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Another riser elbow thread

"Jeff, I got lucky with this m

"Jeff, I got lucky with this mechanic, found him through a marine surveyer. He's a one man operation, works out of his truck, low overhead. He can and will do almost anything. No charge for travel time or any other extras.

The main reason I use him for the exhaust work is those studs, (plus my back ain't what it used to be). There is always one or more studs that is a bitch to get out and the job is much easier if you can get them out first. Once that's done, the riser and elbow can come off as a unit.

I use Permatex #2 on the gaskets. No paint on the mating surfaces."
 
"When replacing my elbows, the

"When replacing my elbows, the manual call for 4 ss studs per side. I am grateful for antisieze which I MUST use even on my Ford F-150 Wheel to Rotor Hub mating surfaces. They seem to weld themselves in place prempting any chance of changing a flat.

I think I will be due for new elbows in 2 more years...IF the 4 year replacement period is cast in stone"
 
"I received my new Osco elbows

"I received my new Osco elbows, risers, and hardware kits last week. After inspecting them and reading some of the directions, I wanted to verify something...

- for the pipe plug fittings.. do you guys use any thread sealant? instructions state not to use any sealant / teflon stuff.

- for the gasket surfaces.. instructions state the parts are primed and to remove any paint. Does this include the primer too or do you guys leave on the primer?

After reading other threads, it seems most people don't go by the OSCO instructions. I've been planning to use a thin "wetting out" layer of Permatex 3 or Ultra Black on the gaskets.

Thanks!"
 
"A THIN layer of sealer is oka

"A THIN layer of sealer is okay--just don't allow globs of it to migrate into the riser outlet holes.

You can use Teflon tape on those fitting long as they are NOT temp switches or sensors (that use the ground connection as part of their circuit). Install them dry.

I know you're supposed to remove the primer from the gasket faces, but I've always wanted to see if leaving it on would prevent the inevitable rusting. Your call.
Jeff"
 
Need your guys help... I finished putting together the starboard motor today with new OSCO elbows, riser, HW kits. It taking me a lot longer given it's my first time, so was happy to have one motor done. The motor started up fine, but had a few leaks... a bottom stud/bolt in one of the risers and at the exhaust joint (just didnt tighten up enough)... No leaks at the manifold/riser and riser/elbow joints..

The leaking bolt was by biggest concern given it was quickly dripping.. After about 45 seconds, the motor started to lose RPM / chug, so I shut it down, fearing water going into the manifold ( i remember one of fastjeff's prior posts about this)...

I was pretty demoralized, but started to pull things apart again to see what was up..
- 1st checked the plugs and they were dry / no water coming out the cylinders
- pulled out the bottom bolt/stud that was leaking and water started pouring out
- decided to drain manifold/riser, then pulled off entire riser/elbow assembly at the manifold
- the gaskets (1 hole at top) were all in the correct order with the SS block off sandwiched between... the thin layer of permatex ultra black looked fine... I looked down the manifold and it looked dry too.

A few initial questions...
- I suspect water was somehow escaping the riser around the stud and funneling out the hole.. gasketing or fastening issue?
- I tried taking the bolts off the studs and it ended up pulling the studs out.. did I not put them in snugly enough?
- does it sound like a dodged a water in engine bullet? I usually have to rev up the engine / give it gas initially since it doesnt have a choke, but I didnt have the chance since I wanted to see what was happening with the motor... maybe it was just flooding.. and not ingesting water.. ?

Either way... gotten order new gaskets and put it back together again..
 
Carech; describe what you have. Is it the older log style or center riser? Is a "bolt/stud" a 2" stud with a nut? Are you using copper washers? Was the drip a raw water drip?
 
Sorry.. I should have been more specific...

- I have the late style manifolds... it sounds like the center riser
- risers are 8" with a 3" elbow
- I've been using the HW kit for the 8" riser with the long studs, nut, and washers
- It was a raw water drip coming from the nut/washer of one of the studs.. when I loosened it, more water would come out.. raw water is only coming out here.. not at the joints... not sure why...
- I pulled the riser off and mating surfaces / gaskets looked OK to me...
 
carech said:
when I loosened it, more water would come out.. raw water is only coming out here.. not at the joints... not sure why...
- I pulled the riser off and mating surfaces / gaskets looked OK to me...
Click to expand...


