Manifolds (Trying to figure out what I am looking at)

[Lou C]

Mine which I checked this fall was 160-170 on all cyls. Same as it was when I replaced the heads 6 years ago. This is with the original never been rebuilt 1988 short block.

 

[Scott06]

I actually compression tested it a week or two before my last big trip... so september or so but there were five or six more outings after that. Figured with nearly 50 hours on the rebuild that would be a good A/B to the original test after the first run. I didn't observe any anomalies... 155-160 psi across the board. I'll note that may seem low for a fresh rebuild but my tester reads lower than most... I've put it on 12:1+ big blocks that have high cranking compression on other gauges and I'll only get 175 as a high. I typically look for consistent readings more than what the number is anyway. While a cold compression test may not be the best it would be something else to check against and I'll add it to the list.

150 psi is stock compression spec on these engines

 

[Pmt133]

Good to know. Then I am in spec lol.

 

[Pmt133]

So a little update. I dropped the engine off at the machine shop yesterday. They're going to test their work and figure out if there is an issue or not and they have jigs to test the manifold/elbow assembly again too. They agree its odd especially given its the same thing that was happening to the engine prior to rebuild. So hopefully we get to the bottom of it. We expect an answer by early next week.

I also took a quick measurement of the static height and it looks like I got about 15 inches to work with. Note, I haven't marked the true resting water line since the repower but I added 2 inches to the existing one which seems about right. Once I get everything back together I'll measure it properly and adjust if needed.

I'll keep you all updated.

 

[Lou C]

It will surely be interesting to find out where the water is getting in. It can be a tough problem to solve.
What kind of cyl head gaskets were used in the rebuild I wonder? And did they use sealer on the cyl head bolts like you're supposed to?
I like Fel Pro Marine gaskets on these engines. Used them on mine with no water intrusion problems.

 

[Pmt133]

I want to say it was felpro marine gaskets. Everything else was. They're good at what they do so if it was a mistake it was a mistake... **** happens. If they didn't seal the head bolts I'd have seen that in the oil too.

 

[Jmunk]

Any chance some water got into the spark arrestor while being in storage ?

 

[Pmt133]

Any chance some water got into the spark arrestor while being in storage ?

Nah. I ran it on the bay, went home flushed and parked it for a week or two, then ran it for half an hour and fogged/winterized it and pulled the manifolds a couple weeks later. Otherwise keep it all covered. It just isn't very likely but not impossible I suppose.

I am really starting to wonder however, if it was condensation. A thought that had occurred to me was that the water at that house is well water... its significantly colder than most city water. Couple that with it Being 29 degrees maybe everything sweated once it went offline... still seems like a lot given the air space but who knows. I'll hopefully have a better picture in a couple days...

 

[stresspoint]

on the subject of gaskets: i only use OEM head gaskets on Mercruiser motors , been caught out using feproo shyt on marine engines with leaks and what not ( over priced rubbish is my opinion).

OEM head gaskets ( generally cheaper in the long run) have a heat activated glue , it activates on the first start dry and there is an instant seal.
felpoo gaskets fall off if you have to remove the heads and people look at them and think they are reusable , i have been caught out in automotive use when i reused a gasket , a few hours later it blew between cylinders.

there are too many different expansion and contractions with the water temp changes to consider so the glue IMO is necessary.

OEM gaskets have to be destroyed if you want to remove them after heat cycled.

OP have you had a chance to prod the exhaust port yet ?.

 

[Pmt133]

on the subject of gaskets: i only use OEM head gaskets on Mercruiser motors , been caught out using feproo shyt on marine engines with leaks and what not ( over priced rubbish is my opinion).

OEM head gaskets ( generally cheaper in the long run) have a heat activated glue , it activates on the first start dry and there is an instant seal.
felpoo gaskets fall off if you have to remove the heads and people look at them and think they are reusable , i have been caught out in automotive use when i reused a gasket , a few hours later it blew between cylinders.

there are too many different expansion and contractions with the water temp changes to consider so the glue IMO is necessary.

OEM gaskets have to be destroyed if you want to remove them after heat cycled.

OP have you had a chance to prod the exhaust port yet ?.

I poked around the exhaust port while I had it on the hoist at eye level. (Could see what i was doing) Wasn't able to cause any damage or get leaks or observe anything that looked obvious or an issue. Beyond that quick check, I want them to handle it.

If this had happened a few years down the line I'd have pulled apart everything but we're talking about 4-5 months since rebuild. So they want to look into it and while I don't trust people to work on my stuff... they kind of want it back since it is doing what it did before the rebuild kind of. Just kind of sucked the motivation out of me for now.

