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Need help removing North* crossover


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Hey everyone,

My 94 Northstar has a severe leak right above and to the right (2 o'clock) of the water pump. I pour coolant in and it goes out just as fast as I pour it in. Replaced water pump. Radiator hoses were almost impacted with the sealant. It seems to be leaking from the crossover. I can’t see the exact spot though. I'm pretty sure that I need to remove the coolant crossover from the back of the engine. I have the Helms shop manual, but it does not specify how to do it. I purchased the 4 replacement gaskets that I will need. Do I need any sealant? There seems to be red sealant on it now. I have everything off except the water pump and the throttle body.

Any help would be appreciated tremendously!!!!



94 STS 232k Miles

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Are you talking about the twin tubes that traverse along the back of the rear head near the valve cover or are you referring to the aluminum water manifold where the water pump is mounted (and bolts to the back of the front / rear heads)?

If it's the aluminum manifold - you don't need sealant. Make sure you clean the surfaces CAREFULLY with a plastic scraper and cloth. Use a torque wrench for the proper torque values. There are 4 bolts that hold it onto the rear head - two on the upper and two on the lower "arms" of the manifold.

Make sure you don't miss the bolt just under the water pump housing on the front head. It's at about 5 o'clock when looking at the cover on the water pump.

If it's the twin tubes, there are 3 - 4 screws along the rear of the head area. Loosen the hoses and pry them loose (cutting them will probably be required). Loosen the screws, and the pipe will pull free. You will probably want to remove the coil pack and wires to make it a bit easier to work in the space.


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From your description you have a leak in the aluminum crossover housing located at the back end of the engine, and not in the metal tubes that run along the rear (side) of the engine.

The aluminum crossover is a bit of a pain to remove, but it can be done, I have repaired one leak that way myself. Remove anything that will be in your way, i.e., the tie bar strut, all of the air filter system, etc.

There eight (8) bolts that hold the crossover in place, a small hose attached to a hollow bolt, and two screw clamps that are hard to see, below and to the right of the throttle body. The screw clamps are for the two short silicone heater hoses.

These silicone hoses will outlast the car, if someone working on the engine does not damage them. I doubt that they will need replacing, but if you decide to replace them you must get OEM ones, regular heater hose will fail if used in this location due to the high heat from the proximity of the EGR heat riser tube.

Just unscrew one top and one bottom screw clamp of the silicone hoses, choose the easiest ones to get at. If that means that one hose will come off with the housing, and one stays on the metal crossover tube, that is OK. Do not forget to retighten all four (4) screw clamps after installation; this can be easily overlooked. Typically they won’t leak except at high RPM and appear fine when watching for a leak at idle speed.

Do not forget to clear the hollow bolt above the water pump and the return line to the surge tank. These are in place to allow the air to bleed off the water pump and prevent cavitation.

On to your question of sealant. Unless the block or crossover gasket surfaces are severely eroded, no sealant is needed or desired. The OEM gaskets are made of very high quality material, with silicone beading on both sides. Just make sure all mating surfaces are carefully scraped, a little careful sanding with fine sandpaper to remove any oxidation. Flush any sand residue off so it will not get in the cooling system. Wipe all of the sealing faces and leave them clean and dry. That being said if you decide to use sealant due to surface conditions, use red (high heat) silicone sealant.

When slipping the crossover back in place be patient and careful. Being cut on sharp engine protrusions can easily damage the gaskets.

Good Luck.


Drive'em like you own 'em. - ....................04 DTS............................


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