OMC Cobra Volvo Penta SX Exhaust Seal Flapper Damaged/Stuck
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- Опубліковано 30 вер 2024
- Wondering why your OMC/Volvo sounds like garbage? Your exhaust seal/flapper is probably stuck closed. It's not the end of the world if you need to replace it, just make sure your seal/flapper doesn't fall down the pipe when you try to remove it.
If you do not find any exhaust lappers they are most likely downstream and blocking hot exhaust water.
Hello, nice videos. I was just wondering if you know about the service bulletin that volvo penta issued years ago stating not to use them. They say they are not effective in preventing water ingestion and fall apart and clog the exhaust system.
Yep, I totally agree to remove them. Great idea in theory to have them. When they get stuck, the negative effects quickly outweigh the positive.
I removed mine on my previous boat….never had any water ingress. Boat ran better without them! Less backpressure I guess
That is the result of a past bad overheat. The melted part is probably in the lowest part of the exhaust housing and may not be reach-able unless you pull the outdrive. OMC used them till the end of their run but Volvo discontinued them as per their service bulletin. I think they discontinued them in '99 or so. I do think flappers are good to have, due to the risk of water coming up the Y pipe, they are not hard to replace.
I saw this happen on a 76 chevy once and I was dumbfounded for hours trying to figure out why the motor never ran right.....stuck vacuum operated butterfly valve. Same type of restriction on the exhaust and the symptoms were identical.
If the exhaust hoses are really stuck on you can try spraying silicone spray up in the joint between the hose and pipe, and CAREFULLY use a hair dryer to heat the rubber just a bit to help it expand and come off. They can get really stuck on.
What a pain right? I like that idea!
Michael!
AGAIN, awesome video!!!!
Come fix my gd boat!
I'll buy you a super burrito!
Thanks, this helped me understand what the rubbery cap / flap looking thing was underneath the stern drive where the exhaust comes out. Turns out the flap broke off and got pushed down and was blocking the outlet! Cheers man!
I'm looking at the exact same thing!
Exact same thing on mine. I couldn't understand why it would overheat around 3000 rpm. Tried everything, then when taking drive off to replace bellows, I found the rubber part blocking one port and the fibreglass part blocking the other.
Do you have part number??
Micheal,
I am pretty new to the OMC System. I have an 1989 4.3L V6 GM. Engine is running fine when not engage. I can run the engine up to 4000RPM and so on without issue.
When the boat is engage in forward and start moving I cannot reach more then 2500RPM and you can feel the engine loading. I have looked your videos about the ESA System and also how to change the shift cable and now this one... I am bit lost and i would like to have you thought ? Thanks
This is a lack of power scenario. Consider checking the plugs, compression, cap and rotor, timing, and also the coil.
What if you look and all that is there is the metal pin? Lol thats all i had in mine. No flap. Have no clue where it went.
If the motor runs fine, it blew further down near the bottom and it’ll break down over about 20 years of use. If the motor ever comes out, you can remove the pieces then.
Appreciate the video. I posted this last night on a forum for help. I ran across your video. Not sure if stuck flapper is part of my engine miss but sounds like I can do without it. I run in an East texas lake and have done away with my thermostat already. Think the flapper could be causing the engine miss?
Engine miss and new rattle developed in exhaust manifold:
91 OMC King Cobra, 5.7LE Chevy
Just rebuilt carb, and reinstalled, changed fuel water separator. Motor started on first bump and bench settings were perfect. It idled as smooth, as good as it ever has. Measured 15-16 inches Hg vacuum and needle rock steady. Took it out for test drive and ran great. Opened it up to 4000 RPM @ 45-50 mph. Was ready for a great weekend. Wait for it...
Couple hours later, daughter wanted to go out, as soon as I started to throttled up, I could feel Engine miss and got progressively worse with more throttle. Engine sputtered and popped. I turned around Immediately. Did the following checks.
Fuel Pressure ~ 5 psi
Base timing 8 -10 BTDC per manual
Checked Distributor and rotor. Noticed significant green corrosion all way around inside cap. I touched up all contacts with sand paper, shined up the rotor.
