Engine knock

[cobra427mnsi]

Hi guys

I have an engine rattle which is louder at start up (especially if the engine hasn't been started for a week or more), as the engine warms up the rattle quiets down to just barely audible.

The engine is an FE 406.

Oil pressure is as follows: (electric sending unit)
COLD - idle 30 lbs / at speed 55lbs
HOT - idle 20lbs or less / at speed 30-35 lbs

I tested no1 piston connecting rod to crank bearing with plasti-guage. It was good.

I quess the next step would be to guage the main crank bearings.

If there is too much clearance, what is involved to correct the problem, short of yanking the engine and sending it to a machine shop

Paul

[Mr.Fixit]

Your oil pressure is way low. Smokey says 10 psi per 1000 rpm. I like to see 50 psi at temp with rpm. Electric gauges suck, get a decent mechanical to verify the pressure readings. Plastigauge is a waste of time. You'll need to measure with tools not a strip of wax. I'd guess that the knocking you hear is the lifters clattering until they fill with oil. Anyway, if it were my car, I'd pull the motor out before it destroys itself. To take it all apart and check everything will only cost you a set of gaskets, that's cheap piece of mind.

[niles]

Need more input info:
1. what weight oil are you using?
2. What kind of lifters do you have?
3. When you start it up after a couple of hours does it still raddle?
4. Suggest you stethascope the engine and determine if the rattle coming from the head area or from the pan rail area; that will provide loads of insight.

gn

[SuperHart]

Several things need checking. First, what weight oil are you using? Too light may result in lower oil pressure. Also, certain oil filters create too much back pressure resulting in low oil pressure in the engine. Also, are you running oil cooler line or a remote filter?

A knocking sound may be caused by an underpressurized or sticking hydraulic lifter OR perhaps a connecting rod wrist pin fitted too sloppily in its piston. A sloppy wrist pin will knock when cold and disappear when the motor is hot. At any rate it sounds like you have tome serious diagnostics to perform before the entire motor waves bye bye. Good Luck.

[SFfiredog]

Hello,
If your engine is indeed an orginal '62/'63 406 is has mechanical lifters. The 406 blocks DID NOT have the lifter galleys drilled to allow the use of a hydraulic cam. I would first adjust the valves and then install a mechanical oil pressure gauge as Mr. Fixit suggested. If the pressure is still low (your oil pressure is not terribly low but is lower than normal), change the oil and filter. Depending on the viscosity oil you are running you can go up one weight of oil (5W/30 to 10W/40 or 10W40 to 20W/50) and see what happens. If you do end up having to go through the engine
remember that pre-'65 FE blocks use a different crank thrust bearing than the '65 and later.
HTH
--Mike