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OMC Cobra Exhaust Manifold Question

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  • OMC Cobra Exhaust Manifold Question

    HT32BSX115 Hi Rick, I realize this post (OMC Cobra 4.3L Exhaust Manifold Overheating) was 6 years old, but would like to work off some of the past info if possible... Are the manifolds in the above schematic the "bat wing" style?

    I have these on a recently acquired 88 Reinell 173E with the 4.3l OMC Cobra... and I like the way they look and would hate to get rid of them...

    I purchased the boat with the disclosed knowledge of an overheating problem and a seized motor... completely rebuilt the motor with a new block because the original was cracked and went through the outdrive to inspect and replace the seals in the water pickup tube and so on... upon inspection I found a lot of melted plastic which I'm guessing were the flaps you were referring to (#22)?

    Anyhow, just fired it up yesterday afternoon and ran it for a good 15-20 minutes with the ear muffs on and all seems to be functioning fine.... looks like 160-170 degrees with tap water running through it?

    Thanks.
    Last edited by Fun Times; July 30th, 2017, 03:12 AM. Reason: Created new topic as required.

  • #2
    Originally posted by nutnboltguy View Post
    hi Rick, i realize this post is 6 years old, but are the manifolds in the above schematic the "bat wing" style? i have these on a recently acquired 88 Reinell 173E with the 4.3l OMC Cobra... and i like the way they look and would hate to get rid of them...

    i purchased the boat with the disclosed knowledge of an overheating problem and a seized motor... completely rebuilt the motor with a new block because the original was cracked and went through the outdrive to inspect and replace the seals in the water pickup tube and so on... upon inspection i found a lot of melted plastic which im guessing were the flaps you were referring to (#22)?

    anyhow, just fired it up yesterday afternoon and ran it for a good 15-20 minutes with the ear muffs on and all seems to be functioning fine.... looks like 160-170 degrees with tap water running through it?
    You should not be posting on an old thread. That being said, get rid of those batwing manifolds if you boat in salt water. Ticking time bomb that will take out your motor.
    1998 Wellcraft Eclipse 24 Cuddy
    Volvo Penta Duo-Prop 7.4L "LK"

    2006 Sun Tracker Party Barge 21
    Mercury 90 4-Stroke FI
    "Common sense is not very common"
    "Failing to prepare is preparing to fail." -- John Wooden

    Comment


    • #3
      You may like the way the batwings look, however when (not if) they fail and take out your motor, you will curse them
      1988 Cruisers Rogue 2420 -VP 290 DP now powered by custom 468 - http://forums.iboats.com/forum/owner...988-rogue-2420

      Past Boats
      1970 Wooster Hellion - Merc 9.8
      2002 SeaRay 190BR - 5.0 - A1G2 - "Cheasheads in Paradise"
      1984 Avanti 170DLI -3.0 stringer- "Ship Happens"

      What’s behind you doesn’t matter.Enzo Ferrari

      Comment


      • #4
        Originally posted by nutnboltguy View Post
        HT32BSX115 Hi Rick, I realize this post (OMC Cobra 4.3L Exhaust Manifold Overheating) was 6 years old, but would like to work off some of the past info if possible... Are the manifolds in the above schematic the "bat wing" style?
        Howdy, Yeah. Don't answer old threads unless you started them yourself!

        Batwings......Indeed they are and I agree with Bruce and Scott,

        Those older style manifolds-risers ("batwings") were discontinued long ago. I don't think you can even buy them now (except for old used and new-old stock) In either case, you DO NOT want to use them. (new ones might be ok for a good long time in fresh water)

        If your manifolds are even the least bit suspect (and if they're old and rusty) replace them with modern center-riser style new ones.

