Do I have a rod knock? - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

jam24.0s13 · 11-10-2013, 12:57 AM

okay just looking to see if there is a way where i can tell if i have a rod knock before i rip out the whole engine.
Story:
engine had 150xxx miles on it. the head on my s13 crapped out about a month ago cuz i was running only water with no coolant (i know stupid) and eroded away the coolant passages and was leaking water to the cylinder.
So i bought a complete s14 engine of some dude who claimed he fried his rings after boosting the stock engine but head was still good. Got it for 120 and head looked almost new. get it home, take it apart and head studs are loose enough to loosen by hand.. i take the head off, and block is in perfect condition. I had the head pressure tested, valve seats redone, new valve stem seals, everything re-lubed and basically rebuilt.
I saw some guy post a "stock cam swap' for the ka running the s13 248 exhaust cam on the intake side and s14 232 exhaust cam just like normal and it would give you a little more power, so i gave it a try. i put the s14 rebuilt head with 248/232 cams in it on my known-good s13 block used s14 got it up and running. everything was peaches for the first day.

Next day coming back from school i start to hear a little ticking, so i pull over in fear it was a rod knock. open hood and it sounds like oil starvation and cams are hitting lifters with no oil, i put my hand on the valve cover and feel a strong tapping coming from the intake side. come to the conclusion that its oil starvation. push it to buddys house in fear of burning the cams. go check it out the next day rip off the valve cover and turn it on like that (yes i covered around to catch the splashing oil) and to my surprise its getting oil to the head just fine.. now sound is lighter but sounds like its coming from timing chain cover. but i highly highly doubt its chain related. i put it back together knowing its not a head problem and drive it home. to my luck i find the slave crapped out so i have to drive without pressing the clutch now.. my house is about a mile and a half away and knocking sounds gets louder and louder. i get home and check with a stethoscope to see where noise is coming from but its no louder or fainted anywhere. same noise throught the top, bottom, front, back of the engine.
so now im stumped. is there any way i can check if its a rod knock before i take it out. i just put the engine in this same week and i didnt touch my bottom end at all while doing all this head madness. healp pleaseeeee

Rich260z · 11-10-2013, 01:16 AM

Have you checked the oil for metal shavings?

jam24.0s13 · 11-10-2013, 01:23 AM

yep. oil is brand new prob 10 miles on it.. checked dipstick and drained it...
clean as can be

Ka-t in progress · 11-10-2013, 08:56 AM

Unplug your spark plugs one at a time and see if the sound goes away,if it does that is the cylinder with rod knock. Done a compression test?

jam24.0s13 · 11-10-2013, 02:00 PM

Cool thanks man ill try the spark plug thing. And I did a compression test the night I got it runnin and all cylinders were withing spec. Haven't done one since it crapped out. Would it change..?

Ka-t in progress · 11-10-2013, 02:45 PM

It never hurts to test it,I would just for the ease of mind ya know

Frank_Jaeger · 11-10-2013, 04:10 PM

Post a video. I'd be more concerned about piston-valve contact due to bad timing.

jam24.0s13 · 11-10-2013, 07:47 PM

Well I did the spark plug test and sure enough when I pulled the plug for cylinder 4 it stoped making the knocking noise. So rod knock there?

Well even if the compression is low doesn't really matter since I'll be switching out the block and putting the s14 block and bottom end on it.

And I know timing is spot on. I've done it dozens of times and quadruple check it and have other people check it as we'll just in case. If it was a timing problem and I had bent valves it would of bent them on the first time I cranked it and had it running like shitx but it ran fine for that day and day after.

killakees · 11-14-2013, 10:30 PM

Compression test you would know if you had a rod knock if you heard it more than likely the spark plug or wire as you said

Sent from my iPhone using Tapatalk

jam24.0s13 · 11-15-2013, 12:25 AM

i dont see how a compression test would define if i had a rod knock. correct me if im wrong but the pistons rings can still be in okay condition even with a rod knock... ive seen people replace just the bearing on the crankshft journals for the connecting rods and the engine ran fine again so there is no direct relation between compression numbers and a rod with excessive clearance that it is slapping around on the crank.. right...?

