is it normal to have a bit of a "knock" after initial startup??

[Forces32psi]

and if so how long will it last and what all could it be??? everything in motor is brand new except the head and lifters. head gasket, new springs, cams, pistons, rings, bearings etc. i started the motor let it run at 2500 rpm's for 10-15 minutes or until the motor got to 130 degrees an then shut it off, let it cool down, put anitfreeze in it and then restarted it, car has good oil presure, drove it around the block ran good. i wont be running it all weekend but as soon as i get home il be putting mobile 1 fully synthetic oil in it and changing the filter, it seemed to have a knockk around 2500-3000 rpms it hasnt run very long so im wondering if its just the lifters or something .. it doesnt really sound like a lifter "tick" though, pistons are coated w/ ceramic on top and teflon on the skirts.. any opinions or suggestion?? thanx steven

 

[Forces32psi]

i also cant get the car to idle, im going to replace the O2 sensor but i dont know if thats the culprit or not .. its not shooting a check engine light..any suggetions on the no idle and bit of knock?? i had a local shop around here built the shortblock and i think im going to have the guy that assembled the shortblock come over here and listen to it next week.. i dont think its any kind of knock that should be there at the 1st startup... steven

 

[94Jettameowpsst]

You probably just have really bad lifter tick or you have piston slap if they're forged. If your knock sensor is goin like mine is, you'll have sparratic knock everywhere tho. As for not getting the car to idle, try a boost leak test, make sure you dont have any vaccum leaks and replace ur o2 sensor. My friends car had all of the above problems, changed the necessairy stuff, and it runs fine now

 

[Forces32psi]

yes i have forged pitsons, and im thinking that the knock sound is piston slap is that normal??? the motor has been to temp 3 times now. i have the 1g lifters in it but they never really ticked before. i also have a set of lifters w/ the bigger hole in them sitting in the garage. its right around 2900 rpms and then goes away and i was watching my knock count on my palm and its pretty spuratic, im replacing my O2 sensor today, cause its had gobbs of race gas pass through it.

 

[Turbo Talon DL]

I just started running my brand new forged motor as well. I believe some piston slap is to be expected from forged internals. I have some going on too. My lifters ticked really bad at first too, but went away after the engine got warm on the initial start-up. It doesnt tick anymore, and I've also put about 23 hard miles on it but only at 9psi max boost.. I havent monitored my knock sum yet because my Honda Civic Optima Yellowtop battery is crap right now When I get a chance to monitor it, i'll post some more..

 

[Forces32psi]

i put a new O2 sensor on today, got the motor to idle but when i hit the gas and let off it just dies. when i start it, it starts and idles now.. i think its just my vpc settings or the timing may still be a little off, etc.. just dumb shit. but as far as i know a motor that has forged pistons SHOULDNT have the piston slap going on that means that something wasnt clearanced correctly and the pistons or piston that is slapping has to much room to play in there..and if im not mistaken that would lead to tearing a motor back apart. luckilly for me i had a local shop put my shortblock together so the guy that assembled it and had everything bored etc is comming over to hear what i think is piston slap, and more then likely have to rebuild the whole bottom end.

 

[94Jettameowpsst]

Most all if not all forged pistons will have some type of slap until they heat up. Then need time to expand to push the rings against the cylinder walls, dont beat the car till its at normal operating temp. As far as still not idling right, i cant help ya out there, i have no experience with the vpc.

 

[Forces32psi]

well ive had the car to temp 4 times now driven it around the block etc.. shouldnt stop after the motor gets to temp ?? this is the 1st time ive ever had a motor built that has had piston slap, thats why it doesnt seem "normal" to me.. thanx for the input and suggetions though..keep it comming if anyone has anymore help/info. thanx steven

 

[TSIfreek]

I am running ross pistons and hear no knock like you hear. I would put the upgraded big bore lifters in and see what happens.
When you talk to him ask him what he set the piston to wall clearance at. I would run wiescos at .004 thats 4 thousands. Ross pistons are set looser becuse they are made of a diffrent aluminum and need more room once heated up.
Our lifters when new and just installed sound like a sewing machine once the engine is stared and can last up to 45 minn but slowly goes away. What oil are you running??