        Regards,

        Rick


        1987 FourWinns 211 Liberator, Originally an OMC 460 King Cobra.
        Re-powered in 2006 with a 1997 Mercruiser 7.4L Bravo III

        Comment


        • #5
          funny, usually on other forums one would get chastised for not looking up threads pertaining to the topic at hand... and so i digress...

          back to the bat wings - i ran my boat for the first time last monday, then tuesday and all last weekend. put about 6 hours on the new rebuild and she runs like a top... no overheating whatsoever... looks like 160 when im cruising at 2500rpm?

          so anyway, my point is, i don't think this boat was ever run in saltwater and i know im never gonna run this boat in saltwater - ever. the boat had 600 hours on it when i got it and im pretty sure the previous owners ran it in fresh water (mountain lakes) ever since the boat was new...

          so the question is - do i really need to worry about the bat wings letting me down? if so, whats a good replacement/upgrade?

          Comment


          • #6
            Originally posted by nutnboltguy View Post
            funny, usually on other forums one would get chastised for not looking up threads pertaining to the topic at hand... and so i digress...
            Ok, I am just posting a quote from up top of this page if you didn't see it......I am just going to suggest following the forum policies.

            Help Tip: If you have a question that has not been answered to your satisfaction in the archives, it is always best to start a new thread of your own. By starting your own thread, you will receive the maximum number of views by forum members.

            Below are some additional forum policies in hopes of all iboats members will follow, Thank you.

            1. Please do not reply to old topics or hijack existing topics. Old topics of a technical nature are like a library book, Please do not write in them.

            2. Old topics should be considered archives and used for reference only. Please do not reply to them.

            3. Do not take over someone elseís topic (aka hijack) with your own question, even if it is similar. If you have a question that has not been covered to your satisfaction in the archives, it is always best to start a new topic of your own.

            4. If you have a question for the original poster (OP) and the topic is over 30 days old, send the OP a PM, he may not even visit the forums any longer, or may not notice your question in the old topic.

            5. By starting your own topic, you will receive the maximum number of views by forum helpers that may not even notice your question when itís posted at the end of someone elseís topic. And those answers will be specific to your particular issue.

            6. Please do not post to topics that have been inactive for more than 3 months unless you are the original poster. We have very active forums and any topic that remains inactive for that long should be considered "dead". It is especially confusing when there is an entirely new question posted to an old topic.

            7. Posting at the end of any topic is considered to be hijacking the original posters topic which in turn subjects the topic to be closed if it continues to happen thus not making it fair to the original poster in the future had for some reason he/she needed to return for additional information or provide an update of the problem solved which is always welcomed within a reasonable amount of time frame.

            8. Please note that you should see a red banner pop up near the bottom of each inactive topic asking you not to reply to old topics. The Red banner will read: Please note this topic has been inactive for 90 days. For the best results, please start a new topic.

            Thank you all in advance for doing your part in helping iboats run a smooth ship.

            Additional forum rules linked below.
            http://forums.iboats.com/forum-rules-guidelines-405/

            [Emphasis mine]
            There's absolutely no problem looking up and referencing old threads. In fact, it's encouraged. The problem comes when writing in them long ofter they're "dead" sometimes when the original poster ("OP") is long gone.....

            It does however help YOU when you start a new thread and you "REF:" any old thread. We can all click on the reference and get a feel for what you're talking about if there's a question. posting a new thread gets it to the top and it's totally all about you and maximum visibility!

            Now, "Batwings" They were discontinued for a reason. You're "rolling the dice" by using old ones.

            There are enough people here who have ruined their engines when a manifold/riser leaked internally, and left them "winterized" with water sitting in cyls in SEP then didn't find out about it until JUNE when they decided to use their boat for the summer.

            With separate manifold and risers, every 5 years or so, you can break them apart and inspect. fresh water manifolds and risers DO last longer when only operated in fresh water. BUT, they don't last indefinitely. I had to pull my former OMG 460 King Kobra apart because I had intermittent hydrolocking. (after shutdown, I had water leaking past riser gaskets into open exhaust valves)

            Mine were only operated in fresh water from new. 1987 to 2005. There was still rust in both the risers and manifolds.

