Replacing the Intake Manifold Gaskets

Photo Gallery Here

After Blazer`s told me my intakes were leaking, I started gathering the bits I would need to replace them. I already had the gaskets themselves, but I also wanted to replace the intake manifold to plenum sleeves as well as all the injector seals.

Would the old parts have been reusable? Possibly. But I wanted to be certain everything was new.

The sleeves I got from Cip1. I had forgotten to order the injector seals though. So instead of paying $4 for a complete set from Cip1 or Bus Depot, I ended up paying $2.44 per injector. Ugh.

I also had a new reproduction S-Boot from eBay. Yes, I`m happy with my PlastiDip coating job, but if I`ve got the new one anyway, I figured I`d use it. The original one will still be there when I need it.

Everything gathered, I popped the cover on the engine bay.

Typical late bay window fuel injected engine.

First thing I did was remove the air cleaner, AFM, S-Boot and hoses, and the decel valve.

Looks awfully naked! I probably didn`t have to tear it down quite as much as I did, but I wanted to make things as easy on myself as possible.

First, I relieved the fuel pressure on the fuel rail.

I then removed the 3/4 injectors. Remove the 10mm nut and lock washer from the injector retainer plate and loosen the hose clamp at the rail. Do both of the injectors on the same side, then it will be easier to pull them from the intake manifold and then the fuel rail. You can easily remove the electrical plugs now.

You WILL have gas dribbling from the fuel rail when the injectors are removed. Keep rags handy to clean these spills up, and clean the moment any fuel spills. Not only can you start a fire, but the gasoline will eat away at the foam engine compartment tinwork seal.

It is unnecessary to label the plugs on the injectors. All 4 fire at the same time. Still, I like to put everything back the way it was, so I kept track of which plug went to which injector.

Now, the 13mm nuts holding the manifold to the head must come off. I like to loosen them a little at a time until they`re all free just to be certain there is no warpage of the head or manifold. Be sure to catch all the lock washers too.

If you have clamps on the sleeves from the manifolds to the plenum, loosen these. The intake manifold should slide right off the studs and out of the sleeves. If the sleeves won`t let go, and you have spare sleeves, don`t hesitate to attack them with a utility knife/razor blade!

Here is what I found when I pulled mine apart:

The green arrows point to the leak locations. This is the 3/4 head. On the 1/2 side, only the #2 cylinder was leaking. Here`s the 1/2 side:

Yeah, I`d say I was leaking! I`m surprised the bus ran as well as it did!

Now here`s what it`s SUPPOSED to look like:

By the way, can anybody identify the brand of the bad gaskets? I know the new one is Victor Reinz, but I cannot make out the branding on the old ones.

When I got the 3/4 side manifold off, I took a pic of the intakes on the head. I just wanted a peek.

Yes, I cleaned the intakes out and the gasket surface before putting the new gasket on. Sheesh.

The injectors were ugly:

But the ugliness is on the outside, between the fuel rail and the intake manifold. Who cares what THAT looks like. It`s the nozzle inside the manifold that matters, and all four of mine looked good.

I`m glad I replaced the injector seals. The large ones were cracked and ugly, and the small ones (the most important ones) were visibly compressed.

I used new Echlin brand seals from Napa. $2.44 per injector set. One of the large seals came out of the package cracked. But out of the 4 old ones, one was like new, so I used that. Gotta love modern quality control!

I found it to be much easier to install the injectors to the manifold, then install the manifold and attach the injectors to the rails. You can visually check the seal of the injector that way.

So that`s what I did. Injectors to manifold, plug connector pointing up. New gasket on the head studs, install the manifold sleeves on the plenum (air distributor) 1/2" first, then wiggle the manifold into them while guiding it onto the head studs. It sounds harder than it is.

Torque the nuts on the manifold to 14 ft lbs. I built up to that rating in 3 stages: 8ft lbs, 12ft lbs, then finally 14. Again, it may not matter, but better safe than sorry.

Once the manifold is torqued down, and seated into the sleeves, slide the fuel rail nipples into the injector hoses. (Yes, that sounds dirty. Deal with it.) Tighten your clamps.

Repeat for the other side, and reassemble the engine components!

The new S-boot was really nice to work with! I didn`t have to stress over putting new cracks into the old and brittle original S-boot. I have no idea how long this Chinese repop will last, but it will be interesting to see.

One obvious sign of the questionable quality of these reproductions is the mis-aligned mold markings:

So we`ll just have to wait and see what we get out of this new reproduction.

I`ve said before I`d be willing to pay real money, $100 or so, for a Viton rubber quality reproduction. It would last forever, or darn near... Hopefully someone will take up the challenge!