Freshly built ls1 knocks
Freshly built ls1 knocks I fired up my freshly built ls1 and immediately shut it down. It had a significant knock and the oil pressure did not pick up. It is an aftermarket guage and sender, so if it was just the low oil pressure, I wouldn't be so concerned, but with the knocking, I am very concerned. This is going into a 56 chevy. I have had the computer programmed and the harness is custom as well.
Could I have assembled or installed the oil pump incorrectly? Could it have anything to do with the computer if it was programmed incorrectly?
Yes, there is oil in it.
Ideas/suggestions are greatly appreciated
Could I have assembled or installed the oil pump incorrectly? Could it have anything to do with the computer if it was programmed incorrectly?
Yes, there is oil in it.
Ideas/suggestions are greatly appreciated
Found the problem for no oil pressure Ok, in my infinite wisdom, I thought that the two ports above the oil filter were for an external oil cooler and since I didn't have the little part that bolts to the oil pan, I used a block off plate! Thus completely starving my brand new ls1 of oil! What an idiot.
So, I got the part from a salvage yard and got it put back together(enough to crank it, complete minus waterpump and accessories).
Fired right up and idles fine, but when I touch the throttle, it kind of stumbles and knocks.
Sounds like it's too late doesn't it?
If so, what can I expect to have damaged and to have to replace when I tear it open.
So, I got the part from a salvage yard and got it put back together(enough to crank it, complete minus waterpump and accessories).
Fired right up and idles fine, but when I touch the throttle, it kind of stumbles and knocks.
Sounds like it's too late doesn't it?
If so, what can I expect to have damaged and to have to replace when I tear it open.
well if you have starved it of oil the the main bearing should be gone witch also means your crank will have to be redone. also a possibility of ruined rod bearings/ rods, and lots of other stuff.
as long as your learn from your mistakes it's OK. don't take it hard on yourself.
good luck, i wish you all the best.
as long as your learn from your mistakes it's OK. don't take it hard on yourself.
good luck, i wish you all the best.
Yeah, I expect a full bottom end rebuild (main/rod bearings and crank probably turned). Do you think damage has been done to any of the top end?
I started the engine twice with the oil supply blocked, for a total of no more than 5 or 6 seconds. Now with the oil flow issue taken car of, it will fire up and idle fine, but starts making knocking noises when the throttle is pressed.
What is the likelyhood of cylinder, valve, lifter, roller, cam/cam bearings etc damage? I'm hoping that I can get by with just a lower end rebuild. What do you think?
I've got the engine out of the car and will open it up on Monday.
I started the engine twice with the oil supply blocked, for a total of no more than 5 or 6 seconds. Now with the oil flow issue taken car of, it will fire up and idle fine, but starts making knocking noises when the throttle is pressed.
What is the likelyhood of cylinder, valve, lifter, roller, cam/cam bearings etc damage? I'm hoping that I can get by with just a lower end rebuild. What do you think?
I've got the engine out of the car and will open it up on Monday.
TECH Addict
Joined: Dec 2001
Posts: 2,907
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From: Bergen County, NJ
It's not a good sign but there is generally more heat, stress, and speed on rods and crank (cam and all associated parts are turn at half speed). With luck, you only scored up the bearings and might catch a break.
For what it's worth, I keep a little pad in the shop and jot down questions on things I am not sure of and then when I take a break I post up the questions, much better than getting the answer after I have broken something or put it back together.
For what it's worth, I keep a little pad in the shop and jot down questions on things I am not sure of and then when I take a break I post up the questions, much better than getting the answer after I have broken something or put it back together.
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If it only ran for 5 or 6 seconds, and started knocking, I think you had problems that good oil pressure wouldn't have prevented anyway. You probably didn't run it long enough to hurt the top end but something wasn't right with the bottom end to start with.
