Loss of power/knocking sound (1 Viewer)

[CrippleCrawler]

Hello everyone, I have a bit of a doozy.

So a few weeks ago, I started having an issue while driving down the highway.

The truck started gaining RPM, without gaining speed. So I pulled over, waited two or three minutes, started it back up and it drove fine.

This issue happened just about every time I would do 10-15 miles on the highway.

The fun issue though, started two weeks ago.

It developed a knocking sound, barely had any power, and didn’t want to shift into the next gear. I checked it all over, and from my ear, it sounded like the knocking was coming from the bell housing/flex plate area. Inspected the flex plate bolts, no issues seen there. Pulled codes, and had a code for transmission solenoid. Replaced the solenoid, and issue remains.

It doesn’t want to shift into the next gear up, unless I let off the gas a bit.

I took it to a transmission shop, and they heard the noise and didn’t even inspect it. Would I be wrong to assume it could be the trans?

Checked compression on all the cylinders, and while low (I’m also using a s*** harbor freight compression tester) all within 20 psi of each other. Range from 120-140.

All the injectors are firing evenly.

Any ideas?

I’m not convinced it’s not something in the transmission.

 

[Kernal]

What model/year 80 series are you driving?

 

[CrippleCrawler]

What model/year 80 series are you driving?

Sorry, forgot to include. 1996 1fz

 

[Kernal]

Miles on the transmission, any recent codes, ATF level good (checked with a fully warmed up engine/transmission, transmission in Park, idling on a level surface)?

Have you changed the ATF recently, what type fluid, add any additives to the ATF??

 

[CrippleCrawler]

Mileage should be 252,000. Unsure if it’s been replaced, but I’ve owned it for about a year.

ATF was replaced last weekend when I swapped the solenoids. Replaced with Valvoline ATF recommended for the cruiser.

This is going to sound weird.

But I have a stethoscope from my paramedic days. I put it all over the engine, front, sides, oil pan. Finished with the transmission pan and the bell housing.

Of everywhere that I put it, the sound was loudest and most distinct in the bell housing.

I could hear it all through the engine, but the most at the bell housing. I’m willing to bet it’s the flex plate/torque converter.

I also have that stuck in my head, so that could be why.

I’m going to take it to another transmission shop on Monday.

 

[Mark W]

So, you have problems with the tranny...

"The truck started gaining RPM, without gaining speed."
"didn’t want to shift into the next gear"
" it sounded like the knocking was coming from the bell housing/flex plate area"
"It doesn’t want to shift into the next gear up, unless I let off the gas a bit."
"had a code for transmission solenoid"

...and you wonder if it is the tranny???

I think it's the tranny.


Mark...

 

[CrippleCrawler]

So, you have problems with the tranny...

"The truck started gaining RPM, without gaining speed."
"didn’t want to shift into the next gear"
" it sounded like the knocking was coming from the bell housing/flex plate area"
"It doesn’t want to shift into the next gear up, unless I let off the gas a bit."
"had a code for transmission solenoid"

...and you wonder if it is the tranny???

I think it's the tranny.


Mark...

I know I know.

But when I took it to a trans shop, they said “it’s not the transmission, it’s the engine”

But literally everything points to the transmission.

I’m decent at motor work, but transmissions scare the s*** out of me for some reason. Plus, not having a lift or transmission jack.

 

[TheBussman]

cracked flex-plate is possible.

 

[mudgudgeon]

Drop the engine oil and check for sparkly bits

 

[baldilocks]

You could also drain the transmission to look for sparkly bits that could be coming from the torque converter.

 

[fjbj40]

Drain oil, inspect.

Also cut open oil filter and inspect.

Simple, cheap and effective at the process of elimination.