Propeller

[Galacticia]

I need some advise again friends. I have a 1986 Century with 140 mercruiser four cylinder. I need to replace the prop due to damage. The prop currently on the boat is 14.5X19. I bought this boat used and I am not sure if this is the right size prop for the boat. The seller embelished and lied to me just about everything on the boat so I am unsure if this prop is the right size for the boat. With the current prop the boat hesitates upon immediate full throttle and takes a bit to plane or get to full speed. I'm really not concerned with increasing speed or hole shots just the right size and pitch to prolong engine life. Appreciate your input.
Thanks,
John

 

[steelespike]

Re: Propeller

If you read the stickys at the top of the page it will tell you what info we need to evaluate your setup.Hesitation may be a tuneup issue.
There really isn't a standard prop,Basically There are power props and speed props
And these are opposites.There are other props for more unusual applications.
Your 19 is surely within the typical prop range.

 

[Silvertip]

Re: Propeller

Not only should you read the READ THIS FIRST sticky, but read a few of the other posts in this forum. You will find the question you asked is repeated time and time again and the answer is always the same. We can't help you unless you have as a minimum, the following bits of data: 1) Your current "observed" wide open throttle rpm with what you consider an average load. 2) The current prop diameter and pitch 3) The problem you are trying to correct. And whatever performance improvement you expect to see will not happen if the engine is not in a good state of tune or is simply tired (as in worn out and down on power). No prop can provide the best hole shot, best cruise rpm, and maximum WOT speed. You either prop for power for skiing/water sports, or you prop for WOT RPM at or near the upper end of the manufacturers recommended rpm band. Whatever prop does that is the best prop for your boat.

 

[Galacticia]

Re: Propeller

Gee, sorry I asked.

 

[steelespike]

Re: Propeller

Don't take it personal he treats everyone the same.
I'm ready to do what I can. Just get us trhe info.

 

[boat1010]

Re: Propeller

Don't be sorry you asked. It is just that we can't do much if anything without some more information.

 

[john cole]

Re: Propeller

sounds like me, they have been doing a good job with trying to help me with my problem. couple of things i have learned is your questions isn't a easy one to answer, and i have done a lot of reading on the subject, various forums on here answered a few of my questions. but if your reaching max rpms with this prop it is probably ok to use, if you want faster "hole shots" go to a smaller pitch prop by a couple of degrees, again depending on your engine rpm. as far as hesitation that is most likley in another part of the engine.

 

[Galacticia]

Re: Propeller

Thank you steele spike and boat1010, I just went to a sporting good store and got some advice from the clerk there and purchased one. I am new to the site and just learing how to navigate through it as well as boating too. I did not know what terms like pitch on a prop, WOT etc meant I was just looking for some quick help so I could take my grandson fishing. I read that this was a family site so I did not think it was such a big deal. I was taken back a bit that I would be treated like a two year old for not using the site correctly or posting appropriate intake data for a solution.
Anyway I went to a 4 blade prop, from what I could find out the four blade cuts a bit on vibration. The 19 pitch was within normal limits for the boat, but the clerk suggested that when going to a four blade to go to a 17 pitch. As far as the hesitation upon quick acceleration I found two fuel filters on this mercruiser 140, its either a 1984 or 1986. One is on the fuel pump and the other is in the carb. The filter on the carb was totally clogged. After replacing them hesitation is no problem. I just have one more issue to deal with so I you have any suggestions please post back to me. This engine has a vent near the starter motor bendix/gear. There is fresh oil spewing from this vent when the engine is running. I found one oil leak on the valve cover gasket and replaced it, no more leaks were noted from the cover after the replacement but there was still oil spewing from the vent slits. My current thinking is that the oil is coming from the rear main or oil pan gasket, despite which one I figure the engine must come out to repair the problem. If you run the engine for about 4 hours it will loose about a half quart. If anyone knows (and this would save me a lot of time and money) if the rear main or oil pan gasket were leaking would the leak have the ability to make it to that part of the engine or is this part of the engine sealed from the rear main and oil pan gasket. If it is sealed I then need to look elsewhere like the rocker gasket, or oil sending unit. If someone knows this answer it would save me lots of headaches. I know that I am posting this under the props section, but my thinking was that the two gentlemen that got back to me about the prop may have knowledge of this particular situation.
Thanks,
John

