Engine making the letter Z sound?

[Mike Phillips]

Hey everyone,

 

Figured out the timing and successfully fired up my project 1974 Datsun Truck today.

 

Engine fired right up, adjusted the idle and it seems to run really good. Took the truck for a test drive and the used engine and used automatic tranny both seem to be working really good except for a noise coming out of the engine.

 

When running, there's a sound coming out of what seems to be the front of the valve cover, I assume the timing chain.

 

It sounds like the the letter Z, as though you put your teeth together and make an extended letter Z sound, like ZZZZZZZZZZZZZZZZZZZZZZZZZZ

 

It doesn't sound like it's grinding anything, just the letter Z sound.

 

I have not taken the valve cover off to inspect yet, thought I would ask here first for some Ratsun Wisdom.

 

I hope this is just a guide or something as I don't want to tear everything apart and install a new timing chain.

 

Any ideas?

 

 

Thanks,

 

Mike

[Phlebmaster]

You may end up changing the timing chain anyway..... You said the sound is coming from the front of the valve cover? The chain guides are lined with plastic and this may have come loose?? The other bad thing is you may have an overextended chain tentioner. :D Where is your timing mark on the cam sprocket in relation to TDC?

[Mike Phillips]

You may end up changing the timing chain anyway..... You said the sound is coming from the front of the valve cover?

 

Yes, a constant ZZZZZZZZZZZ sound.

 

The chain guides are lined with plastic and this may have come loose??

 

Have not taken the valve cover off or any other component from the front of the engine. The only thing I've removed is the intake and exhaust and they have been re-installed with little or no problems.

 

The other bad thing is you may have an overextended chain tensioner.

 

I'm going to go take the valve cover off right now and inspect. Can I see the chain tensioner with just the valve cover off?

 

Where is your timing mark on the cam sprocket in relation to TDC?

 

Don't know, have not removed anything off the front of the engine or the timing change cover.

 

The engine runs great except for the zzzzzzzzz noise and it actually drives really well. It starts up on the first rotation of the engine without giving it any gas and idle real smooth. Engine runs smooth through the entire RPM range, at least as high as I've revved it.

[Phlebmaster]

Ok...when you pull off your valve cover turn the engine to TDC. Then look at your cam gear's timing mark and see if it is lined up with the mark on the cam tower.

 

You may not be able to see much of the tensioner due to the fact it is behind the chain on the passenger side.

 

Check to see how tight the chain is when you push on the side of it below the cam gear.

 

You can run your engine with the valve cover off...but it gets very messy. lol

 

Take pics.... :D

[Mike Phillips]

Does Ratsun.net give out the Bonehead of the Year Award?

 

Pulled off the valve cover and inspected and found the bolt I used to hold the thermostat housing was too long and the threads were hitting the timing chain. It wasn't long enough to stop the chain but it did grind some of the end of the bolt off.

 

Off to NAPA to get a shorter bolt and the new valve cover gasket. Hopefully I didn't get too may metal particles down into the gear and chain area to cause future problems. Will change the oil ASAP

 

Will update after I install the new bolt and start the engine again.

 

Doh!

 

:)

[Phlebmaster]

Ok..since you asked...:lol: Glad you found the problem.

 

 

Enjoy!

[datsunfish]

That sounds about right. Now that you mention it I think I have done that before too.:o As well as many,many other stupid things. So dont feel bad its how we learn sometimes.

[Mike Phillips]

NAPA had one bolt that was the right size in their metric bolt bin, so it's already bolted in and fits correctly.

 

Took a picture of the problem and will post it later so maybe it will help someone down the road.

 

Going to go bold the valve cover back on in a few minutes and then will fire the engine up again and see if that fixes it but I'm sure it will.

 

Anyone have an opinion on placing a magnet on the bottom or side of the oil paint to collect any metal particles chewed off the bolt by the timing chain?

 

Good idea? Bad idea?

 

:)

[Phlebmaster]

Sound like a good idea....but think about how you will get that metal out once it is magnetized to your oil pan. You would have to pull it off to clean it out.

 

I think your filter will clear most of the metal out...just be sure to change your oil a couple of times. That's my 2 pennies. :D

[Mike Phillips]

Any opinions on running oil for a diesel engine through for a few oils changes, friend of mine told me that diesel engine oil has more detergent in it and will clean the engine out.

 

Engine has been sitting for at least a couple of years.

 

Fired it up for the first time today and so far it's running good.

 

:)

[Mike Phillips]

Victory!

 

Yep, 100% having too long of a bolt was the problem. Engine sounds and runs like a sewing machine.

 

Thanks everyone for the fast repies.

 

:)

[bonvo]

pics?

[Mike Phillips]

Here's the bolt that caused the problem...

 

 

 

 

The bolt in the picture is 3" long. You need a bolt 2 3/4" long. 2 1/2 is too short by the time you add a washer.

 

:)

[SHADY280]

if you were here in canada it woulda been a zedzedzedzedzedzedzedzed noise!!! just think of the bolt as a auxillary timing tensioner. and tell ppl its a supercharger

[]2eDeYe]

:lol:

[datzenmike]

The oil filter will collect any metal particals but don't forget those particals have to pass through the oil pump first and will grind it up. I wouldn't worry, they are heavy and will sink to the bottom back of the pan and flush out with an oil change. Diesel oil is not good in an older motor. It can remove the carbon deposits that help seal in compression around the rings. There are products you can use just before an oil change to clean the motor but i'm not a fan. Change the oil regularly with good oil and change the filter too, about twice a year should do it for a daily driver.

[banzai510(hainz)]

Pulled off the valve cover and inspected and found the bolt I used to hold the thermostat housing was too long and the threads were hitting the timing chain. It wasn't long enough to stop the chain but it did grind some of the end of the bolt off.

 

hey that was in my vid about those long bolts!!!!!!!

http://www.guba.com/general/search?query=datsun&set=5

 

PS you dont need RTV on the stat housing.

 

if anything use black or the clear blue Permatex RTV and harldly any at all.

I hate gobs of Red RTV !!!!!!look like a CRACKER did it!

Most Jap motors are machine good enought just to use tha gasket itsself. If anything maybe the front timming cover but minimal if that around the water passage.

[Bugeye]

hey hainz, have you ever used the stuff General Motors uses, its called GMS, and its 10x better than rtv, only down side is its a grey color, but man a little bit goes along way. thats what they use for oil pan "gaskets" on the chevys

[Phlebmaster]

hey hainz, have you ever used the stuff General Motors uses, its called GMS, and its 10x better than rtv, only down side is its a grey color, but man a little bit goes along way. thats what they use for oil pan "gaskets" on the chevys

 

I used something like that that I got from a dirtbike shop. That stuff is tough!

[hang_510]

It wasn't long enough to stop the chain but it did grind some of the end of the bolt off.

little longer and it woulda went away by itself :blink:

 

There are products you can use just before an oil change to clean the motor but i'm not a fan. Change the oil regularly with good oil and change the filter too, about twice a year should do it for a daily driver.

 

i like marvel mystry oil (better than ATF) if you use it for this, 1/2 dose ~100mi before an oil change.

assuming you have already changed the oil!

 

 

2x ...a year??? maybe if your DD is a bike :P