Exhaust Manifolds and Risers, Unknown age

[jakwi]

Hi all,

I noticed that there was a little rust on my starboard side exhaust riser joint.

Temps have been normal, 175-180, probably closer to 180.

I can place my hands on both risers and hold them there. Although the Starboard side is hotter, neither is too hot to touch and I didn't notice any hot spots on the risers or manifolds. From what I've read it is normal for the starboard side to be a bit hotter, although I don't understand why. IE after a half hour running down the river I can still place my hands all over the risers, and manifolds without any issues, temps seem uniform.

That being said, I don't know how long it has been since they have been replaced. I was told that the repower had 30 hours on it when I bought it last summer, but without a meter who knows. I flush the motor every time I use it, by running the engine until it's up to temp on Muffs. The previous owner stressed the importance of this to me so I assume he also did this consistently. The boat is used primarily in brackish water. The motor looks good, runs good, my oil is clean, I pulled the plugs and they looked fine, but I replaced them anyway.

The port side has no rust at the gaskets, I haven't pulled it apart yet, but I will.

I know the safe answer is just to replace them, but on the other hand I don't have the money right now. I can start saving for next year, but if I have to replace them right now, then it will sit this summer, That would be a real bummer.

So my question is, how many years do you guys think are on these manifolds/risers and extensions? I've googled about exhaust riser inspections but all you can find for pictures are extreme cases where they are completely shot, I'd love to see some pictures that show what they look like at the 3 year, 4 year, 5 year inspection points, so that I have a point of comparison.


From my point of view the extensions look fine, The manifolds also look pretty good, although the rust inside shows that my gaskets were leaking.

The risers look rustier, but I couldn't find any rot, looks mostly like surface rust with plenty of meat left. I've posted all of the pictures on imgur. The flapper looks droopy, but I don't know if that is normal.

Thoughts? Thanks for the help.

https://imgur.com/a/6i9E7k5

 

[Lou C]

I'd hate to see you rust up your exhaust valves on a nearly new engine! You could take em off and bring em to a machine shop to deck the mating surfaces after filling the manifold up with acetone (after removing it that is) to make sure there are no leaks, Still that will cost some money as well. Here we usually replace them between 5-7 years and that will keep you out of the danger zone. How solid are the rusted parts of the elbows, if you tap them with a hammer?
Flapper looks like it should be replaced. If it were me I'd try to find the $$ for a new set. Barr makes good stuff for the money. Made in USA. You already did half the work of the job.

 

[achris]

Hi all,

I noticed that there was a little rust on my starboard side exhaust riser joint.

Temps have been normal, 175-180, probably closer to 180.

I can place my hands on both risers and hold them there. Although the Starboard side is hotter, neither is too hot to touch and I didn't notice any hot spots on the risers or manifolds. From what I've read it is normal for the starboard side to be a bit hotter, although I don't understand why. IE after a half hour running down the river I can still place my hands all over the risers, and manifolds without any issues, temps seem uniform.

That being said, I don't know how long it has been since they have been replaced. I was told that the repower had 30 hours on it when I bought it last summer, but without a meter who knows. I flush the motor every time I use it, by running the engine until it's up to temp on Muffs. The previous owner stressed the importance of this to me so I assume he also did this consistently. The boat is used primarily in brackish water. The motor looks good, runs good, my oil is clean, I pulled the plugs and they looked fine, but I replaced them anyway.

The port side has no rust at the gaskets, I haven't pulled it apart yet, but I will.

I know the safe answer is just to replace them, but on the other hand I don't have the money right now. I can start saving for next year, but if I have to replace them right now, then it will sit this summer, That would be a real bummer.

So my question is, how many years do you guys think are on these manifolds/risers and extensions? I've googled about exhaust riser inspections but all you can find for pictures are extreme cases where they are completely shot, I'd love to see some pictures that show what they look like at the 3 year, 4 year, 5 year inspection points, so that I have a point of comparison.


From my point of view the extensions look fine, The manifolds also look pretty good, although the rust inside shows that my gaskets were leaking.

The risers look rustier, but I couldn't find any rot, looks mostly like surface rust with plenty of meat left. I've posted all of the pictures on imgur. The flapper looks droopy, but I don't know if that is normal.

Thoughts? Thanks for the help.

https://imgur.com/a/6i9E7k5

No word on what the engine is (the photos show it's a V8, but little more), what year it is, the engine serial, or even if it's used in fresh or salt water.

We are clever, but not that clever. Please help us to help you....

Engine year, model and serial number at the very least. Then how the boat is operated...

Chris.........

 

[jakwi]

Thanks guys, sorry about the missing info.

It's a Mercruiser 357 Alpha 4v repower. I'll look for the SN, Not sure on the year either.

https://www.mercurymarine.com/en/us...emanufacturing/plus-series-alpha-sterndrives/


It's used in Brackish water almost exclusively usually every other week in the summer and about once per month in the winter, stored on a trailer, Flushed after every use. I'm in Florida.

