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Sierra 18-7703 Marine Knock Sensor for GM V-8 Stern Drive Engines

Manufacturer

Picture for manufacturer Sierra

Part Number

18-7703
14 reviews
Sale Price

$72.13

In Stock (5)

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Usually delivered within 2 days

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No Hassle Returns

No Hassle Returns

Live-in-stock inventory

Live-in-stock inventory

Fitment guaranteed

Fitment guaranteed

Product Details

The Sierra 18-7703 is a marine-grade replacement knock sensor engineered for GM V-8 powered MerCruiser, OMC, and Volvo Penta stern drive engines. This sensor monitors the engine block for the vibration signatures associated with detonation (knock or pinging) and sends a signal to the engine control unit to retard ignition timing, protecting internal engine components from damage.

Key Features:

  • Detects engine block vibrations caused by detonation or pre-ignition knock
  • Signals the ECU to retard ignition timing when knock is detected, preventing engine damage
  • Direct OEM replacement — no modification required for installation
  • Engineered to meet or exceed original equipment specifications for marine applications
  • Compatible with GM V-8 engines displacing 454, 502, 540, and 572 CID

OEM Cross-Reference Numbers:

  • MerCruiser / Mercury Marine: 805544T, 8M0077616
  • OMC Stern Drive: 3854512
  • Volvo Penta: 3854512
  • Mallory: 9-33500
  • EMP: 1300-36040

Common symptoms of a failed knock sensor include persistent engine knock or pinging, loss of power, and poor fuel economy. Replacing a faulty sensor with the Sierra 18-7703 restores proper ignition timing control and engine protection.

Such a smooth shopping process. Prices are super competitive, thanks autoplicity! :)

great prices

Autoplicity must have sent my Airaid CAI within hours of my order because UPS delivered it right away. I even got it before I received an e-mail indicating the order had been processed or a notification of shipping e-mail. <br><br>The online advertised price seems to vary by about $20 and that means that you must monitor the site if you are to get the lower price. However, Autoplicity has arranged with BuySafe to give you the difference if you establish an account with them and go through the process. This process was not easy as there was an apparent database problem where the Autoplicity URL was not taken by BuySafe. A call to BuySafe got that worked out, I am hopeful that I will receive the refund promised via paypal. It looks like a good system if it works.<br><br>The bottom line is that Autoplicity offers the best online price by far and although my unfamiliarity with how they do things caused some confusion on my part, they do have a good order processing and price guarantee in place.

good friendly website

Quick response. Fast shipping.

wON'T KNOW UNTIL MERCHANDISE ARRIVES

Great Clutch kit I got, did have to contact customer sevice to see if my item shipped but was very nice about it. I would do business with them again. Item shipped quickly. Great price to.

great

Autoplicity had the lowest price on the item I needed, shipping price was not out of line and item was shipped in the time frame promised. Who could ask for more.

check out was easy

quick and easy, Product was delivered quite fast ,was as ordered and pictured

Easy to find parts and order. Great prices. Wide selection of parts for all my cars and trucks!

GOOD PRICES AND QUALITY

Super fast shipping,lowest price I could find, will buy from again.

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