what went wrong with this engine?(lots of pics)

[thelostartof]

http://thelostartof.net/omnidead_7185.JPG
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not volvo but i need more input on what killed it ...

engine always had a rattle that almost sounded like ping since it was put together under load/boost. car never saw over 12psi. ran on 6psi for 50% of its life. pistons are forged wisco(or something like that) engine had maybe 6k miles before it was installed, and then about 3k since it was put in. head came off a few times in the first 1k and it was fine. engine died on the drive from noral to AZ from what might of been overheating(stock guage is retarded) .... CR was 8:1 one would find it hard to believe it would knock with larger injectors, and a calibration on the ecu setup for the engine size and mods. car also had a 3" turbo back, FMIC, and ported head.

so yea engine guru's what does it look like caused this damage? overheating? detonation? all 4 cc's on the head look like #1 just not as bad as they all look like lots of litlte holes were starting to form

[thelostartof]

owner of the car will post more info about it once he gets done cleaning stuff up

[Alex Buchka]

The scorched and pitted head and pistons indicate to me that it's overheating caused by detonation.

[CAPT_BLOTTO]

eee

is that harry's?

[thelostartof]

Yes. The GLH is dead, once again. Fun while it lasted. Back to driving the slow mobile.


-Harry at mike's laptop.

[HRPufNStuf]

Was the valve impact a result of broken timing belt, broken valve spring or broken rod?
New head gasket used each time when head was removed in the first 1k?

edit..... actually the mark looks too far off center bore to be a valve impact????


owner of the car will post more info about it once he gets done cleaning stuff up

[Mesoam]

thats quite a bit of buildup/crap for 6k miles

[thelostartof]

Was the valve impact a result of broken timing belt, broken valve spring or broken rod?
New head gasket used each time when head was removed in the first 1k?

edit..... actually the mark looks too far off center bore to be a valve impact????

Engine is a Dodge SOHC 2.5L, non-interference engine. New cylinder head was used along with new headgasket both have has less than 3k on it.


After noticing the overhead problem on the way back to AZ from CA, the car was cool off and drove another 60 miles where I can get within 100miles radius of Mike's house. Following a Semi at 55mph, didn't get overheat.

[HRPufNStuf]

The mark in the piston crown certainly looks mechanical. Was there any foreign bodies in the combustion chamber.. broken off sparkplug, something fall in the intake manifold during one of the head replacements or original build? any residual metal swarf or residue in the exhaust tracts?
I saw some damage sort of like that when someone I know dropped a small washer by accident into his Jag V12 spark hole and thought it would just blow out the exhaust on startup. He said it made a pinging noise and actually blew some bits of metal back into the intake tract and the bits made it into other cylinders. There was even steel bits embedded into the aluminum head.

Is the ignition system in good shape on the Dodge?? Timing was set up properly?



Engine is a Dodge SOHC 2.5L, non-interference engine. New cylinder head was used along with new headgasket both have has less than 3k on it.


After noticing the overhead problem on the way back to AZ from CA, the car was cool off and drove another 60 miles where I can get within 100miles radius of Mike's house. Following a Semi at 55mph, didn't get overheat.

[JohnLane]

Cross-firing of plug wires for Detonation? That is ugly. Looks like it ingested something too.

[IceCold4x4]

bad tank of gas?

[tryingbe]

Timing was right, no foreign object, no idea on shape of ignition.

[Tabor]

Timing was right, no foreign object, no idea on shape of ignition.

http://thelostartof.net/omnidead_7185.JPG

You think this was done by something other than a foreign object?

[stealthfti]

The pics shown are helpful; more would be better. And a comp test before diassembly would have been nice.

But, from what pics are there:
....the indent in the piston was where the detonation wave impacted the most. Right at the 'seam' or 'shelf' of the head CC side: you melted the piston right there.

...possibly preignition, but most likely detonation.

...bigger injectors guarantee only more fuel injected. And too much fuel can lower the detonation threshhold.

A complete disassembly will allow for more exact analysis and examination of the piston(s) itself (themselves). Close exam of the ringlands is in order. For some reason, things got REAL HOT right there.
...which is why the musing of preignition or detonation as the primary culprit.

[preignition and detonation are not mutually exclusive: you can have detonation-induced preignition and you can have preignition-induced detonation.]

