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Bent valve?


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A vacuum leak allows air in to replace what should be your fuel mixture, so the engine goes lean.  Then it diesels and stalls.  Fix ALL the vacuum leaks before starting the engine again, or you WILL be pulling the head soon.  

A loose rocker is what you were supposed to be looking for when you pulled the valve cover.  Get a manual and read it until you understand what to look for.  If you're looking at parts that you can't identify and don't know why they are there, what are you expecting to find?  Start by figuring out "valve lash" and what lash pads are.  

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if the rockers are slightly loose when the cam lobe is up that is a good sign the valve is closing.



be honest I don't think its a head gasket. It tales a long time at idle to build up pressure esp with a motor that don't run right.


it was a to dramatic of a change that it stopped running right.


Buy some Cheetos and get naked and watch this on the timming chain to see if the cam and motor is timed its simple.

Most cases the chain is fine just the Chain tensioner and slack side guide take the most wear. I seen a chain off a tooth and it still runs.


also you check the distributor if loose and turned out of time like the bolt loose.

Edited by banzai510(hainz)
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first thing you need to do before another single thing is fix the vacuum leak. then, put a small amount of oil in each cylinder. then do a compression test. twice on each cylinder to verify accuracy. then record the results. make sure the motor is warmed up when you do the test. you need to hold the throttle to the floor as you spin the motor to ensure the motor is producing accurate compression. also, don't forget to unhook your coil wire before you start the compression test. it will either end in a fire-y mess or the motor will start running. while you have the plugs out, grab a few pics and post them here. there are plenty of people here with insight if you send us a few pics. plugs can tell you a lot about how a motor is running. keep track of which plugs came out of which cylinder, it will help you identify which cylinder or isn't firing. check the oil in the motor. what's it look like? if it looks like chocolate milk, you probably have a headgasket gone bad. your valves & rockers are supposed to have slack between them. It probably could use a tune up, but its not for an amateur, take it to someone who KNOWS how to set valve lash. I happen to have access to 2 ASE certified mechanics of 20+ years when i need help or insight, (dad and grand dad) but we are not all so lucky.

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Side note I did wanna pull it apart at some point so either now or later but I do wanna do an overbore and small block flat top pistons and get a little more power I don’t know if that’s familiar with you guys or not but a local mechanic brought it up

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3 hours ago, Scrapson said:

I can get naked and watch that tonight when I get off work.


More information than we wanted to know....


2 hours ago, Scrapson said:

 I do wanna do an overbore and small block flat top pistons and get a little more power I don’t know if that’s familiar with you guys or not but a local mechanic brought it up


Find another mechanic, and forget anything about a small block.

Flat top pistons, OK,

but forget small block mentality,

and shy away from anyone who has never worked on a Datsun, and prays to a chevy bowtie every morning.

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4 hours ago, Scrapson said:

..... and I’ll put the timing chain and stuff back on to do a compression test. 




W in T F ??????? You couldn't have taken the timing chain off the engine. Do you mean you took the timing chain off the cam sprocket?????

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2 hours ago, datzenmike said:




W in T F ??????? You couldn't have taken the timing chain off the engine. Do you mean you took the timing chain off the cam sprocket?????

Yes I took it off the cam sprocket. I’ll post photos here in a second of the plugs and where the tensioner is missing. 

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The tensioner is now out because you took the chain off the sprocket without properly securing it first.




Now you have to take the entire front off your engine to fix this. Don't run the engine or this...



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There are marks on the head from the chain slapping onto it which explains the rattle noise I could never find which occasionally happened. I’m going to watch that video I got Cheetos but I don’t think I’m getting naked and watching it. 

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So the guy I bought it from said it was “rebuilt” but something tells me he wasn’t being honest. I also don’t know how much it would make a difference considering all the backfiring and misfires before I got it to run at all to get it home which side note was sketch as all get out. I opened the links so anyone can see it I thought they were. I don’t have time to run a compression test because I got work till 8 and little sister goes to bed at 8 I think it’s not necessary to pull the head but I do want too just know how it looks inside and replace it because the shotty work on it. Also timing chain, tensioner and rails are like $60 I mine aswell pull the top end off and the front since I am there. 

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I posted 2 pictures of the timing chain above. That's what it looks like. Might as well pull it all off and replace everything. The kit should have the two guides, ( tension and slack side) the two sprockets, (crank and cam) the tensioner and the chain itself. You don't have to take the head off to do this.


Plugs look good.They should be BP6ES no (R) resistor plugs.

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60 $ for a timming Kit? sounds to cheap unless you got very lucky for a Japan made timming kit.. Make sure you get the Japan made one with the brite links on the chain


PS your motor has a tensioner in there. otherwise the oil would run out the tensioner hole.


I cant see your photos

Edited by banzai510(hainz)
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Probably mold or casting revision number. In order to cast heads in the proper numbers and fast enough there were probably dozens if not hundreds of molds made (that might be mold #72?) and used at the foundry. There would have to be a way to identify them if it was found later there was a problem with one. Also during the run of L series engines there may have been a revision, maybe some added thickness, port larger or smaller and this had to be able to be identified.

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Okay, I will post a picture of the valves because the intake valve for cylinder 1 looks a little messed up so either I am going to pull it completely apart and clean it or full send with something to get the carbon and shit off, So the timing chain kit is actually $129 which is my entire paycheck. side note you do not have to remove the exhaust and intake manifolds just unbolt the flange with a little knuckle thing and just wiggle the shit out of it till the exhaust pipe falls out also it is heavy but maybe it's just because I am a small person. Also to get the timing sprocket off there is a notch in the cam for a crescent wrench to tighten onto and then just make sure it is tight and break the bolt loose and take off the timing sprocket for those who look at this in the future. Hopefully Ill have the scrapson put together by next week when I get my paycheck.

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