Intake manifold off again...Crap

[tortuga]

Rear RTV seal leaking...Think this time i'll screw in studs so i am sure the manifold goes straight down.

Any advice to ensure the damn thing doesn't leak? The front is tight as a nun's punany...

[ACademic]

Get some nylon bolts from Home Depot in the same thread pitch but a little longer. Cut off the heads and hand screw them into the block on four corners. Essentially removable studs once you lay the intake down and start the remaining bolts.

[1795]

You may want to inspect the intake manifold to make sure that it is not faulty. I was having repeat problems with intake manifold gaskets getting torn and leaking oil into the cylinder and the last time that it was getting replaced my mechanic noticed that my RPM intake manifold had a slight twist to it and would teeter corner to corner. Bought a new intake manifold and the problem has never resurfaced again. Every now and then you will get a bad casting no matter who the manufacturer. If your intake manifold is not sitting square it will lead to problems.

Otherwise, I would just follow the advice given above.

[madmaxx]

Make sure you are using Permatex Ultra Black not the POS Loctite sealant. The Loctite failed overtime i used it and the Permatex worked perfect.

[DAVID GAGNARD]

Originally Posted by ACademic

Get some nylon bolts from Home Depot in the same thread pitch but a little longer. Cut off the heads and hand screw them into the block on four corners. Essentially removable studs once you lay the intake down and start the remaining bolts.

+1, I just use some bolts that are an inch or two longer than the manifold bolts,cut off the heads and kinda round that end off on the grinder,then screw in on the four corners finger tight to act as a guide.....

test fit the manifold on dry and mark the underside of the manifold where it will sit on the block "ridge" with a sharpie.....remove the manifold and I like to use "The Right Stuff", follow the inside of your marked line and be generous,give it a minute or two to get tacky and then drop the manifold straight down on your four corner studs......screw in the middle bolts just barely more than finger tight and then remove the studs and put in the four corner bolts and tighten down in sequence and you should be good to go..

let it dry completely without touching the sealant, trim the excess the next day with a razor blade......
So far, knock on wood, this method has not failed me,,,,,,,,,,yet.......

David

[Three Peaks]

I use the same method as David, but I usually use RTV. If I have a really tough situation, like a corner that may not be fitting absolutely perfectly, I put RTV on both sides of the gasket and spread thin with my fingers before dropping it over the guide bolts, then slide on the manifold and tighten down as above.
Be sure to tighten down your manifold in stages. Most SBF manifold bolts need to be tightened to around 18-20 ft/lbs for proper torque, if I remember correctly. Tighten in sequence the first time to around 10-12, then step up half way to 12-14, then wait about 10 minutes for the gaskets to "relax" then tighten to the final torque spec. I've found several times over the years that if I wait an hour or more, the manifold will require another retorque even if not started or driven. I've always thought it was because the gasket was compressing (or what I call relaxing) over time and in a little while it will compress as much as it is going to and you can torque it for the final time. This has never failed me over many years of dealing with this issue. It was taught to me by a friend of my father who built race engines.

Bob

[Tom Wells]

tortuga,

One more suggestion: get a friend to help. Get on opposite sides of the car and carefully lower the manifold together as level as possible. Practice dry, then do it for real.

Tom

[*13*]

Leaking oil out the back? Or leaking coolant into the oil? What engine do you have?

[tortuga]

Took a bit of advice from all, the rear leak seems gone; used four 5/8-18 SS all-thread studs chased with a die, chased all head threads, cleaned everything as if the pope were visiting, test fitted, striped the intake of everything, and voila seems no more rear leak...

Thanks for all the help fellas!

[tortuga]

Well FACK it blew again today: Its always from BIG throttle to off throttle: Solved the oil leak and now back off again (i am getting quick at it): My confidenc in this motor is quickly dwindling to zero...need to check the manifold and heads for flatness, and use the best gaskets i can i guess: Its a small block making a crap load of power...

One thing i am wondering about is tapping into the back coolant passages and plumbing them back to a return? Seems weird having a stagnant passage back there? i would suspect that the cause is likely a big sudden vacuum spike off throttle at high rpm...

Gonna do some research before bolting this ***** back together yet once again...

[DAVID GAGNARD]

Originally Posted by tortuga

Well FACK it blew again today: Its always from BIG throttle to off throttle: Solved the oil leak and now back off again (i am getting quick at it): My confidenc in this motor is quickly dwindling to zero...need to check the manifold and heads for flatness, and use the best gaskets i can i guess: Its a small block making a crap load of power...

One thing i am wondering about is tapping into the back coolant passages and plumbing them back to a return? Seems weird having a stagnant passage back there? i would suspect that the cause is likely a big sudden vacuum spike off throttle at high rpm...

