Hello everyone, long time lurker first time posting. I have one that I am sort of stuck on here. I had my lower intake manifold spring a leak the other day, and I have since tore it down, and have the old gaskets removed, purchased the Fel-Pro Perma-Dry gasket set, I have already replaced the valve cover gaskets. I was reading the instructions that come with the gasket set, and they mention using a non hardening bolt sealant on the bolts that go through to the water jacket. I have found on here (using the search) that I need to get either Loctite 592 or Permatex #2 form-a-gasket, to put on the bolts in question. I have read that the sealant isn't necessary, and that it is. If anyone knows which way would be best please advise. If the advice is to seal 'em, which of the bolts in question need the sealant and what is the proper way to apply it so as not to interfere with the torque on the bolt?

Also should a med grade thread locker be used (like blue)?

I also noticed that the gasket set came with 4 o-rings, one big, two small ones and one smaller one. I was curious if anyone could let me know what they go to, (I am guessing two go to the fuel lines, and one is for the ...purge on the passenger side i guess) but I would rather find out from someone who actually knows and I can't seem to use the proper search criteria. Thank you in advance for any help you can toss my way.

 

Either way on the sealant. If you need peace of mind, put sealant on them. If not, then don't. I have done it both ways without issue. To apply it, just coat the threads on the bolt, filling the threads, scraping off the excess. The bolts you'll use this on are the ones that go through the LIM into the heads.

Do NOT use thread locker on the bolts. It is not necessary and could cause problems with disassembly later on.

On the o-rings, i'd have to see them to tell you where they go...

*EDIT* - I found a picture of the Felpro MS98002T gasket set:

I believe that the o-rings you are talking about go to the PCV valve fitting (large one), fuel lines (next two - larger of the two is the feed line & the smaller is the return line) and then the EVAP purge solenoid is the last, smallest one.

If you didn't take any of these things off, I wouldn't worry about replacing the o-rings. You should have disconnected the fuel lines though so I would replace those. Be careful with the lines. The fittings can be somewhat easy to cross thread.

 

swartlkk,

I was actually hoping to get a reply from you, I have seen all the advice you have given to other members and it seems you are a clear and concise advice giver. I believe I will do the thread sealant just because I need the peace of mind ( I am the kind of guy who wont seal em and have to tear it apart in 30 days to repair it again). I guess I will skip the blue thread locker, and go for the permatex #2 or the loctite 592. I have made this repair take WAY longer than it should have but this is my first 4.3 and I have been using online guides as I don't have the extra loot to pick up a GOOD manual (Haynes manuals suck, and leave too much to guess work). My first GM ride had two manuals with it (Factory service manual and a body manual by Fisher) and I could disassemble the entire ride and chassis without any doubt how to reassemble.

Now on a side note, it was recommended to me by several people both ways on this question, and I think I will take your advice on this whatever way you recommend. How long should I leave the RTV to cure after assembly before filling up the fluids and cranking over? I have been told that RTV cures FAST, and that the reassembly time should be long enough to cure, but I was also told that it should be reassembled and then just left to sit for 24-48 hours before filling and starting (to avoid sucking the sealant into the intake.) Which camp are you a member of?

Thank you again for your rapid response.

 

I am a member of the "do what the tube says" camp. Too many times I have been burned by trying to do things too fast. Some people get lucky though. It all comes down to how much RTV you are using.

For the LIM gaskets, unless the gasket surfaces are pitted badly, you shouldn't need to use any RTV. If they are pitted, a light coating of RTV to smooth the surface around the water ports where the pitting mostly occurs, allowing 5-15 minutes for the RTV to cure a bit before reassembly is all that is really required. The gaskets will take car of the rest. You shouldn't goop this stuff on with the gasket designs used on these engines. That can cause more problems than it cures.

But yeah, from there, I always like to allow 18-24 hours for a full cure before putting the water/coolant to it.

On the thread locker & sealer. You can't really do both effectively. It's one or the other. Whatever you do, make sure that the bolts are nice and clean before applying either product. The torque values used on the LIM bolts is VERY light and dirty threads can skew the actual clamping force.

 

What size thread chaser should I use then? I have a couple of tap and die sets but have them "misplaced" or lent out at the moment and just want to do this right the first time and worry about getting back in there when I have to do the fuel spider/poppets (too expensive to take on this time). I meant the RTV that goes along the front and rear of the block where the gaskets don't cover when I was asking about the cure time. I figured that the bolt sealant would be fine to just run down as is and if it sets up great, if not well, it's just an added line of defense against my dreaded "why doesn't the heat work again" problem. I have been lucky so far as I could tell all the leaks were coming out of the intake as opposed to going into the oil.