            Granted, it didn't rust through..........it WAS a leaking gasket. Bat wings don't have gaskets. so for them to leak, they MUST rust through. (or crack from freezing etc)

            After 30 years though, I would replace ANY manifold salt or no because you cannot see inside well enough to ensure that they'll NOT leak at some point.

            Yes, I would replace those Batwings. There are plenty of kits out there (you can buy them right here on iBoats even) The 4.3L engine is so popular that there's a great many choices out there.

            AND if I were replacing any engine with a new/rebuilt engine, I would replace 20+ year old manifolds and risers even if I thought they might still be usable.
            1987 FourWinns 211 Liberator, Originally an OMC 460 King Cobra.
            Re-powered in 2006 with a 1997 Mercruiser 7.4L Bravo III

            Comment


            • #7
              HT32BSX115 Thank you Rick.
              [ATTACH=CONFIG]temp_270443_1499813187632_202[/ATTACH]

              Comment


              • #8
                batwings are like playing Russian roulette with your motor. its not if they will fail, it is when they will fail. thin castings with core shift issues

                so the answer is yes, they will fail. it may be this week, it may be next week, it may be next year.

                PS, thanks Rick
                1988 Cruisers Rogue 2420 -VP 290 DP now powered by custom 468 - http://forums.iboats.com/forum/owner...988-rogue-2420

                Past Boats
                1970 Wooster Hellion - Merc 9.8
                2002 SeaRay 190BR - 5.0 - A1G2 - "Cheasheads in Paradise"
                1984 Avanti 170DLI -3.0 stringer- "Ship Happens"

                What’s behind you doesn’t matter.Enzo Ferrari

                Comment


                • #9
                  hey guys, i read up on the rules and guidelines and i get it and apologize for any inconvenience or confusion ive caused... didn't mean to ruffle any feathers and it makes sense how this forum works. thanks!

                  on a more forward note - what is a good replacement for the batwings on my OMC Cobra 4.3L? a link or picture please?

                  and again, im never (i repeat - "NEVER") going to run this thing in salt water - and for the 598 original hours this engine had on it im pretty darn sure it was never run in anything but mountain lake fresh water.

                  as you can see by the attached picture the engine seems to be running at 160 degrees at 2500rpm's.

                  thanks for your advice.

                  Comment


                  • #10
                    Originally posted by nutnboltguy View Post
                    hey guys, i read up on the rules and guidelines and i get it and apologize for any inconvenience or confusion ive caused... didn't mean to ruffle any feathers and it makes sense how this forum works. thanks!

                    on a more forward note - what is a good replacement for the batwings on my OMC Cobra 4.3L? a link or picture please?

                    and again, im never (i repeat - "NEVER") going to run this thing in salt water - and for the 598 original hours this engine had on it im pretty darn sure it was never run in anything but mountain lake fresh water.

                    as you can see by the attached picture the engine seems to be running at 160 degrees at 2500rpm's.

                    thanks for your advice.
                    Without verifying your temp gage, 160 doesn't mean much. 160 is also ok by the way..... You can verify by using a Infrared temp gage (obtainable at Harbor Freight cheep!)

                    just point it directly at the thermostat housing and read the temp.

                    Manifolds can be obtained just about anywhere..... even here!

                    Here's a GOogle search suggestion. https://www.google.com/search?q=omc+...k1.WL3Jxcff4KU
                    1987 FourWinns 211 Liberator, Originally an OMC 460 King Cobra.
                    Re-powered in 2006 with a 1997 Mercruiser 7.4L Bravo III

                    Comment


                    • #11
                      thanks for that H232BSX115. and yeah, i need to have an infrared temp gage around the shop anyway.

                      my concern on a generic manifold is fitment. will it all line up with my exhaust fittings when it reaches the Y pipe or do i need to do a bunch of cutting and fitting? anyone have experience with this?

                      im capable of fabbing and fitting things up but im just trying to avoid a big project while im trying to eek out the last warm days of the year on the water....

                      thanks again

                      Comment


                      • #12
                        Originally posted by nutnboltguy View Post
                        thanks for that H232BSX115. and yeah, i need to have an infrared temp gage around the shop anyway.

