From the sounds of it you did everything correct. The only thing is missing is the use of alignment studs when you lowered the intake. If you didn't use them, when you lowered the intake, did you have to move it a little to get the bolt holes to line up? If yes, that might disturb the RTV enough to cause a leak. Did you confirm that it's not the valve cover gasket leaking?

 

You know, now that you mention it, that may be one issue I didnt think of. I dont use alignment studs. Im not saying it was off or sliding around, but Im sure it wasnt dead nuts on setting the intake on leaning over a fender. When I bolted it down Im sure it moved a little forward or back more than likely as I cant exactly look right over the engine to ensure its 100%. Im going to put a stud in the front and back holes to align it this next time, hopefully its that easy but figured Id ask as Ive never had an issue before, let alone twice in a couple weeks. The second time I felt I was very thorough and it still leaked. I know its not the parts as its been perfect previous tome taking i take off.

 

I started using Ford motorcraft TA-31 diesel silicone on the China rails instead of black rtv. Stuff is amazing.

 

Is this a dealer product?

 

You can get the TA-31 many places now but the local parts stores don't carry it. Amazon eBay to name a few. And that tube lasts a long time if it's resealed properly.

Amazon.com: Genuine Ford Fluid TA-31 RTV Silicone Sealant - 5 oz. : Automotive

Buy Genuine Ford Fluid TA-31 RTV Silicone Sealant - 5 oz.: Silicone - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

 

Might have to give it a try!

 

Hello venomv8, I used this trick once and had good results.

You take your lower intake and flip it, take a hole punch and punch a line of holes along the china rail.

Do the same for the engine block.

When you lay the RTV and set the intake, the RTV will sink into the holes you made, making for a stronger seal.

 

sometimes it's hard to make sure the point where the china wall meets the head gasket is squeaky clean. I try to clean with brake clean then inject silicone into the point where the head meets the deck and china wall. Forcing in silicone can help at that spot.

 

The alignment studs do help a lot. I've only done intake installs using studs and using studs to drop the intake down does make lining everything up very easy.

I don't typically do the rails in RTV only. What i've been doing lately is using the explorer style intake gasket set that comes with the blue silicone end pieces rather than the cork. I only put a dab of black RTV in the corners and then use studs to drop it down and torque in sequence. Been fine like this.

 

Studs are a life (or RTV) saver.
I actually just use 2 studs. One in front right corner and one in left rear corner. You could do one at each corner, but really don't need more than 1 on each side to get the lower intake to drop down straight.

 

A note I learned from Woody, is adding silicone to the angle edges of the china rails that the heads don't 'clamp' too. Ideally you would do this when building an engine before placing the head gaskets and heads on.

Your slow leak sounds like you might have a small leak in the area indicated below. Best you can do is clean that area from the outside and seal it with some good sealant. In my place of work (OEM transmission and axle company), we use Loctite 5699 and it will seal anything. Leagues better that your local auto-parts store. Get a reusable canister for $17 on amazon.

My additional notes for china rail install, is to scuff it good with 36 grit paper and clean it well. Like so clean you would lick it, sober...

 

My additional notes for china rail install, is to scuff it good with 36 grit paper and clean it well. Like so clean you would lick it, sober...

That don’t take much

 

I think the bigger issue is some head gaskets aren't long enough to reach the end rail so there is a void the the oil flows thru. That's where you would put a dab of sealant.

 

Are you certain it is the intake and not the corner of the head? Is there any RTV in the corner of the head, or possibly a tiny bit of remaining RTV at the head / block?

As others have said, studs are mandatory, use 4, the Ford or Toyota RTV (I have a buddy that is a Lexus mech), nice thick single bead, don't let the RTV skin over (you want it sticky) have someone help you lower the intake (1 person at each fender) and torque the intake 3 different times over the first 30 hours, then put the upper on.

 

This may be a dumb a$$ question, but might it be weeping around the plug behind the cam or the oil pressure port? Or did I miss something??

 

I agree with cornman. After a couple unsuccessful attempts of re sealing my intake for a rear leak I decided to remove the intake one more time. Instead of doing it the right way and removing the heads to apply rtv I took a drinking straw and slid it in between the back of the head and china rail and used a pressurized can of ultra black to force rtv in and slowly pulled the straw out as I was still applying rtv. Filled the gap up perfectly and didn't leak anymore. My head gasket was a little too short though and didn't go to the end of the rail like stangjumper was explaining. Next time I definitely won't forget to rtv that spot before putting the heads on.

 

Same thing here with the head gaskets not going up the China wall far enough.

 

Yep update, it definitely wasnt the intake to begin with. I did everything over to T and started it up, it was coming from the top of the gasket portion, had to slather RTV toward that top portion and it stopped the leak as of now. Piss poor design.......