Pulled plugs, dry. A couple had some light carbon but I’ve seen them worse before rebuilding carb. Double checked gap @ 35 degrees. To no avail, engine miss still there and I noticed
a new noise. Sounded like a faint rattle. I thought it may have been rocker arm or something worse deep in the engine, but after listening more closely, I think it’s coming from the port side exhaust manifold. I read through the cooling system section in the manual thinking there might be some sort of flapper in there. I thought perhaps it might be contributing to the engine miss some.
The way to check for a stuck closed flapper is to buy a thermal reader.
Etekcity 1022D Dual Laser Digital Infrared Thermometer Temperature Gun Non-contact -58℉~1022℉ (-50℃ ~ 550℃) with Adjustable Emissivity & Max Measure for Meat Refrigerator Pool Oven (Not for Human) www.amazon.com/dp/B01BV0YMH4/ref=cm_sw_r_cp_api_i_AKTTEbY525C4M
You take and measure the riser and compare it not by a measurement I give you rather compare it to the temperature on the other riser. If they are around the same temperature, it’s likely not the issue. They need to be within ~2 degrees of each other. 5-10 degrees off means one has a flapper issue. This is the quickest way to find out.
I also like to see 6-8 psi of fuel pressure. But that would likely be more of an issue at WOT.
Also, if you can’t remember the last time you swapped your cap and rotor, do it. They are available in Amazon for cheap. Plus, I appreciate the sand paper trick, but I’d want to rule it out completely.
You also you need check your coil. I have a video on that, so look for it on my channel.
Everything that can go wrong with this boat, has likely already been covered on my channel. Hit that subscribe button please!
you didnt show how to installit
I wouldn’t be installing new ones if I were you.
Do you think if this is damaged, it could cause water to be getting into the engine and mixing with the oil?
Hey mike is this a must to have fixed ? I only operate on fresh waters . But I recently overheated my right manifold and I’m sure if it was made of fiberglass it got ruined. It runs fine with. No weird noises. Mehta do you think?
I would make a note of this and complete the repair during winter.
@@michaelromer2016 perfect,my thought exactly
An easier way to do it, spray the grommets with silicone spray, then buy a spare pin and use it to drive the old pin out part way then pull it out with a vicegrips.
There you go! Great idea.
Do you have videos on replacing the Y pipe and gaskets?
Here you go: ua-cam.com/video/BU_WGKl2Cc8/v-deo.html
Did you expropriation any loss of power? My volvo penta 7.4 seems to be struggling to get up on plane. I'm wondering if this may be my issue. To much exhaust restriction
Hey Michael, my exhaust flapper melted and made it all the way down to the sterndrive. What a bummer. I'll tag you in the video . Thanks for all of your videos.
-Randy
Oh no!! Did you see one or two? I hope both came out. I’ve seen it where one gets stuck in a closed position.
@michaelromer ua-cam.com/video/6IP0IUHVzTU/v-deo.html
luckily only one went down the tubes... removed the other - it was burnt and ready to go as well.
Do you have a part number?
Check here: www.crowleymarine.com/
Found mine in the lower unit housing the shift selector rod caught them, the pins were in the bottom of the exhaust y pipe
hey i know this is an old video but could this be the reason of smoke/steam coming from the transom?
Oh for sure! Plus watch my other videos where I disassemble the lower exhaust, showing the other gasket there too.
@@michaelromer2016 Why not leave a link instead of forcing us to hunt for something that we want to see in a hurry?
So I have a 1997 4.3L GL with the sx cobra outdrive. I had a bit of an overheat in my driveway. (Earmuff fell off) pegged the temp gauge. Cooled right down after moving ear muff back into place.
Thinking I may have to replace this. I'd like to put them back in. How do you get to them with the motor in(slide exhaust bello or boot down then remove pin?)And do you have a part number of a set of flapper valves that will work for me?
Hey Scott if you're running your boat in saltwater it wouldn't hurt to replace them if you're running it in freshwater I would probably leave them out. If you're really interested in how to remove them I do have a video that will show you step-by-step it's part of a transom rebuild project I'm doing I'll send you the link.
ua-cam.com/video/dE7MZ-JNkcU/v-deo.html
Thanks! No, its freshwater..
However. Running it on the ear muffs, the tone hasn't changed any, the exhaust manifolds are not heating up, or the risers, and the engine temp is running 160°, no water I the oil, and the oil is clean, not burnt it nice and gold.
