Is it really neccessary to replace that impeller?

[kohath]

I have a 1983 90 HP Chrysler engine on my boat. The motor has about 85 hours on it. I took it out today for the first time in 4+ years, and it ran like a top. I have heard many times that the impeller should be replaced every year. I looked for one for my motor, but could not find one. The motor is pumping lots of water, and seems to run just fine. I bought the boat used back in 1990, and have put about 45 hours on the engine since then. I have never replaced the impeller on the motor since I bought it.<br /><br />I suppose if a guy uses his motor 400 to 1000+ hours per year, it might be a good idea to replace the impeller every year, for from the way it sounds, if the impeller indeed needs to be replaced every year, the manufacturers must make the impellers with a core of used newspaper surrounded by heat treated bubble gum. What is wrong with aluminum is my question. Practically every thing else on the motor is aluminum, I beleive!<br /><br />Anyway, I do question having someone replace the impeller every year, if they only put 10 to 50 hours on the engine every year, like me.<br /><br />I have overhauled car engines, motorcycle engines, 2 stroke and 4 stroke, and I must say it is a job I do not like to do, very time consuming. I have plenty other things to do other than work on engines. Fortunatly, since I bought this boat, I have not had to do anything to the motor other than replace the plugs, and I have replaced the lower unit oil a few times. I did replace the wood for the seats about 7 years ago. I also cleaned out the gas tank a couple of times. Other than that, zip. <br /><br />Am I missing something here, other than replacing the rubber impeller in the aluminum motor is simply cheap insurance from having the motor overheat when the impeller finally goes south, especially if you are a bass tournament fisherman that puts 8 to 16 hours on the motor every day?

 

[moderator1]

Re: Is it really neccessary to replace that impeller?

Moving to Outboards.

 

[andrewkafp]

Re: Is it really neccessary to replace that impeller?

It doesn't need to be replaced every year.<br />Mine was replaced about 3 years ago (50 hp Merc) and it's pumping lukewarm water no probs.<br />If you have an Auxiliary motor, you can run the main motor normally and if you see signs of restricted flow or temp gauge inrease, shut it off and use the kicker. Then think about replacing it.If you don't have a kicker, then it might be worth the effort. <br />You can spend time and money changing the impeller and cause other problems inc entry of water into L/U. I don't LOOK for trouble, just fix problems.

 

[rogerwa]

Re: Is it really neccessary to replace that impeller?

I believe your last paragraph sums it up.. For me, I replace mine every three years. In minnesota it takes four years to get a whole years boating in. I only put about 50 a year max on my rig.<br /><br />I did just help my neighbor replace his impeller that self destructed and spread its little part throughout the cooling system. By some stroke of luck we cleared the bits and pieces out of the cooling lines and he now has a strong stream.<br /><br />In this case it was two hours and an $11 impeller. Doing this even every two years is not that bad and the alternative could be a wrecked engine..

 

[turtle1173]

Re: Is it really neccessary to replace that impeller?

Kohath,<br /><br /> There really isn't a right or wrong answer to this and there are a ton of variable. I've got a 1975 55HP Chrysler that my Dad bought new. I believe in all that time he only replaced the impeller once or twice. The overheat buzzer came on once when the impeller went out. No damage to the motor. He never did much maintanence to the engine but it was reliable. But we lived in CA and it was stored in a garage. Did that make a difference?? Who knows!<br /><br /> However, I recently bought a 1972 85HP Chrysler. It had been sitting for 10 years or so in a barn. I decided to replace the impeller before I ever even tried to start it. The impeller was missing 2 vanes and was in horrible shape. How often had it been replaced?? Who knows.<br /><br /> There is something to be said for "peace of mind." But every person must decide what kind of maintanence they want to do on their motor. I hate taking my lower unit off (because it's a pain to put back on) but I would hate even worse to be in the middle of the Mississippi River and have my impeller stop working.<br /><br /> Some people suggest replacing every year. Most posts that I have read suggest every other year. If you don't use the motor that much, you might be able to get 5 years out of it. In fact, you might get 20 years out of it. Who knows?!? One problem you see on this board is the people that buy an engine and don't know any history on it. They start it up, have an overheating problem or burn up an engine and don't know why <br /><br /> You can wait how ever long you want to wait on some of these things. But where will you be when it goes out??<br /><br />Shane

 

[JasonJ]

Re: Is it really neccessary to replace that impeller?

