Help with mechanic

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California Dart

California Dart

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Nov 6, 2011
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Location
Oceanside, California
I had my 318 rebuilt and have posted on here about vibration problems. Come to find out it's the engine. They didnt balance it and from what I hear they are internally balanced and ths engine shop should have known that. They are giving me crap about fixing their mistake. What I need is any documention you guys can give me to show this motor should have been balanced when they built it. This way I can support my complaint. Whatever you can give me would be REAL helpfull to me as I paid $2500.00 to have this done and it still vibrates when accellerating in park.
 
What year engine? some were internally balanced and some externally balanced. Do you have a weighted converter?
 
This is a 1974 dodge dart. Before I take this back to the rebuilder I would like to know if there is any test that can be done to prove that the engine is the cause of the vibration. Just sitting in park, the motor vibrates upon acceleraton.
 
California Dart said:
My mechanic tells me the NEW harmonic balancer is not weighted. The trans is stock.
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have you tried an OLD/USED harmonic balancer to make sure its not a defect in the balancer? hate to see you pull an engine and have to fight with a shop over a bad balancer
 
Usaually on a stock rebuild you can get away without a reballance. It depends on how close it was originally and how much difference there is between the old pistons and the new ones. Should have been checked out though. Did you ask that the engine be ballanced? Around here that is an additional service and some basic rebuilder shops are not set up to do it. Might want to check the timing and carbutration just to make sure it's running correctly. What is your timing set at now? Most engines will run better with more inital timing. If you are using a larger cam it's not going to be as smooth as stock either.
 
Last time I had an engine rebuilt, the shop asked me if I wanted the assembly balanced. They had a checklist of questions/items that they wanted answered.

I used the same harmonic balancer that was on the engine.

Why did you buy a new one?
 
TO my knowledge, the 318 has not never been externally balanced even with a cast crank. I could be mistookened all up but I think that is correct.
 
StrokerScamp said:
TO my knowledge, the 318 has not never been externally balanced even with a cast crank. I could be mistookened all up but I think that is correct.
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It's correct, the 318 has always been Neutral / Internally Balanced. Like the 273 and most 340's (late 72 - 73 340's excluded). Even the newer 5.2 Magnum version was Neutral Balance
 
Does it vibrate on accelleration in Park....AND keep vibrating while you hold the RPM at around 4000?.....or just shake while it's accellerating up to that speed? Because then it could actually be a misfire or a low compression hole, if it does NOT shake while holding it at say, 4000 RPM. If it's a bad balance problem, it should be consistent and usually get worse with higher R's.
 
DFX 340 Duster said:
Last time I had an engine rebuilt, the shop asked me if I wanted the assembly balanced. They had a checklist of questions/items that they wanted answered.

I used the same harmonic balancer that was on the engine.

Why did you buy a new one?
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the old balancer looked shot with the rubber ring tore up.
 
.......Yes, its definately out, unless u have a misfire....find out what parts they changed, get the weights and compare to factory.......maybe the new balancer is crap......kim.......
 
If 1 cylinder has had a larger piston installed than the others or different mixture of con rods?.....I'm just thinking of what could make it so noticeably out of balance.
 
things that can make a engine viberate or shake

1) out of time
2) bad wires or plugs
3) stale or bad gas
4) wrong balancer (one for 360?)
5) bad carburator
6) shop frigged up
 
From my experience, balancing of internal balance motors is only done at customer request, or will at least be charged for and noted on the invoice if performed. Most rebuilders will not perform this on a basic rebuild for free. Good luck.

Grant
 
OneOfMany said:
From my experience, balancing of internal balance motors is only done at customer request, or will at least be charged for and noted on the invoice if performed. Most rebuilders will not perform this on a basic rebuild for free. Good luck.

Grant
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I only know two ways to do things, right or wrong. Since this shakes upon acceleration I assume it was the "professional" engine builders responsibility to know this. Who on this site would have built a 318 without balancing it to be sure?
 
