coolant leak passenger rear of L59 engine

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strad

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Ok small stain of coolant under general area of starter. I can see it's dripping off the rear of the motor. I traced it up to the head from underneath. Using a mirror on a stick, I inspected the rear of the head around the freeze plug and it is dry around the plug, but wet on the ledge where head meets block. So I looked upstream. I THINK it may be the crossover steam vent block off that is the source of the leak. At least I think it's a block off -- I cannot see if there is a steam crossover on the rear like there is on the front.

Anyways, has anyone else seen one leak from here? How likely is it that I'm correct in other words. I assume there's an o ring inside that block off and that might be the cause. It's really tight in there so I'm wondering if the manifold has to come off. . .

Update: I did take the manifold plastic cover off, which gave me a better view, and I did inspect the rear block off on the other head. It does not have coolant pooled around it like the passenger side one does. Can anyone provide a part number for that o ring?
 
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iamdub

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Fel-Pro has a kit with both the gaskets and O-rings to cover both styles- #ES73027. Dorman has the gaskets- #56390. OEM ones are like $8 each- #12602541

I took my block-off and old O-ring to Napa and got some nitrile O-rings from their bulk bin. I don't recall their part number, but they were super cheap:


I recommend replacing the other three as well even though they're not currently leaking.
 
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strad

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Is there a rear heater and rear a/c? Coolant tees?
That was the first thing I looked at. First I felt them (dry) and then I looked at them from the underside with my mirror, after I thought about using it. That is not the source this time around, although I used to drive another GMT800 for work and I did see that problem on that one.
 

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