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

yes 496s are the same. There are temperature sensors in each manifold. If they get to hot, will send alarm off and limit rpm.

You can check for blockage in your intercooler (if it is in series in sea water system), also check for debris before the oil cooler(port side under exhaust). The oil cooler is were the debris used to get caught in my engine. Would cause high sea water pressure though.

Okay, i couldn’t wait. I found the 496 procharger install instructions here:
https://www.cpperformance.com/instru...charger496.pdf

On page 22, line 14, the map sensor with one way valve and vented line is correct. I attached photo of this line in the instructions.


https://cimg4.ibsrv.net/gimg/www.off...540dd9518d.png


https://cimg2.ibsrv.net/gimg/www.off...1388aea107.png

Underpsi,

When you say, "send off an alarm", is that an audible alarm, or a code? And how hot is that? And how much would it limit RPM? We just ran it this morning and, while the left side manifold and riser warmed up quicker and remained warmer after shutting down, it was still cool enough you could leave your hand on the riser almost indefinitely, and there was never any audible alarm. Engine temp stayed right at 160-165 throughout the run and after. I do not have an oil temp gage. I will investigate water routing.

For the record, performance was exactly the same as previously. There was some inkling of hope the plug wires were the issue (don't know how old they are) and new wires would solve it, but I wasn't holding my breath on that.

I have not had the chance to check the plugs yet. We put the boat away and I had to actually get some work done (those damned customers....)

Pretty sure the intercooler is not clogged. We are getting plenty of water output through the overboard fitting. Plus, the air input side, after an extended WOT run, was considerably warmer than the output side, and the aluminum elbow between the intercooler and the throttle body was cool to the touch.

We did see 2.5lbs of boost at ~4350 RPM, so I think we have ruled out a boost loss. Take off and planing is still really sluggish, even with just two people in the boat, so something is still amiss. We saw 46-4700 RPM with the 28P Bravo prop before we dropped to the 26P we are now running, and take-off was stronger.

I will report findings, if any, with the plugs this evening.

Thanks. Brad.
(937)545-8991

SB,

I was just sitting down to call ProCharger to get the skinny on that. Thanks for the clarification.

That pic shows my exact arrangement (my wires for the MAP were tidied up a bit better; I'd guess at original install). I have very similar pictures in the manual I have, but the pic cuts off just shy of actually showing the one-way valve. 😐

Page numbers are different, too. Obviously, the manual has evolved over the last twenty years. Same info, though, so.....

Seriously.... I'm all ears on the idea of running this thing on a scanner, I'm just reluctant to blow that kind of coin on one, just for a (hopefully) one-and-done. I know there's always the potential for future issues, but it's just a jagged little pill to swallow ATM. Anybody know of anybody within an acceptable distance with a scanner that would be up for a joyride? I'll cover all costs. Seriously....

Thanks. Brad.
(937)545-8991

Im really surprised those super duper, 1 off, no one else has them plug wires by pup didn't fix all your problems.............:D

F2,

Meeeee, toooo….! 😇

Not really. But there was a chance. I’ve been told by a couple people that leaking spark was the root of a problem that looked just like mine.

In all honesty, the new wires were just insurance against a false flag indicator. I’ll be pulling the plugs here in a couple hours, and we’ll see what we find. If anything.

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?

Thanks. Brad.
(947)545-8991

Well why not do a compression and leakdown like I mentioned earlier? Other than a bit of time it doesn't cost anything.

DrFeelgood,

I did a compression test. Results are posted above. Those numbers look good, although the starboard side was stronger than the port side. I don't know if that means anything or not. I have no means to do a leakdown test and I can't find anybody willing, able and ready to do one until the middle of September. I am scheduled to take the boat to Kunkle's the third weekend in September, and I'm sure that's one of the first things they'll do. In the meantime, I'm pursuing other possibilities.

Thanks. Brad.
(937)545-8991

So scanning a ill running engine is a waist of time and Mr Good-wrench suspects head gaskets after you have done a compression test that looks ok, Im not sure if Id let Kankles touch it

F2,

That's why I asked. I'm not too keen on ANYONE digging into an engine that doesn't need dug into. I'm not one to go hunting for zebras.

I'm still thinking this is a relatively simple fix that has so far eluded diagnosis. And I'm going to keep exploring possibilities that rule out hypotheses until I run out of them.

Riddle me this..... Which "goes" first? Compression numbers or leakdown?

Thanks. Brad.
(937)545-8991

Did we use the spark tester yet ? No ? Why are we still guessing/wondering about things ?