You think I got away with one? Or could I possibly have problems yet?
I plan to change the impeller pump and the thermostat again. What should i look for and keep an eye on other than the temp gauge and the oil?.
You are tracking just fine with your plan of action. I was thinking impeller pump myself is the issue.
Useful enough for me.. mine was completely off and i did not know which side to face up!
Thanks!
Thanks for your comments!
They do get stuck in the exhaust and they can cause blockage. There's no easy way to know if it's stuck, unless you remove your stern drive.
do you show reinstall? and where did you get them as Volvo discontinued them via service bulletin.
What year is your Volvo?
This one will work:
www.amazon.com/Omc-Exhaust-Seal-Assembly-765166/dp/B007I90Z0Q/ref=sr_1_1?ie=UTF8&qid=1534901406&sr=8-1&keywords=0765166
or
www.crowleymarine.com/parts/388077.cfm
As far as the difference in temp is concerned; your thermostat is questionable. You could also have run into a cold spot in the water. An engine performs best at operating temperature, but 153 is a pretty good temp. 139-142 could mean the thermostat is stuck open. I'd run it some more, you won't damage your engine with a low temperature, so it's worth waiting longer to see if temperatures get closer to 160. Give it a month or so--then check back and let me know how it goes.
They are still available from BRP, who sells OMC Cobra parts. The parts are the same from OMC to Volvo. There is another option, in that you can remove the exhaust bellows from the gimble housing and buy an inboard style exhaust flapper of the correct size that fits over the exhaust outlet. It might be bit louder than having the bellows there but it is easy to install and if it failed it will not cause the problems of the flappers melting and falling down the Y pipe. When mine failed I had to remove the drive and use a grabber tool to get the crispy remains out.
BTW, Volvo also added check valves to the exhaust elbows, what these do is prevent engine vacuum from pulling water back up the exhaust (flappers would not prevent this, its the water that is leaving the elbow and can under certain conditions get sucked back in the exhaust opening in the elbow). They are check valves that allow air in but don't allow air out. They prevent a vacuum from developing in the exhaust system. There is one on each exhaust elbow and are used on nearly all V/P engines with the V6 and V8.
www.volvopentastore.com/Exhaust/dm/cart_id.671979035--session_id.141697864--store_id.366--view_id.769912
part # 5 is the check valve. Later OMCs with this style exhaust also used these. I think the differences on the valve timing with the Vortec engines made exhaust reversion a bigger issue so they added the check valves. You can add them if you have a problem with this...
Mine is broken and way down under the drive
I bought an older bayliner with 460 King Cobra and I have been fixing all its issues. After removing my outdrive I did find the flappers clogging the bellows. Should I replace them? Or just leave it without the flappers? Didn't know how much of a risk it is for sea water to travel up through the Y pipe. thanks for your help
I like the idea of having the flapper installed. Others have said to remove them altogether. I agree, with everyone and I say, remove them.
If you don't mind sea water.. or pond.. getting up in there every time you back up... Personally I use them because if they were pointless they would never have been installed in the first place
@@scotto1432 if you're backing up, you're under power, no water is making its way past the exhaust pressure. Same reason "Jeeps" can drive through deep water up to their snorkel intakes, you don't see snorkel exhaust.
@@michaelromer2016 Is that a yes or no?
@@stevetucker8169I addressed this on earlier comments below. The bellow is for when on the ocean and water splashes back through into the motor when the boat is off. Think about large waves hitting the boat. That’s why they are there; the prior Jeep analogy is not applicable for a marine scenario. If you are on a lake, leave them off, if you are on a busy lake leave your boat idling.
Wow. I just found this.
Great video (without engine) to show what this is all about. We had a water pump go bad and an overheat (happens fast, sand is tough on little impeller) on a VP 4.3 SX. A year after repair and ready for first run of season the left side riser and exhaust were running 100 degrees hotter that the right. An obvious water block somewhere and I suspected the flapper thing. After taking apart the elbow and rubber I see the flapper is not there. Gone. Only the axle pin remained. So i had a skinny guy with long arms reach in all the way to bottom and he can’t find it. The pipe is clear. So where did it go? Melted away? Curious as what to do next? Anything? The obstruction was found in the hoses and thermostat housing. Suggestions?
LT4247 what year is it?
