Stumped on this one guys.... 97 F150 V6 4.2L

Won't knock when the engine is cold but mid day or after its warmed up it a fair amount it starts to knock... When in gear stopped at a light or what not applying the brake drops the oil pressure as low as possible , engaging the light also. Opened up the filter from the last oil change and saw little to none brass shavings , nothing to be worried about.

Any advice would be much appreciated..

 

Test oil pressure with a direct reading gauge and get back to us. What type oil are you using and also the weight? Doesn't sound quick and easy.

 

i am interested in this. I may be getting an angine for cheap that has a knock. I always thought it was an oiling problem. but the one im talking about the guy said it was in one cylinder. so idk

 

well when its cold all your oil is in your oil pan and hasnt fully circulated to the top.. 2 things i would guess... either once it warms up and the oil gets to the top part of the motor, something is clogged and it isnt circulating correctly, or your oil pump went out and isnt circulating at all...

 

maybe too thin of oil and alot of miles. When the engine oil is hot it drops in oil pressure. Try running 20w-50 oil if it has alot of miles

 

i agree on 2050 but if someting is clogged, that would be worse

 

Has 120,000 KM . But haven't had time to test any pressure or anything yet , but will definiteley look into things since everything isn't so hetic anymore.

 

Have reliable sources from ford that claim heavier oil in the 4.2 will wipe out the valve train.

 

sorry to semi-hijack the thread but in response to Bill's post - I run 5/30 in my 4.2 and I know Ford specs 5/20 - is that going to cause me any grief like you said or is that only when you get up to the heaver 10, 15, 20 oils?