 

[94Jettameowpsst]

First of how many miles are on your motor right now...and what was the reason for rebuilding it? Its a possibility its just your lifters but then again if you rebuilt it cause you spun a bearing and you didnt get your crank resurfaced, you may have another bad bearing.

 

[1qwikspyder]

this may sound off the topic but when i had knock that seemed similar to urs it was my motor mounts. I put a prothane in just the drivers side mount and it corrected the problem. All my mounts are going to crap tho so i'll be replacing the rest here in a little bit. As for the noise i don't know what it could be but my 2g had bad lifter tick but it doesn't knock b/c of it unless it's really bad, then i just go get an oil change...

 

[Forces32psi]

ok the motor has about 30-40 miles on it if that. it has that crappy oriely oil in it because it was going to just come out after startup.. this motor was rebuilt because i wanted a stroker motor. crank, all bearings, and pistons are all new from slowboy rods are new, the lifters that are in the motor are the stock 1g's they are NOT new they have never had a problem ticking, i also have some of the revised lifters w/ the bigger hole that ive used before sitting in the garage, the cams are new, new dual valve springs, new valve seats, new titanium retainers, the oil pump and cover are new, new steel headgasket, and o-rings. these pistons are teflon coated on the skirts and ceramic coated on the tops.. ive been reading up on this site about piston slap and im just worried that my brand new pistons that dont even have 50 miles on them are going to be trashed now, and now the downtime il have to while they are RE-rebuilding my shortblock. the guy that assembled my shortblock is comming over tonight to hear the noise as well. then im sure he will be calling the guy that did my machine work. im 95% sure its piston slap though. there is no reason that my lifters would just all the sudden start ticking when they NEVER did on the old motor. and the motor has great oil presure and when i listen close to the motor it sounds like the knocking noise is comming from the block but its not close to the bottom end. im also going to try a compression check tonight and see what i come up w/ just becasue i read that another guy on this site had good comp all the way across except for 1 cylinder was at like 95 and he pulled his motor apart and his pistons were trashed BUT he ran the crap out of it and ran the dragstrip to, my car has only been to temp 4 times and ony had 14psi to it w/ the boost controller off, and i havent ran the crap out of it, so im HOPING that nothing is ruined yet.. thanx for the suggestions .. and il look into my motor mounts, and might go ahead and put the revised lifters in .. i think id rather do that then have the whole motor torn apart etc... but i dont think its my lifters. .again i appreciate everyones help... steven

 

[Turbo Talon DL]

ok the motor has about 30-40 miles on it if that. it has that crappy oriely oil in it because it was going to just come out after startup.. this motor was rebuilt because i wanted a stroker motor. crank, all bearings, and pistons are all new from slowboy rods are new, the lifters that are in the motor are the stock 1g's they are NOT new they have never had a problem ticking, i also have some of the revised lifters w/ the bigger hole that ive used before sitting in the garage, the cams are new, the oil pump and cover are new, new steel headgasket, and o-rings. these pistons are teflon coated on the skirts and ceramic coated on the tops.. ive been reading up on this site about piston slap and im just worried that my brand new pistons that dont even have 50 miles on them are going to be trashed now, and now the downtime il have to while they are RE-rebuilding my shortblock. the guy that assembled my shortblock is comming over tonight to hear the noise as well. then im sure he will be calling the guy that did my machine work. im 95% sure its piston slap though. there is no reason that my lifters would just all the sudden start ticking when they NEVER did on the old motor. and the motor has great oil presure and when i listen close to the motor it sounds like the knocking noise is comming from the block but its not close to the bottom end. im also going to try a compression check tonight and see what i come up w/ just becasue i read that another guy on this site had good comp all the way across except for 1 cylinder was at like 95 and he pulled his motor apart and his pistons were trashed BUT he ran the crap out of it and ran the dragstrip to, my car has only been to temp 4 times and ony had 14psi to it w/ the boost controller off, and i havent ran the crap out of it, so im HOPING that nothing is ruined yet.. thanx for the suggestions .. and il look into my motor mounts, and might go ahead and put the revised lifters in .. i think id rather do that then have the whole motor torn apart etc... but i dont think its my lifters. .again i appreciate everyones help... steven

My piston slap went away fairly quickly as well, if I ever had it going on. I have Wiseco pistons, they are high(er) silicone content, which means they expand more. My lifters were obnoxiously loud when I started up the motor, i got scared at first, but just let it run, warm up, and let the oil get into the motor really well. I primed the hell outta my motor with an electric drill on the oil pump as well, so I knew the engine would circulate oil. I've run my car up to 95 in 4th gear and did a coast-down at 9psi, its doing well aside from 100psi+ of oil pressure and a couple small leaks. I only had it up to 5500rpm at the most, just to get the rings to seat as per Mototune USA. My motor seems to run really well once up to temp though. I like it.