[which ever or which was first is not determinable by the account or pics given, but it is for sure that you got a healthy amount of whichever it was]

A close exam of the head, valve guides and valves is also in order.


Ugly for sure. But, in another way [an unhappy and unfortunate one], it is a rather picturesque example of what happens when the protective shield of the boundary layer cooling effect is ruptured repeatedly and consistently at one spot.

The law of the wall was violated; the piston and head...and you...paid the price.

So, those are nice pics. But I'm sorry that what happened happened: not the way to have a trip go; or to have the motor end up looking like inside.

TF

[Les, slight limp]

Not sure about the piston, only a look with a microscope would tell for sure, the head is detonation caused by unusual circumstances, you've got very rich fuel which is a normal american practise for controlling detonation, the extra fuel cools the combustion chamber and so lowers the detonation threshold, the problem with doing that is it lowers combustion speed, coupled with the high intake temperatures experienced in arizona and the design of the cylinder head with large squish areas means that the fuel in the squish area furthest from the plug has no chance of being lit by the spark plug and so detonates, my guess is if he'd lived somewhere cooler he'd have got away with it. Les.

[thelostartof]

the intake temps were prob about 40deg F .... it is pretty cold here. this time of year and on that drive back it was night and freezing cold out

and i'll try to get more pics of the head and engine today if i can.

because of the trans gearing the car spent a lot time over 3500rpm (prob 5+ hours)

[tryingbe]

More like 4000rpm.

[thelostartof]

You think this was done by something other than a foreign object?

if you are talking about this mark .. that is a valve relief that is cut into all of the pistons on that side for the intake and exhaust. the missing piston on the right of that is melt'd piston which could leave some crap in that cyl to do some damage. but yes all 4 of the cyl's had those holes in the head from what i am guessing as detonation in all 4 cyl? maybe it was sand that got sucked up through the crappy air filter and box

and no valves are bent

[Tabor]

thelostartof,

Good to know. I think JohnLane and I were both reading it as a non-factory dent, so to speak.

[JohnMc]

Yeah, I was looking at that thinking there's no way that was melted or dinged by detonation. The 'chewing' just above the relief looks like detonation damage, though. Maybe it just needed some more squish? Maybe retard the timing a little bit?

[thelostartof]

yea i forgot to get a few pics of the 'whole' picture as it has those marks on each side of each cyl and it has every since he got it they are part of the piston

and tell me what else i need to get pics of and i will try to

[frostburner]

man i just saw that car like 2 weeeknds ago too, yea those dodges will do it to you, i know lol.. im still up in the air debating whether to finish my turbo dodge or not.

[thelostartof]

dump the dodge get a volvo ... soon enough i will get harry to see that

volvo's seem to be a lot easier to make fast and still last


how's that 940 running?

[mfpmax]

Volvo won't help...he's just cursed.

[thelostartof]

well his daytona still runs, as does his saturn so

[frostburner]

dump the dodge get a volvo ... soon enough i will get harry to see that

volvo's seem to be a lot easier to make fast and still last


how's that 940 running?


yea im seriously debating doing that having a 2nd volvo way easier to work on n such and lasts way way way longer with no constant 24/7 maintenance lol.. but i would have to put the car back together and get heer running if i want to get rid of her eietrh taht or part taht car out as well and dump it liek the other dodges, so decisions decisions., but yea the 940 is running fine for now, little ruff when its ass cold in the morning but she just needs a tune up and alittel tlc from me one of thsee weekends

[mfpmax]

well his daytona still runs, as does his saturn so

Thats cause he doesn't mod them.

[thelostartof]

good point ... tho nothing wrong with mod'ing a car ... my n/a volvo is mod'd and runs good .. as does my turbo car ... both get 18mpg or so. sure its not 24-25 like his dodges got but they are both 5spds ... and his omni is only liek 2300 lb's .. so take a 240 volvo, turbo it and make 250whp, run 13's, and make sure you hve a 5spd in it and do a little weight reduction and get 24+mpg

[mfpmax]

No when he mods a car...it becomes cursed :lol:

[PetesDustyVolvo]

damn harry that sucks

good luck with whatever you do

[thelostartof]

No when he mods a car...it becomes cursed :lol:



you see this happens to only happen with dodges those as chris has the same problems with them

[YellowT5-r]

You've found it! The place where every lost 12mm socket hides for at least 30 minutes per job! They are magically transported into the combustion chambers of your motor while the rest of the world searches in vain them. The sockets are only returned to their owners after they have found an old 1/2 inch 12 point socket and thoroughly rounded the head off of whatever they were working on.

