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Mercruiser (Chevy) instrument question

apollard

apollard

Active Member
I am in need of a new oil pressure sending unit for the boat engine. Dealer wants a small forutne, but has it in stock. Internet vendors have it for about twice the price of an auto unit plus $10 or so shipping. Problem is, I want to go boating this w/e.

I know our sending units run 10-70 ohms. The Mercruiser units run 33-240 ohms. Auto parts stores have not been able to cross the part number. The unit itself looks just like the one on my '68, so I'm sure there is an automotive alternative (likely from Chevy, who made the 454 long block). Internet searches have turned up nothing on the chevy sender resistance specs.

Anybody here know the resistance specs for a chevy oil pressure sending unit?
 
May do that, or install the lower ohm unit from my stang for the weekend, knowing that it will be little more than an idiot light. But, if I can get a replacement that works right...
 
Any GOOD parts tech can look up that information in a catalog. It may take a while as it requires going through each part one by one in an illustrated catalog, but I've found parts for customers that way.
 
"Starfury" said:
Any GOOD parts tech can look up that information in a catalog.
Click to expand...

Therein lies the problem. There is one older guy at the NAPA near one of the plants that could dod this for me. GOOD parts guys are almost extinct, along with the catalog :po
 
I don't know the year of your 454 mercruiser but napa part has one (part# 18-5899) for 32 $-----Iboats.com has it for around 19, plus shipping? what year is engine?
 
"Flysure1" said:
I don't know the year of your 454 mercruiser but napa part has one (part# 18-5899) for 32 $-----Iboats.com has it for around 19, plus shipping? what year is engine?
Click to expand...

1994 7.4L Bravo III. I've figured out no auto unit has the right range, so I have one on order. Going to install an auto unit this w/e and just use the guage as an idiot light until the part arrives.
 
Sierra Marine Engine Parts at Go2marine.com
For Oil Pressure. TEMPERATURE SENDER/OIL SENDER APPLICATION. ROVER. 31400000F & UP .... 7.4 (Bravo). B771113-D803117. 18-5899 ➁. 18-5897 ➁ ➅ ➆ ...
The napa # was for marine app.--
 
What about this type, used on "real" boat engines.

https://www.skidim.com/prodinfo.asp?number=R020001

R020001.jpg




I buy most of my boat stuff there, good place!
 
I'd prefer to have the old PCM 351, but that choice does not exist. Now, when that SBC bites the dust....that's a diff story!


Inboard V8's rule, no matter who makes em.
 
My buddy has a 34' sea ray with twin 496 chevy big blocks in it---open it up and watch the fuel gauge drop!!!
 
Yep. I've figured out why the new boat needs a 75 gal tank. The old boat got 3.5 mpg cruising at 28 mph. New one (8' longer) gets 3.2 mpg at 30 mph. Not that different...

Problem is, I'm not spending much time at 30 mph now. :coo
 
Wow, I can get 2 full days of skiing on a tank of fuel (38 gals). That works out to about 2 gals per hour.
 
Let's see - spent around 12 hours pulling kids on the tube & general kicking around. I burned 1/3 tank, so that's about 3 gph. So, not much different when doing watersports - lots of time stopped or idling then.

It's the time spent cruising that eats the gas - I'm probably at 30 gph. Of course, 'cruising has a new definition - that is around 55 mph :)
 
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