I have a 1990 F150 XLT Lariat 5spd with a 5.0L 302ci. It only has 62k original miles and I am now experiencing my first engine problems since I bought it 2 years ago. When at idle you can hear a fairly loud knocking, or it could even be like a clacking noise, you can hear the noise when at driving speeds as well but not as loud due to regular road noise. The noise is the loudest upon deacceleration, when I rev it up at idle and it is coming off the load it will be the loudest. Thinking it was the hydraulic lifters I replaced all of them and the push rods, that had no effect on the noise it was neither louder or quieter. I have had several mechanics listen to it and I have gotten answers from the main bearings to a wrist pin in a piston. I am not sure where the noise is coming from exactly but it sounds like it is coming from the bottom of the engine, almost near the tranny. Another odd thing about this problem is that I haven't lost any power, in fact I just took it up Parley's Canyon here in Utah last weekend and I was able to go 65-70mph in 5th and wasn't pushing it very hard at all. The noise is pretty loud and makes the truck sound kinda like a diesel, I am trying not to drive very much anymore because I am scared of blowing the engine up. Any help on this issue is deeply appreciated.

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1990 Ford F150 XLT Lariat

5spd
5.0L 302ci
K&N Filter Charger
Hedman Cat with MagnaFlow muffler
62,000 Original miles

 

Oh and one more thing, I know it is not related to this subject but, I want to put a picture of my truck on my signature. I have the picture saved on my hard drive can anyone help me on putting it on to my signature. I tried to copy and paste it on there from a word document and it didn't transport the picture. Help.

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1990 Ford F150 XLT Lariat

5spd
5.0L 302ci
K&N Filter Charger
Hedman Cat with MagnaFlow muffler
62,000 Original miles

 

Sorry one other thing, if I do end out replacing the enitire engine can I put a 5.8L 351 in fairly easily or what type of mods will I have to make. Will my tranny mate up to a 351?

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1990 Ford F150 XLT Lariat 4x4

5spd
5.0L 302ci
K&N Filter Charger
Hedman Cat with MagnaFlow muffler
62,000 Original miles

 

I had a knock like that once, in an 81 F150 with 300 I-6. Ignored it until I couldn't anymore...on the way home (easy driving) it put a rod through the bottom of the oil pan. So, either find a trusted shop/mechanic to do the repair ASAP or maybe troll the scrap yards and try to find a good used 302 like yours. Buy it and get it ready to swap and then drive your engine til it dies and then make the swap. I think a similar year 351 will bolt right in, to a standard or auto tranny. Harmonic balancers are different though, and maybe the front brackets for PS pump, alt., smog pump, etc.

 

Hi badhabit,

I agree, what you have there is a serious problem that can cause an immediate & catastrophic engine failure if it is not repaired right *now*, don't drive it another mile, not even to a shop, have it *towed*.

It sounds like a connected rod knocking, or it could possibly be a wrist pin (which is what connects the piston to the connecting rod, just in case you didn't know) problem, which can cause that wrist pin to fail/break, and then a piston to seize in the bore or even penetrate the sidewall of the engine block itself, ruining the entire engine except maybe the cylinder heads, if you're lucky.

Stop driving it *now*, and get it into the hands of a competent mechanic (if you don't feel up to properly diagnosing & repairing this yourself, that is) and get this fixed before you knock a hole in the block and have to scrap the motor altogether.

They'll need to drop the oil pan, and check each piston & *ALL* bearings, etc. to determine the actual culprit. Make sure that *ALL* bearings are replaced in addition to whatever else is going on, and it wouldn't hurt to check the oil pickup & clean it, and maybe throw in a new oil pump while the bottom end is opened up.

If you catch this in time, before the motor blows (and it will, trust us), you can ward off a complete engine failure. If the repair bill is going to be more than 50%-60% of the cost of a new short-block, then you should consider just dropping a new short-block in it, and use your existing cylinder heads after proper inspection.

We don't mean to alarm or scare you, but this does sound like a very serious problem, and one that can hopefully be fixed before a failure.

Good luck!

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Mike Troyer
Performance Products, Inc.
National Distributor of Superchips
(540) 862-9515
Email: mtroyer@compuserve.com
Performance Products F150Online Superchip ordering system: F150Online Superchip Ordering System
First National F-150 Online Rally Event Organizer

 

Thanks for the help guys, if anyone has anything else feel free to post.