The Stovebolt Site Forums The Shop Area Engine Shop New Fenton intake leaks through heat riser

Has anyone had poor results with these repop fentons? Got it new in the box from a vender at the swap meet. When coolant is run through the heating space on the bottom, it is sucked rapidly into the intake, cylinders, what a mess. Still getting it sorted out But that's some pretty poor workmanship

Not to be the bearer of bad news, but most of these inline intakes were never meant to be water heated because of this type of porosity issues. Offenhauser is another one that has a disclaimer against this method of heating. They were originally meant to be exhaust heated. There have been countless people that have been fine using water to heat theirs with no problems, but they can be counted as lucky since they weren't originally intended to be used that way.

With all due respect, I have never figured out why you would want to run water through an intake given ALL of the various spots it could leak and with the idea in mind that a water leak on a road trip is much more serious than an exhaust leak not to mention hoses everywhere. The hoses are really not very attractive.
What is wrong with exhaust heat? It definitely heats up more quickly - like as soon as you fire the engine up! Exhaust is the way Chevrolet and all of the manufactures originally set up these vehicles. It sure seems like the right way to me.

Would someone back the conversation up a few steps & explain what was trying to be done? I've got a better than average understanding of the exhaust/heat riser valve function & operation, but I'm lost here...

A start could be the "Coolant through the heating space" the op refers to.

Brad

New Fenton intake leaks through heat riser

"When coolant is run through the heating space on the bottom, it is sucked rapidly into the intake, cylinders, what a mess."

joethehuman most likely has a Fenton dual carb intake to which he attached a heating plate plumbed to coolant water. The coolant leaked into the intake passage to one or both carbs.

Sounds bad. repair/replace?

This is another reason for not using coolant heat.
(besides it being slower to warm up than exhaust heat, and being an opportunity for coolant leaks at joints or damaged hoses).

I'm with Brad on this one. If coolant is leaking into the
intake, then there must be an intake leak, which is no good
whether it's sucking water or air into it. Bottom line is,
a cracked intake, stock or aftermarket, is junk no matter
what's leaking into it.

dg

I recently danced around with whether to use hot water or hot exhaust gas for manifold heat and opted for exhaust gas heat.
Theres no question that some sort of manifold heat is necessary for "optimum" performance of these engines so which ever method you use will be beneficial.

In any case, a leaking intake manifold is bad news especially when it's in the casting. I don't know how you'd find and seal the hole that's leaking up into the fuel/air passage so basically the intake is toast as it will cause problems with leaking exhaust gasses into the intake also.

Tom Langdon has a tech article on how to seal up a leaky heat chamber but the holes are casting holes on the bottom of the intake and are easy to get to. He says they aren't sealed properly from the manufacturer. He doesn't indicate the make tho.

It's bad to hear of such problems in the casting of these parts.

My Fenton dual intake doesn't leak (thankfully) so theres hope you'll find a good one.

Good luck
Dave

Weather or not its water or exhaust, the manifold is leaking due to bad casting. If its exhaust, you still have a leak, which will make the engine run just as bad. In this case, it was easier to find due to the coolant.

How would you like to track down a poorly running engine problem when it's sucking exhaust back up through the intake casting?

Dad bought of a set of aluminum heads for his Pontiac, we pressure tested them before installing because of what we had read about them. Using soapy water and air pressure, they looked like a foamy sponge with all the casting holes. It took two more heads to get a set that didn't leak. From what we learned, it's all about the quality of the aluminum being used in the casting, in this case it was mostly recycled, they have since swapped foundries and solved all the problems.

Joe

If the manifold leaks water, it will also leak exhaust gas. You really don't need an EGR system on a stovebolt engine, especially one that recycles exhaust gas all the time! The only fix for that manifold other than replacing it would be to run a piece of stainless steel tubing all the way through the heat passage and secure it into the manifold with pipe threaded compression fittings on both ends.

If you bought the manifold new, you really need to return it for credit, and buy a different brand next time.
Jerry

Since you bought it a Swap Meet - no return.

What are you using for exhaust manifold/heaters?

If you are using Fenton headers, you might as well try to run heat tubes to a "block-off plate". You'd have to find a way to block off the holes in the tubes.

A desperate measure for a desperate situation?

If the intake manifold has leaks to the outside air, with a sealed block-off plate, you are SOL (sadly Out of Luck).

Well, I was just at the hardware store researching fittings and copper pipe, was thinking of a small 3/8 pipe from the exhaust mani and running along the inside of my homemade block-off plate or easier yet running in on the outside of the plate and hoping it heats up the chamber in the manifold that is leaking.I have fenton exhaust headers with the pipe threaded holes in each one. Maybe I'll just block of the chamber and run w/o heat. It ran that way when my dad owned it for 20 years

I'd run the pipes to the plate.

The plate will transfer heat to the intake manifold.

As a last resort, I'd mix up some JB weld and smear that on the inside of the heat chamber of the intake. It's pretty fluid and might flow into the pores enough to seal it up. Stuff has done miracles for me and held up. Good luck. Jim I'd clean it up real good first though to get it to stick good.

I'd begin by pressure testing the manifold to see how bad the leak is. It's possible it's so porous than no type of fix is going to work. Clamp some flat metal plates over the intake ports, and another one to the carburetor flange with an air hose quick-connect fitting in it. Apply about 3-5 PSI to the manifold with an air pressure regulator, and use a spritz bottle with a soap solution to spot the porosity in the casting. From there. you can decide whether to try a repair, or just scrap the thing and chalk it up to experience!
Jerry