280Zen Posted March 9, 2005 Share Posted March 9, 2005 I think my l28 na has rod knock, I hear a knock increasing as rpm range goes up but only while the engine is cold, after warmup the engine sounds normal. I read the best way for me to determine this would be pull each spark plug wire one at a time while the engine is idling (while its cold and the knocking sound can be heard) I guess my question would be if this is the case can the bearing be replaced without a engine pull and tear down? Quote Link to comment Share on other sites More sharing options...
SHO-Z Posted March 9, 2005 Share Posted March 9, 2005 I have never heard of a rod to quite knocking after warm up. A rod will knock no matter what the temperature. Lifters will knock when cold sometimes. A cracked piston skirt will also make a slight knocking noise when cold. It sounds like something in the valve train to me. As for rod repair without rebuild. Years ago you could get a rod journal ground in place. The last time that I saw this done was over 30 years ago, showing I am and OLD FART. Quote Link to comment Share on other sites More sharing options...
280Zen Posted March 9, 2005 Author Share Posted March 9, 2005 Hmm, Lifters? as in hydraulic lifters? well if the head was a p90a then yea but this is a p79 so I guess I keep looking ah well, this ought to be a good learning experience for me. I do know its burning about a quart of oil every 3 to 4000 miles. Someone did suggest that the oil pump could be going bad and the engines not getting the oil it needs till things warm up? don't know, im still new at all this. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted March 9, 2005 Share Posted March 9, 2005 Sounds like piston slap to me. Piston slap generally is really bad when cold, and noisiest when just barely giving throttle. Quote Link to comment Share on other sites More sharing options...
Drax240z Posted March 10, 2005 Share Posted March 10, 2005 Adjust your valves correctly before doing anything too rash. Quote Link to comment Share on other sites More sharing options...
Z-Gad Posted March 10, 2005 Share Posted March 10, 2005 Had a head drop a valve seat once...I had similar issues. I guess when the head and valve seat expanded from the heat, the seat would stay in place. When the engine was cold, I would get a bunch of clatter from as loose valve seat. Quote Link to comment Share on other sites More sharing options...
280Zen Posted March 10, 2005 Author Share Posted March 10, 2005 Mike, Now you know Im gonna ask you what you just said in laymans terms and then ask you how I would go about testing and fixing that! of course im still planning on at some point replacing the valve seals but time has been a issue the past month or so. PS. Mike hope is was ok to give Ken Jones your number, he had something he needed to call you about. Quote Link to comment Share on other sites More sharing options...
Z-Gad Posted March 10, 2005 Share Posted March 10, 2005 Yep, all good Regarding testing the valve seats, well, there really is no way w/o disassembling the head... I mean you should be able to tell from the noise whether or not it is coming from the head area, or from the block area. Quote Link to comment Share on other sites More sharing options...
280Zen Posted March 10, 2005 Author Share Posted March 10, 2005 Mike, you know Im just trying to get away from pulling that engine till I have the 3.0L built, hopefully will be buying pistons this month, then I will be contacting you about the shop you had the block done at. Quote Link to comment Share on other sites More sharing options...
Z-Gad Posted March 10, 2005 Share Posted March 10, 2005 Maybe we should gauge interest in a group buy... I believe Clark will be in need of a set of forgies as well. Maybe I could swinhg by tomorrow night and check out the sound and see if we can figure out where it is coming from... Mike Quote Link to comment Share on other sites More sharing options...
Guest 73Turbo240z Posted March 11, 2005 Share Posted March 11, 2005 sounds like piston slap IMO... the b230's i used in my volvo were notorious for it... Quote Link to comment Share on other sites More sharing options...
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