Loud knock after oil change?

[lancelot50]

Hi guy! I posted about this in a different way but this is more basic.im 50 and seen lots of stuff but this doesnt make sense.my boy buys a s10 4.3 drives a week runs good,no smoke,engine smooth and absolutely no noise.checks oil decides to change.immediately starts knocking! Calls me i listen to it,knock comes and goes.pull plug wires no difference.well instead of diagnosing further like i should and normally would.i read up on 4.3.come up with balance shaft.long story short.install gm retro timing chain tensioner kit,new hv oil pump although oil psi was very good b4.lots of labor for nothing and 500 in parts!still same knock.i just dont see a doctored up engine running that quiet prior to oil change? Could a wrong bbrand/type filter? I thought of pulling tc cover and eliminating balance shaft gear? All that will do is a sligjt rough run.but the other thing is if it were a piston noise.i just wouldnt think an additive like stp,rislone etc would cover up for a week long enough to sell?i have a good 4.3 lined up but thought id ask on here before i go that route.thanks for any ideas in advance

 

[demarpaint]

Have you tried a different filter? I'm assuming you have the spec'd grade oil in there now and it's full.

If all that checks out someone could have thrown in some Lucas Oil Stabilizer, or a few bottles of STP with some 20W50, and it quieted it down just long enough for the check to clear. Oil pressure readings and compression reading with the fresh fill of oil would be nice. A UOA of the old oil would be good too.

 

[aquariuscsm]

What brand,synth or dino,weight of oil did he use?

 

[PolarisX]

Did someone load it up with 50 weight oil and sell it?...

 

[supton]

A knock that comes and goes? Like with engine speed, or engine temp; or one that is truly random?

If the latter I'd think outside the engine. If former... perhaps someone put in thick oil to mask something, but then I'd think the question would be, does it go away when warm? there all the time?

 

[NormanBuntz]

If you haven't done it already, I'd replace the oil filter with the specified ACDelco filter. Drive it and see if it still knocks. If so, leave the ACDelco on, drain the oil and fill with Rotella 15w-40. Total cost $20-25. I suppose a 20w-50 oil could mask some engine problems for a short while.

 

[fdcg27]

Assuming that you're on the level, have your son drain the oil and put some cheap 20W-50 in there, or just drain a couple of quarts and make those up with some cheap thick additive.
If the knock goes away you'll have your answer as well as a use for the good 4.3 you have on deck.

 

[lancelot50]

Well before oil change it was as quiet as a new engine.when son changed oil he used 20w50 1qt lucas stabilizer.the knock is internal.i ck'd flexplate and accessories.knocks when warm.oil psi 65 warm.not a steady knock with engine speed.more of loud rapid knock/rattle that when revving will seeming double or triple engine speed.when i put new oil pump in and timing chain i used 5w30 oil but exact same kind of filter.stp ok ill back track before oil change engine had approx 45 oil psi (no knock and mystery oil) sons oil change 20w50 lucas same oil psi knock! My oil change 5w30 new parts same oil filter 65-70 psi knock.when i pulled oil pan no rods were loose to make that kind of noise.i just dont get it unless its holding good oil psi but wrong particular filter or maybe it was doctored up that good and or the knocking could be piston pin

 

[spasm3]

20w 50 plus lucas stabilizer would be an incredibly thick oil. I hope you did not spin a bearing before oil pressure built up through the filter and crankshaft.

 

[SatinSilver]

Well like the other thread you started about the same topic, I'd install an AC Delco oil filter in there and see how it sounds. Any oil lost during the filter swap I'd replace with 0w20, LOL. Oh and I should probably add the correct model filter for the application, a 4.3 V6 S10.

 

[NormanBuntz]

So you're using an STP oil filter? Lose that thing, install the correct ACDelco and hope you got lucky.

 

[another Todd]

20w-50 PLUS Lucas concerns me too. Very thick brew. I would dump that, put on a AC Delco filter, and 5w or 10w-30 oil.

 

[AZjeff]

Really curious, if you and your son thought the truck was OK why did he put in 20w-50 and the Lucas?? That seems a bit excessive even by BITOG standards..

 

[Bud_One]

Originally Posted By: another Todd
20w-50 PLUS Lucas concerns me too. Very thick brew. I would dump that, put on a AC Delco filter, and 5w or 10w-30 oil.


+1

 

[aquariuscsm]

My recommendation. Pennzoil 10W30 high mileage with a "good" (non-ecore) AC Delco oil filter. I think you can only buy those at auto parts chains. Walmart used to only have the e-cores.

 

[PeterPolyol]

Originally Posted By: lancelot50
when son changed oil he used 20w50 1qt lucas stabilizer

Oh my! The 20w50 would be good enough (certainly not ideal), but a quart of Lucas too?

 

[Warstud]

So it now has 5w30 and STP filter and it still knocks. You probably did some damage then.

 

[aquariuscsm]

I'm curious,why in the world add the Lucas??

 

[hardheaded]

before changeing the oil again, run some seafoam though it. could be a lifter making noise.

 

[AZjeff]

Is it really possible the heavy oil & Lucas did harm? Still wondering about the thinking behind that combo if the motor was thought to be fine.