Think my engine has kicked the bucket.

[drifter808]

I have been hearing a knock in my engine lately at idle and it was never that bad. Well when i was driving it to day i noticed that my SAFC II was reading 4 on the knock rating. I drove for about another hour and it went up to 25. The knock at idle is a bit louder but i dont notice any driving differences. Does anyone know if this is the time to rebuild cause i have all the stuff to do it.

[smithers584]

i wouldnt rebuild it for just that reason, my car knocks sometimes up that high but it always comes down, usually when it gets real warm, but after i start to give it gas and drive to cool it down the knock goes down. or if i let it idle for a while like in traffic it will do it, but still performs great. maybe upgrade your radiatior and work out some cooling issues.

[fliprayzin240sx]

well, pop the hood while the engines running and try to pinpoint if the knocking sounds coming from the bottom end. Slowly rev the engine higher and listen to the engine...if the knocking noise goes up with the RPM then its your rods knocking and your rod bearings are DONE. Knock on the SAFC doesnt read physical "knock" of the rod, it reads the detonation in your cylinder when you go lean.

[drifter808]

Yeah when im listening to the engine at idle i can hear a knock in the bottom end. It sounds like mostly in the front of the engine. When i rev up the engine it will go away by about 1500 to 2000 rpms and after that my exhaust is to loud so i cant hear much of anything else. i dont notice any difference in noise when driving but when i did start it up today it was smoking some blue smoke which it has never done. Another reason i suspect that its knocking is cause when i first got the engine the turbo was seized and the oil pump was done for. Who knows how long it was driven like that before me. So maybe that started premature bearing failure. I'd also like to rebuild it so i can have a fresh engine to start with and not some second-hand, raced all the time engine. Thanks for the replies, and smithers, i am running a Koyo radiator and it never got hot on me once, and where did it say i had cooling issues?

[smithers584]

Yeah when im listening to the engine at idle i can hear a knock in the bottom end. It sounds like mostly in the front of the engine. When i rev up the engine it will go away by about 1500 to 2000 rpms and after that my exhaust is to loud so i cant hear much of anything else. i dont notice any difference in noise when driving but when i did start it up today it was smoking some blue smoke which it has never done. Another reason i suspect that its knocking is cause when i first got the engine the turbo was seized and the oil pump was done for. Who knows how long it was driven like that before me. So maybe that started premature bearing failure. I'd also like to rebuild it so i can have a fresh engine to start with and not some second-hand, raced all the time engine. Thanks for the replies, and smithers, i am running a Koyo radiator and it never got hot on me once, and where did it say i had cooling issues?

you didnt mention any of this or else my post would have been different, but that is a very commom problem with sr20dets without an upgraded radiator. SAFC II shows knock when my motor starts to get heat soaked, i just havent decided to upgrade my radiator yet.

[drifter808]

Well i pulled out my engine over the weekend and teared it down and found no signs of worn bearings. I even had a machinist look at them and he said that everything lloks pretty good. I just assembled it back up today and got it running about an hour ago. It is still knocking but runs fine. I have changed the knock sensor and no change. What else can be causing my engine to knock? On the SAFC II it will begin to show knock after the engine has been running for a little while. Just idling to, not underload. I am just out of ideas on what this can be. I really dont want to take this to a mechanic. Smithers, how much knock does it show when you get heat soak? Thanks for the replies, any else know what this could be? its my daily driver and need to get back on the road.

[smithers584]

in the summer time here in SC my fans turned off due to wiring, and when the temp gauge was going up it would go no higher than 30. my mechanic says that its fine though as long as everything runs fine. a knock sensor is just a microphone looking for specific noises, just cuz it picks up noises doesnt mean your engine is knocking. mine usually when it idles will sometimes read a little knock like yours, but once i start driving its fine. it could be a little lean or that my radiator is not cooling well enough, but it doesnt matter that much, my buddy at the shop said dont worry, he gets like 200 on his knock sensor when he sprays NOS. im not going to worry till its a everyday thing and starts reading very high, like over 100.

[drifter808]

Well on the monitor setting display it will read 0 and when im driving it for a while it will just start going up. The highest it got so far was up to 25 then it started to back down to about 16 when driving. When i would go over to the settings menu and llok at knock setting it would be going up to. I've seen that one go up to about 170. I noticed today when driving that when i would go up higher in the rpms it would go down and when i let off the gas to slow down the numbers would go up. Maybe it is just running a little lean or getting heat soak cause im only running the SMIC. The engine still runs great and pulls real strong. I dont notice any kind of decrese in performance at all. I do still hear that little bit of a knock at idle though. Mybe its nothing to worry about. Anyone else have any insight on this issue. And thinks again Smithers

[smithers584]

yeah mine does the same thing, i looked into it as much as possible and finally jeff from epik said it was probably do to heat soak and not to be concerned with the numbers unless they got real high. probably due to the side mount. ive got a greddy vspl but stock radiator so i think thats my problem.

[drifter808]

Ive been talking to some big time 240 guys and they recommend me fixing the bottom end. Since there really is an audible knock there i dont want it to get worse so im throwing in another bottom end tomorrow. I'll let you know the results. It should be done by around saturday. Also mine will show knock about 2-3 minutes after start up so i dont think thats heat soak and i had been driving it for about 5 months before this happened and the knock sensor never moved once. Thanks for the advice though.

[SochBAT]

I beat you.

Im running on 2 of 4 cylinders.

beat that hot shot!

[Flybert]

If you're SAFC2 is calibrated properly, 25 knock after the oil has warmed up is normal. When I have experienced true knock or pinging, it will read 50 and above. I've hit 120 before at the track on a summer day so I through in some 100 octane and I was good to go.

[drifter808]

well the engine is rebuilt as of friday afternoon. I threw in my newly rrebuilt block and an Apexi headgasket and the engine has never run better. Really smooth and alot of nice power. Alot more in the low end then before. The SAFC2 is still reading knock but now i at least have no audible knock of any kind so it must be normal so i ain't messin with it again. And Sochbat, you cant beat me there but i was running on 3 cylinders once since i blew a hole in the number 4 piston. But that was along time ago now. Thanks for all the advice and i am now gonna concentrate more on driving then monitoring the damn SAFC. Thanks, Derek