On the down side, the damage done to your poor motor while they're hidden there sucks heinously. :-(

[mfpmax]

you see this happens to only happen with dodges those as chris has the same problems with them

No i've been convinced he was cursed too :lol:

[benflynn]

detonation, errosion of the head, the spark plugs should have some salt and pepper look to them, when i broke a flame ring one day(boosting it while it was HOT) it had a little erosion where it broke

[stealthfti]

More like 4000rpm.

for 5 hours? That would go a ways in getting to the underlying cause of the problem.

From the pics, it looks like the sharp edges on both the piston crown and around the bathtub CC were NOT radiused to remove any potential glow spots.

The high steady RPMs could have contributed to the problem: from a coolant flow side of things....as in too rapid flow to actually absorb the heat; allowing hot spots and the resulting steam pockets to form.

I am not familiar with the internals of the motor in question; I don't know its coolant flow layout. But, on the redblock 8V heads, running steady Rs above 3000 does lead to higher running temps until or unless the flow through the head is improved. An example of that is to turn on the heater and open the water valve to let the coolant flow out of the head through a second path. The op temp drops back down to normal.

And it doesn't much matter how big the radiator is, or what temp rating the thermostat is...if you are going to be cruising along at 3500-4000 RPM. At one time I commuted for 2 hrs one way at 4100 RPM [AW55 equipped feeding a 3.91 rear]for 1.5 hrs each way. Even with a 6 cyl diesel radiator in there with a 82C T-stat, the op temp would climb above 3300 steady speed....until I opened the water valve. And whether it was summer or winter did not matter.

The high cruising RPM probably impaired the cooling of the head. leading to the hot spots above the piston. Add in the sharp edges on the head and on the piston crown, and you could start seeing some REALLY warm spots; which could have, and probably did, lead to the onset of detonation, and possibly preignition-induced detonation.

Finish the teardown and look things over real close.

Am curious as to what the squish clearance was. Because tight squish improves proximity cooling effect.

good luck with it.

TF

[tryingbe]

2.2/2.5 engines are reverse cooled. IE, cool coolant cools the block first then the head.

Drove Modesto, CA to Quartsite, AZ. 554miles, stop for gas, took less than 12 hours. Mostly 3.5 to 4k. 3.5k = 70mph.


By the way, injectors are batch-fired. Injector 1 and 2 are fired at the same time. Injector 3 and 4 are fired at the same time.

[stealthfti]

2.2/2.5 engines are reverse cooled. IE, cool coolant cools the block first then the head.
That's the regular way....block first, then head, then through the T-stat...

Drove Modesto, CA to Quartsite, AZ. 554miles, stop for gas, took less than 12 hours. Mostly 3.5 to 4k. 3.5k = 70mph.
...then you ran through Mojave? (although your precise route is not important; you did either run through the Sierra Nevadas, or you skirted around them on the southern end via the high desert through Mojave) Whichever way, you did pull some steady long grades. I used to run through that part of the world on a regular basis...the main roads as well as some of those less travelled.
[there were several stretches of 14 and 395 where I could roll along at 140 MPH for a half hour or so in my '68 Charger R/T 440 Magnum (at 4400 RPM, 3.23 posi)...at least one could do that kinda thing way back then.]


By the way, injectors are batch-fired. Injector 1 and 2 are fired at the same time. Injector 3 and 4 are fired at the same time.
...understood...Mopar has just about always done paired pulsing [2 pairs of 2 injs], or batch firing [all 4 at once]. I don't recall any of their EFIs using sequential...at least not in the '80s.

If you had been able to...via gearing...to run at Rs around 3000 for the trip, then I do think that you would not have run into the problems.

TF

[tryingbe]

Sorry Mike, once you driven a 2200lbs car with some power and tight suspension, everything else is just.... boat-like. *Love the go cart*


Well, here are the list of things I plan to do to prevent it happen EVER again.

