Marvin,

How did you come up with 70cc???????? inquiring minds want to know.

Quick first-order approximation: 3800 cc engine displacement, divided by 6 cylinders, divided by 9 (10 to 1 compression ratio) yields a combustion chamber volume of 70 cc.

Definition:
Compression ratio = (cylinder displacement + combustion chamber volume) / (combustion chamber volume)
=>
Combustion chamber volume = cylinder displacement / (compression ratio - 1)

(See, guys, there's a real practical use for algebra after all.)


Edit: I just checked my 1998 Chrysler FSM, and the 3.8 V6 had an actual compression ratio of 9.6:1, which would yield a combustion chamber volume of 74 cc.

[This message has been edited by Marvin McInnis (edited 03-26-2010).]

Basically, you can't hydrolock an engine with fuel.

On any sort of engine with properly sized injectors, even with the injectors at 100% duty cycle, you'll never have enough fuel to fill the combustion chamber, even at low RPM.

And, I bet diesel is more viscous than gasoline anyway... so the flow rate would be less than with gas.

[This message has been edited by pmbrunelle (edited 03-26-2010).]

Marvin, you make no mention of deck height in your "algebra". You cannot figure out compression ratio with just a calculator. You can't determine chamber volume without cc'ng the actual chamber, adding your deck height measurement to that. I'm gonna go out an a limb and say you have not built an engine yourself.

quote Originally posted by daring4: Marvin, you make no mention of deck height in your "algebra". You cannot figure out compression ratio with just a calculator. You can't determine chamber volume without cc'ng the actual chamber, adding your deck height measurement to that. I'm gonna go out an a limb and say you have not built an engine yourself.

When we're talking about combustion chamber, we don't just mean the part in the head that one would cc.

In this discussion, we're talking about the entire combustion chamber, head gasket thickness, piston dish/dome, everything. The entire enclosed volume.

He didn't try and calculate the compression ratio. The displacement and the compression ratio were specified. With those two things, the combustion chamber volume can be calculated.

Given the context (hydrolocking discussion) it's obvious we're talking about the entire combustion chamber, not just the head's "combustion chamber" volume.

I'm going to go out on a limb and say you don't have any education beyond high school.

[This message has been edited by pmbrunelle (edited 03-26-2010).]

quote Originally posted by daring4: Marvin, you make no mention of deck height in your "algebra".

That's because it wasn't relevant.

quote You cannot figure out compression ratio with just a calculator..

I agree. But I wasn't trying to "figure out" compression ratio. I could read it directly from the 1998 Chrysler FSM. I was showing how, given cylinder displacement and compression ratio, that I had calculated the combustion chamber volume.

quote You can't determine chamber volume without cc'ng the actual chamber, adding your deck height measurement to that

You are wrong. By definition: Compression ratio = (cylinder displacement + combustion chamber volume) / (combustion chamber volume)
... and rearranging terms yields: Combustion chamber volume = cylinder displacement / (compression ratio - 1)
The (compression ratio - 1) part isn't immediately obvious.

As pmbrunelle correctly points out, combustion chamber volume is the total volume above the piston top at TDC.

quote I'm gonna go out an a limb and say you have not built an engine yourself.

You are wrong there, too. Over the years I have built several automobile, motorcycle, and aircraft engines with my own hands ... most recently the GM 3.1 V6 in my Fiero.

[This message has been edited by Marvin McInnis (edited 03-30-2010).]

Well my apologies Marvin, I incorrectly assumed you were oversimplifying the equation. My bad. That old assume thing happened again... And to Pm, yes any man can make a mistake even a college graduate.

Darin

[This message has been edited by daring4 (edited 03-26-2010).]

We're good. I just hate to see incorrect technical information posted on PFF go unchallenged, since someone, someday is possibly going to depend on it, with bad results.

I believe anything unburned in the combustion chamber will blow out of the exhaust valve when it opens, unless its too much to compress. Diesel fuel or pump gas through normally operating injectors will not hydro the engine, diesel may not light off but it will blow out the exhaust valve. I'm going with the dealer is trying to pull a fast one.

Darin

Sorry to the good dealer mechanics who were offended, that was meant as a rail at the 90% who are useless. For the record, this is not based on my experiences, but of many friends and relatives in at least 3 states and all makes. Seems up north they qualify mechanics, and hopefully it is being done here, but appears to be slow to catch on.

