Help! Engine Vibration
- Thread starter 71demonz
- Start date
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66dartgt
Well-Known Member
Okay so the damper goes on snug - why does the damper wobble ?
Is it possible the crank snout is bent from the crank having been dropped (not by you but someone at the shop) ?
If you want to check that, you could do it without tearing it down. pull the damper off again and put a dial indicator on the crank snout, turn it and look for run out. Should be next to zero run out my guess if its in okay condition.
Other than that, and checking for torque converter balance weights or a counter balanced flex plate I have no clue and would imagine the internals need to be balanced. Sorry for the bad news !
Is it possible the crank snout is bent from the crank having been dropped (not by you but someone at the shop) ?
If you want to check that, you could do it without tearing it down. pull the damper off again and put a dial indicator on the crank snout, turn it and look for run out. Should be next to zero run out my guess if its in okay condition.
Other than that, and checking for torque converter balance weights or a counter balanced flex plate I have no clue and would imagine the internals need to be balanced. Sorry for the bad news !
greybeard360
Nash Racer
It puzzles me why the old damper started wobbling after it had run a while....
What is the repair sleeve they installed?
It looks like they resized the other rods but not the two used ones? (maybe they had already been resized)
I don't see anything about the pistons on there.... not even pressing them to the rods. Where did the pistons come from? Did they look exactly like the rest of them? Which holes are they installed in? Anything you can think of at all just spit it ut no matter how unimportant it may seem.
Don't fret so much over this, it will get figured out. You have to think of something about an engine vibration.... 4 cylinders do it to a point that most of them (V6's included) have added balance shafts to offset the vibration. It doesn't cure it, just offsets it so the person driving the car doesn't feel it as much. The vibration is still there... just dampended. Same reason there is a harmonic balancer on the front of the motor.... to dampen the harmonics a crankshaft sets up which causes twisting and vibrating. In other words.... all motors vibrate! Some just at an rpm you would never turn it up to or at a low enough rpm you don't feel it.
It is actually nothing that will do any harm to the motor, they are balanced to make the customer that buys a new car happy he has a nice smooth running car. Performance wise, a smoother running engine will make more HP.... if you want to measure HP by the 10th.
Ever ride a Harley?
Why do you think chix like them?
What is the repair sleeve they installed?
It looks like they resized the other rods but not the two used ones? (maybe they had already been resized)
I don't see anything about the pistons on there.... not even pressing them to the rods. Where did the pistons come from? Did they look exactly like the rest of them? Which holes are they installed in? Anything you can think of at all just spit it ut no matter how unimportant it may seem.
Don't fret so much over this, it will get figured out. You have to think of something about an engine vibration.... 4 cylinders do it to a point that most of them (V6's included) have added balance shafts to offset the vibration. It doesn't cure it, just offsets it so the person driving the car doesn't feel it as much. The vibration is still there... just dampended. Same reason there is a harmonic balancer on the front of the motor.... to dampen the harmonics a crankshaft sets up which causes twisting and vibrating. In other words.... all motors vibrate! Some just at an rpm you would never turn it up to or at a low enough rpm you don't feel it.
It is actually nothing that will do any harm to the motor, they are balanced to make the customer that buys a new car happy he has a nice smooth running car. Performance wise, a smoother running engine will make more HP.... if you want to measure HP by the 10th.
Ever ride a Harley?
Why do you think chix like them?
greybeard360
Nash Racer
I keep reading all of your post trying to figure this thing out. You say when you first put the old balancer on it ran smooth.... the engine, the balancer or both? How does the motor run when first started after sitting a bit? DOes it run smoother and then start vibrating? (forget the wobble for now, lets talk vibration).
Did they surface the block and heads?
Is it a new cam and lifters?
Does it have factory rocker arms on it?
I have a good reason for asking these seemingly unrelated questions.
daredevil
Well-Known Member
I would put the car on an engine anylyzer as an intermittent missfire can make a motor vibrate and appear to wobble as it runs slightly rough ,bad plug wire not seated in cap or on plug. check all the little stuff first before thinking it is bigger than it is.
greybeard360
Nash Racer
Sort of the direction I am heading here. I have had many customers lead me down the wrong path by a description that was a little different than the actual problem.... just terminology differences.
If they cut the heads and block, sunk a valve or two a little too far, that would cause a valve to leak and cause a missfire (valve hung open a bit), which is why the question about how it runs right after startup after sitting a while. The lifters will collapse after sitting and pump back up after startup.... sometimes a little on the slow side. If he didn't properly break in the cam (using the correct oil) or used the old cam and lifters and didnt get them back in the same place..... flat cam lobe. Another misfire that could almost be described as a vibration. A lot of people don't know there is a difference but that is they way they will describe it!
71demonz
Member
Thanks again for all the great info. Grey, the heads and block were not surfaced, it has stock rocker arms and pushrods. The cam is new stock and with new lifters. Which reminded me of a problem I had, and haven't thought about.