Michael Romer 1999 Volvo Penta 4.3 SX #4110167984
Those flappers are made of painted fiberglass. Larger motors will destroy them after about 15 or so years. A 4.3 will likely melt them enough to get them stuck in the stern drive. You friend with small arms won’t be able to reach these. I have a video in this series that shows where it will be in a Volvo Penta vs a Cobra. Quick answer, you have to take the stern drive off. I’ll get the link for you.
Boat Transom and Floor Rebuild - Stern Drive Removal - Part 3 11:45
Search for that video on my site or on UA-cam
Nice job..very informative
Hey Michael, just wanted to say I've watched many a video of yours of the last year and you've helped my in my rebuild. That being said I'm back here looking at this video because in my rebuild i didn't put the flappers back in per the comments on here and in other forums I've read. Today however I was heading back to the dock and my engine died. And trying to crank it again it wouldn't turn over. Turns out i water logged it. What i don't know is how, i didn't reverse it at full speed nor did I come to a full complete stop after being on plane. 2 main reasons you'd get water logged without the flappers. Now I'm considering putting them back on. Any insight? Thanks.
Yes - hot manifold and engine heat created a vacuum. All you need is a hot engine. You can do the same at a boat ramp with your trailer vehicle. If you back down on a ramp where your tail pipe is under the water and turn your engine off, the hot exhaust pipes and engine suck water right up your tail pipe and water log the engine.
Hey, great video! my penta 4.3 gx overheated and the flappers are all melted to. So i'm planning to remove them, however i saw some water dripping from around the underside of the y pipe when the boat was in the water. Do you think the gasket of the y pipe is leaking to? Found some small holes in the exhaust below to. And is it possible to remove the y pipe whithout lifting the engine? Thank you in advance!
If you have a V6/V8 you have to remove the motor to get you the y pipe. You could smear 3M marine grade sealant around the flange-it will last roughly one boating season. I heard someone tell me they can remove it with a I4, but no proof was provided. I also recommend you watch many of my videos. I talk about all the things you are going through. Here’s one for example: Boat Transom and Floor Rebuild - Installing the OMC/Volvo Exhaust Manifold Hose/Pipe - Part 72
great video. im having a problem with one side of my exhaust running 20 to 30 degrees hotter than the other. could the flapper valve be stuck cause this problem thanks
Your flapper is indeed stuck. Remove both sides and replace them. Keep in mind Volvo recommends not having them at all.
@@michaelromer2016 It looks like to me, that the location of the flappers is to high to save the boat from sinking. If the water got that high in the exhaust pipes, it's going down anyway. Think I'll take mine out for good. Thanks
@@stevetucker8169it’s less about the boat sinking and more about water getting into the cylinders and not being able to escape. A large enough amount of water pouring into a given cylinder will break something. The reason is because water doesn’t compress so if the piston comes back up and there’s water where normally there’s a gas, cracks will occur rather quickly.
@@stevetucker8169 It's supposed to stop a water surge up the exhaust into the manifold and into any cylinder with an open valve causing hydro-lock. If you aggressively launch a boat or have a big wave lap at the stern with a couple of big guns sitting on the rear deck enjoying a beer, it could enter the engine on some boats where the riser isn't high enough relative to the water level. I've decided to replace mine and check it every few years or if I run it hot.
Mine are intact but very stiff in operation. Can I lubricate them with something?
Remove them altogether. I tried replacing them once and I’ve since just followed Volvo’s suggestion of removing them altogether.
How many hours were on this engine when you noticed this? Thanks for the heads up!!
It appears the fiberglass is coated with a substance and once that wears off, the fiberglass breaks down. It’s likely any boat with more than 100 hours will show signs of deterioration.
Hey man could this cause me to have bogging issues on acceleration by chance? If I slowly walk the throttle up like can hit wot but if I "gun" it like to pull a wakeboard out of the water my engine chokes and falls on its face. I've already done the fuel cell paint clean out and new filters plugs etc so I'm wondering if this could be the one thing I havent tackled. Thanks for any and all help. Love the videos
It can cause the issues you mentioned. To confirm, also try duplicating the same by punching it while outside the water, on the trailer. If it's not that, I would assume your power valve on your carburetor is having issues. I have a video that shows you how to rebuild a marine carburetor.
