The pictures are not all that great, but what I'm seeing is the silicone is not sticking to the manifold in the exact spot I have the leak.

Here is a picture of the area in question on the block. Notice the area near the corner away from the sender. The silicone is there but smooth like it never stuck to the manifold.

http://mysite.verizon.net/resqj941/sitebuildercontent/sitebuilderpictures/enginebk.jpg

This is the front of the engine. Notice the uniform look to it. It was really stuck to the manifold. Like big ass pry bar stuck. :)

http://mysite.verizon.net/resqj941/sitebuildercontent/sitebuilderpictures/enginefrt.jpg

And this picture sucks, but it's the manifold. notice two areas that don't have any silicone stuck to them? Why? everywhere else the silicone is basically ripped in two, one half on the block one on the manifold. I cleaned the heck out of everything, maybe I missed a spot?

http://mysite.verizon.net/resqj941/sitebuildercontent/sitebuilderpictures/.pond/manifold.jpg.w560h420.jpg

Dave, does the manifold have any slop front to rear?

It looks like the castings arent mating near the sender (manifold to block).

Not discounting your abilities but have you checked the gap between the "china walls" and the manifold without the sealer?

I would also suggest you take a small punch and "stiple" the surface of the china wall and the manifold area to give the sealer more area to "Bite".

Make sure the surfaces of the manifold and the block are super dry and free of any oils or chemicals before applying the sealer. A wipe of lacquer thinner or brake clean on the surface but let it evaporate off before applying the sealer may help.

The fitting for the sending unit looks very close to the manifold area. It's hard to tell if it is "pushing" the manifold off it's area.

The only odd thing I could think of is that the manifold or block aren't "square".
There could be a variance in the machined surfaces or some warpage that prevents the manifold from sealing on the back.


Just some thoughts generated from your photos...

i usually get some sand paper and rough up the surface ever so slightly, seems to make the silicone grab alot better and havent had a problem yet.

http://www.nastyz28.com/forum/showthread.php?t=69284

I dont think its your method at all. The castings dont mate up well. Clean em all up and dry fit the manifold on there and push it fwd. you will have a couple eigths movement front to back in the intake. Now push back on the intake. (a few bolts in and not quite snug). Do ya end up with say about 3/16" overlap min?

Just my .02

Hope it helps Dave
Mark

Not discounting your abilities but have you checked the gap between the "china walls" and the manifold without the sealer?

I would also suggest you take a small punch and "stiple" the surface of the china wall and the manifold area to give the sealer more area to "Bite".

Make sure the surfaces of the manifold and the block are super dry and free of any oils or chemicals before applying the sealer. A wipe of lacquer thinner or brake clean on the surface but let it evaporate off before applying the sealer may help.

The fitting for the sending unit looks very close to the manifold area. It's hard to tell if it is "pushing" the manifold off it's area.

The only odd thing I could think of is that the manifold or block aren't "square".
There could be a variance in the machined surfaces or some warpage that prevents the manifold from sealing on the back.


Just some thoughts generated from your photos...

Feel free to discount or even question my ability. I've never ever had a manifold leak until this one, so I'm either over looking something or plain messing up. I just want it done so let me have it all. The things you mentioned I'm going to be checking here in a little bit once things are clean again. The are by the sender has about 1/4 inches width section where it sealed very well. My leak is at the other end of the "china wall"

The silicone was stuck very well to the block side, maybe I got careless on the manifold side?

Dave, if you prop up the manifold on four corners (one at each end) of the end seals, does it sit flat on all four points? Or does it rock from one corner to the other.

Trying to see if this thing might be warped....

Ultim8z, the manifold does not rock as I had previously thought. The sides match the angle of the heads uniformly too.

Without gaskets it sits on the ends. It will slide a bit to side to side due to the gap at the heads. I bolted the manifold on snug with the standard 0.060 gaskets. The gap at the ends both front and rear are uniform at a little more than .040. That's using a 0.040 feeler gage the has just a bit of resistance.

It's not what I had thought. I was thinking I had the manifold bottoming out but that's obviously not the case.

I did notice on the manifold that the area that didn't stick was very smooth, and the area it sealed well had swirl marks. Maybe just rough it up? Mark's idea is looking pretty good about now but I'm not blowing out, just not sealing well.

