what do i do now. my mechanic just teold me that what i thought was a valve tap is now a piston slap...wtf do i do now.
my "valve tap" has been diagnosed as a piston slap...
- Thread starter 7mLove
- Start date
Piston slap occurs when the clearances between the piston and cylinder walls is too large. This is either due to excessive wear, or incorrect machining on assembly. Basically what's happening is the piston is rocking back and forth on an axis perpendicular to the wrist pin.
In reality, the only thing you can do is yank the motor, and bore it out and move up to the next largest sized piston.
In reality, the only thing you can do is yank the motor, and bore it out and move up to the next largest sized piston.
Is this a fresh rebuild and if so what pistons are you running? Does the noise go away once the engine is warm! I'm not a fan of mechanics as most don't know what they are talking about.
gaboonviper85;1468021 said:
nope bone stock motor never rebilt 115,xxx miles on the thing and it doesnt go away when warm just gets a little quiter...i guess its time for a rebuild this summer i beams ct26-57 and low comprssion pistons...20psi anyone?
video wont do much. i have one you'd swear is rod knock from a year ago. Valves on exhaust side where out of spec quite a bit on one cylinder. The noise sounded exactly like others vids of rk, just right off idle instead of 2-3000rpms.
checked the valve clearances lately? I know mine are a bit louder when the motors cold given th 30* weather we've been having..
If its really piston slap, it *should* go away when fully warmed. Adjuster had issues with coated pistons at non coated piston clearances though...
checked the valve clearances lately? I know mine are a bit louder when the motors cold given th 30* weather we've been having..
If its really piston slap, it *should* go away when fully warmed. Adjuster had issues with coated pistons at non coated piston clearances though...
Well he said it gets better when warm, maybe his cyl walls are just much more worn than the base level for slap to occur.
Anywho, it needs work.
Anywho, it needs work.
I can't see a stock motor getting piston slap out the blue....maybe it happens but I just don't see it.
gaboonviper85;1468455 said:
+1, especially piston slap that doesn't go away when the car is warmed up. That went from perfectly fine really bad in a short amount of time.
gaboonviper85;1468021 said:
7mLove;1468347 said:
grimreaper;1468387 said:
gaboonviper85;1468455 said:
SideWinderGX;1468553 said:
I'm forced to agree. Piston slap is almost unheard of with stock pistons on the 7M.
Some of the conditions that piston slap occurs under are:
- Motor is rebuilt to incorrect specs.
- Motor has forged pistons with low silicon content which expand dramatically and need a "loose" bore.
- Pistons with very short skirts are used. (Stock 7M's do not meet this description)
- Motor has insanely high mileage (300,000 miles +)
For example, the Ford 5.4 Liter Triton V8's tend to get it due to Ford trying to squeeze every ounce of MPG out of that 330 cu in motor. The skirts on the pistons in those motors are almost non-existent. (Less mass to move = more performance/economy) My 4x4 Expedition has piston slap when cold started. Once it's warmed up, the motor is 100% silent. It's only after it sits overnight that it will tap away for 2/3 minutes before it settles down.
It sounds to me like you've either got a valve clearance issue or some other rotating assembly is going bad.
Please read this thread:
http://www.supramania.com/forums/showthread.php?t=20486
It will tell you everything you need to know to truly diagnose the issue.
If your mechanic didn't follow the steps in that post, he's full of shit.
You can not diagnose engine noises by just standing by the car and listening to it... Anyone who tells you they can doesn't know what they don't know. You need two trained ears and a mechanics stethoscope to truly find it. Either that or tear it down and mic everything...
Great advice, I don't see any response topping that one, might as well say thanks and close the thread. (not sarcastic)
whitemike;1468730 said:
ill get a video if you want. and since i got the car its had a little ticking but has gotten worse ofver the past month. i have work till 830 tonight so ill have a video up tommorow afternoon
Supracentral;1468763 said:
It's ok, your job is done, let him do what he wants from here, the info is there. If he can't use it correctly, It's nobody's fault but his own, obviously.
7mLove: Did you read what he wrote at all? He clearly wrote, just listening to the problem CANNOT diagnose it. I can't put a stethoscope to my pc speakers, so you're going to have to find someone locally who knows what they're doing.
whitemike;1468765 said:
dude i read it all thats why i said ill get a video if you want...i already have a stehascope no need to give me shit.
i read it and tommorow after work im gonna ground out all the wires and figure out whats going on. i appreciate everyones help hopefully ill get this figured out
Supracentral;1468763 said:
Mike "Nightmare" Donohue
thats funny cause we share a last name...and my dad is mike hahaha
