horrible engine knock
 

Just swapped in a used l98
This motor is not looking so good. It was running fine untill after I changed the oil and took it for a full throttle run and it started knocking bad. It sounds like valvetrain knock but I checked all the lifters and none were loose. It has so much sludge in the heads the oil wouldnt even drain back out of the pass side one!! If a lifted was wad wouldnt I be able to tighten that rocker up ad make the knock go away??
Its not a consistan knock... its like knock...knock knock knock knock......knock knock.....knock knock knock...... lol


Just thought I might ask... oil pressure is good and it doesnt sound like a rod at all but I could be wrong

Re: horrible engine knock
 

Might be good to run a can of SeaFoam through it and see if you can get some of the sludge/carbon build up cleaned out. You can buy that from most Auto Part Stores. That stuff will make the motor run a little hot and smoke, but it'll burn out all the carbon buildup. I usually add 1/3 can to gas, 1/3 can slowly down brake booster vacuum line with the motor running (may have to rev it a little to keep it running), and a 1/3 can to oil (run it for a few minutes to get it nice and warm then change the oil). Stuff worked great on my mother-in-law's V6 Bonneville after she didn't change the oil for 2 years.

Re: horrible engine knock
 

im kinda scared to run it but I guess I got nothing to loose now. It sounds like someone is banging a hammer on the intake

Re: horrible engine knock
 

I hate to tell you this but with that much carbon in there your engine is toast carbon in a engine is from not changing the oil and over heating and that smokes your bearings and the carbon plugs up everything.

Re: horrible engine knock
 

Well if it's smacking around that loud and hard sounds like it has some major issues...

Re: horrible engine knock
 

Sludge and carbon is totally diffrent, sludge is from not changing oil, carbon is what sets up on the vavles and is fuel related.....but yes the motor with lots of sludge is not good........

Re: horrible engine knock
 

well im never buying a used engine again....
I heard it run so I just jumped on it, it was $300 and I should have atleast pulled the valve covers.
My L98 that spun a rod bering looks brand new in the oil pan and under the valvecovers.
This junk I swapped in looks like it has 500,000 miles on it and never had an oil change...
I guess ill just go hold the pedal down till something pops!!!!!!!!!!!

Re: horrible engine knock
 

I believe wear talking about the crankcase not the combustion chamber.:doh:
And yes your right carbon does form on valves and pistons in the combustion chamber and can cause a spark knock but that's not the kind of knock wear talking about