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Posted By: Astro tick tick tick - May 12th 2018 3:20 pm
so the astro has what sounds like an exhaust leak... ticking sound, but only under load.
start it up and let it idle, no noise at all.
I thought it might be the doughnut gasket between the headers and the y-pipe (yes, I have headers), but I can't see it/feel it when I check.
hoping it isn't the manifold/header gasket, but hard to tell since I can't put the engine under load while I'm under it.
Posted By: wrcsixeight Re: tick tick tick - May 12th 2018 7:44 pm
Not an engine pro but the exhaust leak ticks are usually when cold and go away once warm, and are there in the presence of load or not.

A ticking under load when hot could be internal engine issues, and a mechanics stethoscope can be beneficial in diagnosis.

I had a '73 Holden Kingswood in Australia which was ticking, same inline 6 engine as GM's of that era. I brought it into a mechanic and the ticking did not get louder under load and the guy was like its fine. That was in West Australia, and I drove it across the Nullabor Plain and sold it in Sydney some 9 months later.

Some say Marvel mystery oil in the sump eliminates ticky lifters. Some say thicker oil, some say thinner. Some think an italian tune up is the call.
Posted By: Reed Re: tick tick tick - May 13th 2018 2:53 am
Marvel Mystery Oil has always worked well for me in freeing up sticky lifters. It is the only oil additive I will use. Thicker oil has a harder time getting into small spaces, so I don’t recommend it if your motor has problems.

Have you elimnated spark knock/preignition as a possible cause of the noise?
Posted By: Astro Re: tick tick tick - May 13th 2018 1:14 pm
Originally Posted by Reed
Marvel Mystery Oil has always worked well for me in freeing up sticky lifters. It is the only oil additive I will use. Thicker oil has a harder time getting into small spaces, so I don’t recommend it if your motor has problems.


I just did a fresh oil change with full synthetic, haven't added anything to it though.

Originally Posted by Reed
Have you eliminated spark knock/preignition as a possible cause of the noise?


how do I do that?


Posted By: Reed Re: tick tick tick - May 13th 2018 4:20 pm
I don't know much about Chevies. If the Astro ha a distributor, you can try turning it to retard the timing a bit. If it is a distributorless ignition system then I don't have a clue.

On my Ford I recently eliminated a noise that had been bothering me since I swapped engines back in 2010. On hard acceleration, an especially when turning right and accelerating, I would get a very loud "BBURRRRRRRR" noise from under the doghouse. I checked everything I could think of that might make the noise. It turns out the passenger side exhaust piper flange was not fully seating on the manifold and would leak only on hard acceleration or right turns. At idle there was no sign of a leak, and even revving it in park or neutral it would not leak. I only found it because I pulled the manifold and had to reassemble it.

My Ford uses a gasketless union between the manifold and the pipe, and it has to be sealed tight and perfect. Even a little bit loose and it won't seal right. Maybe yours is a touch loose?
Posted By: Astro Re: tick tick tick - May 19th 2018 8:13 pm
finally had time to get more into this, found all the bolts on the passenger side manifold were loose!
I snugged them up and the sound got quieter, so I'm on the right track.
once the motor cools down enough (tomorrow) I'll pull the headers off, replace the gasket and put the bolts back in with some locktite
Posted By: Astro Re: tick tick tick - May 20th 2018 5:04 pm
Gasket replaced.
Hardest part was getting the bolts lined up and started.

You could see on the old gasket where the leak was.
I love a $10 fix
Posted By: Dyno_Dave Re: tick tick tick - June 01st 2018 9:04 pm
Repairs that are inexpensive to make are always welcome.
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