F2 - i luv you man :) :wink

btw: in the last two hrs i just got a seadoo boat with merc 240efi only tunning with 3 cyl’s, too all 6. Getting the fuel psi from over 50 to proper 35 took a bit longer though. 2 weeks+ for a freaking fuel module gasket. Uggghhh

Just putting a timeline out there. :)

SB,

Used the spark tester last night, but only at an idle. All eight were showing spark at idle. Not really sure how I’d use it under load. Don’t know if I want to run down the lake with the sundeck up.

Thanks. Brad.
(937)545-8991

Phone on record or helmet cam.

SB,

Noted.

Thanks. Brad.
(937)545-8991

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.

I’ve also noticed a consistent appearance of oil around the threads of #7 each time I’ve taken it out. Not a lot. And not inside the cylinder. Outside. Might have a leak. 🤨


https://cimg8.ibsrv.net/gimg/www.off...2876c9baf.jpeg
https://cimg1.ibsrv.net/gimg/www.off...51bf44d9c.jpeg
https://cimg2.ibsrv.net/gimg/www.off...01f69b371.jpeg
https://cimg3.ibsrv.net/gimg/www.off...a7fbb0ce9.jpeg
https://cimg4.ibsrv.net/gimg/www.off...e109bf1b0.jpeg
https://cimg5.ibsrv.net/gimg/www.off...3a322632a.jpeg
https://cimg6.ibsrv.net/gimg/www.off...dd0a90df7.jpeg
https://cimg7.ibsrv.net/gimg/www.off...237c71b62.jpeg
https://cimg1.ibsrv.net/gimg/www.off...1322d18a2.jpeg
https://cimg2.ibsrv.net/gimg/www.off...49ef8aa9e.jpeg

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

Water can clean’m too. I see this slot on various engines, usually ones with some cam and marginal exhaust for them.

Got it. Must have missed that earlier.

If you have a home air compress this should work

Harbor Freight Tools – Quality Tools at Discount Prices Since 1977

SB,

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

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. :)

SB,

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

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.

Griff,

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

When you pull the injectors, look at the little basket screen/filters in top of’m. If filled with debris, remove screens and clean, then reinstall.

SB,

Noted. Will do.

Thanks. Brad.
(937)545-8991

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 .

Carnuts,

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.... :ernaehrung004:

Thanks. Brad.
(937)545-8991

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

Boats do this to you............

Deep,

Yeah. I’m well aware.

B-ring
O-n
A-nother
T-housand

I've been boating awhile. And I used to help my dad wrench on our boat when I was a kid.

I did find some on eBay. Gonna try and find one locally, or hopefully someone here on OSO will have one.

Thanks. Brad.
(937)545-8991

Supposedly one in ny. Give’m a jingle
https://www.ebay.com/itm/261528022599

SB,

Yup. Found that. Probably gonna pull the trigger on it. I'm thinking about pulling all the injectors and sending them to Smitty, since the boat is down for a week anyway. Just take them out of the equation. I'm gonna call around some of the local shops first and see what I can find.

Thanks. Brad.
(937)545-8991

SB,

Local marine services shop ordered one from Merc. Can't complain about new OEM parts.

Injectors are coming out and headed to Smitty. Might as well just eliminate them as a possibility, rather than run empirical tests at this point. Won't cost me hardly any additional time. And it CAN'T hurt to have nice, freshly cleaned and flowed injectors, right?

Thanks. Brad.
(937)545-8991

Pretty much a no-brainer there. Good peace of mind.

Won’t hurt at all.

Oh, put’m in marked single bags (and tell dmitty you are doing so) since you have cyl firing issues.

SB,

Yup. Did that. Smitty and I discussed all of this before I even started swapping the injectors. I'm a small machine shop, so I have several sizes of "Write-On" ziplock bags on hand. I numbered them before they went into the boat (no Sharpies allowed on board), and they went into the bags one-by-one as they came out. He's going to flow them before cleaning them for the academics of it. They are going to be on his doorstep tomorrow afternoon.

Nothing like a little bit of serendipity. As it happens, apparently, I'd shredded the upper O-ring of one of the injectors I was swapping but hadn't noticed it until I pulled it back out along with the rest of them. That would have been a major raw fuel leak. That cracked coolant reservoir truly saved my ass. And, yes, I told Smitty about it so he wouldn't mistake it for having been a contributing factor leading to all of this. He also gave up his trade secret for installing them (Hint: it starts with "Vas" and ends in "eline":silenced:).

My hope is that this will get me my (presumably) two cylinders back, along with the lost RPM and planing HP in this injector refresh process. If Smitty can pinpoint a faulty injector or two in the process, that'll just be validation.

I'm not sure what to do next if this doesn't cure the issue, though. Probably bug you guys some more. :kiss:

Thanks. Brad.
(937)545-8991

Silicone gease works even better but harder to find