Carb choke thermostat help

[murguia]

Looking to learn.

Been going nuts hearing a knocking type noise when I am driving 0-30mph. Thought it was lifters, exhaust… but changed all of those and they were good.

Today we looked at the choke thermostat and the coil/spring was broken, so it hasn’t been working. There’s a pinhole directly under that area and sure thing, when we plugged that hole the noise went away.

How does this choke thermostats work and is that hole suppose to be there?

Should I just plug it if my truck has been running well with the thermostat broken and not working?

Thank you

[Steeveedee]

I've never seen that. I'd plug it myself, but maybe more eyes on and reasons will change my opinion.

[RustyPile]

That hole isn't supposed to be there.. The noise you hear is exhaust gasses passing through the hole.

On the bottom of the manifold is a passage that connects the exhaust ports in each head.. Its purpose it to heat the carburetor to aid in cold weather operation.. It gets extremely hot and provides a perfect place to mount the choke thermostat..

You might meet with some success plugging it, but your best approach is to replace the manifold.

[dmjlambert]

It looks interesting, it's a nice round hole. I wonder if it's rusted through and the metal is really thin there.

[murguia]

I plugged it and the noise it gone and it’s running great. I plan to leave it like that and not reinstall the choke thermostat, unless someone convinces me otherwise.

[murguia]

Originally Posted by dmjlambert

It looks interesting, it's a nice round hole. I wonder if it's rusted through and the metal is really thin there.

I was wondering the same thing. Thing for sure and perfectly round.

[geezer#99]

If you indeed changed all the lifters I hope you don’t get unlucky and get rewarded with a flat cam.

[murguia]

Originally Posted by geezer#99

If you indeed changed all the lifters I hope you don’t get unlucky and get rewarded with a flat cam.

Can you educate me? one person told me it was a lifter on the passenger side that needed to be adjusted. So I warmed the truck up and loosened the bolts one by one until I hear clattering. Then I tightened until it was gone, then 1/4 then more. Did this on just the passenger side. All were throwing out oil well. Did I do something potentially harmful to the engine?

[geezer#99]

You’re good.
You wrote you’d changed lifters. I thought by that you’d replaced them all with new lifters. But you had just adjusted them.
The lifters mate for life with the cam.
You adjusted them correctly.

[Stocker]

Originally Posted by geezer#99

If you indeed changed all the lifters I hope you don’t get unlucky and get rewarded with a flat cam.

Originally Posted by murguia

Can you educate me? one person told me it was a lifter on the passenger side that needed to be adjusted. So I warmed the truck up and loosened the bolts one by one until I hear clattering. Then I tightened until it was gone, then 1/4 then more. Did this on just the passenger side. All were throwing out oil well. Did I do something potentially harmful to the engine?

Sounds like you just adjusted lifters and did not actually replace them. So you're good. Problem would be if you installed new lifters and kept the old cam.


Well, Geezer beat me to it by several minutes. I know I type slowly, but geeeezz!

[dmjlambert]

So, how do you plug a hole like that?

[geezer#99]

Self tapping screw would work.

[murguia]

Really appreciate all the quick responses and help, as usual. Love this forum.

To plug I used a self tapping screw with a little copper heat tolerant sealant around the threads.

[Steeveedee]

If you are in LA as in Los Angeles as opposed to LA as in Louisiana and your truck runs fine cold, you could leave the choke coil off.

[murguia]

Originally Posted by Steeveedee

If you are in LA as in Los Angeles as opposed to LA as in Louisiana and your truck runs fine cold, you could leave the choke coil off.

Perfect, I’ll leave it off. I’m in cypress, CA.

[geezer#99]

If your choke blade is tied open then you can leave it off.

[Steeveedee]

^ Yup! Or it could flop around and cause trouble.