It's "fixed" , BUT....

[Buzzbomb]

Update on my head gasket project..

 

First the good news..I fixed my headgasket on my L20B thanks to all the great help on this board! THANKS! I flushed out the ENTIRE cooling system, it all works with no leaks at all- and no stop leak added either :) . That's the whole mission here, and that was accomplished.

 

Now the bad news...It just can't hold an idle, and has a slight miss :( . It actually doesn't run all that bad, but it's not smooth to where you know it's "right". I was getting a little smoke from somewhere, but I don't know if that was just PB BLaster burning off. IT started pretty good, and when it's warm it will start with barely a turn of the key like it used to.

 

I checked the following things: firing order, plug gap, vacuum line routing (seems to be OK ?), and choke operation. If I feather it with my foot, it will run. If I hold it at a certain RPM for awhile, it stays there and actually smooths out, but it holds that high idle. It then starts running a little bad again when the idle comes down.

 

The things I didn't or haven't done yet..I didn't check the valve clearances. I figured I'd get it going before checking that, because it ran fine when I parked it to fix the headgasket. I didn't do anything to cause them to move :confused:

 

I didn't recheck the intake bolts. The reason? I felt that I tightened it pretty good. I used a criss cross pattern in to out. I didn't want to wrench down on it too tight, because I didn't want to strip the holes. The bolts WERE clean as were the holes when I put it on, and I did use anti-seize. Maybe I just didn't tighten it enough? I didn't tighten with a torque wrench; I used the ratchet and felt when it was tight, that was enough. Maybe I was wrong?

 

Any ideas? INtake leak? Valves need adjusting? Anything obvious I might be able to check?

 

Again, thanks for all the help. I get this figured out, and it's gravy :D

Edited March 16, 2009 by Buzzbomb

[Phlebmaster]

Awesome!! You did it! :D

 

Is it possible you are a tooth off on your timing chain? To check that...pull your #1 plug and turn your motor to TDC and look into your # 1 plug hole to make sure your piston is all the way up. # 1 and # 2 cam lobes will be at 10 & 2.....but you know that now. lol Your chain could have jumped or best case you were just off by a tooth when you put the cam gear back on. I have done that, hahaha

 

Then see if the timing mark on the cam gear is lined up with the mark on the front plate on the # 1 cam tower.

Edited March 16, 2009 by Phlebmaster

[Wharf Rat]

Did you change the spark plugs? Sometimes it's the simple things and plugs may look fine yet get a hairline crack from the coolent. Also if the carb got tipped over when the job was done it may have had some settled dirt move into the idle circut or air passages. give it a quick clean job.

 

Good luck WRAT

[Buzzbomb]

Did you change the spark plugs? Sometimes it's the simple things and plugs may look fine yet get a hairline crack from the coolent. Also if the carb got tipped over when the job was done it may have had some settled dirt move into the idle circut or air passages. give it a quick clean job.

 

Good luck WRAT

 

I hear you on the simple stuff. That's why I checked my firing order at least half a dozen times. Number one was obviously the one the rotor was pointing to, and then it was 3-4-2 clockwise after that. Same thing for the vacuum hoses, but those can be confusing...

 

I didn't change the plugs since they have less than 1000 miles on them. I actually was lucky that I wasn't burning coolant. The only way they could be bad is from Carb cleaner, I guess. I sprayed the combustion chambers with them in there when I had the head off. I actually checked them after I sat and idled today, and they look ok. I was really careful with the carb. It was always right side up, and I was gentle with it when I moved the intake around from here to there.

 

I'll tell ya...I must have checked that cam sprocket V notch/dash a dozen times; it almost to teh point of paranoia :D . As a matter of fact, I lubed up my cam with a little Marvel Mystery Oil yesterday, and I checked the v/- while I had the valve cover off, and it was as if I had never taken it apart. It lines up just like Hainz shows in his video. I KNOW with 100% certainty that TDC on my timing tab is true TDC. If it's on 0, it's at TDC; the head was off, it was at TDC, and the piston was flat against the bore. The v/- is so easy to check, I will check it just to be sure, though.

 

Like I said, it DOES run, but won't hold an idle and will stall if not feathering the gas. There is no backfiring, and the miss basically sounds like a V8 engine with one plug wire left off of it. It sounds OK, but it isn't "right". I had the vacuum gauge on it, and was only getting like 9-14 inches (pretty steady, too) depending on where my foot was holding an idle speed. Last time I checked it, it was around 18, and pretty steady.

 

One thing..Can an EGR valve cause this problem? I cleaned out the EGR passage when I had it off because it was totally plugged. My truck was basically running with no EGR for probably years. Can I somehow bypass the EGR to eliminate it as a cause?

Edited March 16, 2009 by Buzzbomb

[Phlebmaster]

I know how frustrating these things are..lol

 

Keep working on it, you will figure it out. :D

[banzai510(hainz)]

is this a stock carb?

 

Later datsuns had a 12volt wire to the idle cuttoff seliniod?

Did you foget to hook this up? It wont idle at all if this wire is missing.

 

try adjust the distributor timming and maybe the mixture screw w/ tension spring at base of carb.

 

 

PS If you now the engine is mecahically timmed no need to do it again. Its not going to chainge.YOu DID IT> Now you ask ITS WAS EZ!!!! Yes it is.

 

Now move on to carb or eleltricall issues.

 

 

Maybe ck the valave lash real quick also.

 

Sometimes no idle is loose intake carb bolt to the manifold or intake to head.

