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My 2005 Insight has developed a noise, my mechanic thinks it's the manual transmission

11722 Views 217 Replies 16 Participants Last post by  FadedBlue
Last summer I thought my IMA battery was dying and bought a grid charger, but it turned out the problem was actually a broken ground strap, so I could have fixed the car for like $10, but spent quite a bit more with buying the grid charger.

Also to get my car to pass inspection last summer, I had to have the one of the motor mounts replaced. Perhaps the broken motor mount was the reason for the broken ground strap.

Anyway since I had the car inspected and the motor mount replaced, I have been noticing a noise during acceleration. Once I am at a steady speed I don't notice the noise. I thought the noise might have been related to the motor mount being replaced, like maybe one of the other motor mounts is shot and the motor is moving around during accleration. However I just took it to the shop to have the oil changed and asked them to check out the noise. The mechanic thinks it is the transmission. I was hoping it might be something cheaper, but thought I would ask the forum for an opinion. Do you think this might really be the transmission? Is this a common problem? Or do you think it might be something else?

If the transmission is going bad and making a noise during acceleration is that something that needs to be addressed soon? The reason why I ask that is a bunch of years ago, I had a 1995 Civic that was noisy in 5th gear, but I just ignored the noise in 5th gear for at least 100K miles, until I needed to get the clutch replaced. Anyway with that car, I bought a rebuilt transmission from a place in California, I think it was called Synchrotech transmissions. So is a noisy MT in an Insight something that is just a slightly annoying noise, but you can ignore it (like I did with my 1995 civic) or is this a sign that the transmission might fail at any moment and leave me stranded? Also if I were to replace the transmission, what would you recommend? A used transmission? A rebuilt transmission from say Synchrotech? Or rebuilt by a forum member?
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I do not think that it is a CV joint. The sound matches the RPM, not the wheel speed. And I question the transmission diagnosis for the same reason.

Start with the simple, cheap stuff (which will make your car sound nicer anyway) before replacing transmissions. The following are easy to check and do if you do them yourself, the first being, to me, the most obvious and the most challenging (because of rust.)
  • The amount of sound the car makes vs the road noise makes it sound like the donut gasket between the first and second catalytic converters is shot. I would start by verifying, then replacing that. The frequency of the note sounds like it is 1/3 of the ignition rate, which makes me wonder if another engine issue is contributing (see second and last bullets)
  • Do a valve adjustment - which is really easy - to see if this changes the idle smoothness and exhaust note.
  • Also verify that the air filter box is solidly connected to the engine. The rubber bushings may be shot.
  • Doesn't sound like loose catalytic converter covers, but check those too.
  • There are three engine mounts. Verify that all are in good shape. (Examine them visually, don't take a mechanic's word that they were done correctly.)
  • The engine harness is attached to the frame on the cross-bar that also holds the battery. This frequently breaks and may squeak or rattle when it hits that bar.
  • Verify that all spark plugs are tight, though if one is so loose you could hear it at all you would probably hear it a lot.
  • Is there a problem with a spark plug or ignition coil? Verify all are good and the gap is proper.
  • Do a compression test while you have the plugs out.
The fact that your car failed an inspection because of an engine mount suggests one of the above is quite possible, since the engine would have been shaking more. Replace the remaining motor mounts, so that whatever you fix doesn't get trashed again by a bad motor mount.

Exhaust pressures will be greatest when the engine is under load, which is pointing me to the exhaust donut gasket as the first item to check.
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So I looked at the air filter box. The bushings seem to be shot.
Yep, that will rattle audibly.
Is this where the engine harness might break off of the cross bar?
Yep, of the two circled, it's the one on the right that fails. If you wiggle the harness up and down and the bracket doesn't move, you're good (for the moment.) Mine squeaked when it failed.
Is this the donut gasket between the 2 cats? Part 13?
You say this is challenging? It looks like 2 bolts with springs holding that together. If you get the 2 bolts out, is there enough slack to replace the donut gasket?
Yep, that's it. The challenge is that the bolts rust on. I sprayed mine with PB Blaster every few hours for two or three days, then worked the bolts back and forth, tighten, loosen, tighten, loosen, not even turning the bolt, back and forth, until enough of the rust in the threads started to break up and the bolt started to turn ever so slightly, more tighten, loosen, tighten, loosen, always making sure never to exceed the bolt torque, until it starts finally loosening.

Or you can just snap them off and drill it out and install new bolts and new nuts like normal people do. I have nightmares recalling things I've had to drill out which did not go well, thus the days of PB Blaster spray and every so careful procedure to break up the rust.

I think the exhaust can drop enough to provide room to swap out the donut gasket.

If the donut gasket is not leaking, no sense messing with it. But it was shot on my car when it had 145K miles, and the car was a lot quieter after that.

Remember that if you don't replace the other engine mounts and they are bad, you'll risk wearing out the new bushings, gasket, etc from the shaking.

These might not fix the noise you have, but if it is like my car was when I got it, getting it in top shape is like peeling an onion. All the work you are doing is good and will help make it identify real issues rather than mask them.
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@FadedBlue That's a great photo of your valve adjustment in progress; there is another owner replacing her engine and this is something she should do before she puts the new engine in.

That's one less layer of the onion to peel. I remember feeling great when I did this to my car. It was a little thing, but having the engine run a little smoother was satisfying.

Oh yeah - another thing. The engine looks VERY clean. This is great!!!!
It's better to have the valve body clocked between the 10 and 3 o-clock positions
@Bull Dog is spot on for catching this and another reason is so that the valve does not protrude below the oil pan where something could catch it and damage or shear it.
Another reason to ensure you have a belly panel in place is because water splashed into the engine compartment when the pan is missing will reach the power steering torque sensor and can damage it temporarily or permanently. In my case, permanently. It appears that you cannot just grab a sensor from another power steering rack (unless you are very lucky) as it appears that the sensor is calibrated when attached to the rack. The sensor is two independent sensors that must report identical values or the power steering shuts off. I ended up replacing the whole rack when this happened.
Did you remove the big circuit board in the instrument cluster or unplug the connectors or disconnect the bulbs underneath? Inside the cluster I'm looking at, there are five wheat lamps in parallel that provide the backlight for the tachometer/temp, speedometer, fuel economy, and fuel/IMA gauges. If the connector inside that powers them were not seated properly, all would be out. Since only half are on, either half of them blew out, or the flexible PCB which provides the bulbs with power has a cut or tear in it that is preventing power from reaching the bulbs on the right. I cannot see how a tear would happen unless the cluster was disassembled more than it needed to be for this switch repair.

The only other thing I can think of is electrostatic discharge damage or a short in one of the switches or that a switch was assembled such that it is always pressed and raising the cluster brightness to its highest, with that being too much for the old wheat lamps and causing them to burn out. Can you use the switches to dim the instrument cluster lighting with the buttons?

I hope this is useful.
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