Gas leak, occasional power loss

[FuzzFace2]

Dave is in the house!

Ok from what I can see he is running EFI exh. manifolds and has a hot water heating plate bolted to the bottom of the intake where the log exh. manifold was bolted to.

If that is the case I was afraid of that happening or the gasket not sealing and the intake sucking coolant in and think a head gasket went bad.

If you were to look over the intake and where the plate is bolted to, coolant will make it up to that point.

My fix for that and now happy I did this, was to install a freeze plug with a little sealer on it.

I have had may carb off a time or 2 and had no coolant leak so guess it is holding.

As for the idle mix screw not doing much what was the idle speed set to?

If it was to high the mixture screw would not do much.

I dont know if the accel pump could cause a rich idle on the Carter carb?

It sits in the bottom of the float bowl and there is a plastic tube that goes from the pump body to the carb body and the passage for the discharge into the carb.

If the pump is bad the rebuild should fix it.

Dave ----

On the carb rebuild before you got it you dont know if anyone messed with the needle / rod for the high speed do you?

Someone messed with mine before I get the truck, carb was a mess with wrong screws used and others missing.

I have to find where I found the starting point is on it, it is not in the rebuilt kits paper, it may be a day or 2 before I can look for it.

You may not know if it is out of adjustment with out looking at the plugs and a AFR meter.

I have a AFR meter to dial in my carb.

Dave ----

[JG2020]

That wasn't meant as a criticism of your pictures.

Just that my lack of familiarity with the 300 makes me question context and what all I don't see...

Perhaps Dave, David, Larry or someone else with a 300 has better answers for you.

Oh, I didn't take it that way at all. I should take some more detailed pics. The mosquitos were feasting on me also.

[JG2020]

On the carb rebuild before you got it you dont know if anyone messed with the needle / rod for the high speed do you?

Someone messed with mine before I get the truck, carb was a mess with wrong screws used and others missing.

I have to find where I found the starting point is on it, it is not in the rebuilt kits paper, it may be a day or 2 before I can look for it.

You may not know if it is out of adjustment with out looking at the plugs and a AFR meter.

I have a AFR meter to dial in my carb.

Dave ----

The carb I got on e-bay. It was from an old auto parts store and was sitting on the shelf in a box that said "rebuilt" and the box was pretty dusty. The carb looked nice and clean and I put it on and had no issues after adjusting. It could have been 20 years old for all I know. The box was a Carter box and looked pretty vintage.

I got the rebuild kit from Mike's Carb when I purchased the electric choke , just to have one. It came with full rebuild directions in a PDF so I can follow those.

Thanks!

Josh

[JG2020]

Dave is in the house!

Ok from what I can see he is running EFI exh. manifolds and has a hot water heating plate bolted to the bottom of the intake where the log exh. manifold was bolted to.

If that is the case I was afraid of that happening or the gasket not sealing and the intake sucking coolant in and think a head gasket went bad.

If you were to look over the intake and where the plate is bolted to, coolant will make it up to that point.

My fix for that and now happy I did this, was to install a freeze plug with a little sealer on it.

I have had may carb off a time or 2 and had no coolant leak so guess it is holding.

As for the idle mix screw not doing much what was the idle speed set to?

If it was to high the mixture screw would not do much.

I dont know if the accel pump could cause a rich idle on the Carter carb?

It sits in the bottom of the float bowl and there is a plastic tube that goes from the pump body to the carb body and the passage for the discharge into the carb.

If the pump is bad the rebuild should fix it.

Dave ----

Thanks Dave! The idle was set to about 675 rpm.

I will post some better pics of the manifold and the carb stand etc tomorrow morning.

 

[Gary Lewis]

Dave is in the house!

Ok from what I can see he is running EFI exh. manifolds and has a hot water heating plate bolted to the bottom of the intake where the log exh. manifold was bolted to.

If that is the case I was afraid of that happening or the gasket not sealing and the intake sucking coolant in and think a head gasket went bad.

If you were to look over the intake and where the plate is bolted to, coolant will make it up to that point.

My fix for that and now happy I did this, was to install a freeze plug with a little sealer on it.

I have had may carb off a time or 2 and had no coolant leak so guess it is holding.

As for the idle mix screw not doing much what was the idle speed set to?