The seller said he hardly used it, maybe a couple of times in the summer when his son was home. So judging from that and his 30 hour comment I'm guessing 3 or 4 years since the repower, but really it's a guess. My hope is to get one more year out of them so that I can save up the $1000 for OEM parts. I'll need manifolds, 3 inch spacers, and riser/elbows. oh and flappers I guess. Good to know about Barr.

The elbow looks bad at the exit side, but it's really solid. I could bang on it all day with a hammer without doing any damage.

I thought the flapper looked a little wierd, but I just wasn't sure.

So far I haven't been able to get the studs out of the manifolds. I sprayed some PB blaster on them and let it sit.

thanks again for the help guys.

 

[achris]

It should have a Thunderbolt V ignition box on it. Get a hold of the Rinda Diacom software and plug it in. That will give you the engine hours.

As for brands of exhaust gear, plenty to choose from. If you do change everything all at once, seriously consider going to the dry-joint system... That will last considerably longer than your current system (wet-joint)... As the dry-joint system has been around for a while now, a few of the aftermarket suppliers are getting into them....

Chris.....

 

[jakwi]

I had no idea this was even possible! I'm not sure where to get ahold of that software, but I'll start researching it.

As far as brands, Do you think alternatives are as good as OEM? It seems like the price difference is pretty minimal. Although I also see there are some cast aluminum options, but I don't know if that's a good idea either.

And whats your thought on me getting through another year?

Dry vs wet. It seems like the dry systems are a lot more expensive, and last about the same amount of time. Are they really worth it?

 

[Lou C]

The dry joint is a superior design as far as preventing water leaks at the manifold/elbow/riser joint. However they can still rust through like any other cast iron exhaust. If I had them on my engine in my salt water environment, I'd still look to change them 5-7 years. But, its very nice to not have to worry about that leak prone gasket, for that 5-7 years. They are quite a bit more expensive.

 

[DouglasW]

If you have the MEFI-2, 3, or 4 ECM, I can give you my free PC software that can read the hours. Soon to come is the MEFI-1. You would have to make a cable but it's not very difficult and costs about $35 in parts.

 

[achris]

If you have the MEFI-2, 3, or 4 ECM, I can give you my free PC software that can read the hours. Soon to come is the MEFI-1. You would have to make a cable but it's not very difficult and costs about $35 in parts.

That's very nice, but it's a carbed engine so no MEFI, just Thunderbolt either IV or V.

Chris...

 

[jakwi]

If you have the MEFI-2, 3, or 4 ECM, I can give you my free PC software that can read the hours. Soon to come is the MEFI-1. You would have to make a cable but it's not very difficult and costs about $35 in parts.

Thanks I wish this would work for me.

 

[achris]

The dry joint is a superior design as far as preventing water leaks at the manifold/elbow/riser joint. However they can still rust through like any other cast iron exhaust.

Yes, but dry-joint manifolds and elbows are ceramic coated inside and out. They are considerably less prone to corrosion than previous generations.

If I had them on my engine in my salt water environment, I'd still look to change them 5-7 years. But, its very nice to not have to worry about that leak prone gasket, for that 5-7 years.

I operate in salt water. Flush after each use. My engine is now 12 years old, second set of elbows, but still on original manifolds. I check them regularly and still no sign of them needing to be replaced.

They are quite a bit more expensive.

Actual purchase cost is higher than wet-joint, but as they last around double the time, that makes them quite a bit better economy....

Wet-joint prices.(V8. approx)
Manifold - $300
Elbow - $260

Dry-joint prices (V8 approx)
Manifold - $420 (35% more, last 100% longer, at least)
Elbow - $370 (40% more, lasts 60-80% longer)

Chris.......

 

[scoflaw]

Ceramic coated exhaust is not specific to dry-joint only. That process has been around for a long time and certainly not a cure all end all.to rust out. Dry joint is a nice safeguard at the joint only, but manifolds can fail in other areas as well.

A marine exhaust systems longevity is directly related to the geographical location you boat.in. Temperature and salinity have a lot to do with it

 

[Lou C]

This was posted up on the hull truth, supposedly OEM Merc elbows after 4.5 years in Fla salt water.
Having seen this I'd at least remove the rubber exhaust hoses to check what they look like in terms of corrosion. Here's my old OMC batwings after 5.5 seasons up here in the Long Island Sound region. I'll see how the Barr exhaust I installed in '17 looks when the time comes....

Most people here keep their boats in slips or on rotating moorings so no opportunity to flush till the end of the season. Even so I got 5-7 years out of my OMC batwings replacing them before there was a problem. With the Volvo style exhaust I installed in '17 at least I can replace the elbows separately if the manifolds are still good at 5 years but the elbows are getting questionable.

