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Cadillac & LaSalle Club Forums => Technical / Authenticity => Topic started by: Philippe M. Ruel on February 09, 2009, 06:19:39 AM

Title: infamous exhaust crossover in intake manifold - RUSTED AND WEATHERED
Post by: Philippe M. Ruel on February 09, 2009, 06:19:39 AM
Hello all :)

I re-start from the end of an older topic (2005) about a cracked 1961 intake manifold.

Quote from: Bruce Reynolds # 18992 on October 26, 2005, 11:00:07 PMI had a problem which I thought was an Exhaust Manifold leak and it turned out to be a leak between the Intake Manifold and the Cylinder Head, at the point where the cross-over port joins /.../. The head material had become corroded away, and there wasnt enough material in both the head and manifold to seal it correctly.
This is exactly what I found to be the cause of an "exhaust" leak on my '52, after removing, inspecting and hand-grinding the passenger side exhaust manifold (that needed it anyway, as it was banana-shaped) on a marble plate from a funeral supplier.

Driver's side of the intake manifold looks good, so do heads surfaces. But passenger side of the manifold is rust-weathered on a good 1 mm (say 3/64 inch) deep - see pictures.

The manifold is not cracked. I wonder how to fix it another way than Bruce did :
Quote from: Bruce Reynolds # 18992 on October 26, 2005, 11:00:07 PMMy fix was to block off the Exhaust Cross-over passage in the intake manifold completely, and then liberally seal the area with a good heatproof gasket cement, and it hasnt leaked since.
Three other solutions appeared to me :

Solution #1 : adding matter by welding the manifold with "special" cast iron electrodes, then machining the flat surface to original level. No one recommends it because it needs to red-heat the manifold, that may get cracked because of it.

Solution #2 : machining both sides of the manifold all the way (both sides, so that manifold remains level). The machinist I saw says too much matter is missing - holes in manifold for bolts and studs may not remain in front of corresponding holes in heads.

Solution #3 : machining 1 to 1.5 mm off this very exhaust port of the manifold only, and inserting a piece of metal sheet (stainless steel or another metal) between manifold and head. Inserting a copper sheet would eliminate the need for a second gasket between manifold and sheet, as tender copper will form a gasket by itself.

I'm looking forward any comments, tricks, good/bad experience about these three solutions (or other solutions). The main issue is, it would be VERY difficult to get a replacement manifold here in Europe, and shipping charges from the US would be far over $100 for such a heavy part.

I have two other questions related to this manifold, I need to post a second message to add pictures.
Title: Re: infamous exhaust crossover in intake manifold - RUSTED AND WEATHERED
Post by: Philippe M. Ruel on February 09, 2009, 06:50:14 AM
The manifold is held in place by four nuts on studs in the center, plus four peripheral bolts.

(1) two of the bolts are 1-1/2" long, the two others are 1-3/8" long. Under part group #8.4326, the parts list mentions four 1-1/4" bolts, or three 1-1/4" plus one 1-1/2" for cars with power steering. My car never had power steering. Do I read it correctly ?

(2) each nut on stud held three washers, one very large and thick plus one smaller, flat one plus one tiny, slotted one. The parts list (group 8.4445) mentions four thick washers (13/32" x 1-3/8" x 1/4", part #400 130) and fifteen smaller ones (13/32" x 11/16" x 1/8", #891 463). The picture in parts book shows a 1949 engine, with one thick washer on each stud and smaller washers on bolts. So, how many washers are there ?

(3) The (guessed-to-be) original manifold-to-heads gaskets were thin and metallic. The replacement ones I purchased are not : they are made of a black, graphite-coated thicker material. Any suggestions or experience about the different materials used ?

Thanks
Title: Re: infamous exhaust crossover in intake manifold - RUSTED AND WEATHERED
Post by: greg 18360 on February 09, 2009, 06:53:10 AM
Hi, look up remflex gaskets I used them on my 41, so far so good.
         Greg
Title: Re: infamous exhaust crossover in intake manifold - RUSTED AND WEATHERED
Post by: The Tassie Devil(le) on February 09, 2009, 07:09:17 AM
G'day Phillippe,

In your case, I would be taking the Manifold to an Engineering Shop and disguss the process of "Metal Spraying" with them.

I have had very good results with that process, from welding up broken Manifolds, and very thin casting ones at that, and joining steel tubing to cast iron.

This process involved completely cleaning up the rubbish around the area, and heating up the piece, then with a special Oxy attachment, spraying stuff that melts as it attaches itself to the area, and builds up the area which can be milled afterwards.   The stuff I used was a Eutectic product.   Not cheap, but worth every penny when other processes don't work.

But, I like the idea of machining and using a filler piece on the one side to compensate.

Bruce. >:D
Title: Re: infamous exhaust crossover in intake manifold - RUSTED AND WEATHERED
Post by: Otto Skorzeny on February 09, 2009, 08:33:39 AM
Of the three options you give, I too would choose #3. Shimming the gap is a good choice.I would, however investigate Bruce's suggestion of metal spraying.
Title: Re: infamous exhaust crossover in intake manifold - RUSTED AND WEATHERED
Post by: Ohio57-62Sedan on February 09, 2009, 10:13:43 AM
I would have to agree with the above... I would still resurface it just a bit to have a good surface to work with... look like you have some meat there to work with ???
Title: Re: infamous exhaust crossover in intake manifold - RUSTED AND WEATHERED
Post by: David #19063 on February 09, 2009, 07:42:22 PM
What would happen if one just blocked it off so no exhaust would get through?
Title: Re: infamous exhaust crossover in intake manifold - RUSTED AND WEATHERED
Post by: jaxops on February 10, 2009, 08:44:21 AM
Philippe,

  I can empathize.   It seems on the 56 that the air intake manifold was prone to cracking, especially when some of the "gorillas" that worked on some cars in the past over-tightened them and cracked them.   There's a lot of heat on top of those engines too.  I'm sure it was true for any of these cars as well.
Title: Re: infamous exhaust crossover in intake manifold - RUSTED AND WEATHERED
Post by: 35-709 on February 10, 2009, 01:14:02 PM
This cracking can also be caused by a stuck heat riser valve that forces exhaust through the intake's exhaust passage at all times not only just when the car is cold.  In time it also causes the intake gasket to leak on both sides where the exhaust passage is and erodes the intake manifold and the engine block in those areas which it sounds like we are dealing with here. 
Those who insist on keeping their heat risers should make it a regular practice to make sure the valve is free and working properly ---- the rest of us gut the valve and plug the holes where the shaft goes through.  OR make a spacer the same thickness as the valve and eliminate the valve all together.  IMHO, those valves are not necessary in cars driven in warmer weather, and for cars driven in cold weather they are not needed if a little patience is observed in letting the car warm up.

My 2 cents 
Title: Re: infamous exhaust crossover in intake manifold - RUSTED AND WEATHERED
Post by: PHIL WHYTE CLC 14192 on February 10, 2009, 01:27:27 PM
The problem with machining the mating surfaces down is that if you take too much off you will have a gap between the cylinder heads and the intake manifold and/or the holes won't line up properly. I would also go with just machining the worn area and shimming or, ideally get it metal sprayed then machined back to original spec. - I just had this done on a shaft in my steering box.
Good luck,
Philippe