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    Fuel pump vacuum test

    My 1977 Mercruiser 454 started running poorly at higher rpm, not going above 3000 rpm, stumbling with the occasional backfire. I tee'd a vacuum gauge into the fuel line before the pump and read 0.5 in Hg at 1800 rpm and between 0.5 to 1.0 at 3000 rpm with the gauge needle vibrating fast. I'm...
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    Stupid plug gap question (?)

    I'm replacing the plugs in my 1977 Mercrusier 454, as per the manual, but the plugs I bought have a gap of .025, whereas the Merc manual says .035, should I regap or leave them as is? To put it another way is the correct plug gap SPECIFIC TO THE PLUG OR TO THE ENGINE?
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    454 V-drive power loss when running hot

    We usually run our 1977 454 v-drive at cruising speeds running 1800 rpm happily for hours on end at 175F. We have had overheating issues in the past at higher rpms (eg 3000 rpm) that I thought I had fixed by replacing the raw water pump and having the heat exchanger checked and serviced...
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    Location of neutral safety switch?

    Had a bit of a scare the other morning in the middle of nowhere when the boat wouldn't start. It's always required a little jiggle of the shift lever while in neutral to engage the switch that allows it to start. This time it took alot of jiggling and finally I found the magic spot just at the...
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    Heater hose sweating coolant?

    I've got about 40' of 1/2" heater hose that circulates coolant in a circuit from the engine to a bus heater to the HWT and back to the engine. The entire length of the hose is sweating and sticky with (must be) coolant...is this something heater hose does as it ages?...(I don't know how long...
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    Grease question, dielectric versus anti-seize

    I replaced my temperature sender and over-heat alarm switch and used an anti-seize grease on the threads (Mariners Never-Seez), remembered after that they need to be grounded...should I have used dielectric grease? (I searched dielectric grease and am confused...it is a non-conductive grease...
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    What thermostat for a 454 Mercrusier Inboard 330 HP with closed cooling?

    I have a question about my Mercruiser Inboard 330 with closed cooling. Mercruiser Manual #3 says I need a 143 degree thermostat. When I tried to buy this at our local Mercruiser Authorized parts dealer he said "no, you need a 160 degree". Is he wrong or has the recommendation changed since...
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    Re-doing my Wet Exhaust

    The 3" dual wet exhaust on my 26' Tolly has been burning out just after the exhaust manifold. The 3" hose does not come straight off the end of the exhaust elbow like it should but instead tries to make a 30 degree bend, kinks and burns. In order to fix this I'll put in a 45 degree elbow, I'm...
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    temperature sender stuck in manifold?

    I'm afraid to force it in case it breaks off - what's the remedy if it does??
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