Gonna do some research before bolting this ***** back together yet once again...

Exactly what blew this time???? a picture or two would be great.....
Do you have any or what kind of PCV system on the car and any valve cover breathers????

Something seriously out of wack,never heard of or seen one blow repeatedly without some major flaw in the system.

David

[tortuga]

Originally Posted by DAVID GAGNARD

Exactly what blew this time???? a picture or two would be great.....
Do you have any or what kind of PCV system on the car and any valve cover breathers????

Something seriously out of wack,never heard of or seen one blow repeatedly without some major flaw in the system.

David

I was all ready to take photos but there isnt really anything visible to the naked eye...What i did find that i failed to mention was the intake bolts all seemed a bit loose, thoe one aft on the passenger side very much so? I think it may be very very critical to follow the stepwise torquing and a post relax torque?

I,ve cleaned the whole thing and test fitted the manifold and ther is no preceptable 'rock'...

Are these big stroked 351s in need of very special intake sealing? Gong to talk to the builder tomorrow.

Really frustrating.

I am thinking studs would be better?

[427sharpe]

Have the heads been milled? If so, you may need to mill the intake to get all the parts to line up correctly.

[1795]

You might want to consider some locktite on the intake manifold bolts if the have world loose. If you use it, do not go back through afterwards and try to re-torque the bolts, as you may break the locktite free.

[jeffgrice]

Originally Posted by tortuga

I was all ready to take photos but there isnt really anything visible to the naked eye...What i did find that i failed to mention was the intake bolts all seemed a bit loose, thoe one aft on the passenger side very much so? I think it may be very very critical to follow the stepwise torquing and a post relax torque?

I,ve cleaned the whole thing and test fitted the manifold and ther is no preceptable 'rock'...

Are these big stroked 351s in need of very special intake sealing? Gong to talk to the builder tomorrow.

Really frustrating.

I am thinking studs would be better?

Sorry to hear this...my 427sr intake let go last year. Bolts were loose.

When I fixed...I torgued the intake bolts in the proper sequence likely 20 times before they didn't need a touch up of torque. And didn't drive super hard until the torque was stable.

I used a thread compound that is suppose to help keep torque (not lockite). I can try to find it for you.

Jeff

[jeffgrice]

Originally Posted by tortuga

I was all ready to take photos but there isnt really anything visible to the naked eye...What i did find that i failed to mention was the intake bolts all seemed a bit loose, thoe one aft on the passenger side very much so? I think it may be very very critical to follow the stepwise torquing and a post relax torque?

I,ve cleaned the whole thing and test fitted the manifold and ther is no preceptable 'rock'...

Are these big stroked 351s in need of very special intake sealing? Gong to talk to the builder tomorrow.

Really frustrating.

I am thinking studs would be better?

One more point...did you use the steel reinforced intake gaskets?

If not please do when you r&r

Jeff

[JBCOBRA]

What did you torque the bolts to, and in what order?

[MOTORHEAD]

Did you ck bolt length to hole depth ? Maybe the bolts are bottoming out.

[car4jim]

I'm gaining a great appreciation for FE builders like Brent. This the fussiest motor I've ever worked on. Mistakes and lessons learned around every corner! I think partly due to the all aluminum nature of the beast! I'm not sure what the letters FE stands for....but certainly not freakin-easy

[olddog]

I found that all four end bolt holes in my heads had not been tapped deep enough. With the bolts torqued to spec, I could slide 0.005 to 0.010 feeler gauge under the bolt heads. The bolt heads were not touching the manifold. I removed the helicoil, tapped them down and put new helicoils in.

I use Victor Rienz (SP?) gaskets. They are metal reinforced.

I am assuming you are not using the gasket that lays across the block and are just filling it with a layer of sealant. All surfaces should be cleaned with a good parts cleaner. I like brake cleaner. Then clean it with alcohol and white cotton. keep cleaning until the cotton stays white. It does not stick to oil.

I think a product called the right stuff is best for this service.

When I torqued the manifold down I must have ran over the bolts in the proper pattern a dozen or more times until the toque wrench clicked on every bolt (nut & stud actually) without any of them moving. Let it set 24 hr. Then ran it normally up to temp. Let it cool over night. Put it through 3 heat cycles, and then re-torqued all bolt again until none moved.

I used all studs with locktight into the heads. Then after final torque, I put a set of acorn nuts over top of the nuts used to torque it, which provided a jam nut to assure they never move. I used stainless steel nuts for looks.

I'm not saying the studs and acorn jam nuts are necessary, but I wanted to over kill this problem once and forever.

I do suspect you may be building pressure in the block. Are you sure the PCV system is working.