Need advanced help from a mercury veteran - engine/lower/prop.

[Puresyn]

Sorry this is a bit long, but I figured the more info I gave, the better chance of solving this puzzle.

I am having a heck of a time getting the right prop for my boat (I bought it this way, shame on me, lesson learned -- drive it first!) I believe however that I have enough information for a veteran Mercury tech/enthusiast to help me out. So if this might be you, please, read on!

Boat: 2002 21? Aries Tournament Edition (fiberglass bass boat)
Engine: 1996 200HP EFI Mercury Offshore

From the first time I put this boat in the water, it would not get on plane. The engine never goes above 1600 RPMs (even at wide open). I know the engine revs fine when not under load and in addition, it was checked by a reputable local boat shop and is mechanically sound ? compression and all. The prop that it currently has is 4 bladed steel and speculated (by the boat shop) to be around a 27 pitch and cupped to about a 28-29 pitch? ? way, way too steep for this heavy boat (I assume this prop was just laying around and fit the boat to sell. Again, shame on me for not checking! However, the plot thickens.

The engine is a 1996 200HP EFI Mercury offshore (confirmed by mercury customer service) ? 0G518498 ? with a miss-matched lower unit ? 0D007819 (no info from mercury that helped specifically ID this). Thus, I am uncertain as to exactly what the lower unit is (I have been told it is possibly and XR4? but that is unconfirmed and I suspect this is the root of my troubles getting the right prop.)

It was suggested from several sources that I try between a 23 to 26 pitch, so I ordered a Mercury SpitFire 14x23 48-8M0084497 and when I test fit it, the Prop-to-torpedo housing O.D. was too large. The prop housing O.D. was nearly identical size to the torpedo housing (would not countersink) so I returned the prop (here is the link to the prop https://www.amazon.com/gp/product/B00JKMPRXE)

As I did more and more digging, I ?think? I have discovered that the standard O.D. for both the stock lower-unit and the XR4 lower unit torpedo is 4.75 inches. After inspection and without the assistance of a micrometer (eyeball and tape measure w/o shaft removal) the O.D. of the torpedo housing is more like 4.25? Defiantly not 4.75! Which would explain why the prop I previously ordered would not fit.

The O.D of the prop-to-torpedo housing on the prop that fits fine but wrong pitch is 3 15/16?, visually the fit/clearances looks fine. This prop does however show signs of millwork so it would not surprise me at all if the prop had been ground to fit, but I am uncertain as the prop does not appear overworked in that area.

Additional information:
The current prop does not have any identification numbers that work or cross-reference to anything usable and no boat shop (out of several) could identify its origins either.

I had exhaust ports drilled into the current prop when I found out it would not plane hoping that it might help, it did not.

I will gladly provide any additional information that might be helpful for finding the right prop, so ask away!

I realize that the prop pitch is more of a trial-and-error than a specific science, so I do not expect and exact pitch, just how to order a properly fitting prop.

Thank you very much in advance!

 

[Faztbullet]

Sounds like someone installed a Xr4/6 lower unit as it is a smaller diameter and gear ratio is steeper(1:78:1) Either way the 4 blade should plane off though it may be slow you just may not reach operating RPM. That motor has a problem if it wont pull over 2000 rpm as it can be running on 4 cylinder and rev up fine with no load.

 

[Puresyn]

Thank you, Fastbullet, for your response.

As I have very little marine engine expertise and a decent amount of automotive experience, (ASE certified) I take for granted that the ignition and electronics systems was tested right along with the compression tests etc. (I asked them to give the engine a once-over and check everything) The motor was also tank tested (so I was told) and they did not disclose any red flags other than 1 cylinder being 3lbs (I think it was, I do not have the paperwork in front of me) lower than the others. If this is indeed a deeper engine issue, do you have any suggestions on where I might look and test for a low torque issue? Flat camshaft lobes perhaps?

My experience in the automotive realm with something like weak/missing cylinders would be a very rough/choppy load run, but this engine sounded as smooth as silk when I attempted to break 1600RPM, just over-stressed (bogged down)... which makes me wonder about fuel pressure now... Thoughts?

Thank you sir!

Edit: I also wanted to mention that simply putting this boat in gear will hit wake speed. (unsure of MPH, speedomoter doesn't presently work). This, to me, at the time, made me feel as if that also pointed to too steep of pitch on the prop.

Edit 2: Remembered I had taken a video. I gave the engine its best shot around 1:05. https://youtu.be/W2CVKTRlK_8

 

[Fun Times]

The engine is a 1996 200HP EFI Mercury offshore (confirmed by mercury customer service) – 0G518498 – with a miss-matched lower unit – 0D007819 (no info from mercury that helped specifically ID this). Thus, I am uncertain as to exactly what the lower unit is (I have been told it is possibly and XR4? but that is unconfirmed and I suspect this is the root of my troubles getting the right prop.)

