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thumping during acceleration


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rmsmith
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Nov 2, 2005, 11:09 PM

Post #1 of 9 (4485 views)
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1991 honda accord lx 2dr 191k mi. Very loud thumping noise coming from front right wheel area. Noise only occurs after about 15 min of driving. First noticed at about 50-60 mph sounds kind of like a sewing machine at that time with several thumps per sec, that was about 2 months ago so i chalked it up to worn cv axle and would replace eventually. but now from a stop the thumps are very violent(shaking the dash, steering wheel)occurring about once per second and gradually increase in speed and lower in noise as speed increases. Just replaced psgr cv axle. 2 days ago, Noise was occurring before that was replaced. And driver cv axle is 3 mo old. Took to dealer and they said the rt front tire belt was shifted. Took tire to tire shop to get replaced and noise still occurs. Dealer also says cv axles look fine. I asked about wheel bearings and they said there is no play in the wheel, and also it isn't a roar, it's a thump. Anything possible besides motor mounts?


Tom Greenleaf
Ultimate Carjunky / Moderator
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Nov 3, 2005, 2:05 AM

Post #2 of 9 (4478 views)
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You may need more but if this does this when still you have to consider the motor and trans mounts as the source. Does this car run well other than that? You have ruled out the CV joints and bearings and they wouldn't be able to cause this when still.

With a helper, watch the engine move when put it gear and brake applied and watch if it moves too much, with some throttle. Of course use all caution trying this. - T
_________________________________________
Long retired now


rmsmith
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Nov 3, 2005, 7:18 AM

Post #3 of 9 (4472 views)
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The car runs great other than that. No loss in power or anything. I noticed last night after an extensive test drive that it seems to stop if i turn to the left sharply. And gets worse if i turn to the right sharply.


rmsmith
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Nov 3, 2005, 9:54 AM

Post #4 of 9 (4465 views)
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In Reply To
You have ruled out the CV joints and bearings and they wouldn't be able to cause this when still.
Just wanted to make sure that there wasn't any confusion. There is no noise when still. Only when accelerating or maintaining speed. Could have possibly gotten a bad axle but doubt it would make the same exact thumping noise. Do you think so? Dealer mechanic ruled out bearings because he got no play in the wheel (trying to rock it back and forth) plus i told him i never heard the typical roaring of a wheel bearing. I'm afraid it's something in the transmission. That would explain why it only occurs after going down the road about 15 min. Give it time to warm up. If i let the car warm up in neutral for 15 min and then drive it still takes another 15 to make the noise.



Tom Greenleaf
Ultimate Carjunky / Moderator
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Nov 3, 2005, 10:00 AM

Post #5 of 9 (4463 views)
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My vote is for motor mounts. They should be totally rubber helped by metal that should NOT allow your engine/trans to move too far or fall out even if bad. When the rubber fails there can be wild vibrations felt thru the car. They have to be ruled out to proceed. There may be 3 or 4 mounts and possibly a stablilizer bar high on the engine and any could do this. They shouldn't all be bad - perhaps one or two. Exhaust parts the hit the body of the car can cause wierd noised and vibrations but NOT usually thru the steering wheel. While cold - shake the tailpipe - you should not be strong enough to make it clunk on anything.

Like I said - with a helper, put the car in gear forward and back with some (easy now!) throttle holding the brakes firmly. Watch the mounts - best from the side of the car in case it moves!! If you find one and don't have competent help it's a good job to send to your favorite shop. Lining up the mounting bolts can require four hands and prying the engine around to line it up exactly. Engine needs to be carefully supported with wood or something with a jack by its oil pan which takes finesse not to wreck it too! I work alone and take those to friends in the biz for the extra hands. Good luck with the diagnosis and fix, - T

Let us know what you find, - T
_________________________________________
Long retired now


rmsmith
Novice

Nov 3, 2005, 10:44 AM

Post #6 of 9 (4460 views)
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Thanks for your help. I've bought one motor mount, the parts store only had the left side one. I have two more, one in the front in the middle right behind the radiator, and another one in the back near the firewall underneath the intake manifold(that one is going to be lots of fun.) I had to order those and they'll be in tomorrow. Brother in law works on cars as a hobby, said he's done many motor mounts and will do mine on saturday. I'll post sat evening with the outcome.(crossing fingers)


photojunky
New User

Dec 6, 2005, 8:01 PM

Post #7 of 9 (4376 views)
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Have you any updates??

94 Accord, EX, Manual, 135000 miles.
I am having the same exact problem. In brief this is what happens

I hear a periodic thumping sound, seeming to originate from the right front wheel area,
After having driven 4-5 miles at highway speeds
When foot is on gas
All gears
Outside temperature is slightly cold (less than 60 deg F)
Wheel is straight or turned right

Based on dealer mechanic assesment, have replaced the following so far

Reman Shaft, Fr. Brake Disc, Fr. Pad Set, Fr. Bearing Assembly, R Fr Caliper, Core Return, L Fr Caliper, Core Return, Brake Dot Fluid, Brake Rotors, Master Cylinder Hasn't helped. From all these forums that I have been on, it has been boiled down to tire problem (solution: rotate them to see if tat takes care of it), bearings and engine mount. Figured I would ask the experts here also - any clues??


rmsmith
Novice

Dec 7, 2005, 1:21 AM

Post #8 of 9 (4368 views)
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I replaced the front motor mount (it's called a torque strut i believe) looks like a dog bone. and i also replaced the drivers side cv axle since it was leaking.. I have had no problems since. (been almost a month). hope this helps ya.


photojunky
New User

Dec 14, 2005, 7:35 PM

Post #9 of 9 (4302 views)
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thanks rmssmith


turns out it was indeed the left axle. took my car this time to an independent mechanic. he put it up on the lifts and showed me the
reason the sound was coming. there was quite a bit of play on the left axle, compared to none on the right-new one. his explanation as to why the sound started only after driving 4-5 miles was that it took some time for the grease in the boot to be less viscous - *who knows*. the motor mount was also cracked - but he said that there is no urgency to replace that. he changed the axle, along with the boot and we took it for a test drive - *NO SOUND*. Cost me $200




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