1972 6 HP Fisherman, water impeller vs. thermostat?

[superflydudebike]

I have not used this motor for a few years as I upgraded to a 15 HP. I usally have been running it about once per year in a can, however. I was putting it away for winter storeage and ran it in garbage can, mostly above idle speed The exahust port was not spitting any water and the engine became heated quicky. I shut it down promptly. Is this a likely impeller problem or a thermostat issue? I looked at intake screen and that did not seem to be clogged. I read in a different post that it is difficult to get adequate water circulation running it in a tank in neutral. Should I try running it with cuffs? In can in gear? Any advice as to best problem solving steps? I have had this engine for about 6 years and impeller has never been replaced while I have owned it.

 

[kfa4303]

Re: 1972 6 HP Fisherman, water impeller vs. thermostat?

Hi superfly. As long as the LU is well-submerged in a tank it should pump water, more like a spit/mist really. Unfortunately, you can't use muffs on these old gems. If it's really not pumping water at all, shut it down and inspect the impeller. While you should always use a t-stat if your motor came with one, it won't affect the motor's ability to pump water per se. Here are some vids other 3 hps running to give you an idea of what to expect. They're probably the best pound-for-pound motor ever made. Small, but feisty and surprisingly strong.

http://www.youtube.com/watch?v=PlqEuEuTV3g

 

[superflydudebike]

Re: 1972 6 HP Fisherman, water impeller vs. thermostat?

How long can one reasonably run the motor with defective impeller before damage can occur? I ran it for a few minutes and the engine was smoking, but I think it was residue burning off from a cleaner that someone had used on engine paint as the engine is immaculate. The entire engine painted area was smoking. It did not come to a grinding halt or anything. It was purchsed from from a private party that had bought it used from a marine shop (likely source of cleaner). He bought it on a fishing trip (his motor died) and used it once and then sold it to me. Is the impeller swap something that I can reasonably do myself? I work on cars and bicycles regularly and I have a repair manual for this motor. It looks relatively easy. I have heard these engines described as "bullet proof." I used to own two of them. A 1971 and 1972. Sold the older one earlier this year. Thanks.

 

[AlTn]

Re: 1972 6 HP Fisherman, water impeller vs. thermostat?

pretty straightforward repair..check out leeroysramblings.com..6 hp. repair as it may help you see what's required

 

[jay_merrill]

Re: 1972 6 HP Fisherman, water impeller vs. thermostat?

Your motor has a water bypass circuit in the head - it should pump at least a little water, no matter what the t-stat is doing. You may have a bad water pump impeller or a clogged passage.

Since you overheated the engine, chances are the impeller is damaged. That being the case, you may as well replace it. Be aware that there are two sizes of impeller for this motor - one is larger in diameter and is for use with the old. metal housing. The smaller diameter unit is used with the newer, plastic housing. Both work just fine.

If you want to check the t-stat, buy a new gasket, remove the three bolts on the triangular cover, which is located on the cylinder head, and remove it. You can then use the hot water test to see if yours is working as it should. I would clean scale, etc. out of the housing, while it is apart.

Since you overheated the engine, it would be a good idea to do a compression check. Remember that you will be using the rope start to turn the motor over, since it doesn't have electric start. That being the case, you probably won't get readings in the 100 psi + range. Anything around 60 psi is fine, as long as the values are within 15% of one another.

 

[kfa4303]

Re: 1972 6 HP Fisherman, water impeller vs. thermostat?

+1. You can definitely change the impeller yourself. In fact, you're supposed to at least every other season. It's a simple DIY procedure and you can get the impeller right here at iboats for about $10, many NAPA autoparts stores do as well (Apparently so does O'Reillys, but I haven't checked them out yet for myself). Here's a link that can walk you through the job. Good luck. Holler if you get stuck.

http://www.leeroysramblings.com/OMC_6hp.htm
http://www.iboats.com/mall/partfind...gd_poid=109111&gd_row=11&session_id=559189021

 

[slate1234]

Re: 1972 6 HP Fisherman, water impeller vs. thermostat?

View attachment 172941Hi superflydudebike here is a pic of my 6hp in neutral pumping water after I had changed the thermostat I was going to sell mine along with a 4.5hp mercury and buy a more modern one but its to bloody good to let go lol

 

[superflydudebike]

Re: 1972 6 HP Fisherman, water impeller vs. thermostat?

you must have a newer model as I do believe my 72 Rude only discharges through exhaust port. my 15 Rude has a separate pee hole, but is a 1986 model. the sierra part # 18-3001 is right one for the original housing, correct?