Dave, this may be a dumb question but are you following the torque sequence for a SBC manifold? Center bolts first then outer bolts?

You are letting it setup prior to putting the intake back on? And just how much of a bead are you putting on? Just seems like not much is remaining on the block or intake when you pulled it apart. I've always used ultra black gasket maker on mine...

Well crap Mike to answer your question, not really. I was snugging the corners first. I guess I better read the damn book huh? :( Another thing I was thinking about. The coil bolts in that corner and the bracket was interfering with the manifold bolts (they hold the bracket). So I use different bolts to tighten it all down and then modified the bracket, pulled the bolts and installed the bracket about ten minutes later. I wonder if that jacked up the adhesion.

BlownBigBlock, I've used the permitex black, ultra black (my favorite too) and some really thick Ford diesel stuff. The diesel stuff bonded like no other, at the front. I let them set up for about 5 minutes before I install the side gaskets, so figure about 7-10 minutes. I fill the corners well so the gap at the head to the block is filled, then I lay a 1/4 inch or so bead in one continuous run.

With the amount of overhang you have off the back of the block, you have plenty of silicone there.
Use the same Ford stuff you used before...
The recommendation to scuff up the surface is a very good one, as well as cleaning with lacquer thinner or brake clean. Rough it up with ~80 grit, clean it thoroughly TWICE with thinner, and re-assembly.
Start in the center of the manifold and tighten the bolts in a criss-cross circular pattern outwards.
Do it in steps, first step should be just to get the bolts to touch the manifold, finger tight, then tighten them a bit in sequence, then keep doing so until you reach approx 25-30 lb/ft of torque. Good and snug.

With the amount of overhang you have off the back of the block, you have plenty of silicone there.
Use the same Ford stuff you used before...
The recommendation to scuff up the surface is a very good one, as well as cleaning with lacquer thinner or brake clean. Rough it up with ~80 grit, clean it thoroughly TWICE with thinner, and re-assembly.
Start in the center of the manifold and tighten the bolts in a criss-cross circular pattern outwards.
Do it in steps, first step should be just to get the bolts to touch the manifold, finger tight, then tighten them a bit in sequence, then keep doing so until you reach approx 25-30 lb/ft of torque. Good and snug.

Looks like I muffed it again doesn't it? http://smiliesftw.com/x/runawaycrying.gif (http://smiliesftw.com)

Did you buy that intake used?

Did you buy that intake used?

Yes

Dave ..... a easy way to see if the intake was milled is to completely clean all gasket mating surfaces . next install the intake onto the block and use (4) bolts one at ea corner to center up the intake to the block . now get a feeler gauge set and measure the distance at the end rails and cylinder head to manifold area . get us those measurements to see if indeed the intake was milled .

like i mentioned before in your other thread i ran into this problem on my old 66 ford fairlane with a 427 ford side oiler . i ended up getting some mesurements and sending the intake off to the machine shop to be milled

Dave ..... a easy way to see if the intake was milled is to completely clean all gasket mating surfaces . next install the intake onto the block and use (4) bolts one at ea corner to center up the intake to the block . now get a feeler gauge set and measure the distance at the end rails and cylinder head to manifold area . get us those measurements to see if indeed the intake was milled .

like i mentioned before in your other thread i ran into this problem on my old 66 ford fairlane with a 427 ford side oiler . i ended up getting some mesurements and sending the intake off to the machine shop to be milled

Chuck, see post #8

Let me see if I've got this right:
You do not have a leak near the pressure sender.
The leak is near the china wall/head junction.
Is this right?

If so, then you definitely have an adhesion problem, as a few people already mentioned.

Personally, I've wondered about running a bead on the intake and a bead on the block and letting them both set before assembly. Then you have a gasket, instead of sealing the parts together. I have no idea how well it'd work.

Id take it to a machine shop and let them check it out and see if its warped.You never know.You dont know how the previous owner tourqed it down or dropped it or overheated the engine.Like you said you never had a problem doin it before.it has to be that manifold.

Let me see if I've got this right:
You do not have a leak near the pressure sender.
The leak is near the china wall/head junction.
Is this right?