 

[john cole]

Re: Propeller

are you talking about the flywheel housing? if so and your losing that much oil that fast i would say it is your rear main seal. with that much oil pouring out i would defiintly stop running it and get it fixed before something else goes wrong such as the motor blowing up.

 

[Galacticia]

Re: Propeller

Hi John,
Last nite I pressure washed the engine so that it is totally clean, I plan on later today putting the muffs on to loook for the origin for this leak. The mild amount of spewing is coming from a vent slit near the rear of the starter motor. I share the same thought with you that it is the rear main; however, I do not want to jump to a conclusion as of yet. My specific question if you know is that if the oil leak is coming from the rear main would the oil leaking escape from the vent slit near the rear of the starter where the bendix is located. If the oil is leaking from the rear main does it have access to leak from the starter slit, I'll look elsewhere. Also let me run this by you, because this is what I am faced with. If it is the rear main how difficult is it to replace that seal/bearing. Do you know if the main caps have to be removed and the crank taken out? The engine is about 84-86 vintage. It has 130-135 compression on all four cylinders. There is noticable blow-by coming from the pvc valve. The outdrive is brand new and the boat is worth saveing. The current engine runs strong I got 35 mph out of it with six adults onboard on lake Michigan when it was calm. It idles and runs smooth through the lake channels and it always starts. My thinking however if it is a lot of work to change the main bearing if in fact that is what it is to just buy another brand new motor from michiganmotorz for a little over 2k. Also(sorry I forgot) I tried rear main oil stop leak, I have been told to never use this as it does not work anyway and clogs other areas of the engine. I tried it anyway just to see if it would stop it a little possibly giving me another direction to look. After adding it , it did nothing whatsoever. Just let me know what you think John or if anyone else has any ideas. Also may I add these forums are great, I had a harley davidson that no one could find where a transmission leak was coming from I had. I spent hundreds to local bike shops and still it leaked. Finally I read in a forum to check the transmission breather tube. I did this and found a nest of bugs in it clogging it up. After blowing out the tube with compressed air the transmission never leaked again. So any knowledge you have is greatly appreciated.

 

[1980Coronado]

Re: Propeller

Hey Galacticia,

Welcome to iboats

I would suggest that you start a new thread in the Mercruiser I/O forum for the question about your oil leak. You will get better responses to this type of question in that forum. Not all of the engine gurus hang out in the prop forum. I had a 1968 16' Starcraft that had the Mercruiser 140 hp motor in it....we swapped the original 120 for the 140, wow what a difference 20hp made....they are great little motors.

Here is a link to that forum: http://forums.iboats.com/forumdisplay.php?f=21

 

[steelespike]

Re: Propeller

I know nothing about the design of the 3.0 but if you think about almost any motor a vent hole near the starter sure could have oil from the main leaking out.
If you pull the starter you may ne able to feel the flywheel for oil.
Its likely the flywheel could be slinging oil almost anywhere.You may find the starter nose
covered in oil.I suppose a cracked block could leak oil out of the oil gallery but the likely hood of it being right at the vent seems slim.
I've only done one rear main seal on a 53 Studebaker,and it was flexible and you fished it around the crank with a special tool and had to remove the pan to remove the bearing cap.
I doubt the 3.0 has that type seal.
You will get a lot more detail in the I/O section.Good luck.

 

[Galacticia]

Re: Propeller

Thanks, I go there with this now. I did find where the leak was coming from using a hand mirror under the motor in the bilge. Its coming from the rear of the oil pan so thus far I am hoping it is the oil pan gasket. I'll go to mercruiser I&O with this .