Total cost for my Barr V6 exhaust was approx. $710. The Merc OE dry joint V6 exhaust can be bought here for about $1500 and the Barr version of the same is $910. So if you compare aftermarket wet to aftermarket dry is only a $200 difference, making a conversion worth it in my opinion.

 

[jakwi]

Lou, well those elbows certainly make me feel better. Mine are not rotted out like that at all.Thank you for the pictures though.

I finally was able to remove the spacer studs from the exhaust manifold on the starboard side. No rust in the threads, but man they were tight. Vice grips, hammer with the nut in place, and PB blaster every day. I'm a bit worried about the manifold bolts. I haven't even tried them yet. I still need to find a machine shop to deck all of the surfaces.

As much as I'd like to go dry joint, and closed cooling for that matter, I'm going to be struggling to come up with the $1200 for the oem wet joint parts. I looked at Barr and Sierra, but I haven't been able to find them with a price much below the OEM price, not significantly anyway. I did find some cast aluminum solutions on ebay for about the same cost, roughly, but I don't know if that is a good idea.

It will be at least a year before I have that kind of money anyway.

Another question I've had is about pencil anodes. I've run across a couple of sites recommending pencil anodes in the exhaust manifold and elbows. What do you guys think of that? Is it worth while?

I did find the S/N tag, but it is so faded I can't read it. It's strange the top of the engine looks really great, but below the manifolds it has pretty thick surface rust. Once I get the manifolds off I'll probably try to paint it, maybe POR15.

Anyway thanks again for all of the support.

 

[jakwi]

So I finished taking the exhaust manifold off of the starboard side, and everything went pretty well. I was very relieved when the bolts came right out, with no issue. Everything looked pretty good.

I proceeded with the port side, which which looked great externally. In fact it looked so great I debated about taking it apart, but I figured better safe than sorry.

Much to my chagrin, and surprise, the port side was in much worse condition. I immediately noticed standing water in the manifold, although thankfully just a teaspoon or so. and much more apparent rust in the exhaust side of the passages.

I've uploaded several pictures of the port side to the imgur album. I don't see any obvious failure of the gaskets, which makes me think that the elbow or manifold has actually failed. Up until this point I was pretty comfortable with the idea of decking the surfaces and reinstalling the parts. Now I am definitely not comfortable. I suppose I could do a pressure test or an acetone test, but I don't know. I feel like I really dodged a bullet here.

After removing the exhaust I spun the engine with the starter until the oil pressure came up, 20 seconds maybe. I just wanted to make sure the cylinders were lubed up with oil and that there was no water in there. I don't see any evidence of water in the cylinders, or spray when I turned the engine over. The exhaust ports looked mostly dry aside from a few droplets, see the pictures. I should probably do a compression test to be sure.

Anyway I am hoping you all will weigh in on the latest. I did finally find the S/N of the motor it's 1G401632. I found some paperwork with it listed in the pile of manuals. Looked like it was installed by a mobile marine mechanic in 2012. I can't be sure, but I think these manifolds/elbows are the originals, which means they have probably been in place since then.

So If that is the case these manifolds have 7 years of "use" even though from what I've been told it was pretty light use. I guess that is all I can expect.

Looking back I have found for the last few months that if the motor sat for 3 weeks I had a really hard time getting it started, Once started it had to not only warm up, but also run for quite a while before it would settle down and really run smoothly, 20 to 30 min. I haven't noticed any difference in power or running aside from this. I changed the plugs on it a few weeks ago which seemed to help, but now I think it was actually water in the exhaust. Which from what I understand, hard starting, is a side affect of a failed exhaust system. Maybe I'm reading to deeply into this.

So now I'm trying to figure out how to come up with the money for new parts. :/

 

[midnightrider1818]

If you plan on keeping this rig for awhile invest in a dry joint design and you will never have to worry about leaky gaskets again. I just bought new manifolds and elbows for mine and did not know they had a dry joint design for my engine. Kick myself in the a@@ for not researching more before I spent the money. Supposedly they match up the exact same. Just my two cents

 

[achris]

.... Supposedly they match up the exact same. Just my two cents

Done the conversion a few times... They bolt straight on.

Chris...

 

[Lou C]

You look like you just caught it in time. Do the acetone test. I did it 2x with my old Cobra V6 units. Just be careful acetone is very flammable. If they pass then get them decked, they don't look bad really.

 

[Lou C]

As a final test after acetone test and decking what I'd do is this: put mani+elbow together off of the engine with the OE Merc gaskets properly torqued. Then prop them up level. Hook up a water hose to the manifold inlet and run water thru them looking for water trails in the exhaust ports. Shut off the water and let it sit full of water for a few hrs, watch those exhaust ports. If no water that's good!