The point about detonation due to the raised compression was an interesting approach, but due to the low volatility of the diesel, I think it would tend to cool off the mix and retard the combustion, similar to water injection. On the other hand, it might be possible that the increased compression level would finally cause the diesel to ignite (with the gas providing the pressure an heat to start it) and that would cause much higher pressure levels as there is more energy to be released in diesel than gas, and that could rupture the head gasket.
Or there is just a problem with certain runs of those motors that are prone to head gasket failure and they are trying to hide it instead of doing an expensive recall.
I would still like to know how this first presented itself, and would also like to know if the owner took his own fuel sample and had it tested.

quote Originally posted by Marvin McInnis: This, and much of what you have posted elsewhere in this thread, tells me that you have no idea what you're talking about. Valve-to-piston clearance has nothing to do with it. Hydraulic lock will occur any time the volume of incompressible fluid in the cylinder, on a compression stroke, exceeds the volume of the combustion chamber at TDC. For a 2.8 V6, that would mean about 50 cc (~1.5 fluid ounces) of liquid in the cylinder on a single compression stroke. Substantially less liquid than that, and some of it will simply be pushed out of the cylinder on the next exhaust stroke. Is is still possible? Yes. Is it very likely? No. Analyzing a fuel sample taken from the tank would certainly establish whether diesel fuel contamination is even present or not. A simple blotting paper test, as is regularly used to test aviation gasoline for the presence of jet fuel, would be a sufficient first test.

i bought a blown 2001 N* engine just for the pistons a while back. the engine only had 16k miles on it( old person owned ). the number 7 piston hydrolocked because the head gasket was faulty, and it allowed the cylinder to completely fill with coolant. as a result, the number 7 connecting rod snapped and punched a hole in the side of the block. all 8 pistons were perfect, like new, as were the heads, cams, and all valves, but the block obviously was now useless. When i tore the engine apart, the number 7 cylinder was still full of coolant, and the cylinder sleeves had begun to rust.

i was kind of shocked to find out this happened on an engine with only 16k miles on it, but apparently failed head gaskets arent all that uncommon on N* engines from what i have found on google. some people believe that dexcool is responsible for eating up head gaskets, and other people say it is the fact that these old people never open up the engine and let the engine break in properly, being that the N* is a high performance engine that likes to rev a little bit. they constantly baby the throttle for the engine's entire life, and as a result, nothing ever seals properly?? anybody else want to chime in on this and confirm those opinions?

I could point out a lot of mistakes here... but I can see that most of you guys can't be wrong so why bother...

but it is ridicules that some of you can’t accept that diesel in a gas engine could cause hydro lock…

I have given several scenarios in which this could happen, and several others have spoken up with their own experiences.

The only point you boys have proven here is that you refuse listen.

Just so I am clear… what most of you all are saying here is that there is no way diesel in the fuel could cause hydro lock???

I used my 2.8 as a test mule yesterday and pulled the coil wire and cranked it for a while. Unburned fuel sprayed from injectors pumped through the engine just fine. I'm not gonna put diesel in my tank just to test this but that would be unburned fuel also, right? I then turned on the key, not started, and cycled the injectors for a few seconds. It cranked over just fine but was clearly flooded as it took a good 7 seconds to light off and run.

Will a gas engine run on diesel? My father's old early 70s dodge ran out of gas one day coming from the field and all he had was diesel. He put in enough to drive home about 10 miles. Granted he wasn't running straight diesel (mixed in the tank), but the truck ran for years afterwards.

J.

quote Originally posted by MadDanceSkillz: For this to happen there would have to be an enormous amount of unburned fuel. Problem is, it should go out the tail pipes, and even if it didn't, if there was THAT much unburned fuel the car wouldn't run

No, nobody is listening to the dealer... It was Diesel fuel hydrolock after the mechanic dumped 12 gallons of the stuff directly into the top of the air intake. It was the car owners fault because they gave the keys to an incompetent shop. Very standard and common thing to happen at many dealer repair shops.

In reality, the shop is trying to snow-ball you. there is No way for your fuel injectors to get enough of any fuel into your cylinders to cause hydro-lock unless there was a Major failure of the ECM that caused the injectors to open up full, AND the engine did not fire so the owner cranked and cranked and cranked and cranked.. Or the ECM was designed and programmed by Toyota. :-)

P.S.: a car CAN run on a gasoline Diesel fuel mix. if the car is a flex fuel car then even more of a chance of it running right on a non standard fuel mix as the ECM is capable to doing lots of on the fly adjustments. In fact one of the "old-tymer" fixes was to put a gallon of Diesel in a full tank to clean the system.

