[updated:LAST EDITED ON 18-Dec-02 AT 10:46 PM (EST)]Allright I have an 86 F-150 302W AOD Extended cab long bed. my problem is that from time to time I hear a noise comming from the engine area. Some people think that it is from my main bearings. well with 174000 miles that can be right? My good friend thinks that well its an old truck and they make noises. my other friend who was a mechanic for 5 years said that it is a combination of rattle from exhaust, and a valve slap. Valve slap?. But he also thinks that the noise could be comming from my water pump.

O.K. know that all the info is out there I'll give you my impression. It seems to come from the front of the engine maybe around the front of the oil pan, with all the noise from the motor running and the belts maybe the water pump?

On idle it will knock not loud but first thing in the morning is when it knocks the most when warmed up it tends to knock less. Sometime it won't even knock at all!!!!!!

with a new motor costing 3200.00 including installation any help can and will be appericated.:-X12

Thanks guys,
Tony
E-mail Tony909(No Email Addresses In Posts!)

 

>valve slap. Valve slap?

Valves "tap" (actually it's the lifters) - pistons "slap".

>...with all the noise
>from the motor running and the belts maybe the water pump?

When the engine is cold, start it and watch the fan. After about 1 min, you'll hear & see it slow down as the fluid in the clutch thins out a little. Use something padded but solid like a tennis shoe sole to stop the fan by SLOWLY moving it into the BACK (not the front or tips) of the blades. When it's stopped, jam it, but don't interfere with the belts or pulleys. This will make it MUCH easier to hear the engine noises.

>On idle it will knock not loud but first thing in the
>morning is when it knocks the most when warmed up it tends
>to knock less.

Sounds like blocked oil passages or too thick oil. Do a compression test to find out the general condition of the engine.

>with a new motor costing 3200.00 including installation any
>help can and will be appericated.:-X12

I converted to a low-mileage EFI engine for $1300 doing all the labor myself. http://www.webphotos.com/list_photos.asp?mi=3&smi=1&a=13217 I have another engine now that's even nicer... http://www.webphotos.com/list_photos.asp?mi=3&smi=2&a=95012

 

[updated:LAST EDITED ON 19-Dec-02 AT 01:14 AM (EST)]Oil may be to thick? I use 20w50. change it less than 500 miles ago put in some slick 50 and an oil leak stopper. Before I changed the oil I put some ATF fluid in the engine to clean it out, when changed it was black put new 20w50 in as above and know I hear the knocking.

What should I Do? Put in some engine cleaner and change the oil again? with thinner oil?

Won't the thinner oil be more proned to louder knocking?

What about the maybe bad main bearings? Possiablity?

woulden't the bearings or the rods get louder upon accleration?

to thick of oil can cause and engine to knock?

SORRY I have a lot of questions

 

If it's more of a *tap tap tap* sound that is loudest at idle and lessens at higher speeds, it could be noisey hydraulic lifters as Steve pointed out. Lifters that don't pump up and hold oil pressure will cause the lifter to collapse when it rides up the lobe of the cam. The collapsed lifter causes excessive valve clearance at the rocker, making a *tapping* noise. Worse at idle when the oil pressure is lower or when the oil is cold.

Thick heavy oil will make the problem even worse when it's cold because it can't flow as quickly and freely into the lifters.

So is it correct that you didn't experience these noises until you started using flushes and additives? If so, it's possible that the combination of flushes and other additives has loosened up some otherwise harmless deposits in the engine and plugged the lifters.

I would start out by first changing the oil and filter, then refill with 10w40 oil if you want a heavier oil that will still flow well. Take all your flushes and additives and give them to someone you don't like. They are doing you more harm than good.

A leaking exhaust manifold will make a kind of *ticking* sound. Follow Steve's advice and try to more closely pinpoint the source of the sound.

To determine a rod knock, you can remove the spark plug wires one at a time. If the knock goes away when the plug wire is removed, that will most likely be the one with a loose rod.

 

O.K. Good info I drove on the freeway today and after i got back home it did not knock at all!!!!! unitl that is later so is that problem going to be the oil? just to thick?

When on the gas and than when I stop no knocking when when idle you can just make out the knock...

 

Sounds like it's just noisey lifters. No worrys, lots of old trucks sound that way. If it's worse when cold, then lighter oil will help at startup.