labor knock turned into major pain!

[paducahshane]

I got some bad gas, I thought. Five minutes after filling up from empty I started getting a labor knock. Took "Green Bean" as the wife calls her, straight home and drained gas and changed filters. New gas and still knocked under load and got worse with loss of power now.

long and short.. I changed timing chain (1/2 in play) and replaced lifters.. wth, while at it put in an rv cam. Did it over night and had her back on the road by 5am. STILL no power and knocks like all get out under load.

Re-ran rockers (this time while running), checked wires (new), checked tdc, Distributer cap was HIGHLY corroded, cleaned it up. I am also running extra rich and most likely have trash in my float (from the bolt used to plug gas line).

I am about to throw my hands in the air and by a crate engine

[bmfm64]

yikes... that's a hell of a knock! my guess is it's time for a rebuild. Welcome!

[paducahshane]

This is my daily driver and was hoping to limp her along till I could build a stroker for her. Thought I had the knock identified.
Mains- At startup and get worse till all the time-- deep tone
wris pin- when you let off gas-- mid to high metalic tone
valves and lifters- under load-- high metalic tone
cracked flywheel- under load to constant / sporadic
cam - not to sure, never had one go bad

Replacing distributor cap and button in AM. Not ready to conceed this battle yet.

[1972hays]

does your oil pan have a dint in it

[paducahshane]

Originally Posted by 1972hays

does your oil pan have a dint in it

No outward dint, A little one at the back corner but not enough to get into anything.

[fastwillie 696969]

check the oil see if you can see bearing material silver ,drain the oil and take a flashlite and check to see if you got metal flake in the oil ,main and rod bearing worn out ,knock will get worst ,changing the cam and lifters did you change valve springs ?
i would check the timing if you got the dizzy off timing .

[paducahshane]

Originally Posted by fastwillie 696969

check the oil see if you can see bearing material silver ,drain the oil and take a flashlite and check to see if you got metal flake in the oil ,main and rod bearing worn out ,knock will get worst ,changing the cam and lifters did you change valve springs ?
i would check the timing if you got the dizzy off timing .

No metal flakes in oil, oil pressure still strong. I did not change springs. timing and was dead on, checked it with light.

[paducahshane]

New distributor cap and button did help it but still not right. Timed with light and did a compression check. Blown head gasket between 4 & 6. Not a big deal but a few things worry me; pitting on head and block mating surface between 4&6, number 6 piston looks brand new and others have normal carbon build up. This engine was in truck when I got it and came out of a 87.

Do I do the JB weld trick and slap it back together? Build a new engine? Or buy a crate?
desicions desicions

[brad_man_72]

turn your flywheel back and forth while watching your harmonic ballancer to see if you have one of those rare corvette 2 piece crankhafts..... That's how my ls swap started.

[paducahshane]

Almost bought an engine yesterday but decided to put this one back together and see what I could see. Purrs like a kitten once again! No knock and decent power. Don't think head gasket will last to long though. Never seen spidering between two cylinders like that before. Mixed up a dab of JB Weld filled, sanded and pollished... who knows. I know this, I am starting a new engine fund for the next time. Thanks for all the replies

[LONGHAIR]

I'll have to say that "labor knock" is a term that I have never heard before...

What are you meaning by the JB Weld trick? Did you "repair" the gasket with it? or just try to fill the erosion of the head/block? Either way, it will not last, save quickly

[paducahshane]

Really? never heard of labor knock...hmm Must be an old school or Kentucky shade tree thing... nope just Googled it and it is a pretty common term. Just a simple way of saying "knocking under load" as I understand it. Usually caused by bad gas, timming out of wack, lifter going down etc. ect. Never had a blown head gasket cause it before though.


Got the JBweld pit repair off of a bmw forum and a few other sites. from what I read seems to be standard practice and was said to be a BMW recomendation. Someone could been out of there head but I found it in several differnt lacations. I don't expect it to last too long, but I have seen stranger things happen. Let you know when/if it goes.

I cleaned the mating sufaces realy good. Got all the bits out of the pitting, sprayed her down with carb cleaner. Aplied small amount of JBweld to the effected pitting/spidering areas, working it. With a 2" putty knife at a 90deg angle removed the excess, sanded it smooth and polished with rubbing compound. I have to say, it did fill nicely and made a remarkably smooth surface. My other option was to junk both head and block. Build a new engine or order a crate. Either way, I would be without my truck for a week, and out at least $1200. Hmm, $20 for a gasket and some JBweld, worth a try.