496HO Down on power
08-03-2022, 07:56 PM
#141
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Referring to reversion? This is a bone stock engine, aside from the ECM tune and ProCharger. As far as I know, this is the same cam that Merc built it with. It’s also the stock 4” exhaust, too. It would seem strange that only two cylinders would do this, though.
My nephew, who works for me, and has done his fair share of fiddling with engines, has suggested this could be a valve train issue, ie wiped lobe on the cam. Possibility? I know. This is starting to sound like a zebra hunt.
Thanks. Brad.
(937)545-8991
08-03-2022, 10:08 PM
#142
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Not saying you have that issue. Just letting people know that can keep plugs looking new (unfired ) also. Have seen it lots of times. Perfectly running engines, go to change plugs or look at’m to make sure all okay, and they look new even after a season huh. 
08-03-2022, 10:20 PM
#143
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I would think that, under ideal conditions, that would be the case for ALL spark plugs. That said…
The Merc 496 is well known for running rich. Hence the legendary “transom soot” they are so well known for. I am assuming that is what we are seeing on six of the eight plugs out of my engine. But TWO of them are squeaky clean. The question is WHY.
I seriously appreciate everyone that has contributed to the solving of this puzzle.
Thanks. Brad.
(937?545-8991
08-03-2022, 11:49 PM
#144
Charter Member # 55
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Griff,
Do they steam? 😁
This is something that “new”. When we did the sea trial, I can remember laying my hand on the risers and they were barely lukewarm, at most.
like I said, I’m not super worried about it. But I AM going to keep an eye on it and look into what might be going on.
Thanks. Brad.
(937)545-8991
Do they steam? 😁
This is something that “new”. When we did the sea trial, I can remember laying my hand on the risers and they were barely lukewarm, at most.
like I said, I’m not super worried about it. But I AM going to keep an eye on it and look into what might be going on.
Thanks. Brad.
(937)545-8991
Guys,
How reputable is Kunkle’s marine? Anybody have any dealings with them?
I just got off the phone with them, seeking an appt to meet up at the lake (Alum Creek in Central Oh) and run the boat on a scanner. He told me a scan is all but useless, and that I was likely looking at more of a mechanical issue, rather than an ignition or fuel delivery issue. He mentioned head gaskets. I’m not hitting the panic button, but his advice being directly counter to what I see as overwhelming consensus here on OSO has me wondering.
Thoughts?
How reputable is Kunkle’s marine? Anybody have any dealings with them?
I just got off the phone with them, seeking an appt to meet up at the lake (Alum Creek in Central Oh) and run the boat on a scanner. He told me a scan is all but useless, and that I was likely looking at more of a mechanical issue, rather than an ignition or fuel delivery issue. He mentioned head gaskets. I’m not hitting the panic button, but his advice being directly counter to what I see as overwhelming consensus here on OSO has me wondering.
Thoughts?
The exhaust manifold temp sensors, I believe, will set off an alarm and throw a code....and put the engine into guardian mode.
08-04-2022, 05:45 AM
#145
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Depending on lake water temp and ambient temps and humidity, I will get some steam from one side sometimes and both at cooler ambient temps.
That is really jumping the gun on his part. The first thing any decent marine tech is going do in your case is scan the engine.
The exhaust manifold temp sensors, I believe, will set off an alarm and throw a code....and put the engine into guardian mode.
That is really jumping the gun on his part. The first thing any decent marine tech is going do in your case is scan the engine.
The exhaust manifold temp sensors, I believe, will set off an alarm and throw a code....and put the engine into guardian mode.
Steam….. Noted.
Kunkel….. Agreed. When I said they had me “wondering”, it was about them, not about the OSO consensus. While he said a couple things I think I agree with, I’d be much more inclined to go with what most of you guys say rather than what one shop looking to boost sales is saying.
Temp sensors…. I don’t believe they getting near hot enough to worry about at this point. My main concern is if something is developing, like an impeller going sideways, or a blockage coagulating, that might leave us stranded 30mi up the South Fork at Cumberland one of these days.
Thanks. Brad.
(937)545-8991
Last edited by Brad Christy; 08-04-2022 at 05:49 AM.
