Hello,

Looking for a copy of TSB # 0421 Date: 02/09/2004
Component: Engine and Engine Cooling:Engine
Summary: Engine knock during initial cold start; the knock will cease after the engine is fully warmed up.
NHTSA Item Number: 10007363

Just purchased an 04 Grand Marquis from local Ford dealer. Engine knock can be heard for a few seconds after starting car after it has been parked for few hours (especially overnight). After a few seconds everything is normal. Car has about 40k. Changed from Motorcraft to Mobil1 filter and oil to fully synthetic 10w30 (live in Florida) and same noise present. Can it be a problem with the timing chain tensioner? Normal valve knock? Thank you for your help.

 

The TSB you posted is for thr Catalyctic Converter shield rattle while cold.I can't get it to post on the site.

 

Thanks. I though that TSB would describe something other than cat. converter. Any suggestions in regards to the cause of knock?

 

It is possible the oil pump check valve is leaking off and allowing the engine to run out of the filter back into the pan causing the pump to lose prime. The valve and spring can be replaced fairly simply. That may be a place to have them start looking.

 

Changed the Mobil1 oil filter to a new Motorcraft (820S) and the knock is now much quieter and stops faster than it did before. I am thinking that the sound is coming from the timing chain area and is because the timing chain tensioners are starving for oil at the first morning startup. May I venture to say that this slight knock is normal and needs no repair?

 

Almost all of our cruisers do the same thing. We have not had any failures due to this. Keep an eye, or ear, on it.