Rebuilt, Knock, missing...valve?
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Rebuilt, Knock, missing...valve?
Hey everyone. Ok, trucks an '84 F-150, I6 300, strait exhaust, no real engine mods or anything like that. Last spring, wiped a rod bearing ont he highway, pulled over when started knocking. Rebuilt the engine, new bearings, rings, etc. No machinging, didnt need it. It was the first rebuild for the engine. Well, since the first drive after the rebuild the engine knocked, not like rattley oh crap its going to explode, but, a solid sounding knock. Have run for...maybe 4 months or so since the rebuild, has knocked all the time, seems to get decent power, knock hasnt changed. Now, its getting a little colder out and the engine is starting to miss real hard under load, sounds like...puffing almost under the hood, starts shaking around, no power, like, going up hill or something. If it warms up for a long time, get out in the highway or something it doesnt seem to be a problem. I am wondering if anyone has any ideas. I am hoping it is a valve. I replaced all the lifters a few months after the rebuild thinking maybe one was collapsed, causing the knock, they were a little worn but in decent shape. It may be wishful thinking but sometimes it seems there is a little exhaust..pop or puff in time with the knock. Anyone have any ideas? Valve? I have hydraulic lifters, so, how hard would it be to change them? Any help would be greatly appreciate. Thanks!
Eric
Eric
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Your initial post made me think a thrown bearing. Is it an extremely deep knock or more of a tap? It is hard to diagnose crap on the internet but a thrown bearing is a much deeper sound than a valve liter etc. Does the sound of the knock seem the same as the reason why you rebuilt the engine? If close but not quit then I would give and educated guess of a bad main bearing or maybe a rod knocking. Looks like your gonna have to go back in, Let us know what you find out is the problem, later and Good luck
Last edited by jwtaylor; Oct 15, 2003 at 12:21 PM.
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From: Spokane WA, USA
Mine had a steady deep ticking- I could have swore it was a loud lifter tick or a rocker arm, when I rebuilt it, the engine had 3 bent connecting rods (bent like an 's' sideways) it was slapping against the piston skirt causing the ticking, very loud tick almost a knock. It's a tough one to diagnose
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Thanks guys, yeah...i can never get a concensus from people that listen to it, guess I cant expect much over the internet, thanks though. The rods were alright when the rebuilt was done, i myself didnt actualyl reassemble the rebuilt, (i was at college, I pulled the engine, tore it down, put it back in). The person who did the rebuild went and checked all the bearing clearances with plastiguage and all that and it was alright. I am going to be putting an offie intake and Holley carb on this weekend (haha, smart when it could be a bearing, right? well, its been laying here for 6 months and i cant take it, besides, if i am going to really rebuild, it, migt as well have a REAL good reason ;-) ), so, i may be able to take a cursory look at the valves. I have also hear that it could the piston slap, if the wrist pins were worn. Oh well...prayin for a valve, I'll post again if i find out anything new. Thanks!!
Eric
Eric
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Hey everyone, been a long time since I last posted about this, but, many months down the road, i hvae just pulled the engine out. ALL of the bearings were shot, i mean, real bad, the number 5 cylinder rod bearing, top half was completly copper colored, all of the rod bearings had places worn to the copper, mains all looked gouged...I dont know how it was even running still. Aparently...it should have been machined last time. So, i have taken it to a machine shop, rods getting turned 30 under, mains 20 under, bored 30 over, new cam bearings, new pistons, also getting a new crane truck cam, new lifters, already had the 4bbl (Holley 550cfm) and intake on it, taking this oppourtunity to convert from TFI to duraspark II too. Also, there was a huge vacuum leak on the #1 cylinder, so i was pretty much running on 5 cylinders. But, will see how everything turns out when i get it back in, should be puting out a decent amount of power, but the best part...I will now have a six thats bigger than all the little 5.0 mustangs running around 
Well, thanks for the help! Any body have any advice before I get this thing together and back in? or anything to say about what I am planning? Thanks again!
Eric
Well, thanks for the help! Any body have any advice before I get this thing together and back in? or anything to say about what I am planning? Thanks again!
Eric