Hi, welcome to iboats!
I'm just sort of wondering how you were able to find or determine the lower unit is/was off of a different engine serial number (0D007819) that you provided vs what the engine serial number (0G518498) is as the lower unit isn't typically stamped with a serial number that I recall.

The 0D007819 is coming up as an MERCURY 2.5L 200 HP L (Long shaft...20")

MERCURY

1991

200 HP

Model number 1200412LD

135 / 150 / 175 200(2.5L) XR4/MAGNUM II

0G518498 is actually coming up as an 1997 MARINER ? 2.5L EFI OFFSHORE 200 EFI XL (EXTRA LONG SHAFT...25") Model number 7200423FD
https://www.mercurymarine.com/en/us/parts-and-accessories/parts-catalog

Are you sure the length of the lower section of the overall engine is set to the right height to fit the boats transom height as seen in the images in the following link...http://www.bing.com/images/search?q=...th&FORM=HDRSC2

 

[Puresyn]

Hello, Fun Times, and thank you!

The 0G I pulled right off the freezeplug and the 0D I pulled off the transom plate. As far as the miss-match, I forget now who originally brought it to my attention. However, from the Mercury Marine parts catalog the only 0D 200 was a 1991 V-200 2.5 (Non-EFI) or alternatively the XR-4. (I am taking for granted that the V135-175 would not bolt up, but again, that is an assumption on my behalf and the boat shop originally suggested the XR-4/6) Not to mention the prop ordered for the 0G did not fit the lower unit.

If you have any other questions that may help further identify it, I would be pleased to provide! All input welcome!

Edit: sorry, I got ahead of myself answering your first question and didn't finish reading until after.

The 0G is titled as a 97, you are correct, I checked the title. It is block stamped 10/2/96 and that was just stuck in my head. That would in fact make it a 97 model.

For the pictures, i'll have to look on a different computer and get back to you, I blocked all bing stuff some time ago (TY Windows 10).

 

[Fun Times]

Sounds like someone just installed a newer engine on the original outboard assembly which happens often.

What color is the lower unit? Have any overall photos you could post as they may help too.
https://www.perfprotech.com/mercury-...g/umodel/17274

Just image search online (How to determine the transom height to outboard length) as you'll see many images like what is shown below as you'll want to just make sure that the length/height is correct or the boat won't perform well at all either.

 

[Puresyn]

Thanks, Fun Times.

Good to know about the engine swap, defiantly something to keep in consideration. Unfortunately, I am still unsure about a finding prop that fits (if that ends up being the issue).

For the transom measurements, I will have to check that out tomorrow in the daytime.

The color of the lower unit is black, the entire engine unit is black.

For photos, here is some that I have https://drive.google.com/open?id=0B_...2QtLThoSW9JNEk (I can get more if needed, I just had these already)

Thank you!

 

[Fun Times]

One thing to know between the two serial numbers provided is if they just happened to have kept the swapping of the engine and lower gear housing together for whatever reason, the two gear housings would have used the same gear ratio of 1.87:1.

Drive shaft has 8 splines. Prop shaft has 15 splines.? It is the 1.87:1 gear ratio lower unit.

The 0D serial number GEAR HOUSING (LONG)(BLACK) is Merc part number 1647-9148T84) (175/200 HP's) and is said to have a Torpedo Diameter of 4.75-inch (120.65mm).
http://www.ebay.com/itm/Mercury-Outb...tWWGjy&vxp=mtr
http://www.ebay.com/sch/i.html?_odkw...48T84&_sacat=0[/Quote]

The 0G serial number gear housing part number is 1647-9148A93 and is said it uses the 4.75" Diameter Torpedo, 25" Shaft. http://www.ebay.com/sch/i.html?_odkw=31211A2&_osacat=0&_from=R40&_trksid=p 2045573.m570.l1313.TR0.TRC0.H0.X9148A93.TRS0&_nkw= 9148A93&_sacat=0
http://boatpropellers.iboats.com/Mer...t_id=266218110

Originally the 0D serial number would look to have came with the 4.75 according to the serial number info provided. But it is interesting to note that in 1991 for the 200 HP/2.5L, the XR4 was also used which like mentioned by Faztbullet, is 1.78:1 and smaller size gear housing. Gear Housing(Propshaft)(XR4/Magnum II)

https://www.perfprotech.com/gear-hsg...product/146015 MARINERMAGNUM II
MERCURYV-135
MARINERV-150
MARINERV-175
MERCURYV-200 (2.5L) 1991 ONLY
MERCURYXR-4

GEAR HOUSING(DRIVESHAFT) https://www.perfprotech.com/gear-hsg.../product/62727
MERCURY105 JET
MERCURY140 JET
MARINERMAGNUM III
MERCURYV-135
MARINERV-150
MARINERV-175
MERCURYV-200
MERCURYXR-6

http://www.boatownersworld.com/turbo...blade-13d.html

 

[Puresyn]

Very interesting!