Edited March 16, 2009 by banzai510(hainz)

[vgwagon]

Check to make sure the vacuum line to the egr has no vacuum at idle. A slightly open egr at idle will cause rough idle and the stumble/miss you speak of.

EGR is supposed to function at part throttle cruise situations. Maybe plug off the EGR vacuum line and see if that changes anything. Could be a stuck EGR pintle or a piece of carbon holding it slightly open.

make sure it operates smoothly with your hand.

[Wharf Rat]

Yes EGR can do it (should have left it full of carbon!)

 

Hope you found the culprit:)

[Buzzbomb]

First of all, THANKS again for posting that awesome video, Hainz. It was a HUGE help :cool: .. USing the instructions I got on here and your video, the hardest part of this was....scraping the old gaskets off! That really sucked. The rest wasn't all that tough :blink:

 

It's the stock Hitachi carb...I'll go ahead and check to make sure that the fuel cut off is even working. IIRC, I can do that by having the key on ON, then unplug/plug to listen for a click. I'll check the lash too. I am certain the valve timing marks are OK, but I can check the v/- in 2 seconds when I check the valves.

 

I can eliminate the carb to intake, because I left the carb on. I wanted to take it off and clean it up some more, but i couldn't find anyone selling a base gasket?

 

Anyway, the intake bolts are pretty tight, BUT I just don't know if tightened those intake bolts enough. I read they call for 11 ft. lbs. I snugged them down good with a 6 inch ratchet, and gave them about another 1/4 turn or so. I didn't want to strip a thread, and I used anti-seize too. Too cautious, maybe?

 

BUT....You try to figure out what you did by changing things, and I did make a change by putting the EGR valve back in the whole system. My whole passage was plugged with carbon for probably years, like wharf rat said, i should have left it that way! SO, I will also plug the hose to the EGR to see what happens. I'm assuming that the hose I plug is the one coming off the valve next to it.

[banzai510(hainz)]

Just to make sure your statement is correct above

Its Vounter Clockwise fire order 1 3 4 2 .

 

Souldnd like you got everthing right to me.

 

I dong have EGR valves. So I dont have a clue on that one.

 

PCV valve??????? Just plug it with your hand to eleminate if thats it.

[Buzzbomb]

Nice catch! I did mean Clockwise on the firing order :)

 

I had some free time this afternoon, so I worked on it. Here's the deal. Part of this is "fixed", BUT...

 

I took the valve cover off and rotated to TDC. My marks are either dead on or the v is just slightly to the right of the -. In other words, the marks pretty much line up, but I think the variance is that it isn't humanly possible to line it up at the exact same spot each and every turn. The engine is much smoother, so I don't think the valve timing is off.

 

Turning the crank also seemed to cause a problem with the carb. I don't know if I blew the needle of its seat, if there was crap in there waiting to get lodged, or what, but I turned the crank a few times to verify the marks, and the carb was dripping gas out of the secondaries. You'd think the needle would just close off the flow of gas here. Nothing different than when I was cranking it yesterday to get gas to the carb? There was gas to the top of the float bowl. Also, when the truck is running, I'm getting gas dripping from the secondary booster due to what I believe is a high float level caused by some THING? If this isn't due to crud in the needle and seat, I don't know what it's from. I babied that damn carb when it was off the truck.

 

ANYWAY, my intake bolts were on at about 5 pounds or less. The 2nd BITCH bolt on the intake was finger tight. I have no idea why that is, but I put a torque wrench to it w/ the miracle Sears U socket :P , and tightened ALL bolts to 11. I believe this was part of the problem with the rough idle. My vacuum reading is back around 17, and it could be a tad low because of it being pig rich from the excess gas.

 

Bottom line here..I DON'T have a rough idle like I did yesterday, but I DO still have a rich misfire, and it's still either stalling or racing. I don't know if something was churned up in the carb. I left for awhile, came back, and the float level was on the dot! I was getting pretty pissed, so I gave up for today.

[Wharf Rat]

Ok, your getting there sounds like some crud left in the carb and you got the float level messing with you. I think those have plugs to drain the float chamber take one out and run some carb cleaner through the fuel inlet. This should get the crap out of the float valve without you having to do a full blown tear down clean it.

 

Sleep on it ..... Sometimes the best thing you can do for a problem is get the F away from it for a while:fu:

 

Peace WRAT

[Buzzbomb]

Ok, your getting there sounds like some crud left in the carb and you got the float level messing with you. I think those have plugs to drain the float chamber take one out and run some carb cleaner through the fuel inlet. This should get the crap out of the float valve without you having to do a full blown tear down clean it.

 

Sleep on it ..... Sometimes the best thing you can do for a problem is get the F away from it for a while:fu:

 

Peace WRAT

 

I saw those two plugs under the float bowl and wondered what they were for..I just don't see how spinning the engine around by hand could cause more problems, but it did. Honestly, it really shouldn't; I know how a needle and seat should work. If a Hitachi works like a Qjet and Holley, there should be NO gas dripping at idle PERIOD, and this is especially true for the secondaries. I'm really hoping that this was just some crud being churned up in there. I wasn't really planning on doing a carb rebuild. It ran fine when I parked it, but leaked like a sieve. Now it doesn't leak a drop of anything, but runs somewhat like crap. It was blowing black smoke out of the tailpipe, and I'm overdue for a stupid E-test. I'll look at the glass half full and say it doesn't run as crappy as it did yesterday since I gave it the :fu: for today :blink:

Edited March 17, 2009 by Buzzbomb