1993 Honda Del Sol - odd drive train issue

honda
delsol

#1

I’ve got a 1993 Civic Del Sol (love it) - it has 130k on it and for the most part the automatic transmission works well, except on cold mornings.

Until it warms up it will not shift out of first gear. When it is misbehaving in this manner there is a siren like wining of gears that increases as you attempt to go faster.

While at speed, if you put the transmission into neutral the sound continues at the same level so it’s connected to the vehicle speed, not engine. Other than the differential, I’m not sure what is in the drive train that is ‘in front’ of the transmission.

Once the transmission has warmed up enough, it will make a chuncking sound not unlike synchronizers being forced to mesh on a standard transmission and once the ‘chunk’ noise occurs the transmission will shift normally. If I let the car warm up first (5 to 10 minutes), I will not encounter this issue.

Here is a link to the sound if you want to hear it.

I’ve checked fluid levels, the fluid was changed probably 30k ago if I recall correctly.

Any suggestion / tips appreciated!


#2

Who changed the fluid, and did they use Honda fluid?


#3

As far as I know they used Honda fluid. It was done by a mechanic I trusted.

The thing is this problem seems to be before the gearbox. If I put it into neutral, the car goes into neutral but whatever is making this sound, still continues.


#4

I’d go over all the vacuum lines and connections, could be a leak, or a bad diaphragm or connection.


#5

The noise you hear might be coming from the pump in the transmission.

The pump provides the hydraulic pressure within the transmission so the transmission shifts into the gears. What can happen is if the pumps seals become hard from heat they shrink when they get cold and leak. This then doesn’t allow the proper hydraulic pressure to be developed to allow the transmission to shift gears. Once the transmission heats up where the seals expand and the proper hydraulic pressure is produced the transmission shifts normally.

The reason you’re hearing noise when the transmission is shifted into neutral is, the engine is still running, and the engine is still turning the torque converter which turns the pump.

Tester


#6

Interesting concept but the noise remains consistent with the speed of the vehicle not the speed of the engine. Revving the engine in neutral doesn’t change the pitch of the noise.

I did put some seal conditioner in when this problem first started and that didn’t change anything (figured it couldn’t hurt)


#7

Oh an Texases, I have checked all visible lines and such and everything looks fine. Obviously there is still something I’m missing but right now the vehicle is used for commuting and the workaround of letting it warm up gets us by. My hope is to solve this before it gets worse - may have to resort to taking to a mechanic I trust.