the picture but you can see the stream/leak after the second carb. it looks just like that for the first and third carbs.