Did you try to tighten while the engine was running? Do you have a good feel that you are about 20 lb/ft torque? Are you inspecting the iron sealing surfaces to insure there are no paint drips, causing a lack of sealing?
 
I didn't try tightening while the engine was running since it started to bog/chug... I thought maybe I was getting some water down the manifold and didnt want to risk it and shut it down.

I used a new torque wrench for assembly and set it to 20 lb/ft.. but didnt recheck prior to starting up. Maybe the bolts weren't tightened down enough, but I would have thought the water would have come out between the gaskets not the stud holes. Wonder if there is less resistance around the stud holes...

I meticously made sure the gasket surfaces were clear of carbon build up, paint drips.. checked with a straight edge too. I'm starting to think I didnt torque them down enough..
 
I suppose i'd put threadsealer blue on those studs (not the locknut end) and try again. Check for tightness manually before and after the first run.
 
Carech,

It sounds to me like you have the older log-style exhaust manifold since you have 1988 engines and you say that the lower bolts between the riser and the manifold are leaking. I don't believe the center riser style would have upper and lower bolts. Those copper washers and the nuts with the plastic inserts are what is suppose to keep the water from leaking out as the area where the bolts/rods are is within the riser water chamber. The washer blocks the hole while the plastic nut stops water from coming down the threads of the bolts. Poor design in my opinion. I was told not to reuse either the washers or the nuts when I replaced my risers and elbows about 3 years ago. I was also told to use some locktite (I forget which color but something that is not too unforgiving) on the bolts that go into the manifolds.

Erich
 
Erich,

Yes, my set up resembles your "before" picture. I didn't realize the studs were within the riser water chamber. That is really helpful to know and explains why so much raw water was coming out. Also, it seems to back my theory that I just didn't torque the nuts enough and maybe a stud was too loose. I've bought blue threadsealer as diver dave suggested.
 
The threads on the "blind" end of the studs should have sealer as Diver Dave indicated. The reason is as Erich stated: the back side of some of those holes are "wet".

Osco says:
Studs: To prevent studs from backing out and causing leaks which can cause engine damage, use red thread locking compound. Follow the manufacturers recommendations for their installation and removal. Do not use anti-sieze on bolts or studs as it is a lubricant and will cause fastener to back out.

Now some will disagree with the anti-seize statement. I've never had an issue with a fastener lossing up due to its use.

Don't forget to get that torque wrench out, again, after running the engine thru a complete cold-hot-cold cycle.
 
Just a quick update to the post above.. I still have a slow drip.. a few times a minute coming from 1 of 4 studs / nut on the 8" Riser. This is after re-torquing them after cold hot cold cycle.

I ran into my usual mechanic and he suggested the following:

- make sure there is no primer or paint behind the copper nut / washer that goes over the stud..originally, I didn't strip this area way.. just around the gasket mating surfaces.. i havent heard about this on this forum

- put RTV behind the copper washer and tighten back down

- do this on all nut / studs since he feels they will all leak with the paint surface underneath

Does this sound like a good solution to you guys? Also, would assume I need to drain the riser of raw water first...correct? What about the manifolds? I was thinking about taking out a few studs to make paint removal around the nut/washer area easier. The studs that seat in the manifolds.. is that an area that is sealed by the stud themselves?

Thanks for any feedback.
 
makomark said:
The threads on the "blind" end of the studs should have sealer as Diver Dave indicated. The reason is as Erich stated: the back side of some of those holes are "wet".

When you say blind end of the stud- you're saying where the stud screws into the manifold, correct?
Click to expand...
 
Throw that damn torque wrench away! That's 90 % of your problem. (Accurate torque readings require EXACT thread friction factors, and you don't have them here.)

