My 94 Knocking, Coming From The Belhousing


Drg racr

15+ Year Member

Joined
Aug 31, 2007
Messages
81
Points
3,101
City
Southern Michigan
Vehicle Year
1994
Transmission
Automatic
My 94 4.0L is knocking, and it's coming from the belhousing area. I used a stethescope and it's loudest where the starter goes into the housing. What could this be? I've driven it like this for about 4 months now, so if it was a rod it would have blown by now. It's barely noticable when cold, but gets louder when warm. I can really hear it between 2500-3000rpm. It sparks-knocks like mad too all the time too. I think I'll pull the motor next week, but is there anything I should look at first? TC? Flexplate? :no2:
 
MAKG said:
I'd be concerned about the flexplate being loose or partially broken.
Click to expand...

X2 or a cracked friction plate or fltwheel if its a 5 speed. if you don't pull it apart you'' soon be walking.


Bob
 
Yup loose or cracked flexplate.
 
Well, I'm pulling the motor this week. I have a lot of the stuff loose, but I can't get to some of the belhousing bolts, or the TC bolts. Ideas?
 
For the bellhousing, use lots of extensions and a U-joint.

For the torque converter, rotate the crank with a ratchet on the harmonic balancer bolt.
 
Well, I got the motor out and apart. So far, the crank is scarred, but nothing else. THe pistons look good, rods good, heads fine, no cylinder ridge (after 132000 miles), so I can't figure out what took a chunk out of the thrust bearing.
I'm going to run the 410 Comp cam in it, as long as I have it apart. Should I do anything else, like head porting, larger injectors, headers, ect? This is mainly a winter truck, but it's in really good shape for a 94.
 
Well, I can't figure this out. I'm thinking of just buying a reman shortblock and hoping it will take care of it. I really don't know what to do yet.
 
If you haven't done yet, I'd replace the oil pump at 132,000.
 
A new oil pump was in the plans. I always replace the oil pump when I have a motor apart.
 
I've got the parts to put my 4.0L back together. Problem is, I don't feel that good about reinstalling it if I didn't find the problem. I can't find a darn thing wrong with it! There's got to be a cause as to the knock.
 
Oops, sorry. The flexplate looks fine, I can't see any cracks in it. Just a thought, could the torque conv. cause a knock? It was around the same time as the knock, that the TC lockup decided to quit working. It would lock up when cold, but when it warmed up, it would kick back out.
Also, another thought is, I noticed some vibration lately. Not a lot, but some. One guy looked at my bearings and said it looked like either too much endplay or a balance problem (harmonic balancer). That might explain the chunk taken out of my thrust bearing.
 
A cracked flexplate or unbalanced torque converter might also do something like that.

Is the flexplate ROUND?

Is there any evidence of a bent crank?
 
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