I have not had the lower unit apart or pulled but I do know that the prop shaft is 15 spline and I do know that the torpedo housing is more like 4.25 and not 4.75.
The only thing I have noticed while digging through the catalog that stands out (by may not make a difference) is that the prop nut assembly that it has on it now consists of a Lockwasher (Toothed), Washer (Splined), Washer (Tabed), and finally the nut. The 0G standard and 0D - with exception - of the XR4/Magnum II used this setup. The XR4/Magnum II just uses a Washer (Tabed) and a prop nut.

It is currently pouring outside so I am not easily able to get those transom measurements but I will first chance.

 

[Dukedog]

From the first time I put this boat in the water, it would not get on plane. The engine never goes above 1600 RPMs (even at wide open). I know the engine revs fine when not under load and in addition, it was checked by a reputable local boat shop and is mechanically sound ? compression and all.
this motor is NOT mechanically sound... either electrical or fuel issue.... needs ta be addressed before ya start with tha prop issue...

As I did more and more digging, I ?think? I have discovered that the standard O.D. for both the stock lower-unit and the XR4 lower unit torpedo is 4.75 inches. After inspection and without the assistance of a micrometer (eyeball and tape measure w/o shaft removal) the O.D. of the torpedo housing is more like 4.25? Defiantly not 4.75! Which would explain why the prop I previously ordered would not fit.

tha underlined above is a problem that will compound tha prop issue even with tha motor issue fixed...... like faz says.. its a small gear case, has 1.78 gears... it came on '87 ta '91 xr4 and '91/'92 xr6.. that shows tha gear case has been changed at one point because it came on neither tha OD or OG (power head swap) motor numbers mentioned... you are very limited on props with tha 4 1/4"... more so dia, than pitch as most that fit tha small hub are 'about 13 3/4 ta 14 inch.

The O.D of the prop-to-torpedo housing on the prop that fits fine but wrong pitch is 3 15/16?, visually the fit/clearances looks fine. This prop does however show signs of millwork so it would not surprise me at all if the prop had been ground to fit, but I am uncertain as the prop does not appear overworked in that area.

this is a common thing with tha small hub props from manufacturer...

 

[Puresyn]

Thank you, Dukedog!

After reading Faztbullet and your response, along with giving some more thought to what is happening with the boat, I am inclined to agree that there is some underlying engine issue. Unfortunately, outside of taking it back to the shop for deeper (and more expensive) analysis, I am not sure where to start with it ? maybe that is what I need to do, I am just trying not to sink much more money into it until I have a good grasp on what is going on. I am capable of ?some? marine engine troubleshooting but with the lack of some diagnostic equipment and solid expertise I am hopeful that the brilliant minds here might be able to assist me in narrowing down what is going on.

You have suggested a possible electrical or fuel issue. I assume there is a fuel pressure test connection on the fuel rail like most automobiles. The catalog does not really show one from what I can tell and the weather does not currently permit me to go and look. Do you know offhand what the fuel pressure should be under normal operating conditions? In addition, as far as electrical, I have a multimeter available if you can think of anything off the top of your head that I might check to narrow down the issue.

Additionally, the engine is equipped with what I believe they called a diagnostic horn? The component that beeps when turning on the ignition. If memory serves, currently when turning the key on it does one long beep and to short ones but I will verify that once the weather breaks.

 

[roscoe]

Thats one sick sounding motor.

Break out the toolbox, Start by checking compression and spark on each hole.

And get yourself 2 manuals, one an oem shop manual, the other a generic Clymer manual for the basics operations of a 2 stroke engine.

 

[Puresyn]

Thats one sick sounding motor.

Break out the toolbox, Start by checking compression and spark on each hole.

And get yourself 2 manuals, one an oem shop manual, the other a generic Clymer manual for the basics operations of a 2 stroke engine.

Thank you for your input, roscoe!

It is certainly adding up to be more that I had anticipated and thank you for the manual suggestions, I will definably look into that (If I do not just sink the boat out of frustration first).

Edit: What is the proper way to disable the engine for compression/spark diagnostics? (unless this is something the suggested manuals cover. Just thinking ahead a bit.

