Justin Tawney Posted August 4, 2014 Report Share Posted August 4, 2014 so got my l20b in my 70 521 running good and driving only drove it around the block like 3 or 4 times and had it idling a little bit a few times. until I put on the weber ran for about 20 seconds amazingly!!! then started clunking really loud.. took off the intake and exhaust manifolds the valves looked good took out the spark plugs vacuumed out the cylinders thought there was a nut or something in one cranked it over no noise cranked just fine put the spark plugs back in cranked it over and the clunk clunk clunk was back.. did some reading found out it could be the main bearing or other crankshaft bearings? any idea on if its something else? I really don't want to pull the engine again and tear it apart. just got it in and running about 2 months ago. any help will be very greatful thanks. Quote Link to comment
datzenmike Posted August 4, 2014 Report Share Posted August 4, 2014 When it started clunking were you driving it or just idling? When you cranked it over with the plugs back in, were you just cranking or did you have the manifolds on and trying to start it??? Quote Link to comment
Justin Tawney Posted August 4, 2014 Author Report Share Posted August 4, 2014 just idling . no the manifolds were still off just checking to seeif the noise was till gone Quote Link to comment
datzenmike Posted August 4, 2014 Report Share Posted August 4, 2014 Try one spark plug at a time. The cylinder that causes the clunk has a loose rod cap. Do not run the engine until this is fixed. Quote Link to comment
Justin Tawney Posted August 19, 2014 Author Report Share Posted August 19, 2014 took off the oil pan went to go get new rod bearings then realized there are different sizes. don't know what the engine is out of just know its an l20 lol. I ordered the standard size for the l20 they'll be in tomorrow hopefully they're right so I can put em in when I get off work tomorrow and get her runnin again (; lets see what breaks on me next!! Quote Link to comment
Justin Tawney Posted August 19, 2014 Author Report Share Posted August 19, 2014 got all the rod caps off the bottom bearin s look good the second one has a little bronze color on a spot on the side of it haven't seen the other side yet. Quote Link to comment
Justin Tawney Posted August 19, 2014 Author Report Share Posted August 19, 2014 I want to thank everyone who has helped me on here. I started out not knowing what a dead battery sounds like to now being able to change the rod bearings with engine still in because im too lazy to pull the engine again lol. ive asked a lot of stupid qestions but you guys have helped me go far with this project. Quote Link to comment
scooter Posted August 19, 2014 Report Share Posted August 19, 2014 While your in there you might as well roll some new main bearings in too. Just remember to set the thrust bearing before torquing!!! Quote Link to comment
zed Posted August 19, 2014 Report Share Posted August 19, 2014 I'm no expert, but wondering how you know if the oil clearance - the gap between the rod bearing and the crank - is right? As an amateur, I always use locktite on rod bolts, main cap bolts.. Quote Link to comment
datzenmike Posted August 19, 2014 Report Share Posted August 19, 2014 If you have a standard crank and standard bearings they are never going to have too little clearance. The crank might wear smaller but it won't become larger. If your rod bearings have worn down replacing them with new ones will only bring the clearance towards perfect. never hurts to check them though. Plasti-gage is a small strip of plastic you place on the bearing cap bearing. Torgue to speck and the plastic is crushed flat. The width is checked against a series of comparitive wisths on the package that tell yo ythe clearance. 1 Quote Link to comment
Justin Tawney Posted August 20, 2014 Author Report Share Posted August 20, 2014 i got the standards. pt them in and it still clunks.. I put one spark plu in and when the piston is at tdc it clanks. does it for every cylinder. with no spark plugs in it doesn't make a sound.. could it be a valve clunking on the piston? the timing is right in cylinder 1 at tdc intake and exhaust valves are both closed. something in the cylinder? I really don't want to the head off to see. I never get the chain to stay in place and half to take the chain cover off too. Quote Link to comment
datzenmike Posted August 20, 2014 Report Share Posted August 20, 2014 Exactly which brand and range of plug are you using? Quote Link to comment
Justin Tawney Posted August 20, 2014 Author Report Share Posted August 20, 2014 ngk orielys said the are the ones I need look like my old ones and it ran fine with them before. when the noise started it ran smoothly then am a clunk appeared. not gradually. like something broke. but all the valves are closed tight I tested with a vacuum on the intake and exhaust with the lug off. all of them sealed Quote Link to comment
datsunaholic Posted August 20, 2014 Report Share Posted August 20, 2014 All 4 cyls clunk? And only with spark plugs in? Are you turning the engine with the starter or by hand? Can't be valves, they'd make noise irregardless of compression. Same for something in the cyls. Bearings, mains won't make that noise. Rods would, but all 4? And you'd be able to feel that- they'd be loose when assembled. Hell, maybe the flywheel is loose. I'm grasping here. Quote Link to comment
datzenmike Posted August 20, 2014 Report Share Posted August 20, 2014 You need an NGK BP6E for your L16. There are several for different L 4 engines but basically all will have that E in the number. E is for thread depth which in this case is 19mm or 3/4". What plugs do you have in it??? Quote Link to comment
scooter Posted August 20, 2014 Report Share Posted August 20, 2014 Don't locktite rod bolts. Torque with oil on them. Same with main bolts. I think you should take it right apart. Quote Link to comment
Justin Tawney Posted August 26, 2014 Author Report Share Posted August 26, 2014 it was the fly wheel bolts. they were all about a quarter turn too loose now I need to find my oil plug fill it with oil and fire it back up. Quote Link to comment
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.