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View Full Version : WTF! Is this reversion?



flying tomato
05-02-2011, 07:21 PM
I have had the exh manifolds off this motor 3 times since putting it together. Motor has a total of 20 hrs on it. These are stainless marine exhaust manifolds, gen 2 (I think).

flying tomato
05-02-2011, 07:26 PM
I have pressure tested the manifolds and BOTH manifolds look the same.
I have added 8 inches of inner pipe to the risers to combat the problem. (It definately helped the situation, but it still looks like I am getting water in the exh)

silverghost
05-02-2011, 08:06 PM
It sure looks like a mild version on exhaust water reversion to me .

What specific engine is this ?

What sort of cam do you have in that engine ?
Is it a high overlap cam where the exhaust & intake valves are open at the very same time ?
That's usually the main cause of this sort of reversion issue.
The high over-lap cam will allow the engine to suck some exhaust cooling water back into it's head's exhaust ports.

Mercruiser several years ago had a severe water reversion issue on their newer Fuel Injected Big Blocks some years back.
What a mess that was .
Many NEW engines were killed with very little time on them.
Mercruiser had goofed-up BIG TIME.

I also had a friend who despite everyone telling him that he had picked a too aggressive high-overlap automotive type performance cam for boat use~~~he installed it anyway in his Chevy MK V big block.
That engine completely reverted large amounts of exhaust cooling water back through it's exhaust ports and hydro-locked the engine hydraulically bending rods & breaking pistons.
That engine was later nothing but scrap.

The very short & level exhaust outlets on many marine manifolds & SS marine performance exhausts complicates this problem issue on our small boats.

Run your engne a short time and pull a few park plugs to see it they are unusually very clean & white or actualy wet with water droplets & mist.

You might try by-passing at least some of the exhaust water though an additional outlet that is T-d into your engines water dump lines before they go to the manifolds themselves..
Put only enough water through this exhaust system to actually safely cool them. Bypass the rest of this water with a small 3/4 "or 1" Hull thru-hull fitting.

Good Luck !

BUIZILLA
05-02-2011, 09:00 PM
whta is the lobe separation of the camshaft your are using?

maddad
05-02-2011, 09:03 PM
Hey ft, I am not a engine expert but I'm wondering, is this happening only in that one cylinder and port, or all eight? Is this happening in the water or running on a hose? Is the motor fresh or raw water cooled?

mrfixxall
05-02-2011, 09:14 PM
your running bobs cam and if you degreed it than its not the cam..are you using ant exhaust flappers? from the looks of those extensions i would say not..not having flappers will make it look like reversion but will injest water when the engine is off.

Look for a set of keith eickerts manifolds and sell those,,only good for mabe 500 hp..

http://www.keitheickert.com/c-441-big-block-chevy.aspx

silverghost
05-02-2011, 09:17 PM
Maddad asks a very good question~~~

If it IS just one cylinder doing this it's possibe that cylinder is mis-firing , or that cylinder's valves are not seating for some reason.

You need pressure from the engine's gasoline explosions in ALL cylinders to force all of the water out and on it's way .

flying tomato
05-02-2011, 09:35 PM
No it is not just one cylinder.
No, I do not have any flappers. (I always flush eng after use, so I do not see how eng could get water up the tailpipes on the trailer)

Cam has 235/242 dur
114 lobe sep (proven cam design)

silverghost
05-02-2011, 09:36 PM
This very problem is why I like to use some sort of exhaust risers similar to the old "Snail" style Holman ~Moody used on these old boats. The knew what they were doing when they first powered these small boats.
The high risers let the water run downhill & block this sort of reversion.
It woud be nice to have the riser elbows almost hit the rear engine hatch and the angle downward to the slightly lower transom exhaust outlets.
This is sometimes very hard to do with very limited space and a raised outdrive X-Dimension.

silverghost
05-02-2011, 09:51 PM
The rubber exhaust flappers are ALWAYS a good idea .
They protect like a one- way check-valve to prevent water from dumping back into the transom exhaust outlets from suddenly slowing your boat down~~~after running fast.
OR~ running in following sea conditions.
They protect from Boat wakes~~~and big waves.
& actually keep water from dumping in those big exhaust pipe outlets while tilting your boat up a ramp an onto your trailer.

There is a reason Mercruiser uses rubber flapper valves in their stock engine exhaust Y-pipes.

mrfixxall
05-02-2011, 10:21 PM
No it is not just one cylinder.
No, I do not have any flappers. (I always flush eng after use, so I do not see how eng could get water up the tailpipes on the trailer)

Cam has 235/242 dur
114 lobe sep (proven cam design)


so your saying you never dock your boat either? when your boat is sitting still with the engine off and a wave crashes into the back of the boat you dont get water in the exhaust? or how about when you come off plane and you throw the throttle down you dont think the engine wont injest water..think again, not to be mean but what i have mentioned above will and has happen..

silverghost
05-02-2011, 10:38 PM
so your saying you never dock your boat either? when your boat is sitting still with the engine off and a wave crashes into the back of the boat you dont get water in the exhaust? or how about when you come off plane and you throw the throttle down you dont think the engine wont injest water..think again, not to be mean but what i have mentioned above will and has happen..

