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8.1 water in exhaust manifold and update

bobct

Advanced Contributor
I’ve been working on the 8.1’s I picked up about a month ago. In the process, I have been delaying the inevitable, the cylinder walls need a clean up so I’m going to do a more invasive teardown. It’s cold out and they’re sitting in my garage so I would be stupid not to invest the time now. That decision has already paid off because....

I found water/coolant in two of the exhaust ports when I removed the exhaust manifolds last night. This was the engine that made note of that in the report from Blackstone. This one also had both exhaust manifolds replaced which I thought was odd since it’s a full FWC engine. I already replaced the risers a few weeks ago and ran it for 10-15 mins.

How to I determine if what I’m seeing is residual damage and the reason the exhaust manifolds were replaced in the first place? (I don’t know how along ago that was done). Or, is there something else going on? I assume it’s nothing to do with me the risers because it looks like residual coolant. Basically trying to figure out if I have a new problem or is this old news? What other components would leak coolant into exhaust ports/top of valves? Maybe the exhaust manifolds were a mis-diagnosis a while ago?



thanks
Bob
 

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Pic on valve side of exhaust manifold. Looks pink to me which would make sense with Dexcool coolant. I see this on two of the 8 cylinders, one on each bank.

Also, at first glance it looks like the intake manifold might have been off at some point. I’ll look closer but the RTV squeeze out looks sloppy. Not sure if they used RTV from the factory or not. Would that have been GM or Crusader? I’ll compare to the other engine.
 

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Bob:

I'm have trouble matching the words with the images....mostly in the second post....is it the cylinder head or the exhaust manifold in the second post's image?
 
Mark,

The second pic is the exhaust port on the head (looking at the backside of the valves). The first pic is the corresponding port on the exhaust manifold, that had some rusty water run out. I have this scenario on one cylinder/each bank. I removed the heads and the head gaskets looked fine.

To summarize this topic. This engine has replacement Osco exhaust manifolds (full FWC) of some unknown age. The same was true of the risers and so I immediately replaced those and ran the engine for maybe a total of 15 mins. No coolant in oil, that seems fine. This engine that makes note of coolant in the oil report from Blackstone so what I see now does makes sense - “if” it’s residual evidence and not a new issue.

thanks
Bob
 
The first pic looks wet but the water doesn't appear to be'new' due to the rust color.....and they isn't unusual if the elbows werepulled right before the manifold was removed.....the raw water residue in theelbow's water jacket is typically orange and will find its way into the exhaustpassage when the joint if unbolted...

the second pic, of the exhaust port, appears to have had some water/coolant in it aswell....but not much....and doesn't appear recent. it could be due to justsitting and not running for a while. Usually, when the coolant finds its wayinto the exhaust port, it will fill that cavity and gravity usually pulls it tothe rear cylinders because of the installed engine.

I can't answer the "why the exhaust manifolds werechanged" question.....I think as long as you put it back togetherproperly, you'll be ok.


 
Mark,

ok, that makes sense - thanks. I haven’t really been able to run them for very long
so some of this likely residual damage is not burning off after a good long run at more than idle speed.

FYI for everyone else, Osco is no longer in the aftermarket marine business.
Not sure if that’s old news but just found that out yesterday.
 
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