1990 Bayliner Trophy with twin Force 120s need advice on prop sizes

[gica]

Since you said that water was definitely getting into the exhaust chamber then I would think as each piston went up and down it could introduce water into that cylinder. The water comes in under force from the water pump so I can rationalize this. On the one piston being wet and the others dry, possibly that one was ready to fire (wet) but didn't due to engine timing not ready for that cylinder to fire when you stopped it.

Compression is fine with me. On the water getting into the bearings, that surely would be something that needed to be addressed immediately. I don't know how to address the how to on that problem, never had it. Maybe one of the guys that answered and know how to fix that problem can direct you.

Yeah I opened it up it and it was definitely water, all the pistons are pretty clean ans shiny. The bolts for tye cover were tightened twice and some were still loose when I opened it.
I took off the exhaust cover and had to re-surface it to make it true, it was off at 0.20in warp which is a lot, I made it to 0.002, it will be perfect now. I got a new separation plate and gaskets, will use some kind of gasket maker for high temp, recommende blue 750 sealant for the bolts and cross my fingers that it solves the water problem.
With the water gone I hope the dying in gear at idle will be gone. It should be.
I took off the power head also. It was holding conpression pretty good but wanted to see inside. This motor is almost all brand new now including the lower drive. Better run like it too.

 

[racerone]

Do not change prop pitch to get the RPM you want.----Repair the motor to get rated power !----Piston is scored !

 

[gica]

Do not change prop pitch to get the RPM you want.----Repair the motor to get rated power !----Piston is scored !

The picture you're reffering to is the piston with some drops on it. Here is the picture after I wiped it.

 

[racerone]

Some will argue.----I see scoring on the side of the piston !

 

[gica]

I don't see it, but the way this motor was running and the adjustments it took to keep it running in gear at idle, I would not be surprised. One thing is for sure it was not running lean but it did have some alarm buzzing from briefly overheating issues in the parking lot on a hose tests early on. Now I run it in a tank and it seems to like it better. But it did manage to have 140 and 135 compression. That is not too bad. So the goal now is to put it back together and resolve the exhaust water leak issue.
Hopefully that will get the idle issue in gear to be normalised. I mean if there is no water entering the cylinder the fuel burning should prove to be better right?
I should have checked the exhaust cover
with a straight edge when I first rebuilt it.
The innitial issue was the number 2 piston. Number 4 doesn't usually suffer all that much. But 3 and 4 did show milky liquids on the side by the exhaust. And 4 showed some serious water bubbles. The machine shop handled the boring of the cylinders and piston install.

 

[Texasmark]

So one would ask why did the plate separating the cylinder's exhaust gasses from the cooling water warp in the first place? My answer would be that it didn't receive the cooling water of the engines original design. My understanding of cooling loops is that they are 2 separate circuits whereby the exhaust gets uncontrolled water and the combustion part of the block gets thermostatically controlled water.

You might check your exhaust cooling water passage and ensure that its not clogged by sand or weeds.....how would you do that? Water hose in the outlet of the cooling chamber, looking for water where the exhaust exits the lower unit, while you have the cover off and then put the LU on muffs with a goodly amount of water pressure, take the plugs out and spin the engine with a good stout battery to see if you are getting water to the chamber......is the way I'd do it, not having done it before but seems a reasonable way to make the determination.

 

[gica]

This engine was rebuilt after cylinder number 2 had zero compression, cyilinder was pretty marked up, and rings were cracked. After 34 years I think it was time.
So it went through some rigorous cleaning. Was completely dismantled.
The warped cover was pretty much overlooked that's all. I checked the engine surfaces but not the cover.

 

[gica]

Anybody have any idea where to find props that fit the 4in gear box? Everything out thwre is for 4.25 drives. I have 13x19 turning point and want to go lower to a 17 or 15. I bought 2,13.5 x15 and they are too large for the inside of the drive by .20 or so. Can they be grinded to fit? That's the only difference.
I have a white 13.5x15-k prop but the end is very thin so I think it was grinded could not find anything similar. It's probably for a yamaha but it fits my 1990 120hp fine.