 

[Forces32psi]

ya everytime ive ran mine ive tried the "coastdown" in 1st and 2nd gear to seat the rings, but it still has the knocking sound.. i think the fastest ive had mine is maybe 30 mph and not for very long. i talked to mike at slowboy today and he said that he had put a motor together "loose" like mine was and he had the piston slap as well and he could never run more the 24psi through it .. and he said the samething ive seen on other threads on dsmtuners that when he has motors built he has the clearence at .004 for the forged pistons.. and im also guessing that now my motor will have to be bored over to .030 instead of the .020 that its suppose to be at now?? i havent heard from the guy that bored and honed my block yet for sure, but for some reason im thinking that he did mine at .006 or .0065???? i would GUESS that he did whatever the paperwork said that ross sent me w/ the pistons?? this sucks i should be running the CRAP out of 10sec supras around here right now..

 

[TSIfreek]

Well what did he bore the cylinders to?? Give me a #. Did you ask him what the final piston to wall clearance was set at.?? Ross calls out for .005 but some have gone looser depending on the boost level you plan on running. 6.0 is way to loose unless its an all out drag car that sees 35 psi + boost.

 

[sbiggi]

ya everytime ive ran mine ive tried the "coastdown" in 1st and 2nd gear to seat the rings, but it still has the knocking sound.. i think the fastest ive had mine is maybe 30 mph and not for very long. i talked to mike at slowboy today and he said that he had put a motor together "loose" like mine was and he had the piston slap as well and he could never run more the 24psi through it .. and he said the samething ive seen on other threads on dsmtuners that when he has motors built he has the clearence at .004 for the forged pistons.. and im also guessing that now my motor will have to be bored over to .030 instead of the .020 that its suppose to be at now?? i havent heard from the guy that bored and honed my block yet for sure, but for some reason im thinking that he did mine at .006 or .0065???? i would GUESS that he did whatever the paperwork said that ross sent me w/ the pistons?? this sucks i should be running the CRAP out of 10sec supras around here right now..

We ahd a motor that sounded like that.

One happend almost exactly like yours.

Ended up that the thrust bearing got trashed right away and all the crap got pushed through the motor. I would drop the pan and look for metal, or cut the oil filter open and inspect for metal.

Something ended up being wrong with the block we got, as the same thing happend with 2 other shops rebuilding the same motor.


-Seth

 

[Forces32psi]

Well what did he bore the cylinders to?? Give me a #. Did you ask him what the final piston to wall clearance was set at.?? Ross calls out for .005 but some have gone looser depending on the boost level you plan on running. 6.0 is way to loose unless its an all out drag car that sees 35 psi + boost.

the guy that assembled the motor said that the piston to wall clearance was around .003 on top of the .020 overbore. BUT the first time this motor was assembled (by someone else and a different owner) it was bored for cast pistons not forged JE pistons so the motor was ran and ended up ruining the #4 piston and scaring the cylinder and i believe it was allready bored over .020 then..so im sure something is not correct again. hence the knocking.. i put the bigger lifters in lastnight but havent run it yet, but i will be tonight. i looked at the oil lastnight and i dont see anymetal its just a little murkey from the white lithium grease used to assemble the motor, but i havent pulled the pan or filter yet either...

and i plan on running 35+ psi w/ this motor but i cant do it when there is piston slap.. il be lucky to get to 25psi w/ the motor like this. steven

 

[TSIfreek]

Steve No dont run the motor like that. What you need to do is some how get a measurement of the bore and then a measurement of one of the pistons. Subtract the 2 and you get your wall clearance. You really should have done this before assembling the motor or got the final bore from the machinist. I think the bores are way over because ross builds the clearance into the piston. So a ross .020 over piston will come out .005 wall clearance if the bores are bored out .020 over stock size. They have a bore size right on the box I cant see how he fked it up. So if he put .003 plus the .020 you have a .008 wall clearance. I would get a new good block and start over and use those pistons, or sell them and go .040 over.

