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motor knocking sound at start up?


Heroez

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I had the same problem. I fixed it by changing the oil with Rotella T. next oil change I'm going to use castrol syntec 0-w30 with ZDDP additive. The 0-w30 syntec is made in germany and it has more cleaning additives than the other weights.

Thank you for adding your experience. I may try the Rotella T after running the ATF through it and I go to change the oil. Im just now getting home from work, and the sun is setting. I will be able to try the ATF and check under the valve cover this weekend, so keep an eye on me please. I would like to add a resolution to this thread one way or another.
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Update- I drained a quart of the 15w 50 and added the ATF. I drove maybe 15 miles, then parked it for the night. Im hoping Tomorrow or Monday the clacking lifter arms at start up goes away. I will let you know what the result is. Castrol syntech is now called Castrol edge. I didnt see Rotella at 2 different stores. Was thinking of trying a 10w or 5w 30 at oil change. Not sure yet.

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I wanted to add that ATF does not have as much detergents as modern motor oils.  This was true back in the 60's and 70's, but newer oils have improved much to prevent sledging.  There is a website called bob is the oil guy, which helps filter through what's what in the oil world. 

 

I used Rotella T because it has ZDDP (zinc).  I don't know what kind of a cleaning properties it has.  The 0w30 Castrol that is made in Germany has one of the best cleaning packages in it.  But it's only the 0w30 that is made in Germany.  The castrol also does not have ZDDP which will wipe out camshafts.  All other weights of the same brand are not the same oil.  BMW and Volkswagen synthetic oils have very good oil cleaning packages in them, but they do not have ZDDP, thus I add it to the mix.  To me it's the best of both worlds. 

 

if your into oil system cleaners there is AUTO RX and a product called kreen, it's made by the same people that make kroil.  Google them if the ATF or oil changes don't do the trick. 

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In a different z I use valvoline vr1 which has a high zinc content. Its interesting to know that another brand has it. Like you said its important on antique motors for cam lubrication. I saw the zddp additive at the store too. I will do more research because I would like to know more. I will look into the products you mention. Im about to hop in the shower and after that I will see what the start up is like. Ive found a head with hydraulic lifters for sale. I was going to buy it for parts just in case I need something.

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Well, no clacking noise on start up today. I took a look at my trip meter. I logged 16.8 miles with ATF in the oil yesterday. Over the next few days I will report what each start up is like. Its too early to tell if the issue is resolved. Mondays commute will be longer harder driving. Wish me luck!

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When I changed oil it took a few months for it to go away, but the trend was less and less frequent. 

 

Concerning the Zinc, The VR1 has more than Rotella T, but less of the clleaners.  AutoRX is not compatible with synthetic oils, so it may not be compatible with a Turbo application. 

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Tapping at morning and after work. I removed the aux fan for clearance. Sorting through search results. Watched a partial mechanical conversion on youtube. Manual specifies a special tool on valve adjustment. I think in one link someone used a 17mm crowsfoot and an extension on a torque wrench.

Edited by Heroez
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  • 2 weeks later...

After 1200 miles I changed the oil Sunday, this time with Mobile1 10w 30. No clacking noise at start up this morning. I will update again soon. Side note- I have my tool man bringing me some feeler gauges. I should learn to adjust mechanical valves.

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You can't adjust the valves on a stock 83 turbo head.

Thanks for keeping an eye on me. Correct. I have another NA z car, so. The fix may be to convert to mechanical lifters on the 83 p90a. I'm trying to learn about the motor, and valve adjustment is worthwhile to learn. Matco rep says he will have the master feeler gauge set on Monday. With tools I can learn. Not really sure which way to go, convert, replace the HLAs...update will follow. Edited by Heroez
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Since the oil change to 10w 30 I hadn't heard the valve train slapping noise. Its been a couple days now. But... There is a light ticking during warm up period that eventually gets quieter and hard to notice. So maybe the switch to 10w 30 from 15w 50 had an effect on the lifter slap the most? The turbocharger has gotten quiet, you can still hear it a little. The dash gauge says its boosting, I see positive manifold pressure. Odd. At 200k, maybe the engine is just worn out. Its hard to admit that. Mostly because the turbo car is still new to me. I couldn't afford to buy one, so I had to make one if I wanted to know. Found one that was sick, and affordable. Spent a year testing, poking, swapping, reading about. I know what the insides of weird parts look like! I even have pictures of the guts inside the FPM,VCM,and such. Found unrelated minor stuff I wasnt looking for too. I threw down my ECCS enemy and smote his ruins upon the tarmac. Victory! Now I know what turbo is like. So these new noises, concepts, have me questioning. I dont see the obvious things as clearly as you guys do. These noises send up an alert on me but its just instinctual. If you are in touch with your car, new noises really get you thinking.

Edited by Heroez
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Do you have a video or sound clip of the noise? The L series Datsun naturally has a louder than normal valvetrain noise. The hydraulic lifters are only slightly better. Just out of curiosity, who is your Matco rep?
I will try to get a recording. This car used to be quiet, now during warm up its ticking medium soft. Danny Gossett used to be my Matco guy, great guy. Changed job location and the Matco rep is Kevin.
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  • 2 weeks later...

The slapping sound occurs less. Maybe less than half the time when starting the car. Which is an improvement. Next oil change I will go back to 15w 50, with another 1/4 quart of ATF. I would like to find some hyd lifter arms, spend some time cleaning them and letting them soak. Then replace mine. May place a WTB ad.

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I changed my oil last monday to the 0w-30 castrol syntec and added zddp.  It now makes a tapping noise when fully hot and I let it idle for over a minute.  as soon as I rev up to 1500 rpm it goes away.  I think it's an oil pressure issue.  I think I'm going to swap out my pump for the larger turbo automatic oil pump and increase the orifice size to the cylinder head.  To me it seems that the oil pressure is just slightly low at low RPM.  

 

To my understanding if a hydraulic lifter/pivot pumps up with RPM/pressure, it's working fine.   

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