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Rotation Sensor
- Thread starter jamepc
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Perhaps this has been thought about already but if there's a spot for it on the block and an actual Mercury part number for it, can a person that's having their motor rebuild have the block modified to install and make the sensor work? Even if it's not connected to the ECU, maybe it could be monitored independently of the existing sensors. Just a thought.
On a similar note, is there a visual different between the old style and new style oil pump crank gear? If I had a scope to put in the hole, would I be able to identify it? Not sure if my engine re-builder is just sloppy or untrustworthy by the quality of the final product...
On a similar note, is there a visual different between the old style and new style oil pump crank gear? If I had a scope to put in the hole, would I be able to identify it? Not sure if my engine re-builder is just sloppy or untrustworthy by the quality of the final product...
Dr Honda
Well-Known Member
Sure... if you found a machine shop that has good CNC machines... they could write the program to cut it open. Then you can just get the OEM parts, and tap into your water warning box. (I think the wire is already there for the sensor)
I use to cut Suzuki heads to add decompression fittings. It's the same process. (but unfortunately, I closed my shop last year)
I use to cut Suzuki heads to add decompression fittings. It's the same process. (but unfortunately, I closed my shop last year)
Well if I ever need another rebuild, I would seriously consider that!
My other question was:
... is there a visual different between the old style and new style oil pump crank gear? If I had a scope to put in the hole, would I be able to identify it? Not sure if my engine re-builder is just sloppy or untrustworthy by the quality of the final product...
My other question was:
... is there a visual different between the old style and new style oil pump crank gear? If I had a scope to put in the hole, would I be able to identify it? Not sure if my engine re-builder is just sloppy or untrustworthy by the quality of the final product...
Dr Honda
Well-Known Member
Yes there is... but I'm not sure if it would be noticeable in the block... on a warn gear.
The top picture is the gear out of my "Blown" engine. You can see that the surface is smooth. (typical plastic) BUT... you can also see that the gear was in perfect shape. Yes, it's a known wear item that can fail... but it only fails when you have overheated the engine a few times. Basically, when you overheat the engine, the bushing that the pump drive shaft rides in, gets tight. When it gets tight, it puts pressure on the plastic gear. In turn, it takes the teeth off.
The lower pic is the new gear. You can see that it's now a fiber filled resin.
The top picture is the gear out of my "Blown" engine. You can see that the surface is smooth. (typical plastic) BUT... you can also see that the gear was in perfect shape. Yes, it's a known wear item that can fail... but it only fails when you have overheated the engine a few times. Basically, when you overheat the engine, the bushing that the pump drive shaft rides in, gets tight. When it gets tight, it puts pressure on the plastic gear. In turn, it takes the teeth off.
The lower pic is the new gear. You can see that it's now a fiber filled resin.
Dr Honda
Well-Known Member
I don't know. In the engine... it's mounted into the crankshaft, and all you can see is the "Teeth". (if you are looing in with a bore scope) Since I haven't inspected my own engine that way... I don't know what you will see. But I suspect that even the new gear... with a little time, and coated in oil... the teeth will polish, and look smooth. (but I don't know)
The only up side would be... you will know if the gear in there is good, or about ready to give up.
I will tell you this... in the few years I've been playing with the Merc's... only about 1/3 of the engine failures are actually from a bad drive gear. I'd say 1/3 are from a bad gear, 1/3 are from a busted connecting rod... and the last 1/3 are just time. (melted piston from low compression)
The only up side would be... you will know if the gear in there is good, or about ready to give up.
I will tell you this... in the few years I've been playing with the Merc's... only about 1/3 of the engine failures are actually from a bad drive gear. I'd say 1/3 are from a bad gear, 1/3 are from a busted connecting rod... and the last 1/3 are just time. (melted piston from low compression)
Well I'm hoping that the re builder replaced the gear, but as stated in other posts, he's either just sloppy but honest or sloppy because he's rushed and untrustworthy.
The boat threw a rod because the oil tank ran dry. In this situation, the original gear may not have any signs of worn teeth, correct?
The boat threw a rod because the oil tank ran dry. In this situation, the original gear may not have any signs of worn teeth, correct?
Dr Honda
Well-Known Member
Well................
I don't think you would have thrown a rod because of lack of oil. You would have melted a piston first. The rods are riding on roller bearings, and they can run dry MUCH longer than the aluminum piston. Rods get "Thrown" because of...
1) Lack of maintenance. If the engine isn't properly winterized... you will build rust on the bearings, and crank. Eventually the bearing fails, and breaks the rod.
2) a bolt will fail, and fall out. (That happened to mine) At that point, the cap will bed/break, and the crank mashes the rest of it out though the side of the block.
With that said... if the mechanic was un trustworthy... then if he looked at the gear, and thought it was OK... then there is a high probability that he re-used the old gear. (Look how nice mine was) But personally... it's stupid to not replace it, if you are that deep into the engine. I don't think the new gear was more than $15.
I don't think you would have thrown a rod because of lack of oil. You would have melted a piston first. The rods are riding on roller bearings, and they can run dry MUCH longer than the aluminum piston. Rods get "Thrown" because of...
1) Lack of maintenance. If the engine isn't properly winterized... you will build rust on the bearings, and crank. Eventually the bearing fails, and breaks the rod.
2) a bolt will fail, and fall out. (That happened to mine) At that point, the cap will bed/break, and the crank mashes the rest of it out though the side of the block.
With that said... if the mechanic was un trustworthy... then if he looked at the gear, and thought it was OK... then there is a high probability that he re-used the old gear. (Look how nice mine was) But personally... it's stupid to not replace it, if you are that deep into the engine. I don't think the new gear was more than $15.
The early 175 Sport Jets had the oil drive sensor. However, Merc deleted it when the oil drive gear was re-designed to with-stand the over revs often associated with the 2.5 Sport Jets. Sometimes the drive gear would skip causing the warning horn to "chirp"; instead of giving the operator a true warning. I saw numerous blown pwr hds because folks didn't understand the chirping was the oil pump stopping and starting.
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