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engine problems... DYNO included.

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bartlomiej

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Discussion starter · #1 ·
This weekend I went to dyno day. On my first run I f'ed up my engine. I took it to 5200rpm, and then POP! something went wrong. car wouldnt start back up. the compression on the 4th cyl is now at 60psi
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I took off my head thinkin it may be a broken valve or a f'ed up piston. But i took it all apart last night and found nothing of the sort. Anyone know what the problem may be? I was having engine probs for a while now, and i couldnt get to the bottom of my backfiring at 5k rpm problem nor my turning right in neutral and car dying problem. the death of my motor was caused by these problems (i'm assuming), but i just cant get to the bottom of this predicament.

you can see where my engine "died" at 5200 rpm. my power was looking decent up till then.
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at first i thought it was a broken valve or f'ed up piston, but now i just don't know. Any ideas of what this may be? thanks!

bartek
 
#2 ·
Does the engine crank ok? you have pics of the exhaust ports?
 
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Discussion starter · #3 ·
i will take more pics tonight, the engine cranks good by hand, but initially (before the dismantling) it struggled really bad while cranking. Any other pics you guys need for a better assessment?
 
Discussion starter · #5 ·
the valve train looks perfect. no signs of broken/cracked/bent valves. #4 cyl is oily probably because we dropped some oil into that cylinder to see if when we retested the compression it would go up a bit (testing for piston ring failure).
 
Discussion starter · #7 ·
even though i tested for the broken piston ring, do you still think it may be a possibilty? how bout a spun rod bearing or something else? I need to exhaust all the possibilities. thanks for all the help so far.
 
#8 ·
Did you check the timing before you ripped the motor apart?
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Do you think its possible that you just skipped some teeth?
 
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Discussion starter · #9 ·
yes, we checked timing plenty of times. my compression on cyl #4 is 60!!!! when everything was in working order they were all at about 170, 160. i have no clue what the deal is.
 
Discussion starter · #10 ·
after i dynoed and backfired at 5200rpm, the car revved down all weird, and when i put it in neutral, it died, never to start again. we checked the maf, retimed the cams to 0,0, and she just wouldnt start. we ran a compression test and cylinder #4 was at 60
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#13 ·
acutally... that I think about it even more... you're right cuz when I had ZERO compression in a cylinder I was even still able to crank my engine over just fine! (ran like crap but it still ran!)
 
Discussion starter · #14 ·
yep, my car wont start. when cranking it REALLY STRUGGLES. and i get a very prominent gas smell. what could be wrong???
 
#15 ·
im just going off a basis of knowledge.. im not too familiar under the hood of my/our cars yet but it sounds like you could have more than one issue... the compression could be totally unrelated to why the car wont start... check your coil pack for ignition problems and you already ran a compression test on cyl #4 try removing the pison and check all the rings and replace the bearings in the process... even if thats not the issue you lengthened the life of the motor a bit but thats where id go with it. how do the plugs look? do you think you may have gone too far advanced with the timing and slapped a valve off the piston maybe? just trying to help out man...
 
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Discussion starter · #16 ·
im just going off a basis of knowledge.. im not too familiar under the hood of my/our cars yet but it sounds like you could have more than one issue... the compression could be totally unrelated to why the car wont start... check your coil pack for ignition problems and you already ran a compression test on cyl #4 try removing the pison and check all the rings and replace the bearings in the process... even if thats not the issue you lengthened the life of the motor a bit but thats where id go with it. how do the plugs look? do you think you may have gone too far advanced with the timing and slapped a valve off the piston maybe? just trying to help out man...
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I have tried multiple plug wires and coils, and the same results. I retimed the cams a bunch of times too. I am going to dismantle my bottom end in the next couple days to see if there is something wrong.
 
#17 ·
acutally... that I think about it even more... you're right cuz when I had ZERO compression in a cylinder I was even still able to crank my engine over just fine! (ran like crap but it still ran!)
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we where able to crank and run a motor with 4 holes in the block and only 2 cylinders working. i dont think the compression is the main issue, yes it needs to be addressed, but that will not cause the car to not run. I would look into a seized up fly wheel or starter. oh well good luck and keep us posted.
 
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#19 ·
im just going off a basis of knowledge.. im not too familiar under the hood of my/our cars yet but it sounds like you could have more than one issue... the compression could be totally unrelated to why the car wont start... check your coil pack for ignition problems and you already ran a compression test on cyl #4 try removing the pison and check all the rings and replace the bearings in the process... even if thats not the issue you lengthened the life of the motor a bit but thats where id go with it. how do the plugs look? do you think you may have gone too far advanced with the timing and slapped a valve off the piston maybe? just trying to help out man...
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isn't the Zetec a 'non-interference' engine so to speak? i.e. the pistons don't come close enough to the head to touch the valves? correct me if I'm wrong at all though...
 
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