 

[Scott06]

I poked around the exhaust port while I had it on the hoist at eye level. (Could see what i was doing) Wasn't able to cause any damage or get leaks or observe anything that looked obvious or an issue. Beyond that quick check, I want them to handle it.

If this had happened a few years down the line I'd have pulled apart everything but we're talking about 4-5 months since rebuild. So they want to look into it and while I don't trust people to work on my stuff... they kind of want it back since it is doing what it did before the rebuild kind of. Just kind of sucked the motivation out of me for now.

It can be deflating but look at it this way -

If they correctly magnafluxed or pressure tested the cooling jackets on block and heads before rebuild it would have to be a gasket or assembly issue.

Also you have caught it early enough that it wont damage any of the machine work you have done.

Before you put it back in run it on the ground

 

[Lou C]

Agreed I think you did the right thing paying attention to a warning sign and doing something about it. In that same vein I think it is a good idea to do oil analyses on new or reman or repaired engines each year, to see trends in wear metals, water intrusion, fuel dilution and if the oil you are using is holding its viscosity in your use.
I have done this on my engine a number of times, and what I learned:
the OEM head gaskets from GM started leaking even before the overheat, because sodium showed up in the oil as far back as 2011
This continued but wasn't much worse, after the overheat
However, finally the head gaskets leaked salt water into a cylinder
the sodium in the oil (salt water) was associated with high wear metals for iron, alu especially
After the repairs I've done 3 more analyses, no significant sodium in the oil and wear metals have dropped to normal levels for all metals. This did take time though.
So think about doing this, it is not expensive and I could have pro-actively changed the head gaskets (and probably the heads) back in 2011 and avoided some down time.
I plan on continuing to do an oil analysis each year on the boat. This time if I see signs of water or sodium I will act on it right then, to avoid problems down the road.

 

[Pmt133]

It can be deflating but look at it this way -

If they correctly magnafluxed or pressure tested the cooling jackets on block and heads before rebuild it would have to be a gasket or assembly issue.

Also you have caught it early enough that it wont damage any of the machine work you have done.

Before you put it back in run it on the ground

Exactly. And I plan to run it a bit before installing. Sadly at this point, I can pull the engine in about 40 minutes so overall not a massive headache if I have to lol.

Agreed I think you did the right thing paying attention to a warning sign and doing something about it. In that same vein I think it is a good idea to do oil analyses on new or reman or repaired engines each year, to see trends in wear metals, water intrusion, fuel dilution and if the oil you are using is holding its viscosity in your use.
I have done this on my engine a number of times, and what I learned:
the OEM head gaskets from GM started leaking even before the overheat, because sodium showed up in the oil as far back as 2011
This continued but wasn't much worse, after the overheat
However, finally the head gaskets leaked salt water into a cylinder
the sodium in the oil (salt water) was associated with high wear metals for iron, alu especially
After the repairs I've done 3 more analyses, no significant sodium in the oil and wear metals have dropped to normal levels for all metals. This did take time though.
So think about doing this, it is not expensive and I could have pro-actively changed the head gaskets (and probably the heads) back in 2011 and avoided some down time.
I plan on continuing to do an oil analysis each year on the boat. This time if I see signs of water or sodium I will act on it right then, to avoid problems down the road.

Funny you mention that. I did do an analysis after the first 10 hours. Machinist reccomended changing oil at that point and then running out for another 30 hours after that. That oil is still in the engine as I planned to change it out in the spring. Not ideal but I did suck a small sample from the dipstick to check when I discovered all this. Here is the analysis and there wasn't anything odd and it looked good for a fresh rebuild.

 

[Lou C]

What’s interesting is that no water showed up. It didn’t on mine either but they were done before the head gaskets really leaked. I’ll post mine up too. I do love those old cast iron 4.3s. They can take a beating!

 

[Lou C]

My Blackstone oil reports going back to 2011.

 

[Pmt133]

So based on your reports, I'd say I'm looking g pretty good being a fresh rebuild. I also was expecting elevated sodium being I boat 99% of the time in the salt.

I always forget you are on LI no?

 

[Lou C]

Yes your results look very good. Yep I’m on the north shore of Long Island. Nice boating area with access to local harbors & LI Sound. On a nice calm day you can run across to Ct it’s only 8-9 miles.

 

[Pmt133]

I spent the first few years of my life there. That's where dad was originally from. We used to run out of tanner Park on the great south bay. Dad used to run out of the power plant before I was around on occasion on north shore. He had some friends up there.

 

[Lou C]

Every year they have the Long Island Bluegrass festival at Tanner Park. We boat on the north shore but go 4 wheeling on the south shore…Sore Thumb & Democrat Pt.

 

[Pmt133]

Just an update:

So far, they haven't found anything. I guess that's good news.