If so, then you definitely have an adhesion problem, as a few people already mentioned.


Right, the leak is on the other side of the "china wall" from the sender. The silicone is compressed just like everywhere else, it just didn't stick to the manifold. While it's rough everywhere else from being torn apart when the manifold came off, that area is smooth and nothing came with the manifold. The silicone just didn't adhere to the manifold and the oil leaked between it and the manifold.

I don't see how it can be a fitment issue at this point. The manifold sits on the heads flat. The witness marks on he heads are clear impressions of the gaskets. The gap front and rear is a consistent size, and the manifold is not contacting the block.

I think the manifold was too smooth at the failure point. I'm going to clean the old one up tonight and see how it fits in comparison.

Another thing I was thinking about. The coil bolts in that corner and the bracket was interfering with the manifold bolts (they hold the bracket). So I use different bolts to tighten it all down and then modified the bracket, pulled the bolts and installed the bracket about ten minutes later. I wonder if that jacked up the adhesion.

BlownBigBlock, I've used the permitex black, ultra black (my favorite too) and some really thick Ford diesel stuff. The diesel stuff bonded like no other, at the front. I let them set up for about 5 minutes before I install the side gaskets, so figure about 7-10 minutes. I fill the corners well so the gap at the head to the block is filled, then I lay a 1/4 inch or so bead in one continuous run.

Dave, another dumb question (or statement maybe): Make sure your coil bolts aren't bottoming out in the holes, otherwise you won't be tightening the manifold once that happens.

Also, what's the point of letting the gasket sealer "set up"? I usually put my manifold on immediately after laying down the bead. Maybe if you're letting it set up, the surface looses some of it's liquidity as it "skins" and doesn't adhere to the manifold surface very well any more.

Dave, another dumb question (or statement maybe): Make sure your coil bolts aren't bottoming out in the holes, otherwise you won't be tightening the manifold once that happens.


That was a issue, and is why I modified the bracket. I just didn't notice it until I had started tightening them this last time. During the set up time, I had removed the bolts and reinstalled them, which could have cause the silicone not to bond.

I just got off the phone with Dougan's Machine here in Riverside. I went over all my checks and we talked for about 30 minutes. They are convinced the manifold is sitting correctly and it has to be a install issue. SO tonight I'll try again. :confused:

Have you tried a different intake. Yours could be warped.

Here's something to try if you don't mind wasting time: Just apply some RTV to the sealing surfaces and let it dry. Then see if it peels up easily or sticks. It should tell you if that is the problem or not, and it is was, try it again after roughing up the surface. Lots of time, but it should give you a confident install.

Have you tried a different intake. Yours could be warped.

I think a few posts back, we confirmed that the manifold wasn't warped.

Here's something to try if you don't mind wasting time: Just apply some RTV to the sealing surfaces and let it dry. Then see if it peels up easily or sticks. It should tell you if that is the problem or not, and it is was, try it again after roughing up the surface. Lots of time, but it should give you a confident install.

Dave, GetMore has a very good idea here. I would definitely run this test before bolting the manifold on. Even if you let sit over night and then do the peel test, you could complete the install by Wednesday or Thursday if the test is sucessful. Which would still give you plenty of margin until the Las Bracas run on Sunday.

Dave, GetMore has a very good idea here. I would definitely run this test before bolting the manifold on. Even if you let sit over night and then do the peel test, you could complete the install by Wednesday or Thursday if the test is sucessful. Which would still give you plenty of margin until the Las Bracas run on Sunday.

That does sound like a decent idea. I still need to make gaskets for the runners and clean up the garage before I break a leg so the time frame could work.

Like Jake said, clean both surfaces with a rough scuff pad, then clean real good with thinner(acetone also works good). Make sure you clean it enough that you see clean metal..dry dry dry..Use enough sealer and tighten in proper sequence..
should seal if alignment is OK..
Good luk
Hulk

This is the way I have put on my intakes, and it works GREAT.

I put rtv on the block and on the intake and let it sit overnight. i Then put on the gaskets with a small bead of rtv as usual, with one more small bead between the intake and block.

This has worked great everytime. I believe the key is letting the RTV set overnight...