Engine/Transmission (1994 - 1998) Loud Heavy Knock

[1dslram]

I had just finished a slow roll of the throttle to WOT against a small car. After letting off the throttle and making a right turn the engine started knocking. A very loud and heavy sounding knock, I suspected something in the gears or the crank hitting the block. I coasted home the engine was running just fine on all cylinders. The knock seemed to come from the front drivers side, but was hard to locate. I turned the engine over backwards several revolutions and it turned as normal. Upon starting the engine the knock was gone. I removed the front cover and there is no signs of any chips, missing screws, etc. Anybody out there have any ideas of what caused the knock?

Bruce

 

[Forrest]

Could it be low on oil ... maybe starved under RPM & got air in the lines?

 

[1dslram]

The accleration was slow as compared to what is available from this truck. It was no where near breaking the rear tires loose, and the engine is full of oil.

Bruce

 

[DMC]

When is the lasttime you changed the fuel filter?



Could it be early signs of an injector or pump problem? A bad injector can cause a motor to sound pretty damn bad.



Could it be a bad valve, when were they adjusted?



Could it be a piston striking a valve?



I remember reading up on valve protrusion a while back, that is a means of determining if a valve is about to drop out of the keeper.



I would repeat the scenario, and see if it happens again.



Good Luck



Don

 

[GHansen]

Left front U-joint???

 

[ronco]

I vote to examine the flex plate.





Ronco

 

[SRehberg]

Engine mounts solid?

 

[Grey Wolf]

Hope you didn't spin a rod bearing

 

[1dslram]

Thanks guys the problem was the flexplate, I have an SFI approved heavy duty flexplate on order from Piers. It will be installed Tue. or Wed.

Thanks for the replys

Bruce

 

[RWood]

I had something similar happen and it ended up being two broken push rods, the knocking sound was the valves staying closed. You can here the knocking through the air filter.

 

[RWood]

never mind didn't read your last reply

 

[Grey Wolf]

Glad to hear it wasn't in the engine

 

[MHalloran]

Following this story guys, but can someone tell me what exactly is a "flexplate"? I don't consider myself a dummy (do most of my truck's needed work myself) but "flexplate" is new to me.

 

[Grey Wolf]

Basically the interface between the crank and torque converter... .

 

[MHalloran]

I guess thats why I'm unfamiliar with a flexplate. My truck has a 5-speed, (no torque convertor)not an automatic.