521 datsun diagnose my issue quiz....

[jrock4224]

Ok so here it is my 521 been running great for a long time... thursday i was driving across town on the high way...70-75 most of the way back..when i exited the freeway truck doesnt wanna stay running, acts like its stalling out wont build rpms very well...I cant say its down on power..cause it never had much to begin with.....now when i start it after sitting it still doesnt wanna idle... it makes this wierd whistling on start up, only for a second, my belts squell(never did that before) and it wont build any rpms like it used to... it will just is a struggle to build them anytime I try and drive it it takes alot of throttle input to get it to move...checked for fuel issue filling the filter fine and pumping it out of the line good....oil and coolant look un contaminated so far but i only had it running about 10 minutes after problem started...nothing metallic in oil...seems to maybe be a head gasket but none of the tell tale signs yet...gonna start by pulling plugs and checking compression....any hints or pointers of direction to look in?????

 

can provide more info if needed but thats the basic issue i am running into right now...hint to 521 owners if you rocking a four spd...dont make high speed runs on highway....apparently hard on prts...thanks in advance for any help...

[jefe de jefes]

Is your carb nice and tight on the intake?

You check your fuel filter?

[D@tsuks]

Yeah I agree with jefe. sounds like vac. leak. I would take some carb clean spray it at the carb base, manifold to head, and vac lines to see if it idles up then you my friend have a vac. leak.

[banzai510(hainz)]

what I do the basics

Ck the vaalve lash and while at it ck the cam timming at TDC. Most likely its good as I never seen a chain jump a tooth but you said it makes a whine? Is this a fan belt issue? only other wine is the tensioner mayby popped out and is stuck at a angle. Look down front cover with a flash light. if that ok

I would ck the distributor for bushing wear and points if still running points. Dizzy shaft has excess wiggle from side to side swap another dizzy in.

 

On the carb ck the idle jet. I assume this is a weber DGV and ck that out. See if plugged.

Does the accel pump squirt gas when you cycle the gas? I had the accel pump arm stuck in the PUSHED IN mode once. I wd40 it and it was OK after that. Maybe the accell pump diaphrame is cracked where it cant get a good stream of gas in there or the float bowl is dying up on you.(needle valve)

 

I myself dont fuck around any more when I trouble shoot.

I ck for spark .ck distributor/or swap. Ck valve lash then swap a DGV as its only 4 bolts as I have acouple spares.

 

 

I do 70mph in my 521 its getting a little on the hight side but 65 I do all the time/ Have taken it to 90 on the speedo but think its really 85

 

as other said ck for tightness on intakes.

For soem reason my 510 loosen up but my 521 I never had proplems. I think the threads are stretched out on my 510

[banzai510(hainz)]

re ck the mixture screw setting also

[jrock4224]

so ok....i havent done anyhting over the weekend it was a tough one on my stable....thursday datsun dumped on me..friday my 97 tahoe lost a fuel pump while on the road...sunday trailer wheel feel off tandem axle trailer on jet boat on way to the lake(theres nothing like being passed at 70 by parts form your trailer) crashed all my remote control helis bored waiting on fuel pump...about the only thing that didn't break this weekend was the lawnmower unfortunately..

 

 

Anyway back to the datsun, the squelling sounds like the belt that never did it before, there is a wierd high pitched noise for a second at start up like a compresion release almost... then it fires up and i have to give it gas to keep it running.... new points at last service....so I m not sure its that...gonna check compresion tonight even though it runs and no noticable clanking....one more tidbit of info. I have to be honest at the end right before i exited the free way... i was pushin her pretty hard wide open for a good 8 minutes up a hill.. probabaly hit 85 was passing a couple of semis trying to make my exit....thats when it happened... I had her wrapped out, could tell on decel there was a problem wouldnt pick back up the power, then would cut in and out like i was losing spark or something... then exited and i could npot keep it running with out holding it at about 1500...then when i had to go took a lot more trottle input...tried the brae clean trick no noticable leak....no this is a carb off my mazda i think dfev....if i remember correct.....trying to talk phixius into pulling his 32 36 and trying it since i have no other...I mean come on i powdercoated his rims...cant i borrow your carb for a few...anyway... hoping to have not jumped a tooth or lost my lash.. but if so not bad.... i still assume if i compreshion test and see if theres any bleed off that i have a head gasket issue...like i said never got hot or tell tale signs..man she was a god runner till i got cocky.....going to work on it tonight assuming the wife doesnt change her mind...if i switch to a petronix i assume i would eliminate the chance of having a issue with distributor ever right?

[banzai510(hainz)]

if i switch to a petronix i assume i would eliminate the chance of having a issue with distributor ever right?

 

Not exactly but more lilekt ot saty running longer.

PS Pertronix is for single point L16 dizzys 68-69

dual point the kit wont work.

But will work in a modified L20 single point.

 

pop valve cover and see if lash fell out.

[jrock4224]

if i switch to a petronix i assume i would eliminate the chance of having a issue with distributor ever right?

 

Not exactly but more lilekt ot saty running longer.

PS Pertronix is for single point L16 dizzys 68-69

dual point the kit wont work.

But will work in a modified L20 single point.

 

pop valve cover and see if lash fell out.

 

 

ok so when i pull it am i measure with a feeler guage or is there something i will notice....i try not to fawk with internals much ..im more of a turd polisher

[datsunaholic]

Is the squeal when you turn the key to Start, squeals a bit before the engine cranks over and then starts?

 

Or is it squealing when the engine is cranking, but stops once the engine "catches" and runs on its own?