New engine, I think the cam, rockers, and lifters are savlagable...
New radiator + new hoses
EGT, wideband, water temperature, oil pressure, volt meter, fuel pressure etc... aftermarket guage
Install a tranny with 3.5 FD instead of 3.85. Roughly 10% reducing in revs
Install bigger tires when the time comes
New knock sensor and wiring
Drive slower on highway
Decode the cal and see if it anything wrong
Send in injectors for flow test and cleaning
New adjustable fuel pressure regulator
Underbody plate to decrease drag

Anything I'm missing to prevent this from happening again? Other than selling the car.

[JohnMc]

Build the motor with tighter squish. That will 'snap' the fuel/air out of the edges of the CC where it is apparently lingering and pre-igniting. You could also look into retarding the ignition slightly. When ignition starts near the spark plug this starts a pressure wave in the CC that can cause the far corners of the chamber to preignite if it was close to auto-ignition already. Retarding the ignition lessens the peak pressure becuse less of the combustion is complete before TDC. And at TDC if you have nice squish the a/f around the edges will get snapped into the center area and result in a lot of swirl, which is good for a controlled burn.

Also, maybe some water wetter, lower temp thermostat, work on the HG to open up the coolant passages (often the are considerably smaller than the openings in the block).

[tryingbe]

Build the motor with tighter squish.


Not sure if I'm understanding what you mean by that.

[tryingbe]

Also, maybe some water wetter, lower temp thermostat, work on the HG to open up the coolant passages (often the are considerably smaller than the openings in the block).

I'm going to use this gasket below
http://turbosunleashed.com/shop/popup_image.php?pID=183

instead of this one
http://turbosunleashed.com/shop/popup_image.php?pID=213

And probably opening up the 4 cylinder coolant passage to going somewhere.
http://www.hardcars.com/headerman/dodge/boost.jpg

[thelostartof]

Not sure if I'm understanding what you mean by that.

you have a lot of reading to do then

[Tabor]

you have a lot of reading to do then

I am always looking for more reading. I know what squish is. I know what tight squish is. I can point to the squish area on a head. However, I don't know WHY tight squish is better or what the optimum squish is. I also couldn't explain to you what the optimum piston or combustion chamber is.

Anyway, do you have some reading to point me/us at?

[740ATL]

I am always looking for more reading. I know what squish is. I know what tight squish is. I can point to the squish area on a head. However, I don't know WHY tight squish is better or what the optimum squish is. I also couldn't explain to you what the optimum piston or combustion chamber is.

Anyway, do you have some reading to point me/us at?

For starters, go to the performance section, search, then type in stealthfti... read anything that comes up.

I'll try to dig a couple up... may take a minute.

ok... here's one... the "squish vs. swirl" thread http://forums.turbobricks.com/showthread.php?t=1549&highlight=squish+swirl

here's another http://forums.turbobricks.com/showthread.php?t=48895&highlight=squish+swirl

and another... http://forums.turbobricks.com/showthread.php?t=51402&highlight=squish+swirl

and another... http://forums.turbobricks.com/showthread.php?t=41698&highlight=squish+swirl

[JohnMc]

I'm sure the links above are better references, but here's the nickel tour:

Squish is when the top of the piston (the raised ring around the edge in the case of a dished piston) gets *very* close to those flat machined areas of the head that stick out over the piston. If the piston gets *really* close to the head at TDC, the air will SNAP out of that area and into the central combustion chamber (the raised area of the head). This creates a lot of swirl and turbulence. This helps promote a more controlled and complete combustion, and helps reduce detonation because the mixture is moving and not just hanging around in the corners.

So you need a precise measurement of where the top of the piston is at TDC. Then you add the thickness of the HG (compressed/installed thickness) to determine the distance from the piston to the head at TDC. You want it very close, but not too close. When a motor is revved up and warmed up, the metal stretches somewhat. The rod expands, and at TDC the momentum of the piston moving upwards can stretch it slightly as well. The figures I've heard you should aim for are a minimum of about .030 inches. Maybe slightly more. Anything less than that and the piston might actually touch the head occasionally (not good, obviously). As the spacing increases from there the 'squish' effect rapidly diminishes, and by about .060 or so it's pretty much completely gone.

A good squish will help make a motor more resistant to ping. Sometimes people put thicker head gaskets on in an attempt to quell pinging, but that can sometimes make it ping worse.

