Lean Fuel Mixture: the Silent Killer

Maclin

Admiral
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May 27, 2007
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6,761
Re: Lean Fuel Mixture: the Silent Killer

Ill fated run where supplemental fuel leaned out while on Nitrous Oxide....
 

QC

Supreme Mariner
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Mar 22, 2005
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22,783
Re: Lean Fuel Mixture: the Silent Killer

I think Jason's on Nitrous Oxide . . . :eek:


Kidding, opportunity for a joke, that's all, running for cover :p :p :D
 

mkpj1

Petty Officer 2nd Class
Joined
Jul 11, 2006
Messages
108
Re: Lean Fuel Mixture: the Silent Killer

Am I missing something, I thought you replaced the heads last year then had a lifter go on you? In the period that you recognized the lifter going you found the motor ran with the valve open?? AM I correct?? Gee, maybe that had something to do with it? Only a matter of time, Blam!! Take it to a Machinist that can put his hands on it and diagnose it properly.

It's lean, it's water, let's not miss the forest despite the trees!

"A man's got to know his limitations." Dirty Harry.
 

JustJason

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Re: Lean Fuel Mixture: the Silent Killer

bondo... nope...
may or maynot be totally clean.. it all depends on the amount of water and the amount of time it's been running.
When 7 out of the 8 cylinders are all pretty much the same as far as carbon buildup goes you have to ask yourself "why is the 8th cyl CLEANER than the rest???"
And it's not running lean....
1.running lean will still add carbon... just not as much.
2. running a bit leaner will increase the combustion chamber temps... but that doesn't clean anything... it's an engine, not a self cleaning oven.
3. running even a bit leaner and you'll be burning a hole in the top of the piston, but not the top of the cylinder head....
4. hopefully you'll never get to 3, and move strait to 4 when your running too lean to a point that your preigniting and the engine running is all over the place or lean popping back through the intake.... in which case anybody would not run their motor.

detonation can be caused by preignition (they are NOT the same thing) but detonation can also occur for a dozen other reasons.

Injecting tiny amounts of water into a running engine can actually increase it's performance (as water artificially increases the octane of the fuel its running, and cools the combustion chamber)... injecting (or injesting) to much water, however, can and will strip the oil from cylinder walls, temper components etc....

answer on the other engine to follow soon!!! care to give it a shot bondo??? :)
 

Bondo

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Staff member
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Apr 17, 2002
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71,082
Re: Lean Fuel Mixture: the Silent Killer

care to give it a shot bondo???

Not Really,.........

I can't even Identify What the motor Is............
 

JustJason

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Re: Lean Fuel Mixture: the Silent Killer

subaru 2.5L naturally aspirated... not that it wholey matters
 

Robj

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Re: Lean Fuel Mixture: the Silent Killer

Sorry Captain, I am with Bond-o on this one. The carbon looks like is has been removed mechanically, by something in the cylinder. Where the piston has been impacted, there is no carbon. I do not think water ingress caused the failure.

Have a great day,

Rob.
 

JustJason

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Re: Lean Fuel Mixture: the Silent Killer

so here is what happened with the soobie motor.
I said that you had to look close to see it...
now look at the first pic i posted... on the outer wall of the left cylinder.
Can you see the white film that is on that cylinder that is not on the others?
You can even see where i swiped it with two of my fingers.
The film is powdered glucose...
What happened with this motor is head gasket failure. I was driving the car on the highway, doing about 65 or so in 4th gear when it happened....
Now before you say "duhh wasn't it overheating???" the answer to that one is no.
The night it happened, actually that whole week, the average temprature was 20 below (that's not the wind chill, that was the actual temperature) Up here in massachusettes we got a wicked cold spell about 6 or 7 years ago that was very polar like to say the least. The car would only come up to temp when i left it idleing in my garage for 1/2 hour or so, as soon as you started to drive it the temp gauge would shoot to cold. (as did my other car, and everybody elses that week!!)
So.... The head gasket failed and was pumping the cooling jacket full of air, that cylinder got red hot to the point that it was vaporizing whatever coolant was left in that side of the block, hence the powdered glucose. The cylinder eventually lost it's taper and whammo... the piston came to a dead stop, and the rod that was spinning at 3000RPM... did not.
 

John_S

Rear Admiral
Joined
Jun 21, 2004
Messages
4,269
Re: Lean Fuel Mixture: the Silent Killer

The google search I did yesterday, indicated lots of head gasket problems with that engine. :(

So, did you see any powdered glucose in Tony's pics? He is freshwater cooled, or since he boats in the LI sound, any salt residue from engulfing seawater from exhaust?
 

FreeBeeTony

Captain
Joined
May 15, 2002
Messages
3,991
Re: Lean Fuel Mixture: the Silent Killer

I'm on the south shore of Long Island.........the Great South Bay.........:)

Took the engine out today...........waiting for my long block from Rapido.........got a great deal on a Vortec long block..........!!!
 

John_S

Rear Admiral
Joined
Jun 21, 2004
Messages
4,269
Re: Lean Fuel Mixture: the Silent Killer

OK, wrong side of the island! :D Does that mean the salt content is higher or lower? ;)

Great to hear the long block is on its way.
 

FreeBeeTony

Captain
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May 15, 2002
Messages
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Re: Lean Fuel Mixture: the Silent Killer

Yeah............Raul is pretty easy to work with..........

Figure I should have the new engine installed in a week or so..........don't wanna rush it!

Think salt is the same on this side................:)

Check out my new thread on PM.........
 

Haut Medoc

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Jun 29, 2004
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Re: Lean Fuel Mixture: the Silent Killer


The south shore is saltier-
Especially around Fire Island!.......:rolleyes::eek:;)
 

FreeBeeTony

Captain
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Re: Lean Fuel Mixture: the Silent Killer

That's where I fish.................Fire Island Inlet...............or try to.....
 

kay

Cadet
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Jul 31, 2007
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10
Re: Lean Fuel Mixture: the Silent Killer

So what do i get for saying the head gasket blew?:D
 

JustJason

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Re: Lean Fuel Mixture: the Silent Killer

you get a gold star my friend...
 

bjcsc

Lieutenant Commander
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Jun 1, 2006
Messages
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Re: Lean Fuel Mixture: the Silent Killer

Tony: If I were you I would get a new intake manifold. I don't know who is right about your failure, but I know that when my similar failure occurred, it was (as I posted in your other thread) due to an intake leak tempering the valve. I also had no obvious signs of water intrusion. I dug around and found some pics of my damage. It sat open for about a week before I took these, hence the rust. None of it was there when it was opened up. Do they look familiar? CYA...

2214636Cylinders.JPG



2214637Head.JPG
 

JustJason

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Re: Lean Fuel Mixture: the Silent Killer

unless those parts sat on the beach with the water rushing over them for a week you definitely had water in that motor......
since it was all cylinders i'd bet it was a bad riser or manifold (exhaust)
 

alaska_av8r

Petty Officer 2nd Class
Joined
May 28, 2007
Messages
184
Re: Lean Fuel Mixture: the Silent Killer

water increasing octane? We inject water into turbine jet engines to increase pressure due to change in density....how does water increase octane? curious here....
 

JustJason

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Re: Lean Fuel Mixture: the Silent Killer

well... it decreases combustion chamber temps and it slows the fuel burn down
 
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