The impeller is made of a type of rubber. If you imagine a wheel with a bunch of fins sticking out, that is the impeller. The housing it sits in is circular for the most part, but the impeller is set in it off to one side, so as it rotates, the fins are going from being bent to straightening out back to being bent. This action is what forces the water up to the engine. If a motor sits for a long time, the impeller can take a "set", where the fins that are held in the bent possition become brittle and can break off. In the end, you should at least drop the lower unit and visually inspect the impeller. Take it out and bend each fin, if the fins flex and pop back, and none are cracked, then continue to use it. The more you use and outboard, the less you have to replace the impeller. It is suggested to replace them every season because they are cheap, it is an easy job to do, and the peace of mind is worth its weight in gold. I had an old Homelite 55 that pumped water just fine, never got hot, and the stream from the pee hole was strong. I blew the lower unit, and while fixing that I checked the impeller. Half the fins were gone and the rest were cracked. It was a nightmare waiting to happen, so at least check yours out....

 

[andrewkafp]

Re: Is it really neccessary to replace that impeller?

I would say if you have it out and in front of you. Then put the best quality replacement in while you are at it..<br />They are inexpensive, the hassle is more to do with taking the L/U apart for no reason and have to then worry about oil/water leaks.<br />But your motor is a real gem Kohath, and I would look after it... They don't make them anymore..

 

[FredM]

Re: Is it really neccessary to replace that impeller?

Hi kohath,<br /><br />I would replace your impeller and any other fibre washers o-rings etc in the pump. At least then you will have a base line to work from. I'd then change every 2 years especially in salt that way you get the leg off regularly, keep the drive shaft free, fix any corrosion and know the pumps good.<br /><br />These aren't the same as auto water pumps. They are a rubber vane type of impeller that although robust when used as designed will break if abused, and believe me it doesn't take long! Unfortunately when buying used motors we don't always know how it's been treated even if it has low hours. Have a look at the post below<br /><br /> http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=17;t=032475 <br /><br />Cheers

 

[alcan]

Re: Is it really neccessary to replace that impeller?

Replacing the water pump empeller. There are more reasons to drop your L/U annually than just the empeller. You have to remember your drowning metal in water. You also have a sealed oil container submerged. You may not need to replace the empeller annually. But you do need to remove your l/u and inspect. Lube the screws that hold it together look at and lube drive shaft splines. Inspect any exhaust gaskets if used. Pull the prop and look for the outboards no.1 enemy fish line. Fishing line has probably killed more outbards than everything else put together. And while your changing gear oil you might as well toss in a new empeller. All this sounds like a big deal. Once you know how, it only takes a half hour. Let that bugger go for a few years and get crusty and you will be in for a real treat. There is no nightmare like a stuck driveshaft. You have a nice clean motor there, but remember it's what's on the insde that counts.

 

[ob]

Re: Is it really neccessary to replace that impeller?

Ditto on Alcans post.Along with any exhaust seal replacement when dropping lower unit its easy to also change the shift rod seal and driveshaft seal.

 

[wayne h]

Re: Is it really neccessary to replace that impeller?

in fresh water i would change it every 2 years in salt i change mine every year they are 12 bucks for my engine its cheap peice of mind i would hate to waste an engine over 12$.like every 1 else said then is a good time to service the lower unit fluid witch should be done every season anyway so what is a few bolts to change a waterpump.and take a look at the seals and gaskets for other problems that might be there.it also keep things from freezing up like lower unit bolts or the driveshaft to the head like i have seen many times.