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West Wight Potter Mailing List maintainer
dfarrell@ridgecrest.ca.us
List hosted by www.tscnet.com
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have followed and studied this issue since the 1970's. It has been very
important to me as I have owned outboards from 2 through 150 HP exclusively.
At one time I had 3 outboards. One of my major concerns was why some
outboards puked and died in less than a year while other lasted forever. I
learned that many of the ones that puked and died did so due to poor oil. It
seems a lot of people still use TCW2 or automotive oil on their new engines!
I always have received exceptional service from my OMC/MERC/Nissan products
because I have always used the right oil (not necessarily OMC/MERC/Nissan
oil). In addition, I have always regularly applied ValvTec - Carbon Free to
detox my engines and a fuel stabilizer to store them.
According to all outboard manufacturer's service manuals I have read (Merc.,
OMC, Nissan) operating engine with a prop that does not allow motor to reach
designed rpm range damages engine by increasing combustion chamber deposits
and subjecting parts to undue stress and wear. There is a threat that you may
not be able to claim damage on your warranty..
Combustion chamber deposits are single major cause of powerhead failures on
outboards. It is main reason manufacturers insist you use TCW3 oil on their
engines through 1999. TCW3 formulation includes an additive to reduce
deposits in comb chamber.
Almost all small outboards are shipped with a prop designed to operate on
light, small dinghies and not heavy vessels. Thus a change of prop is
required.
So.. Use the right prop as required.
Best
SF
In a message dated 3/6/00 9:22:48 PM Pacific Standard Time,
drickert@thegrid.net writes:
<< Not necissarily(sp) I work on internal combustion engines for a living. An
engine is best operating at it's designed rpm. Over-reving or lugging(
under rpm) will affect engine life and decrease service intervals. If the
manufacturer designed the engine to operate at 5000 rpm lowering that to
4500 will overstress the engine and cause premature wear. Run 'em like they
were built to run. HTH
Dan Rickert First mate "THALES" wwp p-19 212 skipper Vagabond 14 dinghy #
316 >>
>Dear Dave,
>
>Thanks for the information, it's nice to see that Nissan is working on their
>web-site.
>
>A couple of things about prop pitch and higher RPM's -
>
>More RPM's will mean more fuel consumption and increased engine wear. Be
>sure to shorten your interval between oil and gear case fluid changes. But I
>agree with Nissan that these small engines do need to turn the RPM's to get
>the maximum performance.
>
>Let me know how your tests go, over the long term, while considering the
>variables. If you're impressed with the performance, I will keep the 7" prop
>in stock or see if we can order the engines that way.
>
>Regards,
>
>Glenn D. Perkins
>IM/West Wight Potter
>
>
>----- Original Message -----
>From: <norris@us.ibm.com>
>To: <wwpotter@tscnet.com>
>Cc: <glenn@westwightpotter.com>
>Sent: Monday, March 06, 2000 4:24 PM
>Subject: Nissan 5hp Props
>
>
>>
>>
>> I found that the new Nissan 5hp 4-stroke motor on my P-19 didn't seem to
>> sound like it was getting to the proper high-end RPM. Or - I did not yet
>> know how quiet these 4-stroke motors really were. So -- I decided to get
>> an RPM reading on the motor under full power with the stock 8" pitch prop.
>> Gut-feel, knowing this motor needed a lower pitch prop, I purchased the 7"
>> pitch prop and had it with me prior to starting the stock prop test.
>>
>> On Sunday morning, after the Saturday 02/26/2000 "canceled" (except for
>> some die-hards needing, as Jerry B. states it, "a water fix")
>> Potter-Yachter outing in the Oakland estuary, I was able to determine the
>> following:
>>
>> Prop Full Throttle RPM Speed
>> 8" 4400 4.8 kts
>> 7" 4900 5.4 kts
>> (sorry if my column "tabs" mess up this data)
>>
>> The RPM was taken with a Sears Engine Analyzer (12V required) using an
>> inductive pickup. Its accuracy is unknown. The speed calculations were
>> obtained averaging GPS readings for four quarter mile runs with each prop,
>> two down-river and two up-river. Accuracy is again questionable, but my
>> point was to show the needed higher RPM on these 5hp motors.
>>
>> Nissan recommends 4500-5500 RPM for optimum high-end operation. Our 19'
>> Potters are heavy enough to warrant the 7" pitch props vs. the standard 8"
>> that comes with all new motors. By copy of this note to IM, I'd like to
>> recommend they ask Nissan to supply their new motors with the lower pitch
>> prop. If buying a spare prop, I would again recommend the part
>> #36964-5141M (7" pitch).
>>
>> The Nissan Owner's Manual states their prop sizes as 200x229mm (7.9"
>> diameter x 9.0" pitch), 200x200mm (7.9"diameter x 7.9" pitch) and
>200x178mm
>> (7.9" diameter x 7.0"pitch). The "Tech_Talk" prop section of their
>> web-site has a misprint on the 8" pitch prop showing 7.2" vs. 7.9". That
>> web-site is: http://www.nissanmarine.com/tech_talk/prop_chart2.html
>>
>> The 5hp prop part numbers are as follows:
>> 7" pitch 36964-5141M
>> 8" pitch 36964-5162M
>> 9" pitch 36964-5181M
>>
>> Fair Winds and fun Pottering,
>> Dave Norris, P-19 #1004 "WightCap"
>> Los Gatos, CA
>>
>>
This archive was generated by hypermail 2b29 : Fri Mar 31 2000 - 03:27:09 PST