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Anyone ever replace heater hose nipples in the block?

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I was under the car changing the oil pan (rusted enough to leak) and I saw one of the nipples that press into the block (actually the lower oil-pan) right next to the thermostat is fairly rusty. I have confirmed subaru cannot get the part.


Anyone ever replace one of these somehow?


I assume if no replacement is available I would have to remove the bad nipple and tap the hole for a threaded nipple (hmmm, steel or brass?), unless I could get lucky and find some steel line (big brake line?) that could be a decent press-fit.


Tapping the hole for a tapered nipple would be nerve-wracking, given how thin the boss in the casting is right there. Would also have to make sure it didn't introduce a restriction as the only coolant flow before the thermostat opens is through that line.

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i think,


that nipple is actually on the water pump. it has to be since it is not on the t-stat housing / cover. a short 'ell' shaped hose connects it to a metal pipe that is bolted to the block and runs back and up to the heater hose.


the other heater hose nipple is on the coolant crossover pipe under the intake manifold. both can rust.


but neither is in the block. i don't know how hard it is to remove the lower one with the engine in the car. i never knew it was there until i did the head gaskets and by then the engine was already out.

Edited by johnceggleston

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The H6 has the water pump more towards the middle, driven by the timing chain so the nipples actually go directly into the huge oil-pan casting right under the lower hose/thermostat. They do actually go into the rear housing of the water-pump which is cast into the lower oil-pan.


If the H4s are different I guess that's why I never heard of them being replaced before.

Edited by CNY_Dave

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Those nipples are usually fairly thick wall tubing. If it isn't leaking you might be able to wire brush it and paint it with rust preventive primer/paint.


Drilling and tapping should be fine. I would probably use a non-pipe thread and coat the threads with pipe dope or Indian Head shellac before installing the nipple to prevent leaks.

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