Hey everyone, I bought an 89 F250 lariat 4x4 with a 460 engine a few months back. Aside from routine maintanance I have never fixed things on vehicles but working on this truck has brought me great joy. My problem is that the engine knocks while idling and when I am in gear but only when I am almost to a complete stop. I have done tons of research on this and realized I should just ask what the experts think. There is no knocking while accelerating or holding a steady speed. I know that the problem could be rocker arms, push rods, maybe one of the belts, and god forbid, a bearing or something else that takes more money than I have right now. I do not know what else someone would need to know to help so I'll try my best. The engine was fuel injected but the guy I bought it off of switched it to carb ( edelbrock, it looks new ) many bolts were loose but I have tightened everything up including the valve covers ( also added those spreaders ) The temp, oil, rpm, and fuel gauges do not work but the engine does not overheat. The headers are fed into one 3 inch exhaust pipe and someone told me that that could even be the problem. Any help would be great. Thanks

 

Like I said, I know the many things it could be. But if I want to do the work myself but I just do not know which order to do them to reduce backtracking and such. Oh and a side note; If anyone could tell me how to set up the gauges so they work that would be great.

 

Well, without hearing it, it could be lots of things, as you point out. All I can say is my '91 Bronco did this almost from when we bought it, with 44K on it, all the way until I put new rod and main bearings in it at 142K. It was a lease truck to the first owner, and I don't think he kept up with the oil changes. But I figured as long as it only did it at idle, it couldn't be too severe. What finally made me change 'em out is when it started to knock VERY LOUDLY for the first few seconds after an oil change.

BTW after the bearing change, that 302 went another 100K+ miles when I pulled it at 250K and sold it to another guy who dropped it as-is in his F150 and ran it some more. The 302 is a tough little booger.

 

Thanks for the reply. I bought the truck because I have always wanted an older ford truck. I look forward to working on her but like I said, I have no clue where to start. I adjusted the idle because it was idling high but since the rpm gauge isnt hooked up ( and can't find anything online to show me how ) I can't get it to the exact rpm's for idling but it sounds better. The knocking is going to drive me crazy though. I want to start replacing some stuff but would like to narrow it down a little bit though.

 

You need to find out where the noise seems to be coming from. Get a long screwdriver or length of garden hose, hold one end on various parts of the engine (both valve covers, intake manifold, both sides of the block, front and rear of the oil pan, bellhousing) and the other end hold tightly to one ear. Should be able to narrow down the location of the noise.
Also valve train noises will be at half engine speed.
Check also for any exhaust leaks and leaks from smog pump pipes (if fitted).

 

As jas pointed out, it's hard to say without hearing it. I would put money on either main bearings and or a wrist pin if it's more of a hollow sounding knock. If it seems to be more higher pitch then I'd say somewhere in the valve train. But since it's only at idle, I'd go with the former.

 

Thanks for the responding guys. Yeah it isnt a high pitched knock, and its louder on the drivers side. I do have an exhaust leak where the headers meet the pipe due to the paper thin gasket used. Based on the advice so far it seems like I should take her apart. Nothing like rebuilding an engine to get your feet wet in mechanics lmao. Any advice on where to get quality/affordable parts?

 

I hear you, but if you're on a tight budget, you're probably better off finding a running engine and dropping that in instead. In my area you can find 460s all day long for around $500 complete (not very popular when gas prices increase, heh heh).

 

What area is that? I would gladly pay that for a complete 460. I am in new england and I see them complete going for 2 - 4 thousand. I found a master rebuild kit for $499, I figure why the hell not? In the mean time maybe I'll drop a smaller engine in. I do not mind the gas guzzling, It really gets under the skin of all the hybrid owners out here...... AND BOY ARE THERE A LOT OF THOSE! Any advice on how to clean the block when I get it apart? Oh and if you ever see a 460 in your area even close to that price PLEASE send me a link. Thanks for the replies

 

What transmission do you have?

 

It's a C-6 automatic.

 

Don't forget you'll probably have to have machine work done on the motor, especially depending on what is failing. Also don't forget the special tools that are needed for rebuilding yourself. You will easily spend the price of a junkyard 460 trying to do a rebuild. That's assuming since you've never done it before that you do everything properly and don't destroy it in the process. Good luck!

 

Seattle WA area, on the left coast! I see used 460s on Craigslist for $500 all the time. Nobody wants one with $5 gas coming to a station near them soon. At this price, I'd seriously consider picking up a spare but I don't have the space to store one.

Now I will be the first one to admit that buying a used engine is as close to a legal lottery as you can get, but some things can be checked. It's always best to buy one before it is pulled so you can hear it run and check the oil pressure, and see the coolant (other tests, like compression and leakdown, can be done anytime).

I was just trying to throw out other options that may be viable if money is really tight. Doing a rebuild yourself is the BEST way to absolutely, certainly know what you've got. Having a good machinist/machine shop is key, however. So don't think I'm trying to talk you out of that option by any means - it does take some time, but if it's not your daily driver, you can work on rebuilding the engine a couple of hours at a time.

 

Does it knock in neutral, does it get louder if you put a load on it while holding the brakes?

 

If I throw it in neutral while slowing down the knocking goes away. My buddy told me with all that I have said that it is more than likely a main bearing. I am just going to take it out and clean it up with gunk hydroseal II, then bring it to shop to do what they do. I found the same year and model as mine at a salvage yard the other day and everything under the hood was in better shape than mine so I am going to see what the guy wants for it. Only thing is that it is EFI, and I would have to switch it over. I will post pics when I take it out and more through the rebuilding process. Thanks for the replies everyone.