All the above things Can & Do happen .
The best you can do is to try everything you can think of to do ~ to try to prevent the water from going down those big transom exhaust pipes in all possible situations.

I knew a guy who had two sets of rubber flapper valves.
One inside the SS transom outlets that came with his exhaust tips & those cheap Sudbury hose clamp-on style flappers on the outside of the pipes.

By the way~~~
My boats sit in the water ALL summer long for six months.
This has been going on since the early 1970s~~~
Never had water go down into my exhaust pipes.
I guess I have been lucky ..

mrfixxall
05-03-2011, 09:52 AM
All the above things Can & Do happen .
The best you can do is to try everything you can think of to do ~ to try to prevent the water from going down those big transom exhaust pipes in all possible situations.

I knew a guy who had two sets of rubber flapper valves.
One inside the SS transom outlets that came with his exhaust tips & those cheap Sudbury hose clamp-on style flappers on the outside of the pipes.

By the way~~~
My boats sit in the water ALL summer long for six months.
This has been going on since the early 1970s~~~
Never had water go down into my exhaust pipes.
I guess I have been lucky ..


Just so you know,,i have been working on boats for 25+ yrs..i have a shop and a ton of customers that have boats to ,so what your telling me is somthing i already know..


are you saying you dont have clamp on flappers??


FT if your boat's carberator idle fuel circuit is not adjusted correctly it may revert water..does the engine load up @ idle?

flying tomato
05-03-2011, 10:57 AM
Hey Fixx, Ghost,
I respect both of you and your opinions. Thanks for the advice. I just bought some Drew Shotgun silencers. Do yall think they will help. I'm thinking about plugging the water jacket at the ends and adding a water dump hose.

Or, kicking around the idea of just going to diff exh altogether. What do yall think about cmi sport tubes????

The Hedgehog
05-03-2011, 11:30 AM
Hey Fixx, Ghost,
I respect both of you and your opinions. Thanks for the advice. I just bought some Drew Shotgun silencers. Do yall think they will help. I'm thinking about plugging the water jacket at the ends and adding a water dump hose.
Or, kicking around the idea of just going to diff exh altogether. What do yall think about cmi sport tubes????

I have CMI E-tops and run a pretty big cam. I use the external flappers. I have no reversion.

I am still kind of baffled. Those SM's should do it. Maybe they don't have enough turn down in the risers.

Lowflyn
05-03-2011, 11:32 AM
Just wanted to share my experience with water injestion. My 22C 454, when I shut it down, would suck enough water back up ~5 ft of 4” exhaust tubing to fill a cylinder, never which cylinder either. At next start up – obviously the start would only click and nothing. I would have to pull all plugs, crank it until the water was pumped out, stab the plugs and then fire it.
My exhaust at purchase was exiting at water level……. Only Donzi 22 C that I have seen with exhaust exiting low at the water line.
Turns out the 454 cam timing has a slight overlap between exhast and intake valves staying open.
My solution – see photos – before and after… That problem no longer happens and I am running the cheapie flappers. Got tired of changing the internal – they just do not last…

mrfixxall
05-03-2011, 12:23 PM
Hey Fixx, Ghost,
I respect both of you and your opinions. Thanks for the advice. I just bought some Drew Shotgun silencers. Do yall think they will help. I'm thinking about plugging the water jacket at the ends and adding a water dump hose.

Or, kicking around the idea of just going to diff exh altogether. What do yall think about cmi sport tubes????


If your going to spend that kind on money on sport tubes that crack and leak and will eventually cause a hydro locked engine i would get the KE ones..they produce more power and torque then the cmi's..if i were to use headers my choice would be Stellings or SS lightenings,,they have way less problems..

silencers,,if they are the ones that have a SS internal flap and are close then blown open with the exhaust pressure that those would work fine..

as already mentioned, if your loading up @ idle your engine will suck in water because the cylinder is loaded with fuel and will not be firing and with out fire it wont blow the exhaust out..with the valve over lap and the cylinder not firing will suck the water back into the cylinder..make sure your idle is nice and crisp, when you hit the throttle and the engine goes bla,bla,bla,bla then smooths out that means your loading up a few cylinders which creates a vacuum..Get the carburetor and engine temps up over 140* first before replacing the manifolds.

