1997 F150 4x4 210,000 4.6L Windsor 5 Speed. Engine totally rebuilt 15k ago (besides for timing chains and tensioners). No codes thrown.

Hey all,

This morning when i started my truck, it made a knocking sound (almost like metal slapping) that seemed to be coming from the bottom end of the engine. At first I thought it was a spun bearing, but then the sound went away after a minute or 2. I have Google'd the problem, and have found a few diagnoses such as: oil draining back from the filter (or something like that), or an exhaust manifold leak that stops when the metal warms up and expands, or even the starter motor not being aligned right and not disengaging properly...

This is the first time this truck has ever done this. I changed the oil and filter about 1000 miles ago with 10w-30 oil and I believe a WIX filter. Also, this is the first time using the WIX filter

The weather this morning was around 51*F, so not too cold (to me).

Also, a few weeks ago when I changed my oil, I noticed milky white stuff only on the bottom of the oil cap, and in the feed neck. The rest of my oil looked like perfect used oil. After I noticed the milky stuff, about 2-3 times a week I would clean the stuff out of the neck and off of the cap. Just recently, there hasn't been as much milky fluid. My coolant level has not changed since I marked it during the oil change. A few buddies have said it might be condensation, but it's never been like this before.

I guess my question is, is this something that could put my truck out of service if left untreated? I'm assuming it's not a spun bearing because the noise goes away, but is there a possibility coolant could be leaking into the case but stay the same level in the reservoir?

Sorry about the essay I've written, but I've never had these things occur and I'm stumped.

If anyone could shed some light on the issues, I would much appreciate it.

Thanks

 

Get the 10w30 out and use a Motorcraft filter.
The correct oil is 5w20.
You need to understand the oil pressure needs to rise quickly but not to high after starting, for a prolonged time..
10W30 won't provide the shorter time on cold starts due to it's flow resistance.
The timing chains are oil hydraulic tensioned so won't tension the chains as quickly at cranking and immediately after start.
After cold start with the 10 weight part, pressure does come up, the oil viscosity is still higher until it heats. This in itself will then put 'excess' tension on the chains.
Use the correct oil and filter to address both ends of the situation as the factory has developed for these engine designs.
They are much different than a push rod design. .
Good luck.

 

Thanks for the reply.

I'm doing some other stuff to my truck tomorrow, so I'll try and get that done as well.

Should I be using 5w-20 all year around? I've always used 10w-30 or even 10w-40 before the rebuild without any problems before.

Also, any idea on why this is just starting now? it's been much colder around here before and there has never been any knocking on start up.

 

5W20 all year around.
The use of 10w30/40 is old time thinking.
This motor design needs fast oil flow at startup in cold temps.
Once you get the right oil and filter in place and still have noise it's something else.
What was done in the rebuild process?
If the piston clearance was increased for instance by honing, the noise could be piston rock in the bores until they expand from heating.
This was a common issue right from the factory through a few years.
Good luck.

 

For rebuild, new parts were:
Oil pump, piston rings, bearings, water pump, gaskets, throwout bearing, clutch, slave cylinder, spark plugs and wires.
Had the engine block cleaned, pistons spec'd (they were 1 thousandth off), cylinders honed, top decked, valve job, crank polished, flywheel polished...

That's all I can think of now.

 

My 98 has piston slap until it warms up.....been that way for over 60,000 miles. It expands when warm (takes a couple minutes)...then all is good. I have always used 5w-30w with no problems. Tried 5w-20 and the only difference was slight oil consumption. I also strongly suggest the Motocraft filter. My GT has that noise slightly also.

 

I'm hoping it's not piston slap... my understanding is that if it is in fact PS, then the problem will be there all the time during cold start ups.

 

It can last forever with piston slap, but not long if it is a main bearing.

 

No noise this morning upon start up, so that can rule out PS right?

And I guess I was wrong about what filter I used, it was a MicroGuard not WIX