GT-40 Zero oil pressure. Ticking engine. Help!

After running perfectly for about 3 hours and over 10 miles. We were coming out of about a mile long no wake zone and I noticed the oil pressure gage at 0. I always check the gages and the oil pressure And it is always between 20 and 40 temp was always perfect. I shut it down as soon as I saw the gage. I tapped on the gage and the pressure sending unit and fired it up again and noticed a pretty good ticking noise. After checking oil level and a couple other things I started it back up a few times but nothing changed. I brought the engine up above 2000 rpm for less than a min to see if something was stuck but nothing changed. We were 10 miles from our trailer so the sheriff towed us about a mile to the nearest launch we’re a helpful bystander took us back to our truck.

First thing I’m going to do is pull the DUI and see if the hex is stripped on the oil pump shaft.. hopefully that’s it.

What damage if any have I done to the motor and is there anyway to check?? I’ve read about ticking going away once oil pressure comes back, but have not found a thread where anyone has suddenly lost oil pressure with full oil level. hoping I have not done any more damage.

Thanks Jq. DUI end looks fine. But the oil pump shaft hex Looks like it’s off center from the hole it goes through. I will post some pics soon but it’s hard to see.

I did drop this motor square on the oil pan when I was doing the stringers 2 winters ago.... wondering if that is catching up to me now....

Looks like I’ll at least be pulling the motor.

camron18 wrote: Thanks Jq. DUI end looks fine. But the oil pump shaft hex Looks like it’s off center from the hole it goes through. I will post some pics soon but it’s hard to see. I did drop this motor square on the oil pan when I was doing the stringers 2 winters ago.... wondering if that is catching up to me now.... Looks like I’ll at least be pulling the motor.

The hex shaft always looks off center in the hole and it's not centered till you slide the distributor shaft over the hex.

It might be hard to visualize, but it's normal for the shaft to flop to one side or another till the distributor shaft is slid over it.

You could use a priming tool for the 351 oil pump with a good 120 volt AC drill running in reverse (BACKWARDS) to see if it develops oil pressure.

Some people use what's available like a long 1/4 inch drive extension with a 5/16 socket firmly taped or tack welded to it so it can't fall off and go kerplunk into the sump. but there's a certain amount of risk there with it falling off if it's taped and not tack welded. Same routine with a drill turning in reverse (BACKWARDS)

You should feel some pretty good resistance if it's pumping oil and you'll see pressure on your gauge if the ignition key is in the RUN position.

No resistance and no oil pressure means you've got some engine disassembly in your future.

From the sounds of things, your pump died or the pressure relief valve failed though.

A mechanical pressure gauge probably wouldn't tell you much, since you have ticking noises that just developed with the loss of pressure indicating that you really did lose pressure..

KENO’s advice is good. You can spin your oil pump drive by power drill. That will provide a good diagnosis on the oil pump status. Follow the recommendations For securing your tools with tape. I use 3m black duct tape when I prime an engine using this method.

Bright side: if you did fry the engine, you can make it bigger, stronger and faster when rebuilding. Easy for me to say, but I’m good at spending your time and money.

JQ

camron18 wrote: If I feel resistance on the pump but the pressure relief valve is stuck how will I know if the pump is working properly if the pressure gauge still reads zero? Will I be able to hear oil spraying or can I pull something off to watch the flow of oil?

Assuming that your oil pressure sending unit and oil pressure gauge are working, simply turn your key to the "ON" position and spin the oil pump using the drill method described above. If the pump develops pressure, you should see the needle on the gauge move. If you are not certain that one or both are functioning properly, then you need to visually see the oil flowing. One way to do this is to remove a valve cover. If the oil pump is still working and you spin it with the drill, you will see oil flowing from oil ports in the head around the valve train.

JQ

KENO's way is better. I like the oil filter method. I'm gonna have to remember that one...

So I tried the long 5/16 drive and drill trick. Full speed on just a regular 20v drill there is no resistance at all. A couple times I could hear the oil pump drive shaft pull up a little bit and “Tink”drop back down when I was pulling the socket out. I know This is normal and this meant I was fully engaged on the hex with the socket.

Seems like the oil pump is toast. I’ll hopefully drop off an oil sample tomorrow and then I’ll know if it’s going to be a full rebuild time. Sounds like 750 hours “is nothing” to most of you guys...

750 hours is nothing, but then again hours don't tell the story. Well maintained since new, 2,000 hours can be "nothing". Poorly maintained, 750 can be a lot of hours. What is your boat, how long have you owned it?

Hoping this works out for you and analysis comes back without any major flags. Not trying to do an "I told you so", I realize you are likely beating yourself up right now, but for future reference if you don't have 10 psi oil pressure, get a tow. Even if you suspect it's the gauge or sender, you can't prove that on the water.

Hoping this turns out well!

I agree with GottaSki. The oil analysis will only confirm that the engine is toast. You had too much run-time with zero oil pressure, so you just need to embrace the madness. Start sooner vs later. If it helps, I feel your pain, bro.

JQ

It will be interesting to see if the pickup is damaged from dropping it on its pan in the past.

excessive fuel maybe because of idling seems possible as i was coming out of a 5 mile long no wake zone! so i was a idle speed for around 10 miles before this.

As been said, in this case oil analysis reports you can reuse the oil, not necessarily reuse the engine.. best look at some bearings when you have it's skirt up.

Oil pump drive shaft is broke in two just above where it goes into the pump. The pump looks and seems to function fine.

As long as you'll be into the oil pan, maybe pull a couple caps off the crank and take a look at the bearings. Throw some Plastigauge in and see what's up.

Pete I don't think our mikes are on