08-04-2022, 06:44 AM
#146
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Guys,
Plugs out. Same as last findings. #4 and #7 showing no signs of combustion. Squeaky clean. MAYBE a hint of a smell of gas on these two. Kind of hard to be sure.
Since #5 was of interest previously, I took some closeups of it, as well. I’m not sure what was going on with it last time, but it looks pretty much identical to the others this time around, excepting #4 and #7, of course.
Thoughts?
Next, I plan on swapping the injectors. Ill swap them the same I did the coil packs; 4-6 and 7-5. I’ll take pictures of them as I do so. I’ll also figure out a way of getting some video of the spark tester in use, under load, on the water.
Repeat…. Anybody have any actual dealings with Kunkel’s?
My hips and shoulders are going to mount a protest before long….. 🙄
Thanks. Brad.
(937)545-8991
Plugs out. Same as last findings. #4 and #7 showing no signs of combustion. Squeaky clean. MAYBE a hint of a smell of gas on these two. Kind of hard to be sure.
Since #5 was of interest previously, I took some closeups of it, as well. I’m not sure what was going on with it last time, but it looks pretty much identical to the others this time around, excepting #4 and #7, of course.
Thoughts?
Next, I plan on swapping the injectors. Ill swap them the same I did the coil packs; 4-6 and 7-5. I’ll take pictures of them as I do so. I’ll also figure out a way of getting some video of the spark tester in use, under load, on the water.
Repeat…. Anybody have any actual dealings with Kunkel’s?
My hips and shoulders are going to mount a protest before long….. 🙄
Thanks. Brad.
(937)545-8991
08-04-2022, 06:47 AM
#147
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Thread Starter
08-04-2022, 08:07 AM
#148
To the best of my knowledge the 8.1 has hydraulic roller lifters. It's not impossible but highly unlikely the cam is getting wiped out, that's usually a flat tappet issue/problem. The tell is glitter in the oil, valve train noise and material in the oil filter .
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Knot 4 Me (08-04-2022)
08-04-2022, 08:13 AM
#149
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We are getting none of that, that I can tell.
For the record, I am not expecting to find valve train damage to be the problem. I am now thinking it's injector related. We'll be getting to validating or ruling that out soon enough.
I had a very informative phone conversation with Smitty this morning. He gave me some tests to perform before we start disassembling. Tip o' the hat....
Thanks. Brad.
(937)545-8991
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SB (08-04-2022)
08-04-2022, 07:45 PM
#150
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Guys,
OK.... So, I just did a bad thing.
You know what they say about every ten-minute job is just one broken bolt away from a three-day ordeal...?
In the process of getting the starboard side fuel rail back into place, I needed just a tiny bit more clearance behind the coolant reservoir. I gave it just a t-i-n-y little tug, heard a snap, and coolant started draining into the bilge. Farq.......
After an hour of trying to figure out how to get the bracket loose that seems to hold it in place, I got frustrated and yanked it the rest of the way out. Yup. Just as I thought. The snout that the coolant hose connects to cracked right at its base. It's toast. Now that it's out, though, I don't think it will be a huge ordeal getting a new one back in.
Looking around, they all seem to be special order or "out of stock". Just wondering if anybody has one lying around...? New. Used. Don't care. liquid tight is good enough for me. I'll pay.....
Thanks. Brad.
(937)545-8991
OK.... So, I just did a bad thing.
You know what they say about every ten-minute job is just one broken bolt away from a three-day ordeal...?
In the process of getting the starboard side fuel rail back into place, I needed just a tiny bit more clearance behind the coolant reservoir. I gave it just a t-i-n-y little tug, heard a snap, and coolant started draining into the bilge. Farq.......
After an hour of trying to figure out how to get the bracket loose that seems to hold it in place, I got frustrated and yanked it the rest of the way out. Yup. Just as I thought. The snout that the coolant hose connects to cracked right at its base. It's toast. Now that it's out, though, I don't think it will be a huge ordeal getting a new one back in.
Looking around, they all seem to be special order or "out of stock". Just wondering if anybody has one lying around...? New. Used. Don't care. liquid tight is good enough for me. I'll pay.....
Thanks. Brad.
(937)545-8991