Tighten the bolts/ nuts until they 'feel' nice and tight, then add a 'flat' or two more. (A bolt has 6 flats--get it?) Next, run the engine until it's fully warmed up and add another flat or two--the bolt will tell you when it's tight enough.

And don't worry about getting water in when the motor is running--it just blows out the back. It's when you shut it off that the water can get into the exhaust ports.

Jeff
 
Yes, the 'Blind' end is the one you can not see.

Accurate torque readings require EXACT thread friction factors - not true! Now, if you want to discuss the tension (stretch) as a function of applied torque, that's another thread.
 
Thanks for the feedback. I have been through several cold hot cold cycles and hand tightened to feel. It worked with one of my riser studs/nuts, but is still there on another.

My follow-up post was mainly to ask.. what now and whether or not the solution I was given from my mechanic sounded legit??? He stated there should be no primer / paint underneath the copper nuts / crush washers that go over the studs. I haven't read this on the forum or hear anyone mention this before. Also, he advised to put some RTV behind the washers.

If this sounds OK, I was going to...
- pull one stud at a time, strip paint away where the nut/washer goes, and re-install.. all while the motor is shut down, so was wondering if draining both the manifolds and risers were necessary.

Thanks again.
 
..."Accurate torque readings require EXACT thread friction factors - not true! "

Wanna bet? Bolt stretch is the ONLY accurate way to tighen a bolt, as racers have found out the hard way (read: $$$)

Installing bolts in tapped holes that aren't perfectly prepared, installing fasteners without proper thread lubrication, and (my favorite) attempting to accurately torque nuts that are self-locking, is more than a waste of time--it's a way to leave an assembly dangerously under-tightened.

A case in point: I had an old snowmobile that the previous owner substitued self-locking (crush thread) locknuts for normal cylinder head nuts. Like a fool I torqued the nuts to specs--and the head gasket leaked whenever it got hot. Being solid copper (and an air cooled motor) it worked fine after it cooled back down, but I spent a year tracking that fool thing down! Had I used the "mechanic's method" (common sense tightening) I might have caught it, but I let that fool torque wrench do the thinking for me.

Jeff
 
Carech:

You need to ensure those threads are dry before applying the thread locking compound on the studs. Both sides.

The ideal solution keeps the fluid from entering the stud passages in the first place. What your mechanic suggests will only keep if from leaking out once it has entered those passages.

Jeff - reread the comment in post #49.
 
I may be in trouble. Our 1986 Crusader 350s will be due for risers and elbows before too many more "years. The engines never saw salt water until late 2006. The problem is that they are in our 1986 Hatteras and have 12" "dogbone" risers. These are no longer available anywhere. I have measured from the waterline to the bottom of the elbows and come up with 12". I was told that you need a rise of 12" above water to keep water from entering the engine when backing up. I guess I will have to settle for 8" risers and don't back up fast. The only other cure I can see is to use an 8" riser and a 4" riser. I don't know if all that crap will line up. Do I really need 12" risers?
 
The current Crusader recommendation is to have 12" from the waterline to the TOP of the elbows. They also recommend following the ABYC guide of 1" of drop per foot of run. As far as the need for the 12" risers, you'll have to determine that.

Stacking the risers will give you the height but will move the hose connection further aft. You want the hose running stright off the elbow so you need to make sure the space exists.

If you have to have the 12" of risers, another option is to switch to the center riser manifolds. Not cheap but the risers (stacked) are still easy to obtain.
 
Maynard,

Have you considered the possibility of re-designing the layout of your current muffler setup? I was looking at adding some real noise reduction mufflers last year but I do not have the room because of my generator placement. When my engines start to reach 2000 rpm they ROAR at 3200 its' deafening down on the fishing cockpit !

Currently mine is really straight forward in that my elbows simply face the transom, my exhaust tips are at waterline and the 4" exhaust hose (2 each engine) runs from the elbow to the tube type muffler then from the muffler to the transom tips. That 40" run has about 10" of slope and all is fine.

Depending on the ease of routing, you may consider that an option. My 2 cents...for what its worth

Mark, did you say the center riser manifolds fit my 92's barring any hull obstructions ?
 
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