Intake Manifold Repair

  • Continuing on with the intake manifold repair job, you should see the banjo bolt replacement.
    Right now, let's get into the intake manifold gasket replacement and talk a little about heater hoses.

    Head inlet faces
    In the picture below you see the right head stripped of the intakes and gaskets, and ready to receive the new gasket set. You'll notice the camshaft oil pipe and new banjo bolts above the inlets if you look carefully. Also notice the cam drive chain over there on the left, and the heater water return pipe running down the length of the valley just below the inlets. The inlets are stuffed with lint-free paper to preclude yours truly from dropping something down into a cylinder.

    Intake manifold gaskets/spacers/isolators
    Sorry about the strong afternoon light, but I needed a lot of contrast to show you the raised lip on the gaskets. These are the new gaskets being fit-checked and then fastened to the head using an M10 nut on the head studs. Notice the camshaft chain drive crossing the "bridge" from the bottom to the top in the picture. This is also a good shot of the oiling pipe and banjo bolts.

    As you can see, there's plenty of room to work once the manifolds are off the engine.

    Heater hoses
    While I had my intakes out and the camshaft covers off, I decided to replace my 10-year old heater hoses. Here's a good shot of the return hose from the firewall manifold to the return pipe in the engine valley. Notice the other two hoses as well - they go over to the water control valve and auxilliary pump.

    That large pipe there over on the left, underneath the heater return pipe is the main water return pipe routing the water from the back of both heads to the water pump. Also, check out the size of those cam lobes - this engine is way overdesigned.

    Camshaft covers
    Nice shot of the engine with the covers on, just prior to fitting up the intake manifolds. You get a good shot of the water return pipes. Also, check out the left distributor rotor, removed as I replace the spark plugs.

    Fitting the manifolds
    Here the right intake manifold (located on the LEFT side of the engine, confusing, huh?) after bead blasting it clean of a lot of oil residue and gunk. It's hard to see, but just above the manifold, but below the cam cover are the fuel return pipes. They get screwed down with the same bolts that hold the manifold, so fit checking at this stage become important.

    Shows you just how LONG those intake runners are.

    Right intake attached
    Intake is on and torqued down. Look down the left inlets and you'll see some gold-colored intake valve guides. Yup, your staring directly at the back of the valves. Notice the two fuel rail mounting posts with the gold-colored allen bolts in place? We'll put those on later, since we need access to those bottom bolts on the intake gaskets. It gets tough to gain access to things once we add the left manifold.

    Also check out the fuel injector bores to the right of the gasket nuts. Injectors simply press-fit into these holes with oversized O-rings. Also brought up the fuel return hoses for the fuel pressure regulators, and the evaporative purge hoses through the chain bridge and into the valley.

    More pictures later. Next installment - the secret trick to fastening the manifold bolts.

    Replacement of the heater hoses, particularly where they connect to the firewall "manifold" is much easier when both the intakes and camshaft covers are removed. It's very tight in the space between the back of the cylinder heads and the firewall, so I took this opportunity to replace all the hoses. While they looked fine, squeezing them revealed they were starting to feel "crackly" due to the extreme heat present here while the engine runs.

    Also, I used this opportunity to align the heater hose clamps properly so I could use an extension and flex drive coupling to gain access in the future without having to remove the cam covers. I tried gaining access to the clamps after the covers were in place, and I think I can loosen the clamps with everything in place. I hope I'll never have the opportunity.

    Obviously, you must remove the intake manifolds before you can remove the cam covers. However, cover removal is very easy - simply undo all the nuts and carefully wiggle the covers off. I say carefully, since the cover contains an integrated air/oil separator tack-welded onto the bottom side. It's equipped with two very delicate "J" drains made from very small diameter piping that can become easily bent or broken during cover removal. Hence, careful wiggling of the cover for it to clear the camshaft bearing journals.

    If you remove the cover, I strongly suggest replacement of the cover gaskets - even the new and improved versions are susceptible to heat damage and cracking after several years on the engine. Also, I used Hylomar, a liquid gasket prep, on any rubber-metal sealing surface. It remains tacky and pliable after several years - and is used by the British car DIYers to keep their trophies stuck together.

    Total time to replace hoses: 1 hour.

    Total time to remove intakes and covers: 2 hours.

    Total time to replace covers and intakes: 3 hours.

    Mark in SBA

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