Crusader Exhaust Risers

I have a pair of crusader 350&

I have a pair of crusader 350's in a small houseboat. The boat was in Florida from 1993 until 2006 when I moved it to IL. Late last season my port engine outboard exhaust hose burnt through. I replaced it and checked closely the next time I ran the engine. Outboard exhaust side is running very hot but inboard bank is fine. I have read alot of posts on the site and it sounds like the riser is plugged. I am getting water through the exhaust although the flow seems reduced. Will the exhaust riser cause these symptoms or is the exhaust manifold likely to plugged as well?

"Most likely the exhaust elbow

"Most likely the exhaust elbow is plugged. I had the exact thing happen to mine at sea. The wife announced smoke behind the boat! If your engine is not FWC, you might consider replacing all iron parts past the heads! If it is FWC, just the elbows, and affected rubber hose."

"Dave, thanks for the info. th

"Dave, thanks for the info. the engines are FWC. I assume that the exhaust manifolds are cooled with Fresh water."

Exhaut is cooled by raw water.

Exhaut is cooled by raw water. Take the exhaust risers apart and check the holes where water is plumbed up to the manifolds for passages plugged with rust/scale.

"Judging the amount of water e

"Judging the amount of water exiting the exaust pipe by eye can be difficult for the professional and all but impossible for the novice. The spray makes a little water look like a lot. Get good information by measuring the output in a bucket. At about 1000 RPM you should be getting 12 GPM. If not, you need to find out why and correct the problem or you will burn out more exaust pipes. Worse yet it can result in a fire. Could be a number of problems that have been discussed herein at length. I have been there. I was lucky in that I only had to replace my raw water pump and two exaust pipes.

My exaust pipes didn't burn through. They just got hot enough to delaminate, which reduced the effective inside diameter of the pipe and put back pressure on the engine. Engines don't run worth a flip with backpressure.

Chuck Hanson"

"most of the newer FWC systems

"most of the newer FWC systems are full, meaning the exhaust manifold is in the fresh water side. if the hoses from the thermostat housing go to the bottom of the exhaust manifolds, its a full system.

the raw water that cools the heat exchanger provides the cooling for the exhaust elbows. if one of the elbows clogs, its flow will be reduced and the elbow warms up. eventually it will burn thru. the elbows should have enough water flowing thru them to be cool enough that you can touch them.

with the boat spending that much time if FLA, i'd change both elbows on the port. and then start saving the same amount of money because i'd bet the starboard engine will start showing similar signs soon (unless service records indicate otherwise).

Chuck - i checked my cooling pump chart and it shows less than 10 gpm for idle speeds. i thinks that's a good check for the raw water side up to the heat exchanger. Downstream of there, you have two paths, one for each elbow. Doing a flow rate check there is tough without disturbing the pressure balance. I'd say the best check would use the IR temp gun and look for "matching" temps on the elbows. Putting pressure gauges at the elbows would work, too, but takes a lot more time."

"I have a temp switch in ALL o

"I have a temp switch in ALL of my elbows so if any of them start to overheat... A good investment, and it's easy enough to do. I simply added another temp switch to the existing circuit so all of the elbows and risers are monitored.

A good item for your own Spring To Do List.

Jeff"

"DANG Jeff another great idea!

"DANG Jeff another great idea! Temp sensor in the elbow. Guess what my next project will be!! Darren I had the exact same problem. Elbow clogged up and burned through the hose. Seems like we aren't the only ones with that problem. I just went ahead and replaced both risers and elbows. Much rather spend a few more dollars and do it at the dock instead of like Dave, at sea. Only thing I want to worry about at sea is running out of cold ones!"

"Makomark, thanks for the info

"Makomark, thanks for the info. I thought the manifolds were on the FWC side. Jeff - that temp switch sounds like a great idea. Where exactly did you install them? I only see one port where the raw water enters the elbow. Why do most of the engine casualties occur on the outboard side of the engine? I guess I'm just lucky, it keeps me nimble and in good shape climbing to the corner."

