How do I know what prop is for my engine?

[massimofinance]

Hi all: I am rebuilding my 1982 115HP Evinrude VRO V4 outboard. The old owner (a friend) told me that the prop that is on the outboard is not the one that came with the engine. I am thinking this is why the engine overheated and led to the work I just did. How do I figure out that size prop I need? Thanks!

 

[Dhadley]

Re: How do I know what prop is for my engine?

The tach will tell all. <br /><br />Just a guess -- did the rings break on one or both of the starboard pistons?

 

[massimofinance]

Re: How do I know what prop is for my engine?

The pistons on the driver's side of the boat (1985 Bayliner Capri 1600) (right side if you are looking from the back) went bad.<br /><br />There is no tachometer??? can you please explain?<br /><br />Thanks.

 

[tvpear12]

Re: How do I know what prop is for my engine?

you will be told by the senior officers to prop it to your wot rpms 5800 rpms would be a good range to run that engine and will make for a long lived engine. be sure you rebuild your carbs as well, this was my mistake when i rebuilt mine. Install a new water pump kit not just the impeller and what ever you do change out those rubber water deflectors that are between your water jackets. you will see 2 on each side of the engine when you remove the heads. they giude the water to go up to the top cyl.change that vro pump to a new one or disconnect it and mix your oil and fuel. those things can wipe out an engine quick if not working well. do not forget to replace your thermostats. any short cuts will cost you in the long run. i have learned this the hard way and do not wish this on my worse inemy, if i had any.<br /><br />INSTALL A TACH.

 

[Solittle]

Re: How do I know what prop is for my engine?

A prop, by itself, will not cause a motor to overheat. A motor will overheat because the cooling water is not flowing through the motor as it should. Possible causes that I can think of include:<br /><br />1. Plastic bag or other over the water intake.<br />2. Defective water pump.<br />3. Defective thermostats.<br />4. Deflectors in the powerhead are shot.<br />5. Blockage due to debris in one or more water passages.<br /><br />As for the prop selection the best bet is to call a propeller shop and tell them what you have and what kind of boating you do and take their advice. You could also get some input from the boat manufacturer. We could give you some input here but you told us nothing about the boat you are putting it on.<br /><br />Outside of that follow tvpear12's advice.

 

[Dhadley]

Re: How do I know what prop is for my engine?

Yep, thats the starboard bank. First, as stated above, lets get a tach. Thats the only way we know when its set up right.<br /><br />Most likely the top capable rpms are too low. That causes coking -- that black, sticky carbon like substance on the pistons. The rings stick and eventually break. <br /><br />Lets get the motor running again and go from there. Tell us more about you rig and the set up.

 

[massimofinance]

Re: How do I know what prop is for my engine?

First off, thanks to all for responding, this is really very helpful!<br /><br />This is a 1985 Bayliner Capri 1600, 1982 Evinrude 115HP VRO V4 motor. I replaced two pistons, and rings on all four pistons, (the other two were fine). I will check out the water pump and thermostats (any tell tale signs to look for?)<br /><br />I can tell you, there was A LOT of salt build up in the water passages.<br /><br />Can someone please tell me about this VRO part? What did it do, mix the oil and gas? I am not even sure it is still in the motor, since the old owner replaced the power-head once. <br /><br />Is a Tach easy to install?<br /><br />Thanks!

 

[C-RAVEN]

Re: How do I know what prop is for my engine?

vro pump is the oil injection system used by omc to <br />feed oil to the fuel mixture.<br />are you currently running straight gas in the tank?<br />if so you're vro system is still working( hopefully)<br /><br />my vro pump is disconnected, and i mix oil in the gas at 50:1 .<br /><br />vro pumps have been known to fail, and this could be part of your problem.<br /><br />good luck

 

[massimofinance]

Re: How do I know what prop is for my engine?

No, I am not running straight gasoline into the head.<br /><br />Where is the water pump? In the lower unit? Also, where are the thermostats?<br /><br />Thanks!

 

[Solittle]

Re: How do I know what prop is for my engine?

By chance are you trying to do your first rebuild without a OMC shop manual? If so you need to get one before you even get within 3' of that motor. I got mine here:<br /><br /> http://www.theoutboardwizard.bizhosting.com/parts_service_and_owners_manuals.html <br /><br />Get the parts maual as well. It has excellent parts diagrams showing what goes where.

 

[massimofinance]

Re: How do I know what prop is for my engine?

Thanks, I got a Cylmer's manual off ebay.