 

[Texasmark]

Anybody have any idea where to find props that fit the 4in gear box? Everything out thwre is for 4.25 drives. I have 13x19 turning point and want to go lower to a 17 or 15. I bought 2,13.5 x15 and they are too large for the inside of the drive by .20 or so. Can they be grinded to fit? That's the only difference.
I have a white 13.5x15-k prop but the end is very thin so I think it was grinded could not find anything similar. It's probably for a yamaha but it fits my 1990 120hp fine.

I have numerous Turning Point Hustler, 13+ diameter, 4" hubs, purchased here, that were 3 and 4 blade aluminum props. Never had a problem. Engines were 90 and 115 Mercs. I didn't specify nor pay any attention to any remarks about the hub diameter. I just relied on the fact that the 13" dia. props ran on the 4 and 14" ran on the larger diameter, higher HP engines......was not disappointed on any of those half a dozen props.

I do recall while playing with different props on a couple of boats with these engines that I somehow acquired a prop that didn't have the notched front end of the barrel that fit up inside the LU casting. I guess it was made for the 4.25" gearboxes. With the OEM thrust washer, the prop would strike the LU casting.

I went to a marine dealer that had been in business for decades and he had a wall full of used props and a box full of thrust washers. I took the box out to my boat and played with the washers till I found one that caused the front of the barrel of the prop to fall about 3/8" behind the LU casting outlet.

It was far enough back so that I could push on the prop in F gear on the low part of the "over run clutch sawtooth" and it didn't contact the LU casting. I ran the prop and even though there was a gap I couldn't tell that it was any detriment to performance. I just figured that any problem would be during high performance operation and the slipstream would go right past it and wouldn't even know that it was there.

 

[racerone]

Changing to a lower pitch prop because of low power output of the motor is so wrong !

 

[Texasmark]

Changing to a lower pitch prop because of low power output of the motor is so wrong !

I totally agree but he doesn't have another prop to match the other engine and I doubt he has access to a dyno. He has to start someplace and after all the stones he has rolled over already, I doubt there is much he missed if anything as far as what, if anything, is wrong with the engine now. So he puts a like prop on that engine and gets out and runs the boat at WOT, same trim, and read both engine's RPMs. That will give him a number to chase.

Besides it will drag the boat down rather than contribute to better speed. Case in point, when I was a teen and had started boating with my boat, was at the ramp one day and a guy launched a skiff with two round cowl, '50's era Evinrudes, sliding throttles on the front of the cowls, a 15 and a 25 HP. Obviously the 25 was the better performer due to HP or a higher pitched prop and back then 4500 RPM was the norm so one would expect that RPM was a moot point..

So when he hammered down on them it just took a second or two for the 15 to **** up, prop spinning.........in the air.

 

[gica]

The lower RPM is on both engines. With the rebuilt one having the water leak at the exhaust cover to #3 and #4, I am sure it didn't help things. They seem to run off each othere the twins. So even though one is bogging a bit the other will compensate and help it. The drive is fully rebuilt, it was full of water and it needed forard gear upper bearing and all new seals.
I got 2 props 4 blades 13 3/8x15.
The props I got are Michigan wheel Vortex 941415.
The only ones that have a 13.75 lip that fits in my 4 in drive. I think they are good props and brand new at 70 bucks a pop shipped. They run 130 each originally. It won't break the bank.
I sure hope this motor will run good with these and the water leak that is my last issue, will get fixed with the new parts I ordered.
I need to get out there and fish. My area of interest is the Channel Islands for halibut, maybe white sea bass and Catalina for some baby tuna no cows.
If I get to do that I am happy.
I think the 19s are too big for these engines even if there are 2 of them which helps. Will see how they handle semi choppy 3 feet waves and wind on following seas at around 5pm.
I still have a 97 bayliner maxum with a 5.7 I/O Alpha 2 drive. That boat took me to the Islands and back on the worst choppossible and it is a runabout no deep V 20 footer lake boat.
The "newer"one is a pretty heavy at least 3500lbs, another reason I got 15 pitch, 1990 Trophy cuddy cabin 24 footer twin shitty force noise makers. I have redesigned the dash and put all new gauges, 2 fish finders 9 inch.
It looks pretty good. Not even in a category with the most decent boats out there but it was cheap and hopefully
it will handle 4 people, fish tank and hopefully some fish in choppy SoCal Islands waters hahaha. Fingers crossed.

 

[Texasmark]

Great prices and nice find on the props. Now how about some performance specks like what are your 2 full throttle RPM numbers?

