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Thermostat housing, Tstat and gaskets, i have questions.

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  • Thermostat housing, Tstat and gaskets, i have questions.

    i have a 1981 Merc 260( 5.7l 350cid) with a MC1 or Alpha drive. I upgraded fron the old cast iorn log exhaust to EMI Thunder center rise exhaust. i aslso changed the thermostat housing to a Sierra #18-3530-1.

    i originally hooked every thing up , without a tstat to get the engine fired up, but the water temp was rising pretty quickly to above 200*.

    I purchased a Tstat kit from the local marine shop. At first they gave me a 160* kit # 807252Q5 and it had a regular gasket for the intake to tstat housung fit. i ased them to give me the 140* kit, #807252Q4, because every thing i have read said that the 260 needs the 140 and that is what was in it before. the only difference is that the gasket in the 140 kit has two small holes on each side, of the bolt hole.

    So my question is, before i install the $50 kit, is do i have the right one? What are the small holes in the gasket for, should i use the 140* or the 160* tstat?

    Here is a pic of My set up.


  • #2
    here is a underside pic of the housing. and gasket. what are the 4 small holes in the gasket for?

    Comment


    • #3
      Those holes are actually brass thru-rivets. They are for grounding continuity for the operation of the temperature gauge. No water will flow through them, but you do need them as those housings are notorious from not carrying the ground path through the bolts.

      Chris.....
      xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
      The world takes on a whole new perspective when viewed from 100’ below.
      1972 Bertram ‘Bahia Mar’ 20
      2006 Mercruiser 4.3MPI (0W617679) w/Alpha One Gen II (0W829301)
      (Original - 1972 '165' In-line 6. Previous - 1994 4.3LX)


      Comment


      • #4
        Thanks Chris. Am i ok with the 140* Tstat or should I have a 160 * in there?
        One more question. Shoud my temp sender, be in the housing or is it ok in the intake where i have it? I have no temp switch for an alarm.

        Comment


        • #5
          Am i ok with the 140* Tstat or should I have a 160 * in there?
          One more question. Shoud my temp sender, be in the housing or is it ok in the intake where i have it? I have no temp switch for an alarm.

          Comment


          • #6
            Originally posted by holorinhal View Post
            i have a 1981 Merc 260( 5.7l 350cid) with a MC1 or Alpha drive. i also changed the thermostat housing to a Sierra #18-3530-1.
            Hate to tell you this but you bought the wrong thermostat housing for the stern drive you have. That's why you are overheating do to housing design of the hose sizes between an alpha type pump to a bravo/engine mounted type pump. Plus the impeller size inside your older drive is of different water pressure and volume...High pressure, low volume pump to where the housings you have requires more of an low pressure, High volume pump in the Gen ll. The Bravo is different flow and psi as well.
            https://www.perfprotech.com/blog/art...ousing-changes
            Here's the same issue you are having with an end report by the OP.
            http://**************/vbforum/showthr...uch-water-flow

            I purchased a Tstat kit from the local marine shop. At first they gave me a 160* kit # 807252Q5 and it had a regular gasket for the intake to tstat housing fit. I asked them to give me the 140* kit, #807252Q4, because every thing i have read said that the 260 needs the 140 and that is what was in it before. the only difference is that the gasket in the 140 kit has two small holes on each side, of the bolt hole.

            So my question is, before i install the $50 kit, is do i have the right one? What are the small holes in the gasket for, should i use the 140* or the 160* tstat?
            Should you continue to try and make this "style" housing work, this particular style housing is more designed to use/fit correctly the OEM 160 degree thermostat vs the 140. Plus you'd need to use the cork brown gasket (not the O-ring) installed first before the thermostat. Then don't coat the brass rivets on the gasket or the grounding system may not work properly. The gasket can go on dry.
            Also the sierra housing needed to come with the white plastic 160 degree sleeve merc part number 23-806922 to help hold the thermostat in place. The sleeve can be seen here, http://www.ebay.com/itm/THERMOSTAT-K...741a04&vxp=mtr

            And I believe (my guess is anyway) they have (< aftermarket) a blue sleeve for the 140 like seen here, http://www.marinepartsplus.com/catal.../18-1989_2.jpg
            < found in the third photo down here, http://www.marinepartsplus.com/catal...mostat%20Kits/ and your housing you have now is the sixth photo down....No sleeve.

            Unfortunately "Sierra" doesn't seem to offer a housing of this design to fit any of the alpha drives (1 or 2) only a bravo/engine mounted pump.

            All that mentioned, according to the service bulletin link Merc part number 860256A 3 should work on your engine using a 160*. This assembly is found in these models:


            https://www.perfprotech.com/mercury-...rtnbr=860256A3

            You running in fresh or salt water?