Lex Zarza · 01-15-2020, 06:20 AM

Question I do have a knock rod was wondering if it’s okay to replace just the bearings on a stock KA. it never had a turbo or anything like that. I am planing to fix the problems buy just replacing the crank bearings

some guidance would be helpful.

inferno s14 · 01-15-2020, 09:30 AM

sure you can - if the piston or piston's didn't slap against the cylinder hard enough to score it or if the crank is good condition for a new bearing.

if the crank is scored you need to smooth it out or it will chew your new bearings up.

Kingtal0n · 01-15-2020, 07:38 PM

the engine is designed to be rebuilt and serviced by the fsm

if you follow the fsm you might be fine. the most difficult part novices with this exact situation have seems to be cleanliness. in my opinion, do not expose the engine to the atmosphere for long and do not open the engine where outside air which contains pollen and fungus everywhere in the world can enter it easily. finally more important than anything, do not overlook a single grain of sand, not a tiny crumble or morsel of anything can be inside the engine or it will clog oil orifices.if you see any material the whole thing needs to be dismantled and cleaned. or cleaned somehow where it is good luck.

11-10-2013, 12:57 AM	#1
jam24.0s13 Join Date: Jan 2013 Location: Corona CA Age: 29 Posts: 21 Trader Rating: (0) Feedback Score: 0 reviews	Do I have a rod knock? okay just looking to see if there is a way where i can tell if i have a rod knock before i rip out the whole engine. Story: engine had 150xxx miles on it. the head on my s13 crapped out about a month ago cuz i was running only water with no coolant (i know stupid) and eroded away the coolant passages and was leaking water to the cylinder. So i bought a complete s14 engine of some dude who claimed he fried his rings after boosting the stock engine but head was still good. Got it for 120 and head looked almost new. get it home, take it apart and head studs are loose enough to loosen by hand.. i take the head off, and block is in perfect condition. I had the head pressure tested, valve seats redone, new valve stem seals, everything re-lubed and basically rebuilt. I saw some guy post a "stock cam swap' for the ka running the s13 248 exhaust cam on the intake side and s14 232 exhaust cam just like normal and it would give you a little more power, so i gave it a try. i put the s14 rebuilt head with 248/232 cams in it on my known-good s13 block used s14 got it up and running. everything was peaches for the first day. Next day coming back from school i start to hear a little ticking, so i pull over in fear it was a rod knock. open hood and it sounds like oil starvation and cams are hitting lifters with no oil, i put my hand on the valve cover and feel a strong tapping coming from the intake side. come to the conclusion that its oil starvation. push it to buddys house in fear of burning the cams. go check it out the next day rip off the valve cover and turn it on like that (yes i covered around to catch the splashing oil) and to my surprise its getting oil to the head just fine.. now sound is lighter but sounds like its coming from timing chain cover. but i highly highly doubt its chain related. i put it back together knowing its not a head problem and drive it home. to my luck i find the slave crapped out so i have to drive without pressing the clutch now.. my house is about a mile and a half away and knocking sounds gets louder and louder. i get home and check with a stethoscope to see where noise is coming from but its no louder or fainted anywhere. same noise throught the top, bottom, front, back of the engine. so now im stumped. is there any way i can check if its a rod knock before i take it out. i just put the engine in this same week and i didnt touch my bottom end at all while doing all this head madness. healp pleaseeeee

11-10-2013, 01:16 AM	#2
Rich260z Zilvia Addict Join Date: Apr 2011 Location: Burbank, CA Posts: 621 Trader Rating: (8) Feedback Score: 8 reviews	Have you checked the oil for metal shavings?

11-10-2013, 01:23 AM	#3
jam24.0s13 Join Date: Jan 2013 Location: Corona CA Age: 29 Posts: 21 Trader Rating: (0) Feedback Score: 0 reviews	yep. oil is brand new prob 10 miles on it.. checked dipstick and drained it... clean as can be

11-10-2013, 08:56 AM	#4
Ka-t in progress Leaky Injector Join Date: Oct 2012 Location: Middle tennessee Age: 35 Posts: 89 Trader Rating: (0) Feedback Score: 0 reviews	Unplug your spark plugs one at a time and see if the sound goes away,if it does that is the cylinder with rod knock. Done a compression test?