During my first highway test run after rebuild, with the motor warmed up it started severe banging noise. What was discovered on teardown was the #8 cylinder intake valve lifter would stick, whick caused the valve to stick open and was smacking against the top of the piston. It only occurred when the engine was warmed up. My machine shop said it was varnish due to aged fuel. The car had sat awhile so I flushed the lines, dipped and sealcoat the tank and fresh gas. When I went to remove the lifters from the #8, I found that I had to pry them out with a hook. They appeared to be oversized for the bore and did measure 0.005 larger that the others so I replaced them.
The #8 piston had only some slight grooving in the top from the valve, so it was smoothed out with a grinder. I had the valve and guides leak tested and inspected by my engine shop, they found no damage.
Based on this memory recall and your questions I see now a compounding effect of problems (this is my first rebuid), that will most likely only be cured by a teardown and rebuild.
I will have the car put on an analyzer to see if I'm missing. Thanks again for the analyization, greatly appreciated.
During my first highway test run after rebuild, with the motor warmed up it started severe banging noise. What was discovered on teardown was the #8 cylinder intake valve lifter would stick, whick caused the valve to stick open and was smacking against the top of the piston. It only occurred when the engine was warmed up. My machine shop said it was varnish due to aged fuel. The car had sat awhile so I flushed the lines, dipped and sealcoat the tank and fresh gas. When I went to remove the lifters from the #8, I found that I had to pry them out with a hook. They appeared to be oversized for the bore and did measure 0.005 larger that the others so I replaced them.
The #8 piston had only some slight grooving in the top from the valve, so it was smoothed out with a grinder. I had the valve and guides leak tested and inspected by my engine shop, they found no damage.
Based on this memory recall and your questions I see now a compounding effect of problems (this is my first rebuid), that will most likely only be cured by a teardown and rebuild.
I will have the car put on an analyzer to see if I'm missing. Thanks again for the analyization, greatly appreciated.
greybeard360
Nash Racer
Before you tear it down, do a compression test on #8 and see if it is real low. I bet the valve is bent. You may only have to eake the one head off.
71demonz
Member
I ddi compression test all cylinders recently and found no problems there. All were reading from 110-140 psi compression.
66dartgt
Well-Known Member
The compression tester was it a leak down type ? You can learn more from a leak down test than a regular straight compression test.
71demonz
Member
Just a straight compression tester. I think this was like most of my projects where I try to save a buck. Spending more to make it work than going with quality new parts, ie., used block, heads, crank, rods.
I have a spare 318. Think I'll start over, maybe with a stroker kit, and balance everthing this time.
I have a spare 318. Think I'll start over, maybe with a stroker kit, and balance everthing this time.
fishy68
Tyr Fryr's Inc.
I agree. I have 2 books written by Chrysler engineers that state this also. 1st book by Larry Shepard and 2nd book is by Jim Szilagyi.
The myth of an external balanced 318 is just that, a myth.
318's had lighter pistons and rods so there was enough crank weight to balance it internally even if it was a cast crank.
greybeard360
Nash Racer
Sorry .... you ain't getting off that easy! We want you to tear it down and give us a full report on what is wrong.:dontknow:
With 37 8X10 color glossy photos with circles and arrows and a paragraph on the back of each one explaining what each one is. :bootysha:
:worthles:
fishy68
Tyr Fryr's Inc.
It's possibly a missfire causing it. I've seen it happen. After it gets warm try pulling off the plug wires one at a time and see if a cylinder isn't hitting.
71demonz
Member
Don't worry it will get inspected. I'm just not going to throw anymore good money for bad.
Another thing I noticed driving it today is the vibration is worse when at low throttle, or no throttle vs. during full or partially-full throttle, ie., heavy load. Don't know what that means????
redfastback
Don't ask me... my garage is empty
i wish the reply you gave was the one i got. i got a sidestep to the answer imo. i wasn't aware of internal balanced 318's cause everyone out here throws them out and doesn't want to rebuild them at all. no one has done mods to one. i have installed 2 intake manifolds on 318's. that's it. no rebuilds, no teardowns, no strokers. thanks fishy, for the explanation of why they are internal balance. now i don't have to go to school.
greybeard360
Nash Racer
It means you have a dead miss at low speeds.... it is still there at higher speeds, it's just that the engine will smooth out a bit literally because it is producing more power at a higher rpm and it sort of covers it up.
You have to picture this..... the crankshaft isn't turning smoothly as it rotates. Each time a cylinder fires, the crank speeds up, as the next cylinder comes up on compression stroke it slows down a bit, then another one fires.... and so on. When the rpms come up and each cylinder produces more power, it overcomes the force needed to compress the mixture on the cylinder that is on the compression stroke making the action of the crank seem smoother.
Me? I would drive it while you are building another motor and just tell everyone it has a big cam..... 8)
66dartgt
Well-Known Member
Why not run a leak down test on it? If it proves you have a leaky valve on #8 then pull that head - fix it and move on. Cheaper than building a new motor if you are bucks down.
Good luck with it !
Good luck with it !
71demonz
Member
Thanks, I'll try a leak down test and let you all know.
TripleJackInGA
Master of None
Did this get resolved?
71demonz
Member
Yea,
Thanks for asking. I pulled and replaced the motor with the original 318 that came with the vehicle. I'm still waiting to tear down the bad motor to see if i can detect the problem.
Thanks for all you help
Steve
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