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  1. CLi87

    Swapping 88' 454 Truck Engine to Replace 93' Mercruiser 454

    After multiple issues with the engine in my boat I've decided to just swap the block and heads out. My neighbor just happened to have an 88' 454 motor (Gen IV?) from a suburban with 100k miles sitting around so I got that from him and stripped it down. I know I have to move the accessory...
  2. CLi87

    Water leaking from block but pressure tested fine?

    I just put new head gaskets on both sides, but even if it was the head gasket, would I not hear air coming out when pressurized?
  3. CLi87

    Water leaking from block but pressure tested fine?

    I tried looking around but if it was coming from the exhaust manifolds and pooling wouldn't I see a rust line coming from the leak or at least some type of residue?
  4. CLi87

    Water leaking from block but pressure tested fine?

    Yea, I pulled the drain plug on both sides then put one back in and hooked the leak down tester to the other hole.
  5. CLi87

    Water leaking from block but pressure tested fine?

    This has got me really confused, Mercruiser 7.4 Gen V I was looking and saw some water dripping from the side of the block, naturally I would think cracked block but just did a pressure test and the cooling system holds pressure fine and I don't hear any air coming out?? I looped the two exhaust...
  6. CLi87

    What are the 2 sensor on the thermostat housing?

    I'm thinking it must the sensor, I got a new one I can put in just waiting for PB blaster to loosen it up a bit, it's stuck on there tight. I switched the gauge out with the new gauge and it's also reading high so it must be the resistance reading is wrong from the sensor.
  7. 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...
  8. 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.
  9. 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?
  10. 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.
  11. 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.
  12. 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...
  13. 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...
  14. 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...
  15. 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...
  16. 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...
  17. 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?
  18. 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.
  19. 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...
  20. CLi87

    Can water get into oil from failed exhaust parts?

    Duplicate post, please delete
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