P.S. there are lots of other stories on the net of Chrysler minivans having this "hydrolock" problem. many dealers blaming it on rainwater. It's probably a faulty engine design. Leave it chrysler to screw up the one engine they made that was bullet-proof.

------------------




Best RV, Camper, and Trailer dealer in West Michigan. http://www.cliffstrailersales.com and he's a fiero owner too!

[This message has been edited by timgray (edited 03-29-2010).]

Ummm... what happen to the original poster who had the problem?

quote Originally posted by timgray: Leave it chrysler to screw up the one engine they made that was bullet-proof.

Agreed. We currently have ~220,000 miles on the original 3.3 V6 in our Dodge Caravan. (The Chrysler 3.8 V6 is just a stroked version of the 3.3 engine. For some reason, the 3.8 seems to have more reliability problems than the 3.3.)

[This message has been edited by Marvin McInnis (edited 03-29-2010).]

74 CC for a combustion chamber seems quite large to me for a 3.8 liter engine… is this an iron head engine??? Or DOHC???

The combustion chamber on my 3.1 TGP was only 28CC???

What gives???

quote Originally posted by Scoobysruvenge: This gives us a 10% increase in compression to 11:1

So what? This discussion isn't about compression ratio, it's about hydraulic lock.

quote 11:1 is well enough to cause detonation, in the engine…

Not at idle in an engine with a design CR of 10:1, it isn't.

quote A 20 lb injector delivers 20 lbs an hour.

So what? Your logic continues to be flawed.

While the instantaneous, maximum sustained flow rate of a "20 lb injector" may indeed be 20 lbs per hour, it delivers far less than that at virtually all operating conditions. The fuel dlelivered by modern fuel injectors is pulse-width modulated, and the duty cycle is usually design limited to about 80% maximum ... which would yield only 16 lbs per hour max flow in service. Applying a BSFC (Brake Specific Fuel Consumption) value of 0.40 lbs/hp-hr to the engine as a sanity check yields a power per cylinder at 16 lb/hr of 40 hp (16 / 0.4 => 40) ... or 240 hp from the entire engine at 16 lbs/hr/cylinder. How many engines do you know that produce 240 hp at startup or idle? Actual fuel delivery at idle is probably well less than 5% of that ... or about 2.0 lbs/hr/cyl. From actual experience, my Dodge Caravan (3.3 V6) gets about 25 mpg at a constant 60 mph, which means that the engine is developing about 36 hp total at that speed, and the fuel flow is only 2.4 lbs/hr/cyl.

And even then, a substantial amount of the unburned fuel from each compression stroke will be blown out of the cylinder on the exhaust stroke.

quote There are 16 [fluid] ounces in a pound ...

Not for fuel there aren't! That's only valid for substances with a density identical to that of water. The specific gravity (i.e. density) of gasoline is about 0.74 and diesel varies from about 0.82 to 0.95.


“It’s not what people don't know that hurts them, it's what they know that ain't true.” ~~ Will Rogers

[This message has been edited by Marvin McInnis (edited 04-01-2010).]

You see Marvin... there you go again not listening...

" Now I know the car was not running WOT, but you can see the injector could dump more than 7cc of fuel (1/4 of one ounce) in a few seconds potentially driving the compression up."

Do you actually read other peoples posts or do you just wait for your turn????

sk8rfiero: I apologize for my part in hijacking your thread. Please let us know how it turns out.

Scoobysruvenge: I'm done here. I'll just let my earlier posts speak for themselves. Rave on, dude.

[This message has been edited by Marvin McInnis (edited 03-31-2010).]

I wouldn't discount the possibility of injectors being stuck wide open, although the likelihood is low... Electronic parts are usually pretty reliable.

Happened to my 2.8L Fiero actually, the power transistor for injector bank 2-4-6 was shorted out, causing injectors 2-4-6 to continuously spray fuel. The moron who soldered the ECM probably didn't take proper ESD precautions, or likely overheated the transistor during soldering. (Oh wait, I assembled my own board :P)

But no, it didn't hydrolock, all it did was cause massive flooding. And this was with 30 lb/hr injectors (turbo project)! I dumped so much gas in the oil during my troubleshooting that the oil became as thin as water. I changed the oil afterwards.

