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Changing risers

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richbraman

New member
I bought a replacement Crusader 270 for my boat. Upon setting the engine in the boat, it became obvious that the 8" risers are to high, about 4" to high to be exact. I realize that I need to change to the 4" riser. I figured I should probably replace the elbows while I am at it as there is some rust scaling on the elbows. The 8" risers and elbows on the engine are OSCO, but it looks like the Barr Marine is slightly cheaper on mrcool.

http://www.mrcool.us/97772-crusader-risers.html
http://www.mrcool.us/20-97386-crusader-risers.html

It seems like only the starbourd exhaust needs to swivel, the port exhaust is inline with the single outlet that runs to the stern.

Any brand preferences out there?

Also, are there any issues I should be aware of in order to do the replacement? Is it a simple unbolt operation?

Do I have to replace the mounting studs? It look like the 4 inch riser uses different stud sizes. Can anyone tell which studs the 4" uses?
 
OSCO & BARR both used to be decent after-market replacements..

Only concern is expect rust to be present if there are lots of house of use. a torch and hammer can help there. if it is fresh water cooled , drain the manifold first.

Studs could be different lengths; parts book could help there.

line up the gaskets correctly when you reassemble...I like to use perfect seal (permatex#3).
 
Allright, I got the risers off with a sledge and piece of wood. Couple thumps after removing the nuts and they broke free. Looks like the manifolds have some corrosion in the cooling chamber. I am attaching some pics of the rust. Any opinions on whether to change these out? This motor was run in brackish water with raw water cooling. Man $1000 bucks in parts and we just got started
 
B O A T remember?

Though OISCO and BARR say not to, I always smear a THIN coating of silicone on both side of those water passage gaskets. Keeps water out of the motor.

Jeff
 
I have been reading on some forums where the engine did not have risers off the manifold but rather just the elbows. I think this is how my last engine was configured because it seems that with just the elbows, the elbow output would still be at the same level or maybe even slightly higher than where the exhaust output is. As I understand it the risers help keep raw water out of the engines. Why do some installations not need them. Thanks for the answers.
 
The installation's NEED for risers is determined by measuring the vertical offset from the engine's outlet to the thru hull fitting....just like a drain pipe, to ensure there's no leftovers. As Jeff noted, some installations don't have enough clearance so they have "extra risk" associated with its use...
 
Here's why.

My boat (32 Marinette) goes all summer without a problem--UNTIL some freak wind/ wave condition comes along and rams water up the exhaust pipe(s). (Yes; I have a flapper.) Happens once a year, just like clockwork. I have to plug spark plugs and pump the water out before she fires up.

Jeff

PS: Made it a ritual if the boat has been sitting for a week to roll 'em over BEFORE trying to start 'em up. If they go R_R_R_R all is well, but if they go R_ lock up R_R lock up, it's plug wrench time!
 
makomark said:
if it is fresh water cooled , drain the manifold first.
Click to expand...

Really wish I found this forum last week. Long story short, Removed risers, ordered new ones, came back 5 days later and my boat had been moved by the dry storage. WTF. Had a shop towel stuffed into the manifold exhaust, but it wasn't enough and I got a decent amount of coolant in the manifold exhuast. Now what? I removed what I could by shoving rags down into he exhaust, but I know that's not enough unfortunately.

I'm new to performing mechanical work myself, obviously.

Any help is appreciated.
 
Long as that stuff didn't go into the motor via the exhaust ports you're okay. If it did, change the oil BEFORE starting up.

Jeff
 
I'd agree with Jeff....but given your self proclaimed status, I'd suggest either turning the engine over, by hand, a few revolutions, or removing the spark plugs and then spinning it over.
 
makomark said:
I'd agree with Jeff....but given your self proclaimed status, I'd suggest either turning the engine over, by hand, a few revolutions, or removing the spark plugs and then spinning it over.
Click to expand...

I plan to remove the plugs today and draining it. Then I was told to squirt oil up into the cylinders. When you say spin it over, do you mean turning over with the key? I drained the oil last week, but didn't plan on refilling till the risers were back on since the filter mounts to the riser. Should I add a little oil to the reservoir first and then remove it after I spin it?? Or will it not matter since I'll only be running it for a second?

