Our mechanic is telling me that the risers and manifolds on our 2004 crusaders engines need to be replaced. Also,the exhaust valves need to checked. Engines have 470 hours. Boat is winterized on ground in Annapolis,Md. Can members guess what this will cost.
I have questions. What vessel and what engines do you have?
1) Risers are made of cast iron. the raw water that is used to cool the fresh water and anti-freeze in the heat exchangers is mixed with engine exhaust in the risers and exits the vessel through the mufflers and out through the exhaust outlets. Over time the water will eventually corrode the inside of the risers. If the corrosion is allowed to expand too far, the riser will actually fail and dump raw water into the exhaust manifold and into the engine through the exhaust valves. Risers have a life span of about 5 to 7 years if well cared for.
2) Many Crusaders use a fresh water cooled exhaust manifold which if cared for properly could last 15 or 20 years. The kicker is if you allow the risers to fail and dump corrosive raw water spray into the exhaust manifold, that 15 or 20 years could turn into 5 to 7 or 10 in your case.
As far as cost, that depends on the quality of the parts you use. There are many companies building risers and manifolds that far exceed the quality of the original parts.
For standard original quality parts, I would think $1,200.00 to $1,500.00 per engine for risers and manifolds (small block - more for big blocks). If you go with fancy ceramic coated parts, you could double or triple that. If you have to do valve work, you could add another $1.5k - $2k per engine or more depending on which engines you are talking about.
Just ball park numbers. labor rates vary greatly from area to area.
Tom and Chris,
I don't mean to hijack the thread but I too am looking at the riser and manifolds on my Mercruiser 502's. The mechanic who did the engine survey suggested the riser gaskets be changed. My engines have the stainless risers and to me the gaskets don't appear to be leaking. I'm not adverse to having them changed just want to be sure it's something that should to be done. Should I expect he same kind of life, 15-20yrs out of my fresh water cooled Merc manifolds? From what I understand, the gasket between riser and manifold, in this case stainless and cast iron presents challenges due to differing rates of expansion. Any opinions on that? Thanks, John
Why was the mechanic suggesting riser gaskets? Did he shoot the risers with a temperature gun?
Stainless risers should last quite a bit longer than cast iron, but they still can corrode over time. Exhaust gasses are acidic and of course stainless steel can corrode (just at a slower rate). Pulling the risers, inspecting them and reinstalling with new gaskets is likely not a bad idea. The best case scenario, you advert a future problem at worse case you find out everything looks good and you have peace of mind.
I don't believe he shot them with a temp gun. In fact they are always just warm to the touch once the engine is up to operating temp. Seems like an easy maintenance item. Any reason why I shouldn't tackle it myself?
If you are very mechanically inclined, I would say go for it. Make sure you clean the mating surfaces very well (use the proper gaskets) and torque the bolts down upon reassembly in the correct pattern and to the correct torque figures. I believe they recommend re-torqueing the bolts after a certain period of time (check the manufacturers directions).
Note 1: Make sure you reinstall the exhaust hoses and cooling lines with all new clamps and make sure you torque them down to the proper settings and the clamps are located in the proper places. One of the easiest ways to sink a boat is blowing off the main exhaust hoses. The raw water engine cooling pump can pump far more water than the bilge pumps can keep up with. Even with the engine off, the right sea conditions can force water up through the exhaust and into the boat. The exhaust openings are the largest holes in the hull at the waterline. Even a small exhaust leak could allow dangerous carbon monoxide to find its way into the cabin or even up into the canvas enclosed helm area. Make sure you check your work for exhaust leaks!
Note 2: When working in the bilge of your boat, make sure you only use ignition protected electrical devices such as power tools and vacuums. Using non-ignition protected electrical devices in the bilge of a boat can create an explosion, especially in a gasoline powered vessel. Best to stick to hand tools if you are uncertain if your device is ignition protected or not. Most automotive electrical tools are not ignition protected as automotive machinery spaces are vented to the surrounding areas unlike an inboard vessel.
Sorry for the preaching, but I have no idea of your skill level and I want to point out the Do-it-yourself mistakes that could be catastrophic.
I was standing on the dock in Bimini Bahamas (20 years ago). A boat the next marina over exploded. I believe it was discovered later that a mechanic was using a non-ignition protected electrical devise (drill - if I remember correctly).
Then there was the 25' Mako Center Console that exploded in Ft. Lauderdale when the owner was using a Sawzall to cut a section of the fiberglass deck and the blade struck the fuel tank.
Chris,
I'm not sure I would classify myself as very experienced however, I am experienced and have tackled many projects over the years. I appreciate all the good info and if I decide to tackle the project I will definitely be careful.
Thanks, John
We had the risers changed last June after 375 hours and nine years of service. The SS blocking plates were also replaced.
The engines are 8.1 crusaders (3100 open) and all crusader parts were used. The cost for parts and labor was $2,447. This is Connecticut so I would suspect it may be less expensive in other areas.
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