The hydrolocking argument is horse crap!

Basically, the dealer is taking you for a ride.

I hope you didn't do anything like an engine flush. If so, destroy any evidence of that - engine flushes are bad and will void your warranty!

quote Originally posted by Scoobysruvenge: Let’s look at some injector math…. A 20 lb injector delivers 20 lbs an hour. 5 lbs in 15 minutes 2 ½ lbs in 7 ½ minutes 1 ¼ lbs in 3.250 minutes And so on until we reach .33 lbs in 1 minute. There are 16 ounces in a pound divide 16 by 3 and we get 5.33 ounces of fuel delivered at WOT in one minute roughly. Now I know the car was not running WOT, but you can see the injector could dump more than 7cc of fuel (1/4 of one ounce) in a few seconds potentially driving the compression up. The diesel gas mix may have fooled the CPU into putting more fuel into the system than it could burn or blow. I am not saying that the dealer is a rip off or not I am simply stating that the diesel could have caused the engine to hydro lock or petro lock… However rare the condition may or may not be… it is in my opinion indeed possible.

You are assuming the engine stays at a nice cold 70 degrees so the fuel would not flash off to a vapor. Problem is in a running engine, the piston and cylinder walls are very hot (hotter than the coolant) and even diesel fuel will flash off to a vapor fast at those temperatures. Plus the ECM has nothing to do with if a fuel burns, if the compression and heat is high enough it burns. a running car engine that has a diesel/gas mix will be hot enough to burn easily. in fact it's way above the flash point of any grade of diesel.

Diesel Fuel (1-D) 100 DegF
Diesel Fuel (2-D) 125 DegF
Diesel Fuel (4-D) 130 DegF

Those are the flash points in different for the 3 grades of diesel, so your opinion is completely and totally incorrect based on incorrect assumptions and incomplete data coupled with lack of knowledge of fuels. And this is ignoring the fact that when the gasoline fires off the exhaust gas is 800-1200 degrees F making the chance that any liquid fuel that has a low flashpoint to stick around even more impossible.

If you need more proof then please by all means go and do a very dangerous experiment. heat a pan to 300-400 degrees (low side for an engine piston after running for a bit ) and dump 7 cc's of diesel into it and see how long it stays there. Call us with the results after the paramedics treat you for facial and all over body burns.
------------------




Best RV, Camper, and Trailer dealer in West Michigan. http://www.cliffstrailersales.com and he's a fiero owner too!

[This message has been edited by timgray (edited 03-30-2010).]

Wow, all i can say is wow. what happened to the original poster ? did he in fact ever find out what parts were to be faulty? no need to flame each other about is it possible or not. there are alot of ways to get hydro lock in a engine.. first place to start is to find out what was in the cyllender, check the head gaskets, check the injectors. I find it hard to believe this is so hard to figure out.. I hydro'd a ford escord engine once. but it was a bad head that leaked coolant into a cyll. got into it one morning and hit the key and it made a groan and stopped. it bent the rod. Pulled the plug out and turned it over by hand to get some of it out.. then knew i had issues. but that is not here nor there. ford escorts had alot of head issues. to the original poster I say, find out what they say, have them show you a bad part, get pictures for us inquiring minds that wanna know. Then, and probably only then can we make a accurate analysis of what really caused it. No point in fighting over what came first the chicken or the egg, fact it it is hatched and we need proof of what happened. I think..

Peace everyone. now go outside and wax down your Fiero and go to that happy place where there is no speed limits and every engine red lines at 18,000 rpms. doesnt exist but it should..

Here is another case….
Sourced at:
http://answers.yahoo.com/qu...0091214053657AAh84U9
“It is vital to get as much as possible out. I assumed for a long time that relatively small amounts of diesel are not a big problem, and in the days of carburetors that was probably true. In a Toyota Prius forum a few years ago somebody mentioned a couple gallons of diesel being added to the tank (family member made a mistake) and the car was driven until it suddenly started acting up - no check engine light until symptoms appeared. The reason it was acting up was a connecting rod was bent. I wondered how that happened and then I realized... the diesel was being injected along with the gasoline but it was not vaporizing and burning, it was just collecting on the bottom of the manifold and being gradually sucked into the cylinders where it collected on top of the pistons like any other oil. Eventually the build-up hydro-locked the engine. And when I was thinking it was a fluke, another member said the same thing happened to his.

