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Engine Had Developed a Chirp Today
Posted: Mon Jun 01, 2020 8:21 pm
by Copterpilot
Today I heard a very noticeable chirp from the engine, most distinct when applying power. Anyone have an idea of what might cause a chirping? I’ve never heard it before that I can remember. Since my last drive, with no chirping, I tuned the carbs (SU) as it wasn’t running very well. Now it runs great but has this noise. Any thoughts would be appreciated.
Re: Engine Had Developed a Chirp Today
Posted: Mon Jun 01, 2020 8:33 pm
by bakerjf
Air leak around the intake manifold
Re: Engine Had Developed a Chirp Today
Posted: Mon Jun 01, 2020 8:57 pm
by theunz
Agree witMr Baker. You can spray some WD40 around suspected areas while the car is running and if rpms increase you’ve found your leak.
Re: Engine Had Developed a Chirp Today
Posted: Mon Jun 01, 2020 9:33 pm
by cole455
Is it super pronounced? If so, probably a vacuum leak. If it’s noticeable when cranking the engine, pull the coil wire and see if chirps with the throttle wide open. If so, look at the insulators and intake gasket as a leaking source.
Re: Engine Had Developed a Chirp Today
Posted: Mon Jun 01, 2020 9:35 pm
by Linda
Are you missing, or have a loose, a smog insert plug? Part 2208 datsunparts.com
Linda
Re: Engine Had Developed a Chirp Today
Posted: Tue Jun 02, 2020 6:15 am
by jrusso07
Agree with others on intake leak. I had a chirp/short screech when accelerating...it was from the alternator belt, it was just a tad too loose.
Re: Engine Had Developed a Chirp Today
Posted: Tue Jun 02, 2020 12:42 pm
by Copterpilot
I was afraid of that! The bottom nuts are virtually impossible to get a wrench or socket on to get them tight. It hasn't shown up till after I've driven for a whole season of driving. Any tricks to get to them? Special tool? anyone had any luck with putting sealant on the outside edges?
Re: Engine Had Developed a Chirp Today
Posted: Tue Jun 02, 2020 2:09 pm
by bajaroadster
Simplest solution would be to check fan belt adjustment as Jrusso suggested if not already checked. Not the likely culprit but sometimes we get lucky.
Re: Engine Had Developed a Chirp Today
Posted: Tue Jun 02, 2020 6:02 pm
by theunz
I don’t remember with the SU’s, but with my Solex’s I can use a 1/4†drive socket and a very long extension to get to them. Might have to use several to get the right length to get to the outside of the carbs. 1/4†sockets and extensions have saved my bacon many times
I had an intake chirp when I rebuilt my engine that like to drove me crazy trying to locate. Had the carbs off several times with no success and finally in desperation I put a small piece of duct tape over the leak and it went away!
Re: Engine Had Developed a Chirp Today
Posted: Tue Jun 02, 2020 7:36 pm
by bakerjf
theunz wrote: ↑Tue Jun 02, 2020 6:02 pm
I don’t remember with the SU’s, but with my Solex’s I can use a 1/4†drive socket and a very long extension to get to them. Might have to use several to get the right length to get to the outside of the carbs. 1/4†sockets and extensions have saved my bacon many times
I had an intake chirp when I rebuilt my engine that like to drove me crazy trying to locate. Had the carbs off several times with no success and finally in desperation I put a small piece of duct tape over the leak and it went away!
I’m in the same boat. I do know it’s easier to get to some of those nuts from under the car believe it or not. I also learned there is a specific order when removing the front and rear carburetor (mounting points) from the manifold, and conversely installing them. A couple of times ago I wrote the order down as a note to myself and stored it in my phone. Nice not to have to reinvent the wheel every time you have to do that job.
Re: Engine Had Developed a Chirp Today
Posted: Tue Jun 02, 2020 8:11 pm
by Copterpilot
There is just no easy way to get at that nut and put any torque on it
Re: Engine Had Developed a Chirp Today
Posted: Tue Jun 02, 2020 8:15 pm
by Copterpilot
Spent all day trying to tighten the nuts, even took the starter off, a job in itself. Got a quarter turn on the problem nut. Chirp seems to be a little worse now, UGH!
This is extremely frustrating as it was running so quietly up to yesterday.
Bakerjf, would you be will to post the order of removing and reinstalling the carb to manifold nuts?
Re: Engine Had Developed a Chirp Today
Posted: Wed Jun 03, 2020 7:21 am
by keith0alan
The easiest way to get to the manifold nuts is to remove the carbs and heat shield. Seems counter-intuitive but it really is.
Re: Engine Had Developed a Chirp Today
Posted: Wed Jun 03, 2020 9:42 am
by Linda
Can you get a box end wrench on it? The torque for the nuts is not that high, I believe.
Also the stubby ratcheting wrenches are handy for many tight areas, though they are not thin walled.
Linda
Re: Engine Had Developed a Chirp Today
Posted: Wed Jun 03, 2020 10:59 am
by Gregs672000
Like Linda, I use a very thin walled box end of a 13mm wrench. I no longer run a carb heat shield as the header shield stuff I'm using is amazing. Carbs are probably off too when I do them (Dellorto). You could try to source a 12mm nut with the correct pitch... I've had some before. Might make it easier to get a wrench on it.