If it was to high the mixture screw would not do much.

I dont know if the accel pump could cause a rich idle on the Carter carb?

It sits in the bottom of the float bowl and there is a plastic tube that goes from the pump body to the carb body and the passage for the discharge into the carb.

If the pump is bad the rebuild should fix it.

Dave ----

Thanks for the help, Dave. I knew you did the hot water bit on your carb and had plugged that hole. Do you remember what plug you used?

[FuzzFace2]

Thanks for the help, Dave. I knew you did the hot water bit on your carb and had plugged that hole. Do you remember what plug you used?

I don't remember the size IIRC I took the intake I to the parts store for the right size.

On the idle speed it sounded good guess a good cleaning and rebuild can't hurt.

Dave ----

[JG2020]

Thanks for the help, Dave. I knew you did the hot water bit on your carb and had plugged that hole. Do you remember what plug you used?

I don't remember the size IIRC I took the intake I to the parts store for the right size.

On the idle speed it sounded good guess a good cleaning and rebuild can't hurt.

Dave ----

I am guessing this is the cause of my mysterious antifreeze loss also.

There is definitely a small pool of liquid in the intake manifold under where the carb sits. Smells like a watery mix of gas and antifreeze. Since the carb was supposedly already rebuilt maybe I should plug that hole and reinstall the carb and new spark plugs and see where that gets me.

It would seem obvious that the fiber gasket wouldn’t keep antifreeze from being sucked into the intake . At least that’s how it looks to me.

Thanks everyone for the help!

[Gary Lewis]

I am guessing this is the cause of my mysterious antifreeze loss also.

There is definitely a small pool of liquid in the intake manifold under where the carb sits. Smells like a watery mix of gas and antifreeze. Since the carb was supposedly already rebuilt maybe I should plug that hole and reinstall the carb and new spark plugs and see where that gets me.

It would seem obvious that the fiber gasket wouldn’t keep antifreeze from being sucked into the intake . At least that’s how it looks to me.

Thanks everyone for the help!

That's a reasonable plan and won't hurt anything.

But I still think you have a problem with the accelerator pump on the carb. Don't forget that you said the engine runs better if you close the idle mix screw. That screw is supposed to control all of the fuel going to the engine, so if you close it and the engine runs, much less better, then there's another source of fuel.

And, Bill/85lebaront2 said "The Carter YFA is a fairly simple carburetor, which has one major weak point - the combination accelerator pump and metering rod control. This is a diaphragm with manifold vacuum on bottom and fuel on the top side. When this diaphragm fails the fuel is drawn directly into the intake." That fits your symptoms perfectly as it would be another source of fuel.

If the carb sat for years it is possible that the diaphragm got old and cracked. So while it won't hurt to plug that hole and put the carb back on, antifreeze won't burn so it isn't the source of the extra fuel.

[JG2020]

That's a reasonable plan and won't hurt anything.

But I still think you have a problem with the accelerator pump on the carb. Don't forget that you said the engine runs better if you close the idle mix screw. That screw is supposed to control all of the fuel going to the engine, so if you close it and the engine runs, much less better, then there's another source of fuel.

And, Bill/85lebaront2 said "The Carter YFA is a fairly simple carburetor, which has one major weak point - the combination accelerator pump and metering rod control. This is a diaphragm with manifold vacuum on bottom and fuel on the top side. When this diaphragm fails the fuel is drawn directly into the intake." That fits your symptoms perfectly as it would be another source of fuel.

If the carb sat for years it is possible that the diaphragm got old and cracked. So while it won't hurt to plug that hole and put the carb back on, antifreeze won't burn so it isn't the source of the extra fuel.

Makes sense! I guess I have the rebuild kit and the carb is off so I shouldn’t be lazy. I’ll get to work on that and see if the local auto parts store has freeze plugs as well.

[Gary Lewis]

Makes sense! I guess I have the rebuild kit and the carb is off so I shouldn’t be lazy. I’ll get to work on that and see if the local auto parts store has freeze plugs as well.

I think you'll be a lot happier if you do rebuild the carb while it is off.

I'm not a fan of carbs that use fabric below the fuel line. Eventually the fabric fails and you have a problem. I'm not saying you need to change to a different carb, just saying that this happens and it has to be fixed or you'll have an overly rich fuel mix.