                        my concern on a generic manifold is fitment. will it all line up with my exhaust fittings when it reaches the Y pipe or do i need to do a bunch of cutting and fitting? anyone have experience with this?

                        im capable of fabbing and fitting things up but im just trying to avoid a big project while im trying to eek out the last warm days of the year on the water....

                        thanks again
                        Just about everyone with the Batwings swapped them for conventional center riser models. I think BARR indicates actual OMC part number compatibility.

                        If your engine is an 88 OMC 4.3L, the manifold is OMC 984222 If you do a search, you'll find BARR and GLM. Go to TC Electronics/Marine site for all the part numbers.

                        GOogle "51472 GLM" it'll be about halfway down the page.
                        1987 FourWinns 211 Liberator, Originally an OMC 460 King Cobra.
                        Re-powered in 2006 with a 1997 Mercruiser 7.4L Bravo III

                        Comment


                        • #13
                          The manifolds and risers will fit fine, what the kits give you are the correct 90* elbows that adapt from the 4" riser outlet to the 3.5" OMC Ypipe. I'd use Barr if you can get em vs GLM. If you get stuck having to use GLM Id make sure to check the sealing surfaces for flatness with a straight edge & feeler gauges. If they are not flat within .002-.003" Id take em to a machine shop and get the sealing surfaces of both the mani and riser re surfaced....should not have to do that but that is the price of made in C***a
                          1988 Four Winns 200 Horizon
                          4.3 OMC Cobra

                          98 Jeep Grand Cherokee 4.0 Selectrac
                          07 Jeep Grand Cherokee Limited 5.7 Quadradrive II

                          "While air doesn't freeze....rust never sleeps"

                          Comment


                          • #14
                            excellent! thanks to both of you for the part numbers and the difference of brand quality.

                            one thing i dont like about the batwings is they are in such a weird place that it makes it extremely difficult to get in to the top of the heads to double check and adjust the valves - which i intend to do shortly. 10 hours on the new rebuild.

                            Comment


                            • #15
                              Sign up today
                              I just upgraded my motor from the Batwings to the Volvo style center riser manifolds & risers using Barr manifolds & risers. I used the Volvo OE 90* exhaust pipes that adapt the 4" riser to the 3.5" Y pipe. The combination of the Barr risers and manifolds and the Volvo hoses and exhaust pipes (I did not want to use the GLM stuff) fits the old Cobra Y pipe perfectly. The Volvo 90* exhaust pipes are pricey but its a one time expense.

                              ​BTW, while my Batwings passed the acetone test (fill with acetone and check for leaks in the exhaust ports), what I noticed was this, if you look up in the exhaust opening inside you can see flaking rust. I was concerned that there were more areas of rust that I could not see, and this could loosen and fall into a cylinder via an open exhaust valve. As a test, I tried tapping the manifold with a small hammer lightly and sure enough, rust flakes appeared in the exhaust ports.

                              https://www.dropbox.com/s/55j6h4dd1u..._2273.MOV?dl=0

                              ​Here's a short vid of the engine running with the center riser exhaust after the top end rebuild (blew both head gaskets end of last season), took it all apart over the winter and installed a pair of re-man marine heads, and Fel Pro marine gaskets. The old Batwings were 6 seasons old and here in salt water that's about all you get, safely.....
                              1988 Four Winns 200 Horizon
                              4.3 OMC Cobra

                              98 Jeep Grand Cherokee 4.0 Selectrac
                              07 Jeep Grand Cherokee Limited 5.7 Quadradrive II

                              "While air doesn't freeze....rust never sleeps"

                              Comment

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