Knocking noise from the bottom of engine

CARGUY513

MEMBER
1999 FORD RANGER
4 CYL
2WD
AUTOMATIC
300,000 MILES

So there is a loud knocking noise seemingly coming from bottom of motor (I think) but it doesn't start knocking until it gets warmed up and then it seems like if I go faster it gets faster but of I stop it still knocks but if I put it in neutral it will stop and become silent but as soon as I put it in drive then it starts knocking again. The truck listed above has 350,000 miles, but had a motor put in so not sure exactly how many on the new engine (used engine). Thanks for any help fellas or lady's.

1 Reply

ASEMASTER6371

MECHANIC
52,797 POSTS

Good afternoon,

You could have an internal issue with the motor. I would start by checking the actual oil pressure to be sure there is sufficient pressure to the bearings.

https://www.2carpros.com/articles/engine-noises

Low pressure could cause this.

https://www.2carpros.com/articles/high-or-low-engine-oil-pressure

The other possibility is a cracked flywheel. It would only make a knocking noise under load which would be when it is in gear.

The transmission needs to be removed to gain access to the flywheel.

I attached a YouTube video for you of the removal.

https://www.youtube.com/watch?v=AyG4xmSWylE

https://www.2carpros.com/articles/transmission-replacement-removal-manual

Roy

Removal
1. Remove the transmission/transaxle.
2. Remove the clutch, if equipped.

imageOpen In New TabZoom/Print

3. Remove the flywheel or flexplate.
- Remove the bolts.
- Remove the flywheel or flex plate.

Installation

NOTE: Engine balancing is not required. Balance weights should not be installed on new flywheel.

NOTE: Special bolts are used for installation. Do not use standard bolts.

1. Inspect pilot bearing (manual transmission only). Install a new one as necessary.
2. Install engine rear plate, if removed.
3. Install the flywheel or flexplate and flywheel reinforcing plate on the crankshaft.

imageOpen In New TabZoom/Print

4. Tighten the bolts in a criss-cross pattern.
5. Install the clutch, if equipped.
6. Install the transmission/transaxle.

Images (Click to make bigger)