[klr142]

Another thing mentioned that you need to keep in mind when you build the next motor is giving all the sharp corners/edges a slight radius so they don't come to a point or straight edge where heat can hang out.

[benflynn]

a proper tune, you can't throw on a tned chip and say it is tunned for the set up, as an engine gets milage the VE changes, no way around it

coolant flow, the lt1 in the caddi cools the head first and then the block, the higher block temps helps w/millage, the cooler head allows gives more knock protection

[tryingbe]

a proper tune, you can't throw on a tned chip and say it is tunned for the set up, as an engine gets milage the VE changes, no way around it


I gave the spec of my car to the guy and along with $220 and had him socket and program the computer. I know it is not perfect but it still shouldn't knock at 6psi. Oh well, guess I'll be buying a chip burner very soon.

[benflynn]

i guess that is all you can do, is it map or amm or vaf or maf? a boost leak on a map system will give very high iat as the comp is out of its eff range w/all the lost boost, just a thought, just keep an eye on those plugs, this did not go down w/o some signs(alum flakes) on the plugs. what dose that thing flow like? what turbo? amybe the turbo is too small, probably high coolant temps caused the detonation tho

i am just thinking out loud

[thelostartof]

Map
turbo is a rebuilt 42/48 t3

[JohnMc]

MS it and add a wideband? Sure takes a lot of guesswork out of tuning to see exactly what is going on, and have the ability to easily change the spark and fuel at any point in the rpm/map range.

[thelostartof]

i've told him that a few times ... maybe now he will listen

[JohnMc]

The $220 for a chip would have gone about halfway to an MS'ed car. And now retunes would only involve plugging in a laptop.

[tryingbe]

I'm going to d-cal the car.

http://autos.groups.yahoo.com/group/D-Cal/

[benflynn]

as long as you can mod the maps a little...knocksense and some dyno time is your freind, i am impressed that you kept it to 6psi, i have less self controll, and make things worse w/an evc3, high button is the devil

[tryingbe]

Drove it for a month or so at 6psi. Then turned it up to 10psi.

At 10 psi, I can spin thru 2nd gear. (while pinging)

[JohnMc]

You might also try (no particular order):
1) Somender Singh's Groove Theory (sounds like a band?) - little grooves cut into those squish shelves on the head that help produce swirl and turbulence. (bad in the intake tract, great inside the chamber)
2) Water/alky injection in the intake under high boost
3) Better intercooler (although at 6 psi, IAT's shouldn't have been a huge factor)

But good squish should be the goal of a rebuild. Find the comrepssed/installed thickness of that HG you are going to use, and then do the math to determine the resulting proper deck height of the pistons at TDC, and deck the block accordingly (hopefully you'll need to reduce height, typically stock motors are built with some leeway in that direction to account for maufacturing tolerances). If necessary, think about getting a copper HG made - precise thickness that doesn't compress, and fairly cheap too (I paid $57 shipped for a .032 copper HG for my Volvo).

[tryingbe]

You might also try (no particular order):
1) Somender Singh's Groove Theory (sounds like a band?) - little grooves cut into those squish shelves on the head that help produce swirl and turbulence. (bad in the intake tract, great inside the chamber)
2) Water/alky injection in the intake under high boost
3) Better intercooler (although at 6 psi, IAT's shouldn't have been a huge factor)


1. I'm not much of machinist. I might smooth out the shape edges on the chamber head, but that would be as for as my skills go. Squishing sounds like it's way beyond my ability to machine and tune.

2. Didn't think 10psi is that high of boost.

3. Don't think the IC was the factor.
http://www.hardcars.com/thepriestmike/omni/omnialmost_3000.JPG
http://www.hardcars.com/thepriestmike/omni/omnialmost_3002.JPG
http://www.hardcars.com/thepriestmike/omni/omnialmost_2996.JPG

[thelostartof]

those grooves he is talking about we can cut @ my place with a hack saw so .. nothing fancy

[stealthfti]

Tight squish makes things easier to tune.

Cometic makes MLS HGs for the 2.2/2.5s. You can go thin enough to get into tight squish with one of them. That aspect of the discussion has been covered as well. Your stock HG is ~65 thou compressed. IF that is the case, then you haven't had any squish action up to now.

There are still a number of unknowns as to the whats and hows and whys of your motor failure. Finish up the forensic analysis before you finalize the new motor plans.