 

[gica]

On the 19s with a leaky exhaust cover and separation plate it was 4200 for the leaking engine and 4400 for the other. 38mph on the lake.

 

[Texasmark]

Rule of thumb on here is 1" change pitch equates to 150-200 RPM change. Running the same engines and same props with the same trim setting smells of engine trouble. Possibly having had the trouble, if you run it for awhile maybe the internals of the bad engine will clean up and the RPMs will balance out.

Course your tach could be in error and they are/can be, especially at the higher RPMs. ebay sells a real cheap digital tach with reflective strips. Before you spend a lot of money that may not be necessary I'd get one, get access to the top of the flywheels, put one strip positioned from the crankshaft out to the perimeter of the flywheel on each engine, go out and make a test run and compare the two readings. You just point the Laser red dot at the flywheel and press the button, let it go and read your RPM. This will eliminate any instrumentation errors.

 

[gica]

Rule of thumb on here is 1" change pitch equates to 150-200 RPM change. Running the same engines and same props with the same trim setting smells of engine trouble. Possibly having had the trouble, if you run it for awhile maybe the internals of the bad engine will clean up and the RPMs will balance out.

Course your tach could be in error and they are/can be, especially at the higher RPMs. ebay sells a real cheap digital tach with reflective strips. Before you spend a lot of money that may not be necessary I'd get one, get access to the top of the flywheels, put one strip positioned from the crankshaft out to the perimeter of the flywheel on each engine, go out and make a test run and compare the two readings. You just point the Laser red dot at the flywheel and press the button, let it go and read your RPM. This will eliminate any instrumentation errors.

I have the one where you wrap the yellow wire around the number one spark plug wire. I had to go through the settings to choose the right option that reads the number of sparks during one revolution per my 4cyl motor and I chose 4x1 being a 4 cyl one spark per cylinder(fires 4 per stroke or rotation of 360⁰ I think) that gave the RPM closest to the dash RPM. Have not tried it at WOT yet. Going at WOT with the laser pointer one and the engine cover removed is not that easy as I have transducers at the bottom and they spray.
So once I get the parts to put back the exhaust cover with separation plate, gaskets plus the head and gasket I will test it again. I got all the parts except the new separation plate. I found it new so I said screw it I am buying it. I don't want any more surprises. I will use some permatex aviation liquid sealer on the gaskets and the RTV blue silicone gasket maker 587 also known as 750 or FT8955 suggested by Crowley and the factory manual for Force bolts.
I could use Loctite also but am not sure which one.
My friend has the Loctite 542 medium sealant that he uses on his motor bykes. I used that on the intake bolts.
The exhaust bolts were pretty loose before. I could not get them to stay.
So when I check the exhaust cover with a straight edge is was off on the sides by 0.020. I used a special stone and repaired the surface now it's at .002 or less. That should fix the issues with the water leak in cylinder 4 and some in 3. But mainly 4. And it should fix the issue with dying in gear at idle if the RPM is set by the book at 750 in gear, which was impossible. I had to set it at 1100 in the water and 850-900in gear and even then it would die. Eorked great in the parking lot on a hose. At 3k RPM it was smooth along with the other engine. By itself it would cough and bog down at first and then work somewhat. So this is where I am at.

 

[Texasmark]

I use that Aviation sealer also on occasion where I feel it is needed. Locktite blue is for fasteners that one expects to remove from time to time. Red is for permanent applications and if removal is required, it is said that heat is a necessary aid. Locktite seals on compression so you have to have 2 surfaces in compression for it to cure.

I find your comment about the screws, not getting them to stay, is a worrysome comment. I never used silicone as a thread sealant.

 

[gica]

I use that Aviation sealer also on occasion where I feel it is needed. Locktite blue is for fasteners that one expects to remove from time to time. Red is for permanent applications and if removal is required, it is said that heat is a necessary aid. Locktite seals on compression so you have to have 2 surfaces in compression for it to cure.

I find your comment about the screws, not getting them to stay, is a worrysome comment. I never used silicone as a thread sealant.

yeah those bolts were from the exhaust cover. It was warped ajd I assume that caused the bolts to not completely torque it. That's why it probably leaked in the cylinders and also the right side bolts showed rust. I will probably be using the blue loctite to make sure they stay put. The cover is now straight and true.