11-10-2013, 02:00 PM	#5
jam24.0s13 Join Date: Jan 2013 Location: Corona CA Age: 29 Posts: 21 Trader Rating: (0) Feedback Score: 0 reviews	Cool thanks man ill try the spark plug thing. And I did a compression test the night I got it runnin and all cylinders were withing spec. Haven't done one since it crapped out. Would it change..?

11-10-2013, 02:45 PM	#6
Ka-t in progress Leaky Injector Join Date: Oct 2012 Location: Middle tennessee Age: 35 Posts: 89 Trader Rating: (0) Feedback Score: 0 reviews	It never hurts to test it,I would just for the ease of mind ya know

11-10-2013, 04:10 PM	#7
Frank_Jaeger Zilvia FREAK! Join Date: Jan 2012 Location: Port Charlotte, Florida Age: 32 Posts: 1,352 Trader Rating: (1) Feedback Score: 1 reviews	Post a video. I'd be more concerned about piston-valve contact due to bad timing.

11-10-2013, 07:47 PM	#8
jam24.0s13 Join Date: Jan 2013 Location: Corona CA Age: 29 Posts: 21 Trader Rating: (0) Feedback Score: 0 reviews	Well I did the spark plug test and sure enough when I pulled the plug for cylinder 4 it stoped making the knocking noise. So rod knock there? Well even if the compression is low doesn't really matter since I'll be switching out the block and putting the s14 block and bottom end on it. And I know timing is spot on. I've done it dozens of times and quadruple check it and have other people check it as we'll just in case. If it was a timing problem and I had bent valves it would of bent them on the first time I cranked it and had it running like shitx but it ran fine for that day and day after.

11-14-2013, 10:30 PM	#9
killakees Join Date: Nov 2013 Location: south bay Age: 29 Posts: 17 Trader Rating: (0) Feedback Score: 0 reviews	Compression test you would know if you had a rod knock if you heard it more than likely the spark plug or wire as you said Sent from my iPhone using Tapatalk

11-15-2013, 12:25 AM	#10
jam24.0s13 Join Date: Jan 2013 Location: Corona CA Age: 29 Posts: 21 Trader Rating: (0) Feedback Score: 0 reviews	i dont see how a compression test would define if i had a rod knock. correct me if im wrong but the pistons rings can still be in okay condition even with a rod knock... ive seen people replace just the bearing on the crankshft journals for the connecting rods and the engine ran fine again so there is no direct relation between compression numbers and a rod with excessive clearance that it is slapping around on the crank.. right...?

01-15-2020, 06:20 AM	#11
Lex Zarza Join Date: Aug 2019 Location: Arizona Age: 29 Posts: 19 Trader Rating: (0) Feedback Score: 0 reviews	Question I do have a knock rod was wondering if it’s okay to replace just the bearings on a stock KA. it never had a turbo or anything like that. I am planing to fix the problems buy just replacing the crank bearings some guidance would be helpful.

01-15-2020, 09:30 AM	#12
inferno s14 Zilvia Junkie Join Date: Sep 2008 Location: QUEENS, NY METS STADIUM Age: 34 Posts: 489 Trader Rating: (8) Feedback Score: 8 reviews	sure you can - if the piston or piston's didn't slap against the cylinder hard enough to score it or if the crank is good condition for a new bearing. if the crank is scored you need to smooth it out or it will chew your new bearings up.

01-15-2020, 07:38 PM	#13
Kingtal0n Post Whore! Join Date: Jul 2005 Location: South Florida Age: 41 Posts: 4,828 Trader Rating: (17) Feedback Score: 17 reviews	the engine is designed to be rebuilt and serviced by the fsm if you follow the fsm you might be fine. the most difficult part novices with this exact situation have seems to be cleanliness. in my opinion, do not expose the engine to the atmosphere for long and do not open the engine where outside air which contains pollen and fungus everywhere in the world can enter it easily. finally more important than anything, do not overlook a single grain of sand, not a tiny crumble or morsel of anything can be inside the engine or it will clog oil orifices.if you see any material the whole thing needs to be dismantled and cleaned. or cleaned somehow where it is good luck.