IROCMAN89

I just replaced my intake manifold gasket because there was coolant leaking from where the intake and heads bond. I started it and it was still leaking. I checked for water in spark plugs and oil (negative). Leaks on both sides. What can it be? Can anyone help?

Atilla the Fun

I've been there. Coolant seeping from the front of the intake, but not getting inside the engine. But there were no other issues with my engine, so I just started adding coolant every Saturday morning. When I finally did pull the intake, I saw that the intake itself was the problem. I replaced it with a new Edelbrock intake and FelPro gaskets, problem solved.

Rolling Thunder

Well lets talk for moment about what you should do when you change an intake manifold gasket and well see if you did it right. First and foremost did you torque down the manifold well? I dont necessarily even took a torque wrench to it (although that would be a good idea) i more did your torque the bolts down in the right order? If you dont start from the middle bolts and work your way to the front and back of the motor it is likely the manifold is not sitting flat. Kinda like how you torque wheels down in a star pattern rather than working your way around in a circular pattern. Next did you clean off the gasket surfaces with a razor to get all the gasket material off? Next did you use the gasket sealer around all the water ports? I like to use it around all the ports but the water ports atleast is a must. I also like to use alittle brake cleaner on a rag to clean the sealing surfaces so there free of oil and grease so the gasket sealer will stick. Be sure to clean it all off though. Did you clean out the treads of the bolts and where they bolt in with a tap befor you reinstalled the intake? If not when you think a bolt is tight it may not really be socked down just hung up again not really putting an even pressure on the manifold a potential cause of leaks. Finally keep in mind that some of the intake manifold bolts go into the water jacket so if you dont use a thread sealer they will likely leak. This ide bet is the most likely cause as it doesnt seem anyone follows that part of it. My final question is are you certant that you have an intake manifold leak and its not something else leaking and collecing on the intake manifold?

Atilla the Fun

I've never once used sealer on the intake gaskets for a SBC. I use FelPro, and I've never had a leak. I've done literally hundreds of these for customers. Sealer usually creates a path for coolant to escape. I'm not the only machinist who will tell you about hot rodders misusing silly-cone. There's inly 8 places in a SBC where you should use any: the 4 corners of the intake joints, and the 4 corners of the oilpan joints.

Rolling Thunder

Now im not sayin you cant make a gasket seal without useing the sealer and ive never been a big fan of just useing it around the water ports as instructed as i always felt that that would cause high spots and low spots where the gasket wont seal. Although in my oppinion theres a reason why the instructions call for gasket sealer. I tell that it can also help with filling in imperfections as well as basically glueing the gasket to the manifolds and heads. I feel like this would help the long term reliability as dealing with the constant expanding and contractions due to heat cycling especially since most of out intakes are aluminum and most of out heads cast iron (different rates of expantion and contraction). From a machienist perspective if youve got some info as to why gasket sealer is bad ide love to hear it as ive never heard that it was bad to the contrary every manual ive ever picked up and the gaskets instructions recomends it? Learn something new every day right

Atilla the Fun

I do use sealer on engines, just not the SBC. I love Edelbrock's gasgacinch, but the SBC doesn't need it.

Rolling Thunder

Any reason why though? I mean every rebuild manual and intake gasket set's instruction manual specifies it. I mean i have to admit i did skip it once but only because i was only swapping the manifold for a weeks to pass emmissions and it did seal but i cant say how it would hold up in the long run.

Atilla the Fun

The backstory. OK. The first machine shop I worked at, they just didn't use sealer for intake gaskets of SBCs. I asked why and got yelled at. The next morning the owner came over and said, approximately "Boy, on 350s, just use FelPros and torque it right." Now, I can't say he never had any comebacks, but I can say there was no way for me to tell how many were for that, if any. So 6 months later when we did a 350 for me, that's how we did it. I drove it 18 months that way, before swapping intakes, from a Performer to a Street Dominator, but I again didn't use sealer, and when I sold it 8 months later, still no issues. That was more than 7 years ago now. I'm not telling you to not use it, I'm saying that not using it is okay. If you've had success with your technique, then stick with it. But blaming a leak on not using it, which you sort of did and sort of didn't, it got my attention.

Rolling Thunder

Well thats ok im not challenging your method or saying that its wrong to not useing sealer im just curious about why thats all. Learn something new every day thats how we move foward right.

Atilla the Fun

yup. And I am glad you thought to walk the OP through the procedure. Sometimes us old hands take too much for granted.

Rolling Thunder

Yea well ive learned the hard way about taking short cuts too many times lol. Sometimes you can get away with it some times not. I guess its a matter of experiance to see what works and what doesnt. Ya know what they say theres always time to do things twice but never right the first time lol.