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kind of what i was thinking, unless absolutely no assembly lube was used... i've seen assembly lube save somebodies *** before and ran damn near twice as long as he did with no oil pressure. (no problems)
5-6 seconds i doubt is going to cause enough heat to damage anything real good... are you sure your not hearing piston slap? if you have good oil pressure now id take it up to temp and see what happens if it were mine... i mean if its only 5-6 seconds starting without oil.... the lifters are going to be noisy, possible piston slap(especially hear this when you step on the throttle) but i doubt you have spun a bearing. you may have shortened their life? but they should be fine for now. and if you did mess up a bearing id just start with new stuff anyway (aka STROKER). maybe take it up to temp and see what happens? i would, but hey its not my motor....
Hate to say it man, but there definitely is a chance that you may have hurt something... A knock is never good even if only for a few seconds.
However, all of the bearings should have been prelubed so 5 or 6 seconds hopefully didn't hurt anything. Get the oiling problem figured out, fire her again and see what happens. If you have oil pressure but she's still knocking, obviously, you will have to rebuild but maybe (hopefully) you'll be okay and she'll quiet down.
However, all of the bearings should have been prelubed so 5 or 6 seconds hopefully didn't hurt anything. Get the oiling problem figured out, fire her again and see what happens. If you have oil pressure but she's still knocking, obviously, you will have to rebuild but maybe (hopefully) you'll be okay and she'll quiet down.
When I fire it up now, oil pressure is about 45psi at idle and it idles fine(I can hear a little tapping noise, but not much). When I try to rev the engine it kind of bogs down and knocks. It won't really rev up. Kind of reminds of a distributor style engine that it way out of time.
I've already yanked it out of the car and will open it up tomorrow to take a look. I will also double check to make sure that the timing gears were set properly.
I built the engine myself and was very careful to prelube everything, but then other projects came up and the engine sat for about two years before I was finally able to get it into the car. I have built several older style engines, but this was my first LS/Gen III build, so I'm kind of learning as I go.
I've already yanked it out of the car and will open it up tomorrow to take a look. I will also double check to make sure that the timing gears were set properly.
I built the engine myself and was very careful to prelube everything, but then other projects came up and the engine sat for about two years before I was finally able to get it into the car. I have built several older style engines, but this was my first LS/Gen III build, so I'm kind of learning as I go.
Opened it up today and it looks great. No damage to the main or rod bearings or to the crank. Everything is smooth and clean with no gouges or significant scratches in the bearings. I had a friend that is a mechanic come by and look it over just to make sure and he also agreed that everything looks fine.
I've got it mostly back together and hopefully I will be able to get it back in the car tomorrow and see how it runs.
I've got it mostly back together and hopefully I will be able to get it back in the car tomorrow and see how it runs.
so what was the problem ?
why did it knock ?
did it throw any codes?
you got very lucky with the bearings. you must of felt very happy when you saw that shiny piece of metal. good luck
why did it knock ?
did it throw any codes?
you got very lucky with the bearings. you must of felt very happy when you saw that shiny piece of metal. good luck
I do feel very fortunate! I did lube it very well when I assembled, so that is probably the only thing that saved me.
The only code that I am getting is p1518.
The initial knock was definitely due to the oil supply being blocked. Once I fixed that it would only knock when I tried to rev the engine. That is still an unknown and will probably still be an issue. Internally, everything looks good. I even plastigaged the main and rod bearings again just to make sure that the clearances were all within specs and they were.
The only code that I am getting is p1518.
The initial knock was definitely due to the oil supply being blocked. Once I fixed that it would only knock when I tried to rev the engine. That is still an unknown and will probably still be an issue. Internally, everything looks good. I even plastigaged the main and rod bearings again just to make sure that the clearances were all within specs and they were.
After doing some research, it appears that the 1518 code is related to the TAC module...isn't that only used for DBW throttle bodies? I am using a cable driven (non-electronic) t-body.
Could my PCM be programmed for a DBW setup? Could this be why the engine bogs down and won't rev?
Could my PCM be programmed for a DBW setup? Could this be why the engine bogs down and won't rev?
