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Im not sure if this is in the correct forum, so if not, I will gladly move it.
Anyway, I have a 1986 Ford f150 XLT Lariat 4spd. It has the 300l
My truck has always done this but lately it has started to concern me.
You can rev it when warmed up, or when you are about ready to shift up, and you can hear a faint knocking. And i mean faint. It has never gotten louder, it has never even concerned me until lately for that matter because i generally tend to overthink things alot. It’s a constant tapping/knocking. I had my engine gone through when my radiator was replaced and was told it was in very good shape. The sound just kind happens when under a load, and it sounds relatively normal from what i have been told. So is this something to concern myself with?
The sound is very quiet over the engine, and you cannot hear it whatsoever when idling.
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UPDATE: Took it to a mechanic where i live and he said nothing seemed off color, and he womped on the throttle a good amount and said nothing seemed wrong. Just an old inline six! so that puts me at ease.
Hey my van has a similar noise as well. It’s got other problems but my buddy says that noise is pretty normal on these ford engines of this vintage. He said it was just valvetrain noise. I’m an over-thinker myself and tend to worry about such things. These motors have some hefty valvetrain components that could make some noise for sure! When I get worried, I keep my eyes on oil pressure. Low soft knocking originating from a part failure in the lower end or valvetrain may cause a noticeable change in oil pressure. I also pop a couple of spark plugs out and give them a looking at. I look for scorching evident of hot spots or a lean condition that could cause knocking. I put some crankcase flush in before my last oil change and that did quiet things up some. Topped it off with Lucas oil treatment and the sound is virtually unnoticeable. Hope you get some peace of mind from this! PS engines don’t get much more solid than the Ford 300 I6
Sounds like pre-ignition. Don’t believe the 86 had computer controls so timing limits can cause lower quality fuel to ignite before receiving spark when under heavy load. Wait till the fuel tank is low and put in premium fuel to see if you notice a difference. Most modern engines have computers that can compensate for lower octane fuel.
First off, i would like to thank both of you. @Astrosonic, yes I am getting peace of mind for sure.
Yes, i do believe pre ignition is a factor because i am almost certain my timing is advanced. A while back my manifolds were glowing due to retarded timing so just as a quick fix, I loosened the distributor and timed it by ear. I also messed with it the other night which caused a misfire going uphills so i set it back to where it was. and it seemed to fix it. I know its not proper but until i can get it a carb tuneup and an all over tuneup itll have to do! the Carb needs adjusting bad!! It has a wonky idle and its even still low with my timing the way it is. Idk how to adjust the carb so im afraid to haha. But my mechanic said with these older fords the noise is normal. And not necessarily bad at all.And you are right, 300’s last a long long time if you treat them well. And that’s all im trying to do. I love this truck so very much, and would hate to have a major hiccup happen at the moment.
I will most likely be getting some oil treatment for it soon, im also planning on getting dual exhaust installed, it’s already straight piped, so that should drown out the noises (Just being sarcastic there) Really am getting dual exhaust though :p
I own this motor as well in my ’94 F-150, indestructible to start, second these do make a lot of valvetrain noise when the hammer is dropped, not much can be done about it, If you look at a blueprint of these motors, except for the spark plug holes. these are practically small diesels that run on gas :dry:. btw I want to hear that, you better post a video! 😆
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