2000 F150 4.2L 4r70w knocking

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    I have a 2000 f150 with only 107k miles on it and recently it started knocking going into overdrive. This became a much more noticeable issue while hauling a trailer. Since then it has become more common and now effects going from 1-2nd. From all my research it is a 4r70w automatic transmission and when I checked the fluid level the other day it was fine. What should my next steps be in resolving this issue? Also I am considering purchasing a salvage yard transmission and putting it in, are there other models of vehicles that use the same transmission, bell housing ect that I can be looking for?


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    Before you head out to the local junkyard looking for a compatible transmission, I would either performance and OBD diagnostic. The reason for my recommendation is that I don’t believe you have a transmission problem. It sounds to me as if it could be a sensor that has failed or is failing. I would start with the anti-knock filter since you say the transmission is knocking, it would seem to me to be best bet.

    You can tell that this is a mechanical problem rather than a transmission issue because it is located in a specific gear, rather than affecting the tranny as a whole. Indeed, that is one of the strongest telltales that the issue is mechanical. If it were a transmission problem or a problem within the transmission (honestly two different ideas, for example, if it is a transmission problem, the tranny then it would be failing in more than one gear. Further, the transmission would likely be exhibiting problems such as slipping in all gears; there might be problems with transmission electronics such as the MAP sensor failing to do its job, turning your pickup’s performance into poor capability, and more.) If it is a problem within the transmission then it would be exhibiting other problems. For example, if it were a problem with the input shaft then you would likely have a pickup with very loud noises coming from that area as the input shaft complained that it had a problem very pointedly.

    Believe me when I tell you it’s to your advantage if you take your pickup into a local full-service transmission shop with NIASE-certified technicians. They will quickly isolate the problem from which your pickup is suffering and report out on it. I would be willing to bet you a large cup of iced coffee you will find that the OBD report shows lots of 07XX errors which, by the way, are for various systems within the transmission. Let me know what happens, please.



    Thanks for the detailed report. I am not wanting to invest much into this truck, I am primarily getting it ready to sell. Is the OBD report the same diagnostic that you can run at auto zone for check engine lights? If so I would want to get it looked into myself before going into a shop. Also I did a quick search for “anti-knock filter” All I found was the knock sensor on the engine, is this what you are talking about or are you talking about the transmission fluid filter?

    I’m doing my best to learn, thanks for the help!

    Also I added some Lucas transmission fluid additive and it seemed to help some but hasn’t solved the issue entirely.



    Indeed, I was talking about the engine’s anti-knock sensor when I mentioned it — I was also thinking about different sensors that might also handle knocking, as well. It is the device that advances or retards the timing automatically as it senses the stresses on the engine. And, yes, it is the same report you get at AutoZone or another shop, though, their tests are nowhere near as detailed as the reports you will get from the dealer, for obvious reasons (they have the latest full diagnostic software from the factory that independents can’t usually get).

    The transmission fluid filter is an internal filter that keeps debris and metal shards from running around the tranny, possibly harming delicate, small parts and openings. It is usually located on the output side of the transmission fluid pan so that the nasty stuff will stay in the sump where it belongs.



    OK, Thank you for the follow up, I have not run the OBDII yet but I added some lucas anti knock fluid and it completely fixed my 1st to 2nd gear change and it is smooth as can be. However, I still have knocking when dealing with overdrive. Going into overdrive it knocks but coming out of overdrive to accelerate is where it really knocks hard it hesitates then has a hard knock. Any ideas what would cause this or the proper steps towards fixing it myself?

    Thank you!



    Ran up to my auto parts store and they ran an OBD scan and everything came up fine no codes for engine or tranny. I first noticed the knocking when going into or out of overdrive and then noticed it from first to second. The lucas tranny oil additive completely fixed first to second but I am still experiencing issues with overdrive. It give a pretty hard knock when I am driving at 60mph then hit the gas and it downshifts. Sometimes going into overdrive I feel a slight knock but nothing like shifting out of it while accelerating. The next steps I’ve read would be a transmission filter change. Is this a good or bad idea? I picked up a new filter and gasket and some mercon V and then was told by someone that may damage the tranny even more.

    Any help is greatly appreciated! Thanks again

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