Air intake Manifold Leak

Yes, you can do this with the engine still in the car.  It's a major PITA because you can't see anything and have to do it by feel, but we all do it from time to time.  Lots of light and mirrors might help!

You'll have to pull the manifold off before you'll know the shape of the intake port openings.  Once you get one off, look at the bottom of the manifold where it mates to the head and get a pair of gaskets to fit.  

http://www.cbperformance.com/s...ults.asp?search=IGIG

I can't tell what you'll have for nuts on the head studs, so just fit an open-end wrench on one to see what size it is.  I use several different wrenches/sockets of different lengths to get something that works - it seems different each time.  I've had mixed luck with all of them, but a socket on a wobbly extender (1/4" drive) seems to be the most help, then another extender long enough to fit in there and work.  

Don't get frustrated - This never goes super-easy for any of us, but you definitely do NOT need to pull the engine (although sometimes I wonder if it might be faster/easier to do so!!) 

You can, if you wish, get a pair of carb-to-intake gaskets at the same time, and then you'll have new gaskets at the top and bottom of the manifold - always a good thing, but I don't know what you have for carbs and the gaskets can be carb specific, so find them at CB Performance.

http://www.cbperformance.com/s...ults.asp?search=BGBG

So it can be done.  Looks like its a bit of a pain.  I did some research on these forums and some of the guys did not like the CB gaskets.  A few people mentioned using a loctite product. What are people suggesting now?

Thank you Gordon for your detailed response.

I have used the CB gaskets with ok results.  I also have very large port openings at the head so there is very little material between the ports.  I used to have a devil of a time keeping the gasket intact between ports - Get on the gas hard a few times too many and one cylinder would suck the gasket into the opposing port and it would run rough.   So Jake Raby recommended finishing the manifold flange very flat, eliminating the gasket altogether and using Locktite 515 flange sealer instead.  

That works for me, but not if you want to use a manifold gasket.  For THAT I just apply a film of automotive grease to both sides of the gasket, using a turkey marinade injector full of grease to squirt it on, then smear it around with my finger.  Wait 30 - 60 minutes or so for the stuff to wet the gasket material, then wipe off the excess grease and assemble everything to torque (if you can get a torque wrench in there) or as tight as seems possible given the small space.

You are certainly welcome to use a Locktite RTV gasket maker on the gaskets, just use it very sparingly AND realize that once you put everything together with Locktite RTV you'll have a difficult time getting things apart and/or cleaned up after taken apart.  That's why I use the grease.   I've also heard of people using Chapstik.  Handy applicator, too, and it works.  

CB gaskets are crap. They squish out because they are soft. Don't do it, you'll end up throwing wrenches in your garage!

You need a hard, thin gasket. Or none and smackempuckey put on real thin.

The real problem is all that weight and vibration(carb and manifold) being held on with two 8mm bolts and a SMALL surface area of contact. The leverage of the carb and manifold makes the gasket squish especially if it's soft. This is experience talking here. Especially the vibration you get if a carb gets a clogged jet. Just watch the engine gyrate around when running on 3........

I laughed when I read throwing wrenches.... seen golf clubs fly

Yeah... this is a job that stinks, and needs done roughly 3x as many times as it actually gets done, because it's just no fun.

I've had some success taking off the surround tin and coming in from the bottom to clean the gasket surface on the head. If you have heater boxes, forget about it.

The smackempuckey method depends on how flat your gasket surfaces are, the relative humidity and barometric pressure at the time of application, and how much you trust your of smackempuckey. Is it a new $30 tube, or are you trying to use it after it's been in your tool-chest for a year? I've tried 515, a product available only at a Toyota dealership, and tears from a blonde unicorn-- it's all good right until it isn't.

If scraping CB gasket material off the head makes you throw wrenches, DON'T USE smackempuckey. I can't be sure, but I think there's probably still some Toyota goop lurking in some crevice in my heads, residue from the great smackempuckey experiment of 2009. I've never tried Curil T on intakes without gaskets, and I use it all the time as a gasket coating with gaskets. Curil T can be removed easily. Most smackempuckey... not so much.

I have used Curil T on all kinds of application. Works great, cleans up easily and I haven't had to fight with it.

I went to a machine shop and got a sheet of hard, thin green gasket material, slightly less than 1/16" thick. I hand cut and port-matched a couple gaskets. And I used Loctite 517 anaerobic gasket maker and spray primer. Also got the steel 10mm manifold nuts(8mm thread) and cut some thick washers to take the load of the nuts without eating into the alu manifolds. A little blue loctite on the studs and torqued to 20 ft. lbs.

I haven't touched them since 2008.

I am thinking if I have the carb out maybe it would be a good idea to clean that out also.

Curil T with a gasket or no gasket?

With

Ditto what Stan said. You don't need much, but cover the gasket.

I sanded the manifold flat and tried a using a gasket by itself and it was leaking. I could tell because cylinder 3 wasn't responding to the mixture screw and also shooting carb cleaner down there. Next I tried it again with a new gasket and curil t and cylinder 4 mixture screw wasn't responding as it should and also confirmed by shooting carb cleaner over the manifold area. This made me throw wrenches!!! Any tips or tricks I should try next? What's the best gasket to use? More torque, less torque, I'm lost.

Dare I ask, what gaskets are you using?

^^ X2

Also, what did you use to clean the mating surface of the head?

It's tough, really tough, to get a torque wrench in there to torque the nuts.  I don't.  I have slim, 11mm nuts and I use anything I can to get them as tight as I can, usually a stubby open-end wrench but it seems like I use a different combination of wrenches whenever I do this because the nuts are such a pain to get to.