hessianben Posted March 30, 2010 Report Share Posted March 30, 2010 Ok- here's another brain-teaser for the Datto-whizzes... I was driving the 521 today, and it was running strong- when, during braking for a stoplight, the engine shut down. I coasted to a stop on the side of the road, and tried to crank it over- -the noise it made was a "REEEEEEEEIEEEEEEEIEEEEEEE" made by the starter. didn't sound like any compression was being made. however, the crank pulley WAS turning while cranking. i removed the valve cover and turned the engine over- the cam pulley WAS turning, BUT, the camshaft was not!!! I apologize, the video doesn't have audio- the camera was crap. seems that the dowel that turns the cam, slipped all the way into the cam gear, and stopped turning the cam. Is this a common problem???? seems like that dowel, as important as it is, should be locked in place ??? Well, since now the engine is out of time, seems like a good time to rebuild anyway. needs some rings! Quote Link to comment
datzenmike Posted March 30, 2010 Report Share Posted March 30, 2010 The dowel may have sheered off? Hope the intakes haven't hit a piston top. Was the cam sprocket retaining bolt loose???? Quote Link to comment
hessianben Posted March 30, 2010 Author Report Share Posted March 30, 2010 sprocket bolt wasn't loose. dowel was intact with no sign of stress. i don't know about valve and piston health yet.. Quote Link to comment
banzai510(hainz) Posted March 30, 2010 Report Share Posted March 30, 2010 sprocket bolt wasn't loose. dowel was intact with no sign of stress. dowel was intact???????? the dowel has to move the cam. Im misunderstanding something? the dowel is STILL in the cam right? looking at the vid I think the dowel would be sheard off. or is pushed in far in to the cam that it not turing it. I would get that timming chain tool and pop that head off. and ck pistons. Quote Link to comment
RoadRace Posted March 30, 2010 Report Share Posted March 30, 2010 i thought i was the only one that this could happen too!! CRAZY - it happened to me as well. the dowel pin got pushed deep into the cam. but the cam casting was cracked around the down pin. it was a brand new cam and i didn't look very closely at the dowel pin as it was already installed in a new cam, so i don't know if it came like that in the first place. but yeah, it moved back and it bent a couple valves, one intake and 2 exhaust. i replace the guides and everything else when i had it apart, but what a pain in the ass!! Quote Link to comment
banzai510(hainz) Posted March 30, 2010 Report Share Posted March 30, 2010 If pistons OK and not too bad swap another head to get back to driving soon. Quote Link to comment
hessianben Posted March 30, 2010 Author Report Share Posted March 30, 2010 The dowel slid all the way into the cam sprocket- the hole in the cam itself is empty!! well, i needed to rebuild the bottom end anyway, so here i go! anyone got an L20 rebuild setup? pistons, rings, bearings, ect...? pm me :) as far as valves, it's likely that some have hit pistons, so, I'll probably be rebuilding that head as well. poo. Quote Link to comment
datsunaholic Posted March 30, 2010 Report Share Posted March 30, 2010 The dowel pin is driven into the cam. I've never seen one come out. But even if the dowel was loose, the cam sprocket shouldn't spin... the sprocket bolt is supposed to have a lot of torque put on it. The bolt had to have worked loose, which caused the sprocket to rock, and worked the dowel pin loose and then it fell "out" of the cam and into the sprocket and since the sprocket was loose it just spun. But that's just my theory. Quote Link to comment
datzenmike Posted March 31, 2010 Report Share Posted March 31, 2010 Anyone notice the retaining bolt and pump eccentric are not turning??? Bolt can't be very tight. Should be 90 - 110 ft lbs!!!!! Quote Link to comment
hessianben Posted March 31, 2010 Author Report Share Posted March 31, 2010 yeah, noticed that- the bolt was pretty snug, but def. not 90ft/lbs !!! I didn't do the final torque on that- i picked it up from the machine shop thinking it was ready to go...? should i assume that nothing is to spec from a machine shop? :( ? i mean, i did a valve lash adjust before installation, but i assumed the cam towers would be to spec as well as the cam. that's what i get for ASSuming... beh. Quote Link to comment
datsunaholic Posted March 31, 2010 Report Share Posted March 31, 2010 i picked it up from the machine shop thinking it was ready to go...? should i assume that nothing is to spec from a machine shop? :( ? You got the entire engine assembled from the machine shop? Usually they just give you the parts and you have to do the assembly yourself. I mean, if you just got the head, you'd have to take the cam sprocket off to reinstall the timing chain. Quote Link to comment
RoadRace Posted March 31, 2010 Report Share Posted March 31, 2010 yeah, noticed that- the bolt was pretty snug, but def. not 90ft/lbs !!! I didn't do the final torque on that- i picked it up from the machine shop thinking it was ready to go...? should i assume that nothing is to spec from a machine shop? :( ? i mean, i did a valve lash adjust before installation, but i assumed the cam towers would be to spec as well as the cam. that's what i get for ASSuming... beh. when i put mine back together, 110 lbs and loctite. Quote Link to comment
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