@@michaelromer2016 I have the Volvo penta 5.7 gsi with the VP dp-sm. On the trailer hooked up to the hose I can rev it up no issues but under load is when it falls on her face lol
@@tyleranderson4608 Do you have a carb. or fuel injections?
@@michaelromer2016 its TBI fueling
@@tyleranderson4608 Are you using a throttle body injection (1 maybe 2 injectors) or tune port injection (8 injectors)?
If these are bad would it cause a exhaust fumes smell inside the boat?
Yes, they could cause this issue. If you have exhaust fumes inside your boat, chances it is coming from the PCV valve on the left or right valve covers. You might have excessive blow by from worn piston rings, or issues with the valve seals on your heads. Definitely perform a leak down check and looks at your flappers.
Ok thanks! I will look into these, do you have a part # for the PCV Valve, its a 1994 5.0 Volvo engine.
@@andyhuff7533 Do you have fuel injection? If so, there's no PCV value. Carburetor, yes. You can test it by cleaning off the tube end and blowing into it. It should only allow air out, one way. If air only flows one way, you have to look into your engine. The good thing about typical exhaust leaks on the manifold side, is exhaust fumes are accompanied by water in those situations. No water leaking, then it's something else.
It has a carburetor. I will try testing it and see what I can find out. I haven't noticed and water leaking but I will double check that as well.
if you have exhaust fumes in the boat, the rubber exhaust hoses that connect the exhaust elbow to the aluminum pipe between the elbow and the Y pipe (there are two rubber hoses, one from the elbow to the exhaust pipe, the other from the exhaust pipe to the Y pipe) are either loose and leaking or damaged to the point where they do not seal. Check that carefully because leaking exhaust fumes can be deadly (carbon monoxide).
Omc 545 king cobra. My engine is getting really tight starter cant turn it after about 5 mins in the water. Boat was turning off when hot randomly and then I have to wait to start it. Took my risers off, no rust inside and looks solid. I notice one of my flaps is close and one is open. Would this cause engine to die and lock like im having?
Did you ever get the flapper out. That’s definitely part of the problem! Please subscribe!
@@michaelromer2016Finally solved this issue and it was not the flapper. Flappers looked almost new, and there was no signs of heat on the paint of the risers which is a sign flappers melted. What was happening was it was a timing issue firing backwards causing large explosion then all the rings locking up the engine. I could not pinpoint the damn Spittfire ignition system so I just thru a 50 dollar Amazon special HEI distributor into it and boat fired up like a champ after being able to time it. Would have liked to pinpoint the timing issue to keep it original but wasn't cost effective. Either spittfire coil issue or magnetic flywheel pickup or knock sensor was the issue. Who knows.
Michael, I have a 90 Donnie levante with twin OMC’s. I just purchased in Sept. and had a month of season with it (I am in MN) before blocking it for winter. In that month the port side engine hydro locked 4 times. All 4 times the engine was at idle and shut off, then go back to re-start and motor is locked. Have to remove plugs to drain out the water before I’m able to re-start. Aside from this the engine runs strong. I am just not sure what is causin water to creep that far up the pipe and into the motor so often, and am really confused as I am stationary when it happens and not pulling the motor out of high revs or anything. I need to check the condition of the flappers this spring, but I am curious is if you know any other malfunction that could be causing a vaccume (or whatever it is) that is sucking the water into the manifolds..?
Any suggestions are very appreciated.. thanks in advance.
That’s Donzi.... not Donnie lol.
If you pull off the exhaust risers, you will see water in the exhaust manifold, level to the height of the heads. This means with the engine off, water doesn’t seep back into the cylinders. If it is, three things are possible. You have a cracked exhaust manifold, the flapper is closed and not allowing water past, or you have a bad head gasket. It is one of these three. To test for a bad head gasket, you need to perform a leak down test. To test the flapper, you need to remove the appropriate pieces to check the condition of the flapper. To check for exhaust manifold leaks, remove just the heavy riser and confirm you have water in your manifold, but not in your cylinders. The reason here is a leak will run downhill, into your cylinders, and it won’t hold water.
@@michaelromer2016 Thank you so much for the thorough response! Ill will be check these things first thing in spring.
Good video!
Thanks I got more videos in the works so stay tuned and subscribe!