Manifolds hot Risers not!

[wakeup 19]

Checked previous posts and could locate on this subject. My 350 raw water manifolds are running hot but risers are cool to touch? I have not taken them apart yet (soon). boat is still out of water but they ran hot last fall as well.
Impellor is 1 year old, Manifolds and risers are about 9 years old. I run in salt but dock in mostly fresh. I have got good life out of these but I am questioning why only manifolds are hot? Don't risers usually go first.
thx for reply's.
I will let you know what I see when I take them apart.

 

[dpmulvey]

Sounds normal. Remember, you have the hot exhust gasses at the manifold that have to be cooled and a lot less space between the surfaces to cool them.

 

[wakeup 19]

too hot to touch, I don't believe this is normal. Other engine I can keep hand on manifold without it burning my hand. both manifolds are hot on this engine. not one side hotter than other.

 

[dpmulvey]

OK. A bit more information than in the first OP. Time for a tear down. At 9 years, RWC, they owe you nothing. Let us know what you find. Post pix.

 

[Air O'Nautical]

RWC 9 years old...your over due.
Throw everything out and start new.

It's a normal wear item and further neglect will cost you a lot more.

 

[Saverio]

they are probably clogged and a lot of scaling inside. Like Mark said they owe you nothing time to start with new. the next step would be water in the oil

 

[wakeup 19]

Pulled Risers last night. A friend who came down later is a merc mechanic and he thought they were not bad but agreed you should replace after 9 yrs as well. Due to the fact that we store in fresh water we get longer life out of our components. I took a picture
gasket was leaking on one side but inside was no scaling. thoughts. they will be changed as preventiative.

 

[Air O'Nautical]

Pulled Risers last night. A friend who came down later is a merc mechanic and he thought they were not bad but agreed you should replace after 9 yrs as well. Due to the fact that we store in fresh water we get longer life out of our components. I took a picture
gasket was leaking on one side but inside was no scaling. thoughts. they will be changed as preventiative.

I'm not of the school that looking at the amount of rust tells you anything.
There shouldn't be rust on the inside at all but, due to humid air in the marine environment it happens.

I'm doing a manifold / elbow job for a customer right now and the inside of the elbow looks like this after 12 years....



Yours appear (to me) to have had more than condensation and humid air rusting them for some time..

I'd change them...

Good luck,

 

[Strecker25]

I'll be pulling mine soon also as a preventative as the dealer we purchased from did not know when/if they've been replaced. May I ask how difficult removing the bolts were? Did you pull the manifold as well? I'm nervous about shearing a bolt head off.

 

[craigswardmtb]

I just changed my manifolds on my 8.1's after 10 years and 350 hours. One of the risers was weeping on the outside so I went to town. My boat was stored in fresh water 6 months of the year for 7 years. Those 7 years were on a tidal river so it operated in and out of salt water. The last 3 years it has been stored in salt water 6 months of the year. For what its worth my manifolds had not nearly the rust/scaling you have shown. I would swap em and be happy I didn't have bigger issues. I PB Blasted the manifold bolts for two days prior to doing the work and was very gentle as I applied pressure to the breaker bar. No issues for me and my rusted bolts snapping.

 

[BryanOnTheBay]

I'll be pulling mine soon also as a preventative as the dealer we purchased from did not know when/if they've been replaced. May I ask how difficult removing the bolts were? Did you pull the manifold as well? I'm nervous about shearing a bolt head off.

It it all depends on the upkeep. I replaced mine last year for the same lack of knowledge and the gaskets were leaking. I could get all but three bolts out, one sheared. Gave up and let my mechanic do the rest as I was going on a cruise. I had tried heat, and penetrating oil for 6 hours one day (Heat, oil, beer, wrench). No luck. They just wrenched them until they sheared, drilled out the old and retreaded new. Boat was running when I got back. The moral of the story is, if you can't get the boosts off, they probably can't either, so what is the difference. Give it a try. If nothing else, it will be less time for the mechanic's bill.

Bryan

 

[Strecker25]

It it all depends on the upkeep. I replaced mine last year for the same lack of knowledge and the gaskets were leaking. I could get all but three bolts out, one sheared. Gave up and let my mechanic do the rest as I was going on a cruise. I had tried heat, and penetrating oil for 6 hours one day (Heat, oil, beer, wrench). No luck. They just wrenched them until they sheared, drilled out the old and retreaded new. Boat was running when I got back. The moral of the story is, if you can't get the boosts off, they probably can't either, so what is the difference. Give it a try. If nothing else, it will be less time for the mechanic's bill.

Bryan

Good point! I'll give it a go, hopefully they kept up with them to this point

 

[Air O'Nautical]

I'll be pulling mine soon also as a preventative as the dealer we purchased from did not know when/if they've been replaced. May I ask how difficult removing the bolts were? Did you pull the manifold as well? I'm nervous about shearing a bolt head off.

Yes, I pulled the manifolds.
A 3/8 drive 9/16 deep socket, screw driver for the hose clamps and 20 min .... removed.

If you have a drip or any reason the bolts might be rusty it can be difficult sometimes.
I've found sometimes hammering on a smaller socket will work.
Worst case a die grinder to remove the head of the bolt works.
You just do what you gota do....

Reinstalling tomorrow if I have time.

 

[nauticaldog]

I did mine a couple of weeks ago, the last bolt on the riser didn't have enough head left to get a wrench on. Ended up taking a cutting wheel to it then removed the rest of the bolt with vise grips. The cutting wheel will nick into the riser but I had already planned to replace so it didn't concern me. Manifold bolts came out fine.

 

[Strecker25]

I've also read getting the motor up to temp prior to wrenching can help too.

Hopefully they come out OK, there's not a lot of room between the inboard sides of the twins in our ER so getting a drill in there would be a nightmare.

Thanks guys