 

[Forces32psi]

Steve No dont run the motor like that. What you need to do is some how get a measurement of the bore and then a measurement of one of the pistons. Subtract the 2 and you get your wall clearance. You really should have done this before assembling the motor or got the final bore from the machinist. I think the bores are way over because ross builds the clearance into the piston. So a ross .020 over piston will come out .005 wall clearance if the bores are bored out .020 over stock size. They have a bore size right on the box I cant see how he fked it up. So if he put .003 plus the .020 you have a .008 wall clearance. I would get a new good block and start over and use those pistons, or sell them and go .040 over.

i didnt think i would have to do anything, i didnt deal w/ the machinist, the guy that assembled my shortblock did. i put the lifters in still knocked like we ALL knew it would, call the guy that assembled the shortblock he wants me to leave it together so he can come over saturday and hear it.. so i think he knows that i will either need a new block and use everything else and he will have to find the block and pay for that and the RE o-ringing, and assembly OR buy me new pistons and try this block again and eat the labor.. id MUCH rather just start w/ a NEW block and use everything else i allready have and that is IF the pistons are salvagable....thanx for the help..steven

 

[TSIfreek]

O Ok I was under the impression you assembled the short block. Im sure the pistons are ok and if not have them buy you a new set. They assembled it and they need to get it right not your fault. That really sucks.

 

[Forces32psi]

so when the block is bored .020 over and the pistons are .020 over what is the TOTAL that the block will be bored/honed to accomodate these pistons?? and when everyone says "clearance" doesnt that mean the bore is a little over (.004 on top of the .020) the overbore for a total of .020 AND the .004??? the guy that assembled my block said the pistons were clearanced at 3 thousanths, .003?? steven

 

[TSIfreek]

Call ross tomarrow and have them tell you. Yes just what I said ross PUTS .005 in there .020 over pistons. If the piston measures out 3.3717 and the bore measures at 3.37635 you would get a total of .0046 clearance thats 4.6 thousands. http://www.rosspistons.com/sport_compact_mitsubishi.php.

 

[TSIfreek]

Sorry if I confuse you. The really only right way to do it is to measure each piston and add what ever wall clearace you want and thats your final bore size you bore/hone the cylinder to.
If your going to have them do the short block again have them right down each piston size 1-4 and each bore size 1-4 and go over it with them when you pick up the motor. What about ring end gap do you know what they set is at??

 

[Forces32psi]

your not confusing me .. i should have known all of this before i put my motor together and checked mine.. i just didnt think i would have to. i dont know what size the ring gaps were filled to, il find out sat. im sure il be yanking the motor out sunday to go back to the guy that assembled it.. i think id rather just opt for a fresh block that isnt bored out yet and just use everything i allready have, if my pistons are still in good shape, i pulled the intake manifold off the other day, and #4 runner and port in the head had oil allover in it, but the car isnt smoking.. hmmm wonder which piston is slapping??? steven

 

[Forces32psi]

remember when i said that the #4 runner of the intake manifold and the head had oil all over the place in it?? well i pulled the plugs tonight to do a compression check and 3 of the plugs are bone dry and look normal i guess, and the #4 plug is COVERED in oil.. the comp test was 140,130,150,150 w/ 150 being on the #4 cylinder. BUT i think i might not have done all 4 exaclty the same so im going to do it again tomarrow and do all 4 exactly the same.. does it matter how many times i let the motor rotate?? or as long as i do all 4 the same??

and hey TSIFreek didnt you say that the cylinders SHOULDNT be bored/honed anymore then the standard .020?? so the machinist SHOULDNT have bored anything MORE then the .020 right? and the ross pistons would be fine correct? because i think thats how the block was machined .020 +.003 for clearance.. im just trying to get all my ducks in a row before the guy comes over here because the possibility is there that he might try to tell me that it was done correctly etc.. but who knows. thanx for the help.. steven