TF

[tryingbe]

There are still a number of unknowns as to the whats and hows and whys of your motor failure. Finish up the forensic analysis before you finalize the new motor plans.


You mean take the piston out of the bottom and and show the pictures of the spark plugs?

Regarding to Squishing, I had another head on this car *for less than 1/8 mile* before I put this head on. The head was cut at least three times, the main issue with head that was the timing belt tensioner couldn't keep the timing belt still and the timing belt jumpped.

I bought a new head and belt never jumped.

[stealthfti]

You mean take the piston out of the bottom and and show the pictures of the spark plugs?

yeah....and then some.

a complete block disassembly; an exam of each piston and bore; putting each spark plug under a 10-X magnifier so that you 'see' what the plugs look like; an exam of all four CCs of the head, to see if the prob was only at the one cylinder, of if things were beginning to go at any of the others.

A quickie analysis may not determine the real causes. Which could lead to a repeat of what happened. How thoroughly you decide to be in the analysis is yours to decide: your motor, your time, your money.

There ain't no such thing as a quick fix. Especially when you don't really really know what the problem actually was.

It is seldom a good idea to ASSume things.

...so the choice is yours to make and act upon.

good luck

TF

[thelostartof]

from what i've seen it looks like all cyls were starting to end up like this as all CC's on the head were starting to look like #1

[tryingbe]

It's getting late, this are the best pics I can get you for now.

http://home.pcmagic.net/amazinghl/spark1.jpg
http://home.pcmagic.net/amazinghl/spark2.jpg
http://home.pcmagic.net/amazinghl/spark3.jpg

[JohnMc]

1. I'm not much of machinist. I might smooth out the shape edges on the chamber head, but that would be as for as my skills go. Squishing sounds like it's way beyond my ability to machine and tune.

2. Didn't think 10psi is that high of boost.

3. Don't think the IC was the factor.

1) Simple cuts, no special skill involved. Probably some slight risk in going too deep? I haven't done this to anything, but there was a huge thread here on it, and people actually found improvements. Which I found to be very interesting, even though it seems to create sharp edges that in theory might heat up and promote detonation, apparently the enhanced air movement under compression more than makes up for it.

As for squish, it just takes a couple of steps. First, trial assemble your motor. Put the crank in, and the pistons. Then get a deck height measurement on the pistons at TDC. You can do this with a straight edge and feeler gauges to a decent level of accuracy. Measure along the centerline of the motor, so you don't inadvertently measure the piston cocked over sideways slightly in the bore. Sometimes the deck heights will vary from one end to another on the engine, depending on how well the factory was working the day they made the block (there's no absolute guarantee the main bearing boring was perfectly paralell to the deck planing). But anyhow, that's your starting point. Whether you are above or below, you need to try to aim to .032 gap between the top of the piston and the bottom of the head. This will be a combination of the piston's deck height (either positive or negative, sometimes pistons will stick up from the block slightly) and the compressed thickness of the head gasket. Then either get the block decked (shaving metal off the top surface where the head mounts, done by a machine shop) or get a head gasket of the proper thickness (copper or MLS) if the standard one isn't going to be right. Sure, it's more work than just tossing parts together, but it makes the difference between a ping whore that won't ever be happy running hard and one that is very hard to ping.

2) Sure, 10psi isn't a lot of boost. But it was too much for your motor, as the detonation damage shows. If you put it together the same way the next time, it might do the same thing again.

3) It's an IC, all right. But not an incredibly huge one. If you don't have an IAT gauge it's hard to know what's really going on. Your turbo could be out of it's efficiency range and blowing hot, hot air into it. the IC might not be getting much airflow through it for some reason. But like I already said, that's not that likely to be the problem at 6 and 10 psi.

[klr142]

Which I found to be very interesting, even though it seems to create sharp edges that in theory might heat up and promote detonation, apparently the enhanced air movement under compression more than makes up for it.Not anymore than resurfacing the head creates edges at the bottom of the combustion chamber. But, you can bet that on my heads I'll be sure to round those edges, including the ones for the grooves. You won't see me with any sharp edges. If you just use a file, sure there're going to be some sharp edges, but I made sure that everything was somewhat smoothed/rounded on Seth's head, and plan to do the same.

Sadly, he never took any pictures... :grrr: