91pathmkr Posted April 6, 2009 Share Posted April 6, 2009 i recently rebuilt my 91 vg30e, bored .020, ballanced crank welded the snout, all new bearings, seals etc. I primed the oil pump, put the plugs in and fired it up, it ran like the crap at first but after a few start ups it ran like new. then one night it didnt build oil presure for about 30 sec or so and ever since it has a knock after 3k that sounds diesel like when rpms are held steady. if i adjust the timing it goes away but so does the power, im thinking its a lifter but since it goes away with timing im not sure. could it be a sensor somehow messing ignition up? PLEASE HELP!!!!! Link to comment Share on other sites More sharing options...
94extreme Posted April 6, 2009 Share Posted April 6, 2009 count the teeth on the t-belt between the cams... or you could be off by not being fully TDC when you put everything together... check that oil pump ASAP.. you need oil moving around otherwise you're killing that brand new motor already. Link to comment Share on other sites More sharing options...
91pathmkr Posted April 6, 2009 Author Share Posted April 6, 2009 count the teeth on the t-belt between the cams... or you could be off by not being fully TDC when you put everything together... check that oil pump ASAP.. you need oil moving around otherwise you're killing that brand new motor already. im taking the timing cover off to check everything, i just installed an oil pressure gauge, mechanical not electric, the kit came with a new oil pump and my worst fear is that it doesnt work properly but the dummy light goes off right after start up and well im still figuring out the gauge. it idles perfectly so im confused, it sounds like detonation or a crushed lifter but im not sure. ill check all the timing and let you know. Thanks Link to comment Share on other sites More sharing options...
91pathmkr Posted April 6, 2009 Author Share Posted April 6, 2009 count the teeth on the t-belt between the cams... or you could be off by not being fully TDC when you put everything together... check that oil pump ASAP.. you need oil moving around otherwise you're killing that brand new motor already. oh when i installed the timing belt there 40 teeth from cam to cam and 43 to crank. Link to comment Share on other sites More sharing options...
Channel595 Posted April 10, 2009 Share Posted April 10, 2009 are you sure its a knock from detonation or from metal contact like rod? as far as the oil light goes i wouldnt worry about it since it turns off quickly, need heavier oil? Link to comment Share on other sites More sharing options...
91pathmkr Posted April 19, 2009 Author Share Posted April 19, 2009 are you sure its a knock from detonation or from metal contact like rod? as far as the oil light goes i wouldnt worry about it since it turns off quickly, need heavier oil? well i thought it was a lifter, more like i hoped. but it started getting worse. i put an electric oil gauge on and found that the oil pressure was bleeding off after start up. down to 4psi at idle, so i tore it all apart again and every bearing, main and rod were scratched to hell and took it to the machine shop, FYI it only had 100 easy miles on it since the rebuild, everything had 2-3 thousanths cleareance when it was put together and at first it ran better than it ever had before. the machinest was baffled at first then spotted a bearing with a slight flat spot and said it was caused by detonation. i have never heard of detonation killing an engine that quickly, especially how i drove it. so now that im rebuilding it yet again, how do i pull more reliable power out of the little f-er? Link to comment Share on other sites More sharing options...
SouthTexasOffRoad Posted April 23, 2009 Share Posted April 23, 2009 I have a 95 Pathfinder and it started making a knocking sound along with rough idle.. I traced the problem down to the clucth on the A/C compresser so try to Oil that with spray lube or light motor oil if thats not the problem i would have a shop look at the motor to avoid future problems from the knocking Link to comment Share on other sites More sharing options...
veilside180sx Posted April 24, 2009 Share Posted April 24, 2009 are you sure its a knock from detonation or from metal contact like rod? as far as the oil light goes i wouldnt worry about it since it turns off quickly, need heavier oil? Just find a 3.3 shortblock, then don't have to worry about that. Link to comment Share on other sites More sharing options...
GrimGreg Posted April 24, 2009 Share Posted April 24, 2009 the machinest was baffled at first then spotted a bearing with a slight flat spot and said it was caused by detonation. i have never heard of detonation killing an engine that quickly, especially how i drove it. so now that im rebuilding it yet again, how do i pull more reliable power out of the little f-er? Lucky the piston was in one piece. The first time I ever worked on a car was my Step-Dad's Citation when I was 9(I did the work, he just stood back and told me what to do), it had a detonation that blew a dime sized hole through the top of one of the pistons. Link to comment Share on other sites More sharing options...
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