318 as mentioned before are internally balanced.

when i built my 318 I had to buy a new crank and it came pre balanced and I installed it (didn't balance the engine as a whole rotating assembly) and mine runs just fine and as steady as can be.

regardless if its a matter of your have the wrong balancer,or bad plugs or wires or timing off or the shop did something wrong. the SHOP put it together,so it should be their responsibility to make it right!.

at the very least take the car to another reputable shop and have them go over everything and give you something in writing stating what they think the problem is. Then use that to back your claim up. worst comes to worst and the shop does not want to do anything about it. Just mention the court system and see if that puts a fire under their butts lol
 
also....a couple other things I could think of that it MIGHT be.....is maybe a bad/loose motor mount or transmission mount. loose is very possible being that all the work was just done maybe someone was groggy on a monday morning at the shop and forgot to tighten one of the mount bolts or something.
 
California Dart said:
I only know two ways to do things, right or wrong. Since this shakes upon acceleration I assume it was the "professional" engine builders responsibility to know this. Who on this site would have built a 318 without balancing it to be sure?
Click to expand...

Unfortunately many rebuilders. This is even more true if your rebuild did not require machining where critical measurements might have to be rechecked. If it was a simple bore/hone job, it is conceivable that they simply cleaned up the rods and slapped on the new pistons/rings.

I would have to question the amount that was paid by you, if it was a lot, then they probably should have included it.

Good luck.

Grant
 
would a weighted converter cause a noticable vibration in a car with an internally balanced 318? say, if someone rebuilt a 727 and used a 360 converter and flexplate, and bolted it to a 318, would you be able to feel a vibration while sitting still?
 
Here's the complete story.
Bought this and it had a flat cam and stock 904 trans and shook like crazy. When I took it to the rebuilder he knew this. I paid over $2,700.00 to have them pull, rebuild and replace this motor. When I got it it had the vibration. I had requested all new mounts and they installed them. I had the muffler system re-done with all rubber hangers. Had another mechanic double check the front balancer. The original rebuilder gave the car back to me stating the front balacer was wrong because he could not time it, he was wrong and set the timing 15* advanced "by ear". Come to find out the rebuilder had the wrong timing light. Just got it back from a second mechanic that removed all belts and did a thurough inspection and found nothing. I'm taking this back to the rebuilder in the morning. If he doesnt do anything I will have to have it disassembled by a high performance shop, inspected and have it rebuilt again, balanced correctly. At that point I'll have postive proof. I can only hope this rebuilder does the right thing and redo the motor.
 
also, odds of this being your problem are slim...but I figured i would mention it.

a couple of years ago I bought a jeep grand cherokee that had a transmission problem (no over drive) the jeep vibrated like crazy!.....I drove it like that for a few weeks.....and one day the trans burnt up on it ( I knew it was a matter of time with how bad it was vibrating and being that it had pre existing problems).....so I purchased another transmission and installed it. took it for a drive and it shifted correctly and everything with the trans was working correctly ...BUT it still vibrated like crazy!

at this point i was second guessing the reputable shop I purchased the transmission from and thought maybe i was looking at another junk trans.

well.....before we ripped the trans out we decided to give everything a once over and inspect everything to make sure it wasn't something else.


well we ended up finding that the water pump shafted was just SLIGHTLY warn. When we took the belt off and removed the tension we could feel a slight "wobble" in the shaft when we wiggled it. so we went ahead and put a new water pump on and TADA problem solved. all vibration went away and it ran like brand new as smooth as could be.

Im not talking about a slight vibration that it was doing.....this thing would shake rattle and roll and you would think that the balancer was getting ready to fall off or the transmission was going to blow apart from how bad the vibration was.

that was the first time that I had had a water pump do that....but now I know to never rule something as small as that out of the equation when dealing with vibrations.

just food for thought.
 
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