Edit 2: Here are a couple of manuals I was able to deduce from your suggestion. Are either/both of these what you had in mind? I know from automove experience that some manuals are just better than others.

https://www.amazon.com/Mercury-Mari...68121&sr=8-1&keywords=mercury+outboard+manual

https://www.amazon.com/Clymer-Two-S...36&sr=8-13&keywords=clymer+two-stroke+Mercury

 

[Dukedog]

send an email addy and i'll send ya a pdf file....

and forget tha clymer or any other NON-OEM, generic manual.. they jus get ya inta more trouble

 

[Puresyn]

send an email addy and i'll send ya a pdf file....

and forget tha clymer or any other NON-OEM, generic manual.. they jus get ya inta more trouble

I messaged you my email, thank you!

@Fun Times

I have got some measurements for you. Because this boat came with a jackplate, exact measurements that included the transom where difficult because it sits back so far from it. However, here is what I do have.

Note: I added more photos of this to my google drive. https://drive.google.com/open?id=0B_...2QtLThoSW9JNEk they are on the end. (boat is a bit dirty from mowing the other day, sorry)

From the engine trim pivot bolt to the bottom cavitation plate is approx. 20”. The diagram you suggested measures from the top of the transom, so the actual shaft length “may” be a bit an inch or so shorter?

The bottom cavitation plate is approx. 3"” above the bottom of the boats V (EDIT: 3 inches above the horizontal of the inset, NOT above the V) and the top of the torpedo just about sits even with the bottom of the boats V.

The boats transom height, including the height of the inset (see photos for inset visualization, from the top of the transom to the bottom of the V) is approx. 24 ?” while the transom excluding the V inset is 19” (just the flat/engine mount part of the transom. This makes the inset (V) height approx. 5 ?”

The jackplate is current set all the way up (again, I got it just like this and assuming it was how it ran I did not touch it) it has 4” of adjustment to lower the engine. The jackplate is also 10” deep if that helps visualize it.

It was a bit crazy trying to get measurements on this so if anything does not add up or you would like more information, just let me know and I would be more than happy to provide it if I can.

Thanks!

P.S. After re-reading this and giving it some thought, some of these may need remeasured for better accuracy. Let me know if you need that and I will work out a better way.

 

[Faztbullet]

Looking at pic's boat/motor is set-up pretty close and that is a Xr4 lower unit(intake holes give it away) From the video sounds like you got a ignition issue(switchbox/trigger or stator) as its not running on all cylinders...

 

[Dukedog]

what faz says... its a 20" motor (L)

for prop a 23 trophy (not trophy plus) ta try would be best bet with that gear case after ya get tha motor straightened out..... jmo

 

[Puresyn]

Looking at pic's boat/motor is set-up pretty close and that is a Xr4 lower unit(intake holes give it away) From the video sounds like you got a ignition issue(switchbox/trigger or stator) as its not running on all cylinders...

Awesome! Then at this point then I feel it is safe to say that this is in-fact an XR4 lower, I was unaware of the intake difference; great! Now I will need to look into diagnostics for the switchbox/trigger and stator. Roscoe was kind enough to send me an OEM pdf manual, it should be in there I hope!

Any additional feedback/input is always welcome! You guys have been awesome!

 

[roscoe]

The reason I suggested a non oem manual, is so you can read up on how a 2 cycle motor operates/is different from a 4 stroke. Your comment on "flat lobes" indicated you are thinking 4 stroke.
A non oem manual will give you a chapter or 2 on the basics. A factory manual will not cover basics, as it is written for service techs that have a background in these motors.

 

[Puresyn]

The reason I suggested a non oem manual, is so you can read up on how a 2 cycle motor operates/is different from a 4 stroke. Your comment on "flat lobes" indicated you are thinking 4 stroke.
A non oem manual will give you a chapter or 2 on the basics. A factory manual will not cover basics, as it is written for service techs that have a background in these motors.

Noted and thank you again. Yes, it has been quite some time (High school) that I have piddled with small engines and two-strokes. I am not typcially a person to dive into a mechanical diagnostic without knowing I can at least diagnose it succuessfuly, so your input (and others) has been invaluable. I have spent the past few hours digging around at testing the stator and triggers ect. with a little bit of luck on the stator tests.

My first thought was "Well, if it's not overly expensive, I'll just replace the parts to be certian." Um.. that stuff is pricy! (up to $500 USD for a stator!) So, my next thought is to disconnect the stator and check that with a multimeter for shorts and ressistances, etc. and start there. If that looks good I'll move to redoing the compression and spark test, and if that passes... so on and so forth.

I did come across a video on youtube of a guy having a somewhat similar issue on an optimax (excpet his was dying most of the time after load), his entire left bank was not firinig but it surprised me about how similar it sounded to mine. It ended up being the stator for him and now he said it runs great. So, I figure that is a good place to start.

Thank you!

P.S. I am still fairly surpised that none of this was brought up from my local boat shop during the "checks." These guys have been in business since I was a young boy!