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  1. CLi87

    Mercruiser 7.4 Oil Pressure Alarm Goes Off Randomly?

    I have an alarm that keeps going off randomly, sometimes I run the engine and it'll never go off, other times it starts buzzing and doesn't stop, I think it's the oil pressure sensor anyway, it's got a white with blue stripe wiring going to it. My oil pressure gauge on the dash reads perfectly...
  2. CLi87

    What are the 2 sensor on the thermostat housing?

    To be honest I didn't compare the temp gauge with IR reading at the thermostat when it was "working", but it stayed between 160-180 originally, right now it's going up to 220 on the gauge while the IR is only reading 150-160 at the thermostat.
  3. CLi87

    What are the 2 sensor on the thermostat housing?

    Well I spoke too soon, my temp gauge works but it's reading about 60-70 degrees high, it was working fine previously, gauge go bad suddenly?
  4. CLi87

    What are the 2 sensor on the thermostat housing?

    Found the problem, connector at the sensor was badly corroded, sliced open the heat shrink and the wires to the connector were green and basically dust. Cut the wire back a bit, put on a new connector and the old temp gauge is reading again.
  5. CLi87

    What are the 2 sensor on the thermostat housing?

    I did some more testing and when I ground the tan pole out on both the old and new gauge the needle does max out, so I guess it's a wiring problem with the tan wire, gonna do some more diagnostics to try to find the break.
  6. CLi87

    What are the 2 sensor on the thermostat housing?

    I just took my dash apart and checked voltages, i'm getting 12.4v in from the purp wire but the tan wire was only sending 8.2v out, so I figured the gauge is bad and I just happened to have a brand new temp gauge so I installed that real quick, with the new gauge I'm getting 10.2v out from the...
  7. CLi87

    What are the 2 sensor on the thermostat housing?

    I did have ignition switched on, and actually the buzzer does work, I didn't realize there was a 3 second delay before the buzzer sounds, however grounding the tan wire for the gauge still didn't work. Should I be getting 12v from the tan wire to ground? Also, not sure if it matters but when I...
  8. CLi87

    What are the 2 sensor on the thermostat housing?

    I grounded out both wires but the gauge didn't move and the alarm didn't sound. I traced the wires into the cabin, the tan wire goes to the gauge and the tan/blue wire goes to the alarm. I'm kinda curious though, how does grounding out the wire make the alarm sound? From what I can see the wire...
  9. CLi87

    What are the 2 sensor on the thermostat housing?

    Ok so I must need the other sensor, the one with the cover on it, upon further inspection the actual wire is tan with a blue stripe, someone had spliced in a short extension that was just a blue wire. Any idea which sensor that is? On the diagram both of the #11 sensors look like the bronze...
  10. CLi87

    What are the 2 sensor on the thermostat housing?

    Actually I think I found the answer, both are temp sensors but one is for the gauge and one is for the alarm. My gauge was working but suddenly stopped so I figured the sensor is the problem, looking at the diagram which sensor am I supposed to get? Part #11 and which sensor goes to the gauge...
  11. CLi87

    What are the 2 sensor on the thermostat housing?

    I have a Merc 7.4 and was wondering what the 2 sensors are on the thermostat housing, I'm sure one is a water temp sensor but what's the other one?
  12. CLi87

    Can water get into oil from failed exhaust parts?

    The engine had been sitting for so long that 4 valve stems were badly corroded and when I went to turn the engine over it bent 4 push rods, 3 on one head and one on the other, so I had to take both heads off to clean everything.
  13. CLi87

    Can water get into oil from failed exhaust parts?

    When I assembled the heads back together I used a wire brush to clean all the mating surfaces, put on OEM head gaskets and new head bolts with sealant already added. I used a tap to clean all the head bolt holes and followed the proper 3 stage torque procedure in the service manual. It's always...
  14. CLi87

    Can water get into oil from failed exhaust parts?

    Duplicate post, please delete
  15. CLi87

    Can water get into oil from failed exhaust parts?

    Gotcha, just want to check to see if I have this correct, I was looking at this water flow diagram for a 7.4, can I just need to block off the big hose that feeds water into the water pump and the small hose at the top of the water pump right? Shouldn't that isolate the block and heads without...
  16. CLi87

    Can water get into oil from failed exhaust parts?

    ooo, I see what you're saying now, and then set the engine to TDC so all valves are closed?
  17. CLi87

    Can water get into oil from failed exhaust parts?

    I can block off most of those hoses but I'm not quite understanding how to block off the risers to the Y-pipe connection? Can I actually block it off at the exhaust exit on the transom assembly?
  18. CLi87

    Can water get into oil from failed exhaust parts?

    Also I ran the boat to operating temp on the hose and noticed quite a bit of steam and a few droplets of water coming from one of the hoses from the valve cover to the flame arrestor, is this normal just blowing out condensation or is something not right?
  19. CLi87

    Can water get into oil from failed exhaust parts?

    I wanted to do a pressure test of the cooling system but I couldn't figure out a good way to block off the risers?
  20. CLi87

    Can water get into oil from failed exhaust parts?

    So I finally got my Merc 7.4 up and running and unfortunately after running it for about 20 minutes at idle on the hose I noticed my oil level was rising. I just put new head gaskets and intake manifold gaskets on so I don't think either of those are leaking. I also inspected the heads and block...
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