Okay guys, I know that this has been somewhat beaten to death but I'm going to ask anyway. I am getting what to me seems like an awful lot of rattle on cold start up. My truck is a 01 Scab 4.6 4x4 with automatic. I am running Valvoline 5W20 Durablend on 3-4K mile change intervals with a Motorcraft filter. The truck has 46K miles on it. Is this something I should be wary of? I have heard of piston slap issues but I thought that was just in the 5.4's or just the windsors. Mine is a Romeo. Comments, thoughts etc. are appreciated.

Thanks!

 

Since you don't know excatly what you are hearing at startup, it is difficult to settle on any advice.
The term rattle is usually associated with engine bearing noise before the oil pressure begins to rise. This should only be for a few to about ten seconds at most.
Piston slap is a change in piston skirt size versus temperature and will be heard for several minutes and gradually reduce as engine temp rises.
Any other situation that causes noise just has to be found by process of ellimination and test.
What do you have?
My 4.6 with 45k is absolutely quiet with motor craft 5w20 oil,820s filter, right from a cold start. The cold pressure is 75 psi.

 

So after checking the oil this morning I started the truck and it sounded like valve train noise to me. It lasts for about 3-5 seconds at most. Is that normal? I watched the 'automated dummy light' (oil pressure gauge) and it jumped up just as the truck fired. I have never had an overhead cam engine before so this is noise I am not used to. By the way I am running an FL820s filter. Some mornings or after it has set for a couple days it will really get bad. It really seems like oil drainback to me but I thought that was covered by the antidrainback filter. Any suggestions?

 

Sounds like lifter leak down. Happens in many engines if they set long enough or in very cold temperatures.
Engines used everyday should be quiet.
I have no answer to what or why, for you except lifter replacment.
You might try 1 qt of Lucas additive to see if it quiets them down, at least you know for sure.
The oil "indicator" on the dash is not a real gauge. The sender is a switch that closes at a low pressure and signals the dash and the PCM to operate the 'indicator' (a voltmeter) to about half scale using a resistance to set the deflection, and fool you about what pressure you really have. Notice it never moves after it is up to location.

I have a Autometer 100 psi oil pressure gage because of it, and run 75 psi cold start and 45 psi hot running with about 25 psi hot idle. 45,000 mile engine is totally quiet at start up on 5w20 MC oil.

 

I don't think you have CSK. I had a GMC, a Chevrolet, with CSK, so I buy a Ford to get away from that, and this bitch is slapping now! Makes me think I'm doing something wrong, but I'm no idiot, use to wrench for a living. Always change my oil 3-4 months, 3-4,000 miles and use OE filters. My Ford is a 2003 5.4L built in Romeo. Sometimes it knocked on start-up, but other times it would take 30-60 seconds before it started!? Looking at a Dodge now.

 

my truck did the same thing found out it was a bad belt tensioner your fan, alt, ac, etc all in one belt. tensioner cheap fix easy then go from there. worked for me and no more rattling on cold starts let me know if that was it. good luck.

 

Belts tensioner huh? That's an interesting idea. I will have to have a look at that. Any other ideas?

By the way Ed: What is CSK? Sorry haven't seen that acronym yet.

Thanks!

 

how do u check a belt tensioner? and also is there a fix for them or do u just buy a new one... if so how much roughly>?