 

The first is a loose/bad battery cable (or corroded connectors) and the noise is coming out of the starter (it's not getting enough current, then the bad connection heats up and makes a better connection letting it crank over). I've also heard that noise when the timing is WAY too advanced, and the engine tries to start backwards (fights the starter).

 

The second is a loose alternator belt.

[jrock4224]

yeah to be hoest theres two squells one is obviously the belt for the alt, which is wierd cause it never did it beofre onec but turning those kinda rpms can loosen up anything i guess...the other is a wierd much lower frequency squell..it starts about have way through cranking once it catches and runs on its own(well as i run the trottle to keep it runnin.) and stops about 2 seconds after it fires...its wierd like a comphresion release...almost kinda noise...I am thinking it might be ignition related to timing and what not....cause when i got it off the freeway it was acting like it was loosing spark on most holes but would catch one and keep it running...thanks for all the great info guys...thats why i tell all my datsun frineds about this great place...

[banzai510(hainz)]

ck point gap also beside the above mentioned by me

[jrock4224]

what should the gap be on the points....

 

clearly i cant spell sqweelll

[dimedriver]

Take your fan belt off.

 

Bet you can't turn the water pump. Your water pump bearing is gone. Thats the squeal. bearing fights the belt until the engine is running and can turn it.

 

 

 

Check your compression. Head gasket its probably leaking between #2 and #3. Thats the no power. I have seen L16's and KA's run but loose power because of this.

 

 

Your water pump probably gave up the ghost when you were pushing it up the hill. Then you lost the head gasket or it was already on its way out and you just kicked over the edge.

 

 

If the head gasket was on the why out, power will go way up when you change it out.

 

-Avery

[datzenmike]

First thing I thought of was head gasket. Do that comp. test. I've seen a head gasket leak out the side of the block and the compression would whistle out the hole for 5-10 seconds until it heated up.

[banzai510(hainz)]

i thought of the water pump but never actully seen one where the bearing froze up. Mine usuallu disinegrate!!!!!! wobble then coem apart if I dont cath them in time. Now soon as they leak I swap them out.

 

also ck the 2nd barrel of the carb make sure the plate is closed. Otherwise you might not idle

 

if you not losing water and not overheating and spark plugs look ok I think the headgasket is fine

[jrock4224]

well were back up and running....started with the suggestions, compression good, strong across all holes...plug wires all good no breaks, plugs all fine....little fouled, dist all fine, points fine, went to take the valve cover started loosening bolts lost balance steadied myslef by leaning on the carb....low and behold the winner is .....gigantic vacuum leak...the carb was wobbling all over the place...the stupid weber adapter had come loose on my intake... the counter sunk screws for the adapter, they leave to much gap and leave room for screws to back off...and they did... dissasembled the whole adapter plates loc tighted them, re assembled and runs and idles...thank god I accidentally found that out before i dissasembled the head any further.... thanks for the insight and pointers for my issue... its always nice when something turns out to be easy...now i can go back to fixing my 7 other probelms now that i have a working datto again...thanks to all for the grea suggestions... your help was invaluable and much appreciated...

[jrock4224]

Is your carb nice and tight on the intake?

You check your fuel filter?

 

 

you are the winner....I am concocting a prize for you....you will have to share it with Datsuks...i wish i woulda checked this first but the way it was running i had figured it to be far more complex.... sometimes its the easiest to check the simple stuff first...thank you..the squell was air swooshing past the adapter plates...

[banzai510(hainz)]

jefe de jefes = winner

Banzai510 = loser.

 

well i said your head gasket wasnt bad

[dimedriver]

Is the squeal on startup gone?

[jrock4224]

banzai your always a winner in my book ... you have helped me more than anybody here so let jefe bask in the glory for a bit...i do thank you both and for saying my head gasket wasn't blown you get the concolation prize... i will powder coat your wheels any color as long as its neon pink...for free...you pay to ship them to me and i make them neon pink...sqwell is gone think it was air rushing through the adapters for my weber... oh and alt belt was extrememly loose never re checked it after saturn alt swap...funny story got it back up and running started it and heard this rythmic pinging of metal on metal... i was freaking i dropped something in the intake and now it was rattling around in my head on it's way to the oil pan ... i came around the truck freaking out and saw the orange handle of my pry bar stickin up bouncing... man my heart was racing...stupid thing slipped and was rubbin alt pulley....hey even better news i just scored a2.0 and a 5sp out of a 77-78 620... you know what that means I can go 80 with out turning 6 k now it will be a more managable 45k...so i assume the easiest way when i go to do that swap is just to scrap the two piece and have a driveline built.... or is the 77-78 620 driveline needed to save some coin....does a 620 run a two piece driveline.... rpobably gonna pull the head on the 2.0 ofter i check compresion and make sure the head gasket is ok....oh yeah and it came with a weber...not bad for 200 for all of the motor and tranny, and carb...

[banzai510(hainz)]

yeah

My best 1st guess was a lash pad fell out!

[jrock4224]

yeah

My best 1st guess was a lash pad fell out!

 

 

luckily no .... but i will be thinking twice befoe i put that kind of rpms to my datsun....was it worth seeing my bad ass 521 go 80....up a hill....im gonna say no...how bout that driveshaft question from page 1...i researched in the general discusion but didnt see a difintivie answer

[banzai510(hainz)]

datdoug is more of the truck guy when it come to 620 parts.

All I know on the 521 you can use the dogleg 200sx 5 speed but got to mod the rear mount part that goes on the trans. otherwise just slip to th yoke in. WONT need the treaded nut part thats with the 4 speed. Might be angle sensitive as he had 5 gear noise. but when he raised the carrier bearing it stoped(truck had 3inch blocks in back)

 

Datto510 did this conversion if you want to PM him.