Now I know why mechanics charge so much...

Thanks for all of your help.
 
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.."Now I know why mechanics charge so much..."

They earn it! Don't spin her over without oil in it--especially now. Coolant is a lousy lubricant.

Jeff
 
fastjeff said:
.."Now I know why mechanics charge so much..."

They earn it! Don't spin her over without oil in it--especially now. Coolant is a lousy lubricant.

Jeff
Click to expand...
Well... I didn't. But it makes sense now that you say that. I did remove plugs, squirt a generous amount of oil into the cylinders. I spun it just for a short bursts and a small amount of coolant came out of one cylinder. Couple more short bursts and nothing. Hope no damage was done. I replaced the risers, reattached all the hoses and installed new plugs. Going to make sure oil reservoir is completely empty today and add new oil and filter today. Going to splash it tomorrow, run it at the dock and add the coolant lost during the riser change out. Run her for a half hour at cruise and see what happens!

Thanks again fellas. Just bought this boat a few weeks ago and couldn't find any mechanic within site and risers were shot. Engine is an '07 and hasn't had any maintenance since at least when the last owner bought her in '12. Hell, oil was jet black so I'm not sure it has ever had an oil change since then. Good news is that it only has 200 hours and compression was all between 165 and 175.

Been doing the work with a coworker who is just a little more familiar with engines than I am. Really excited about learning about engines. It's pretty fascinating but overwhelming for a total novice. It's admittedly partly out of necessity, but it's also something I've been wanting to learn. I've aways been jealous of those who could work on their own trucks and boats.

I had an Albermarle back in the day with a similar volvo set up (boat now is a 25' Carolina Classic), but was young and didn't really care to learn about the mechanical side of the boat. I only cared about blue marlin. I also had a mechanic.

EDIT: One more question. The temp gauge read at about 180 degrees the one and only time I have run the boat. Is that about what I should be looking for? I'm assuming it should be a little lower considering the risers were almost completely clogged, it was low on coolant, and the oil was likely a few years old.
 
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most FWC engines with carbs have a 160 degree t-stat; the newer injected engines have a 170 degree stat. If the gauge is accurate, it should show these values within a few degrees...an IR temp gun will let you know about the accuracy...when running in warm (80+ deg) water, the gauge may go up a bit but not over 10 degrees....and its likely the temp will rise when you come down off of plane, but it should go back down after a minute or two.
 
Thanks Mako. I'm not far off then. It's very warm down here in Fl, so around 175 should be the norm I guess. Think I was high near 180 and average around 178 last and only time out.


Definitely buying and keeping a temp gun on the boat.
 
when you get it right, take the IR gun and measure key points like the Tstat housing and the tops of the elbows....and write that info down in your log....you will find it very helpful in the future
 
Well, with everything reassembled and oil/coolant topped off I ran the boat today.

Temp wasmuch lower at 170 degrees, oil pressure great, seemed to cruise fine, and no leaky seals. But, there was a pretty loud ticking noise. Seemed to be located under the starboard side of the manifold somewhere and Changed rhythm right along with the rpm's.

I say cruised fine but I've only spent 10 minutes at cruise in this boat prior to doing any work so I'm not sure if I was running on all 8 cylinders or not. That noise definitely wasn't there the only other time I've driven it. What could I have done when changing risers and plugs?

One friend who is mechanically inclined said a valve rocker or lifter may need adjusting? Thats way past my level of engine tinkering since I don't know what a valve rocker looks like.

After a little more research one of the spark plugs may be the issue? Guess I'll remove them and reinstall on the side?

Anyone else offer any dignosis?
 
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Might be cured by adjusting the valve lash, but some of those Chevy-based engines have fixed valve adjustments.

I suggest you add some Lucas Oil Stabilizer first, in case it's just a lazy lifter. That stuff is marvelous.

Jeff
 
check to make sure the spark plug leads are on tight and not "leaking"....pretty easy to see after dark but not always convenient....

and make sure they are in the proper order...

finally, misses are easier to hear at slow idle in gear....that said, they are always obvious..
 
