Well 22 years after the engine was rebuilt now my 78 2.3 liter has a mild knock.It sounds like engine ping and its most noticeable under load not there at idle as far as I can tell.And after driving a few miles it goes nearly completely away.Its alittle louder than a ping but not as loud as a knock. One person says its a lifter another one said its a wrist pin,but I dont think that would go away (nearly) after warm up? Im tempted to get the cam and rockers and lifters changed but might be wasting my time/money?
Anyone have any advice on determining what its most likely to be? The oil pressure is good as ever. It has a gauge. One thing though it does idle real low lately after it gets hot.
toni when under a load it does sound like pinging that's when the fuel explodes instead of burning that causes pistons to rattle bad deal so you either retard ignition or up your octane and if you want to really up it go to propane then you can advance distributor to 30 degrees and that will up gas millage and you have a clean air car. Fred :)
I really want to think that,but I tried 91 octane and even some octane booster it didnt seem to help a lot.And its getting a little louder,but still goes nearly completely away.
Get a spray bottle of water and spray some down the carb while the engine is at a fast idle. You cant spray too much out of a spray bottle. Don't use the water hose please.
Might be an intake leak. Take a can of carb cleaner and spray it around the carb base and the intake gasket area while the car is idling. If you spray an area and the motor changes rpm or changes from normal then you have a leak at that point. Seems like a small leak will cause it to run lean and ping and as the engine warms up the expansion of the metal might be closing off the leak a little...causing it to go away (loose manifold bolt or bolt's). This is just a thought.
Thanks everyone I will let you know as soon as I get to try some of these suggestions.I had heard of spraying something like wd 40 around the carb base before to check for leaks. Im supposing the idea with the water spray is to raise the compression Im not a mechanic so Im just saying :) Normally I would be worried that might plug up something in the carberatur? Plus it seems to do it most under light acceleration,not so much at idle.
the water down the carb is to break up any carbon on the top of the pistons. there is a post called "poor mans decarbonizing" that explains this. carb cleaner works best for finding a vacuum leak.
if it is indeed a carbon related "ping", it will be a very fast rattle noise because all 4 cylinders are affected. if it is a cam lobe, rocker, lifter or wrist pin it will be more of a taptaptap.
ok how long should I continue the spraying ? I read one time somewhere they used walnut shells or something to break off carbon too. I guess they have machines or equipment to do it? It is more of a taptaptap though but my ears arent trained well to determine if its a double tap like a wristpin.It does seem fast though to make me think its in the valvetrain.
16 oz bottle of water should do it, like i wrote in that other post I use fords liquid carb tune-up and slowly put it in with a vacuum hose and let it soak overnight.
we have one of those walnut blasters but I've never used it. you blast it through the spark plug holes so it doesn't work that good. besides, have you ever changed the plugs in say a dohc 5.4 navigator? :cheesy_p:
I can imagine after watching my mechanic change the plugs in my 89 lincoln continental. I couldnt believe they make it so hard to do something like that. I can change the ones onmy Pinto though :)
Exhaust leak is another possibility
Quote from: tonij1960 on May 14, 2010, 08:00:26 PM
ok how long should I continue the spraying ? I read one time somewhere they used walnut shells or something to break off carbon too. I guess they have machines or equipment to do it? It is more of a taptaptap though but my ears arent trained well to determine if its a double tap like a wristpin.It does seem fast though to make me think its in the valvetrain.
With a spray bottle, there's no way you can put too much water down the carb. And there's nothing in water that will hurt the carb.