So yes, essentially all the diesel has to be removed. Siphoning would not be very effective - it is hard to get to the lowest point in the tank - but it is possible to redirect the output of the fuel pump and use the internal fuel pickup to empty the tank. I've used this method a few times and it works pretty well - it takes about 5 to 15 minutes to empty a tank. Adding another gallon of gas and pumping that out should be enough to remove the diesel to a level the engine can deal with it.”

Sk8rfiero I think I speak for all to say we would like to hear what became of it if you're OK with telling us. Cool if not also btw.

Many of you have stated here any liquid fuel would be discharged out of the exhaust valve during the combustion process…
By this thinking so would the water from a blown head gasket preventing hydro lock not causing it.

I don’t think Flashpoint is not the measurement you want…what you want is an Auto-Ignite.

Flashpoint is measured with a measured flame…

Auto-Ignite is at what temperature the fuel will self ignite with out a flame and diesel ignite some where around 410* F.

The cylinder wall temp will indeed be higher than the temp of the coolant which should be around 190* but 210* hotter???

Hey scooby, I have seen somewhere else a discussion on the autoignite temp of diesel being over 400 deg. I would think normal combustion would light that, or do you disagree? The exhaust manifold is hotter than that so the combustion process must be. I could see the head gasket scenario if a cylinder filled with coolant while parked, when started it has a very good chance of hydrolocking. When I have seen small head gasket leaks they are found as steam in the exhuast and, or bubbles in the radiator. I dont believe a normal running engine with a lil diesel in it will blow up, imho. Play ball! Is the original poster just hanging back watching us come up with ideas about the bullsh%% story?

I was trying to stay out of the argument, but yes spot temps on the piston and cylinder walls can be in excess of 400 degrees. Steel and cast iron are poor conductors of heat.
Water hydrolock in a car only occurs in a specific situation, head gasket leak or crack that allows a cylinder on the COMBUSTION stroke to fill with water while the engine is shut off. as was pointed out, a running engine is usually a steaming motor, or one that dies/runs rough due to the loss of one or more cylinders.
diesel is a whole nother story. as I said earlier, only an injector with a blown out bottom half could introduce enough fuel to cause a lock. if it is in the mix, you will have smoke, running rough, ses lights, or if the ratio of diesel to gas were high enough, the motor would not run at all.

That is the reason I asked in the past posts for the OP to supply the original failure scenario that caused him to bring it to the dealer. all the rest of this is pure speculation. some logical, some not, and I am not going into that.
Or I could state the obvious, if you bought a chrysler/dodge product, it was just a matter of time til something major blew up, but that is pure speculation on my part, as I do know one person who never had any problems with those makes.

What I think is that the introduction of diesel into a gasoline engine could in some way shape or form cause an engine to hydro-lock…

This could be from detonation blowing the head gasket, too much fuel on top of the cylinder from a confused CPU calling for more fuel, a piece of trash in the diesel hanging an injector open or one of several other scenarios…

I am in no way saying that this is... or is not the problem… my intention is only to say it is plausible.

Many of us can speculate on this subject and never get any where, but some here have posted with their own personal experiences on this subject. I and others have also posted some accounts from the web on this subject as well.

It seems this phenomenon doesn’t just lurk here at PFF.

Like Big Foot, the Lockness Monster, and a good woman this legend lives on.



The truth is out there.

I completely see the potential for diesel to hydrolock - I just dont see it as likely. the above Prius example is a good one, in that the diesel collected elsewhere. and, next - if diesel DID collect in the cyl, it did not get burnt, and it did not get pushed out the exhaust - now - we will have a flooded cyl, which will not fire. the car would run really bad. and still continue to collect more fuel.

now - say the diesel did ignite with the fuel/air burst. would it burn fast enough to NOT ignite the next fuel/air mix coming in? it is not properly atomized. it does not have enough air. having the diesel ignite sounds like a recipe for an intake fire. gotta remember the pressure needed to atomize diesel so it even is usable as a fuel for a combustion motor. I have doubts about "burning it off" as a likely answer to this.

Man, I wish sk8rfiero would give us an update.

[This message has been edited by katore8105 (edited 04-01-2010).]

He's prob in jail after shooting the service manager.