96 5.7 Intake Manifold Gasket replacement

"Chris" wrote

It's unfortunate that you dis-assembled this part of the intake as there is no need to do this, unless you were also replacing the upper plenum gasket. I would re-install the upper on the lower, take those small fuel line sections that connect to the CSFI and make sure they are re-installed on the upper "before" you install the entire manifold assembly.

Not a good idea....just make sure the gasket surfaces are clean and dry....and make sure the end sections are "perfectly" clean and dry. There is no need for any extra "sealers".

I don't know what else you can use. If you make sure both the block and the intake is perfectly clean and dry, and you apply the proper amount, and you are careful to basically levitate the manifold above the RTV until you are exactly above the RTV in the correct position..and then lower the manifold straight down on it....it will seal quite well. As an added precaution...you could torque down the manifold and then let the RTV setup for a few hours, or overnight.

You are probably missing a nut. There are three long bolts that run through the bracket, one is down low...close to the harmonic balancer, two are in plain sight at the top of bracket. There is also one stud with a nut at the top of the bracket. Then.....there is a bracket with a nut securing it down behind the ps pump on the drivers side head....and there is one more bracket with a nut....way down low on the drivers side of the block. The nut behind the ps pump can simply be loosened, the bracket is slotted there....the other nut down low, must be removed.

Just install new Dexcool, and I would install a new radiator cap.

Remember to clean the threads of your intake bolts and apply some Loctite medium strength threadlocker before you install them.

Ian

I personally wouldn't use RTV.

Apparently the gasket is designed to allow for the slippage between the intake and block. As the 2 are different metals, they expand and contract differently.

He needs to use it or it won't seal right and he'll be right bac k where he started. RTV, when fully set is quite flexible, allowing for this "slippage" you refer to.

Doc

Ok.

dex-cool is garbage. this will be confirmed if you look at the bottom side of your radiator cap because you will see where it is all caked up where it has leaked past the seal. this i also believe to be why intake gaskets and water pumps go bad more now than in the past. i have even got a gm field engineer to agree with me that dex-cool is inferior to conventional green coolant. he has changed all his own cars to green. they say dex-cool is good for 150k, but i d't think anything makes it that far w/out needing intake gaskets so you can't prove it by me!

oh hell yes there is... just try to do any work above 20ft in the air and be OSHA compliant.

-Bret

Chris,

I hope by now you have your truck back together. I have not developed any leaks (yet). I won't profess to be an expert on the topic no, but I can give you my opinion on a few of your concerns. I will say that all of the imput i received was great and gave me more confidence to start this project with the end in mind. GET A HEATER. YOU CAN'T THINK IF YOUR FREEZING!!!

1) I set a timeline on the project by doubling the garage time of a professsional. 2) keep your shop manual handy and study it often even when you are not working on the truck,like when taking lunch during the session. 3) do a marathon session. You have a few days off use them and keep the pests away. 4) get a powersteering pully puller to remove the pully to get at the bolts and just slide it forward not all the way out. don't tear shit off that does'nt need to come off. remove top half of shroud, alt and slide bracket, fan off, bungee the a/c unit up with the wiring ( you may need to prop hood due to weight. bend back brackets and get all the shit out of the way of the manifold so you can set it straight down. 5) use the RTV and nothing else. this silicone sealer will probably last the longest. Kind of like doing the bath tub. Lacquer Thinner is a great cleaning solvent. Clean,clean,clean no grease. use the whole tube of RTV in the kit. You wiil get more for the next project. don't be cheap; your saving $600 as it is. 6) reading the manual i quickly realized that i did not need to disassemble the top manifold. no coolant up there and fuel system was just fine. i would get the manifold together on the bench then fit into the truck. 7) you only put sealant on the heads around the coolant passages and on the ends of the block. install the gaskets (tabs push into the block) then put a bead of sealant(RTV) 1/2 in up the gaskets on the gasket at the block ends. 8) Dex-Cool is for aluminum from what i understand. I also lubes the water pump in these models. In fact i do know the warranty on the pump is void if you don't use DEX. don't mix the two coolants.

respectfully,

BTK

As Doc said use the RTV. I am a mechanic in the Aviation Industry and although I use some of those chemicals from work around the house I not to sure that sealer would be a good idea on that intake. Its not as flexible as RTV and could foul out your O2 sensors.

Good Luck JRE

I buttoned it up today and all appears to be fine. No parts left over - which I believe is a first for me. No "Check Engine" lights yet either.

Just have to change oil and coolant (again) now and put the shrouds & skid plate back on.

Man, the interior surfaces sure needed a good cleaning.

Thanks to all of you who responded so thoroughly to my questions - the help was invaluable to me. It's good to know that there's somewhere to go to get some help from such knowledgeable people.

Next project will be replacing brake booster & master cylinder.

'Til then - yall take care.

Chris