TPIShark

Hi all,

As described, the intake manifold is very slowly seeping coolant out by the right water port, just below the sending unit. At first I thought it was around the sending unit threads, but it's actually forming droplets just below it. There are no apparent cracks; it just seems the aluminum has become porous. Has anyone had experience with this? I already tried some of the old stop-leak powder, with no luck.

Any advice appreciated.

Thanks!

jim lockwood

A picture would help.

Avispa

The manifold could have internal cracks that don't have any obvious external exposure. I have cracks like that on my intake near the head ends of a couple of intake ports. They can be welded. Paragon Reproductions does that service.

63 340HP

The manifold is porous and will likely need to be removed to be repaired.

If it has not suffered structural cracks, sealing the water passage interior surface with epoxy is often the least noticeable solution.

DZAUTO

This is not really common, but I have seen this occur and a few alum intake manifolds-----------------------------including FI adapter plates. And it's always the coolant passage of the manifolds. If I were to guess, the leaking that is occurring is the result of severe corrosion that has developed INSIDE the water passage. I've also seen this occur at the REAR of manifolds where they mate with the rear water port of the head.
The corrosion occurs from the inside, thus, it is not obvious. The alum is so thin in the corroded area, that the coolant can weep through the pores of the alum, but from the outside, there is no obvious damage.
To save the manifold, I have HEAVILY blasted the corroded area, flushed it with brake cleaner of lacquer thinner, then I had the corroded/pitted area welded by a VERY EXPERIENCED alum welder and grind the welded area back to the original contour/surface..

dmaxx3500

clean the it inside /out,and go find a good 2-part epoxy [thin liquid] ,marine stores carry it to fix boat eng colling systems,[there are a few companys that do this too],you can paint it on,the whole water jacket inside the manifold

Vitaminmopar

I repaired a 64 FI adapter plate with corrosion at all the water passages and also repaired cracks around three plenum lid bolt holes . DZAuto and dmaxx3500 gave two practical ways of repairing your manifold. In my case I did not have epoxy on hand plus I questioned how long the repair might last with the antifreeze solutions in use now days. I have three experience's with having three different welder's weld aluminum from the 50's and 60's and each time has been messy, so I decided to experiment.

What I did IS NOT practical but it worked for me and if you can not get epoxy to hold or have a welder that you trust the job with or the cost of the welding is not favorable, then it is DIY time.

1. Position the manifold so the flange side is up and level. The top side being down keep the working end exposed and accessible.
2. Poke, prod and gouge with a pointed steel tool to loosen and remove the corroded metal.
3. I used a small hammer and punch at times also to find weak areas that looked questionable. You may be surprised what you find, I was when the punch went all the way through in one area. The metal just turns to powder when tapped.
4. I used a Dremel tool and debrided the wound area with small rotary stones or bits and then smoothed the wounded areas out
5. Purchase a package of low temperature aluminum brazing rods from Harbor Freight, Home Depot, etc.
6. Using a hand propane gas torch (large tip with a flame spreader) I heated the area and melted the brazing rod filling in the wounds. Keeping the manifold end exposed and accessible you can heat from the bottom. This will take much time as the aluminum sheds the heat so if your torch is not big enough melting may never happen. I had to supplement the propane torch with an additional MAP torch to get to temp. If you need to use an additional torch use it to only reach or maintain heat. The aluminum brazing rod melts at 750F, aluminum melts at 1221F so there is a wide margin between the two temps. At this stage of the repair you need to keep the solder molten because it won't stick unless you remove the oxide on the manifold aluminum substrate that forms when aluminum is exposed to air.
6. While the solder is still molten use a sharp pointed steel tool (screwdriver worked for me) and run the tip under the solder and scrape the manifold metal. If my memory is correct you can visually tell when the solder bonds.
7. Allow to cool then use a coarse file to dress the gasket flange.

The adapter plate took me about 5 hours to repair with most of that time spent trying to get the adapter plate up to temp.

Couple of cautions:
Working with open flame make sure your work area is open and clear.
Have a fire extinguisher on hand
If you have penetration to the opposite side like I did, do not use aluminum foil or steel wool to back fill. I cut part of a steel can and tooled the metal so it filled the void from the back. I had to improvise a way to apply pressure to this nickle size steel piece as I did not want it to come free.

As I stated this is not practical but it is an option.

ejboyd5

Remove manifold, clean area, apply green Loctite, reinstall manifold.

TPIShark

I want to sincerely thank everyone for all their input here, and so quickly. This is the type of stuff that makes the hobby/our community so great.

I personally think any one of these methods might work, depending on the extent of the damage I find when I start digging into this.

I'll try to remember to take some pictures, and will let you all know how I make out.
Fair warning; it may be a short while, as I have a few different (customer) cars I'm working on.

GTOguy

Stopleak will also work. Personally, if it were mine, I'd pull it and use JB weld on it if I could get it clean enough. Have done it before with other aluminum intakes, timing covers, etc, with zero issues years and years down the line.

TPIShark

Just a follow-up. I got lucky with this one. After much closer inspection, (leaving little bits of paper towel as witness, for example) and removing the temp sender, it was actually leaking very slowly from there, hidden by the support bracket for the fuel filter. As much as sealer is frowned upon, I applied a little sensor-safe grey to the threads, and also inspected the interior of the manifold while it was out. All is well. Thanks again for all the input; I know it will come in handy on another adventure. :-)

jim lockwood

Thanks for posting a follow-up. It always helps to know how problems get resolved.