"The elbow temp switches are a

"The elbow temp switches are a great idea. On V8's, you do run the risk of having one side having good raw water flow, and the other side, very little to no flow. This causes the rubber hose to burn thru, meanwhile, the engine is running normal temperature. I caught mine when they burned about half way thru, and I was already 12 miles off shore headed to 120 miles out. My elbows were not quite 5 years old, and were OEM crusader. The left elbow on the port engine suddenly plugged; later testing would show rust clogging allowed zero water flow."

FJ - what type of temp switche

FJ - what type of temp switches did you use? A thermocouple? Did you drill and tap? Do tell!

"I'd bet the switches are

"I'd bet the switches are similar to the overheat warning switches used at the thermostat housing. install would go into the pipe plugs used for draining.

They connect into the 'warning buzzer' system that sounds when the key is turned on (due to the oil pressure switch being open). You could wire them into that circuit at any existing point, oil temp, or gear switches. Don't use the ground side if you use the gear switch.

The only caveat in doing this is similar to the basic warning horn system. There's no easy way to test these temperature switches, like the oil pressure switch."

"try this from Digikey: 317-1

"try this from Digikey: 317-1021-ND

you can either hose clamp it on, or a small screw, or even epoxy paste. My elbows have no unused pipe plug fittings. They should trip before the engine coolant sensor, if you happen to start-up with the seacock closed."

I need something for my transm

I need something for my transmissions and turbos. Will probably just monitor temperature of both... inclusive of turbo boost. (cummins) Can't afford to break that stuff. Problem is running wires to the flybridge.

"To install the temp switches,

"To install the temp switches, all you need is a threaded drain hole somewhere in the elbow. The switches are 1/8 inch NPT. I got mine from Jeggs on-line ("radiator fan switches"). They come in 160 and 200 (or so)'F set points. The motors get a 200 'F switch (they nuisance tripped with a 160, though they run 150 most of the time). The elbows get 160 and rarely go off--I backed up a 100 yards tot he gas pump at Two Rivers and tripped one last year. (Grabbed my infared temp gun, isolated the cause, and let it cool and reset.)

The connector, that comes with it, is a standard auto design, a good one.

Jeff"

"Okay guys, thanks for all of

"Okay guys, thanks for all of the info. I pulled the first riser today and am happy to report I had the riser and hoses out in about 45 minutes. Everything spun off by hand once I broke them loose. Now my question, The new riser matches perfectly but the gasket set that came with the riser just has one green paper gasket with the open slots. The existing riser had a paper gasket on both the top and bottom of a stainless spacer. I assume the spacer seperates the FWC from the RWC system. The instructions from OSCO said to only use the one gasket?? Any help?"

"Darren:
look here for the FW

"Darren:
look here for the FWC setup:
http://bpi.ebasicpower.com/mm5/apps/master/crusader/index.php?MODEL=7&IMAGE=60

Since you are freshwater cooled, you'll need another gasket & to reuse the stainless block-off plate. Yes, this plaate and the gaskets separate the fresh & raw water cooling loops.

Osco's link:
http://www.oscomotors.com/catalog/catalog20.asp
give you the option to get a pdf version.

BTW, 'risers' elevate the 'elbows' and the need for them is driven by your hull design. risers are optional where elbows are required.

Glad things separated cleanly!"

"Makomark, thanks for the clar

"Makomark, thanks for the clarification. Actually it is the exhaust elbow (osco 9015) that I have. I guess it is kind of a riser and elbow in one piece. I had purchased two gasket sets so I can use the second one on the first elbow. Thanks again for the help!"

"Okay, I put everything back t

"Okay, I put everything back together and it went well. I used the double gasket and stainless steel seprating plate. I could not test run because the boat was still out of the water. THe Marina put the boat in today and they are reporting that the engine is knocking badly. They asked if rust dropped into the exhaust while working on it. I am more concerned that I have water leaking inside. I am planning to pull the elbow and check visually. ANy other suggestions?"

"Hopefully, you drained the ma

"Hopefully, you drained the manifolds of coolant, before you removed the risers/elbows. Otherwise, coolant will shoot into the exh manifold gas passage and onto the exh valves, some of which will be open. I can't tell what knocking means; is it at all rpms, no load? I'm not worried about rust falling in. Even some water is not too bad, unless there was too much and hydro lock occurred during cranking."