That makes sense Mako, and I hope that's the problem. I didn't connects the leads on that side and I had to double check the other side 3 times to make sure they were on the right plugs.

The ticking did sound like a spark popping.

ya'll have all been very helpful. Hopefully today I can confirm the diagnosis.
 
Mako was right. I tightened the front plug on the starboard side with my hand just to get it started and went on to something else. My buddy finished up the plug replacement but thought I had tightened that one! It was totally loose. Tightened it down, and she ran like a champ. 26 knots at 3600 rpm!

I did drain a quart of oil and added the oil stabilizer like you recommended, Jeff. Going to change the oil again after a couple of trips. Old oil was so bad the new oil is already dark.

Thanks again fellas!
 
I did find this dangling. And after reading all of the manuals can't find out where it plugs in.

Cant attach the photo but it's labeled "transmission temp"
 
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no picture makes it hard to do anything besides guessing....may wanna post to some picture site and then enter the link to the pic here....

I'd guess an electrical connector; if so, if its only one or two wires, the color code is likely to tell you what function it enables...
 
makomark said:
The installation's NEED for risers is determined by measuring the vertical offset from the engine's outlet to the thru hull fitting....just like a drain pipe, to ensure there's no leftovers. As Jeff noted, some installations don't have enough clearance so they have "extra risk" associated with its use...
Click to expand...



Thanks Jeff and Mako Mark. I need some advise on this measurement to make sure that I don't need the 4" risers, which may fit my installation. I am not sure if the original engine had risers or not, but if it did, it must have been the 4" because there is no way 8" will work. When you say the "engine's outlet" are you talking about the height of the middle of manifold exhaust port or the height of the middle of the exhaust after the 980068 elbow is installed? Also when you mention the "thru hull", is that referring to the thru hull that lets the exhaust out the back of the boat? What is the number of inches per foot drop or angle or whatever benchmark used to determine the need for a riser.
 
richbraman said:
Thanks Jeff and Mako Mark. I need some advise on this measurement to make sure that I don't need the 4" risers, which may fit my installation. I am not sure if the original engine had risers or not, but if it did, it must have been the 4" because there is no way 8" will work. When you say the "engine's outlet" are you talking about the height of the middle of manifold exhaust port or the height of the middle of the exhaust after the 980068 elbow is installed? Also when you mention the "thru hull", is that referring to the thru hull that lets the exhaust out the back of the boat? What is the number of inches per foot drop or angle or whatever benchmark used to determine the need for a riser.
Click to expand...


exhaust slope.jpg

So I bolted up the elbow directly on the manifold to try and get an eyeball on the angle of the dangle between the muffler and the elbow. i put a stick in the muffler on stern side of the exhaust and the elbow as you can see in the attached picture. The motor side still needs to come up 2 or 3 inches still to get the transmission/shaft coupling to line up, so in the end the motor side will be even higher. You can see the motor is still a good bit higher than the muffler even without the 2-3 inch lift I still have to put in. I believe the muffler is even higher than the thru hull, but I still have to check. What do you guys think about going without risers in this install? I am in the Bahamas, so everything has to be shipped and there's no mechanics except me and my friends.
 
The pic posted appears to be cropped and doesn't show the detail you described....

I screwed up in my earlier post regarding critical dimensions....guess memory isn't always best....Anyhow, the critical dimension is from the top of the elbow to the waterline. Usually measured using the transom/gunwale as a reference point...easier said than done if the boat is in the water....the crusader spec is 12" (though mercruiser says 13" in their older manual)...

The other item is to have a constant drop to ensure the water drains out....they have other recommendations but many are hull specific.

As far as omitting the risers, that's your decision....same applies for deviating from any other OEM requirement...as long as you know the risks associated with the decision, and you're aware of the consequences, follow your gut...
 
Like all of these "rules of thumb, it all depends upon circumstances. My stock Pursuit 3000 flunked the survey because the drop from the elbow did not meet "standards". But I never have had a problem. But then again I rarely back down on a big fish (and never into a heavy following sea)....and maybe I do have the recommended 12", I have forgotten. I think the real rule for elbows is "the higher the better". But if you pay attention to your engine rpm and the following seas you may avoid problems that others with the same setup incur.
 
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