VetteLT193
05-03-2011, 12:40 PM
you have a gt 21 right? exhaust location at the transom? A 22 won't suck in water without flappers, and a 21 shouldn't either if the tips are all the way up like the 22... but I seem to remember the tip location on the GT21's being quite low.

If that is the case, you need flappers. if they are way up high, it's something else.

flying tomato
05-03-2011, 01:48 PM
My exhaust exits the transom about 12 inches above the waterline.

Eng is not "loading up" or misfiring at low rpm. Have idle set at 900 rpms.

pipnit
05-03-2011, 02:14 PM
Sorry to hear about your problems. I'm getting very close to buttoning up my 18 and am going to use Stainless Marine Manifolds with pipes added on. Do you have any pics of your engine and the tail pipes? I'm basically trying to emulate what MadPoodle did since I have a very similar boat, have the exhaust go straight up and then go down towards the transom at as extreme of an angle as possible. Can we see what yours looks like?

flying tomato
05-03-2011, 02:42 PM
This is the exh in the boat.

blackboat
05-03-2011, 03:41 PM
I would have suggested adding inner pipe extensions like you have already done,although if you are still dumping all your water right at the end,it might still be sucking some water back.
You might want to consider just buying dry to the end tailpipes from stainless marine with an external through transom dump and use your mufflers at the ends.
Send them your manifolds to make sure you dont have any problem with them.

BUIZILLA
05-03-2011, 03:52 PM
get rid of the Fram filter... :)

the decal on the manifold is discolored, like it gets real hot... are you sure you have plenty of water going through there?? you may have steam residue and not reversion going on here..

cutwater
05-03-2011, 04:32 PM
get rid of the Fram filter... :)

the decal on the manifold is discolored, like it gets real hot... are you sure you have plenty of water going through there?? you may have steam residue and not reversion going on here..

+1 ... It looks like the manifolds (and even where the risers connect) are getting HOT...

maddad
05-03-2011, 06:09 PM
Looks like the powder coating near the collar is wrinkled from being remelted also. I did that on my sbc set with a serious meltdown.

flying tomato
05-03-2011, 10:21 PM
The discoloration around the top round gasket is from water intrusion and leakage to the outside of the manifold. The water intrusion was a LOT worse before I added the pipes to the risers.

Before I added the extra 8 inches to the inner pipe, water was literally pouring out of the joint where the manifold and the riser connect.

Lee

Donzi_Dude
05-04-2011, 07:10 AM
I have CMI E-tops and run a pretty big cam. I use the external flappers. I have no reversion.



your running forced induction. it makes a big difference.

BUIZILLA
05-04-2011, 07:58 AM
The discoloration around the top round gasket is from water intrusion and leakage to the outside of the manifold. The water intrusion was a LOT worse before I added the pipes to the risers.

Before I added the extra 8 inches to the inner pipe, water was literally pouring out of the joint where the manifold and the riser connect.

Lee if you had water leaking at the joint connection then your tails have an internal leak.... i've never, ever, ever, heard of water coming out of that connection

MOP
05-04-2011, 08:51 AM
Correct me if I am wrong! That is a dry joint how you got water out of it is very strange!

Fishermanjm
05-04-2011, 09:51 AM
i like your avitar MOP

Rumblefish
05-04-2011, 11:58 AM
get rid of the Fram filter... :)

the decal on the manifold is discolored, like it gets real hot... are you sure you have plenty of water going through there?? you may have steam residue and not reversion going on here..

Yes.. Impeller Check. could be down to 1 fin.. plus as stated above your secondary issue may be cam design versus pulsing of overlap at low idle speed. Check your not idled down to far.. Its possible that your only 100 -200 rpm away from no more Problems.

mrfixxall
05-04-2011, 12:35 PM
FT i have also seen in the past if the engine temps are to cold and the exhaust coming out hot will make the inside pipe sweat and make it look like reversion..from the looks of the pipes it looks like their is no restriction of the water coming out at the outer pipe which wont let the pipes get warm to burn off the sweat..fill the gap with 1/4'' 316 ss rod and tig with 317 ss rod..leave a 1 1/4'' gap at the top like the pic..

flying tomato
05-04-2011, 02:21 PM
Ok to address the water leakage from the top dry joint. I did not realize that I had this water in the exhaust problem for a while. Corrosion ate up the gasket and then I had water dripping out of that top joint. That is how the stains got there. And again, adding the tailpipe dramatically reduced the problem, but not completely eliminated it.

Again, thanks to all!!!! I love this site. I learn so much. Keep it coming.

FT

MOP
05-04-2011, 04:42 PM
You have to look more closely at what you have, those extensions should stop any reversion even with a wild cam. There should not be any water there period, I would be going over those risers very carefully. Phil