            OEM Quality Gear Lubes And Greases Available @ iboats.com 'By Bel-Ray Marine Lubricants -- BOAT SPECS -- FORUM GUIDELINES -- Volvo, OMC & Merc Stern Drive Technical Information For DIYers. -- OEM VOLVO PARTS POWERED BY iBOATS.COM -- All OEM Parts / Parts Lookup Now Available Through iboats.com --

            Comment


            • #7
              Originally posted by Fun Times View Post
              Hate to tell you this but you bought the wrong thermostat housing for the stern drive you have. That's why you are overheating do to housing design of the hose sizes between an alpha type pump to a bravo/engine mounted type pump. Plus the impeller size inside your older drive is of different water pressure and volume...High pressure, low volume pump to where the housings you have requires more of an low pressure, High volume pump in the Gen ll. The Bravo is different flow and psi as well.
              https://www.perfprotech.com/blog/art...ousing-changes
              Here's the same issue you are having with an end report by the OP.
              http://**************/vbforum/showthr...uch-water-flow

              Should you continue to try and make this "style" housing work, this particular style housing is more designed to use/fit correctly the OEM 160 degree thermostat vs the 140. Plus you'd need to use the cork brown gasket (not the O-ring) installed first before the thermostat. Then don't coat the brass rivets on the gasket or the grounding system may not work properly. The gasket can go on dry.
              Also the sierra housing needed to come with the white plastic 160 degree sleeve merc part number 23-806922 to help hold the thermostat in place. The sleeve can be seen here, http://www.ebay.com/itm/THERMOSTAT-K...741a04&vxp=mtr

              And I believe (my guess is anyway) they have (< aftermarket) a blue sleeve for the 140 like seen here, http://www.marinepartsplus.com/catal.../18-1989_2.jpg
              < found in the third photo down here, http://www.marinepartsplus.com/catal...mostat%20Kits/ and your housing you have now is the sixth photo down....No sleeve.

              Unfortunately "Sierra" doesn't seem to offer a housing of this design to fit any of the alpha drives (1 or 2) only a bravo/engine mounted pump.

              All that mentioned, according to the service bulletin link Merc part number 860256A 3 should work on your engine using a 160*. This assembly is found in these models:https://www.perfprotech.com/mercury-...rtnbr=860256A3

              You running in fresh or salt water?

              Ok i will bite! I have known that this could be a potential issue, but i have searched and searched, to no avail, for a definitive answer. This may also answer a wied, to me, situation that i just discovered, but i will get to that in a minute.

              Here is what i did. I went today and puchase a 140* kit #807252Q4 and the white sleve #23-806922. I do realize that i should have probobly got the #5 kit which is the 160*.

              When i assembled it, i did install the cork gasket first, then tstat, then the sleve, 3 sided part up, the brass riveted gasket, without any coating. i reconnected the hoses and started the engine. after about 1 minute or less the temp started climbing again, droped a few degrees, asuming the tstat opened, the started to rise to about 220, then i shut it down., so the tstat kit did nothing for the temp rising.

              Comment


              • #8
                Ok so here is the wierd, to me thing.
                I decided to check water flow from all the hoses. Started at the transom water suply. diconected, started engine and watched for flow. had a good fllow of water comming out. disconected the suply at the Tstat housing and had good flow there. Disconected the hoses from the Tstat housing to the bottom of the exhaust mannifolds and had good flow there. Diconected the jumper hose from the exhaust Manifold to the riser, started engine and it took about 15 seconds before any water came out, but once it did there was good flow. Now here is the wierd thing. i diconected the large hose from the Tstat housing to the engine water pump, there was very little water comming from the hose, still attached to the Tstat and alot of water comming from the engine water pump. How ever the temp did not climb and stayed at 150*. Hooked the the hose back up and the temp quickly rose to 180-200 then shut it off.
                Its as if the water is going the wrong direction at the engine water pump? is this the result of the Tstat housing, or am i thinking of it *** backwards?
                I disconected the suply at the tstat and no water was coming out either the engine waterpump nor the hose. alittle water was comming out of the exhaust tips at the transom . reconected the hose and then was getting a lot of water out the tips, but it was hot water, not warm.
                Last edited by holorinhal; April 18th, 2015, 06:19 PM.

                Comment


                • #9
                  What circulating water pump did you buy and install? type, brand, part number?
                  OEM Quality Gear Lubes And Greases Available @ iboats.com 'By Bel-Ray Marine Lubricants -- BOAT SPECS -- FORUM GUIDELINES -- Volvo, OMC & Merc Stern Drive Technical Information For DIYers. -- OEM VOLVO PARTS POWERED BY iBOATS.COM -- All OEM Parts / Parts Lookup Now Available Through iboats.com --

                  Comment


                  • #10
                    ]Below is a quote from one of our main members here even thought the quote came from another boating site that I can't post here. It should help with the idea of having the incorrect housing. Also here is your old water flow diagram for you.





                    Originally posted by bondo View Post
                    "&#34;Thinking about it you guys are right, and maybe the hose could be collapsing also, cause the motor needs more water then the alpha can deliver at idle.&#34;

                    Ayuh,... The in-coming hose can&#39;t collapse,...
                    The motor ain&#39;t Sucking water, the drive is Pushing water...

                    The alpha 1 impeller moves less volume at idle, than motor mounted pumps, or the bigger vaned Alpha Gen.II pumps...
                    At rpms, things even out,+ the Alpha pumps enough water...

                    10 years ago, I dropped a 4.3LX into my barge, it formerly lived ahead of a Gen.II drive, mine&#39;s an Alpha 1...
                    Being a trollin&#39; Fisherman, it idles for 8 to 18hrs. a day,... For years I had an occasional, sometimes often overheat at idle Problem,...
                    I changed,+ chased thru the cooling for Years trying to figure it out,... Bumping to neutral,+ reving was the crutch I used, til I Finally figured out the error of my Swap....

                    That error was the Lack of Check-balls in the T-stat housing...
                    Mercruiser&#39;s crutch for using outboard motor impellers in their sterndrives was the check-balls, which slow the water flow out of the motor, at Idle....

                    I swapped on a earlier model T-stat housing 3 or 4 years ago, With the check-balls...
                    I haven&#39;t had an Overheat situation Since....

                    The OP states the drive is 83,.. That&#39;s MR/Aplha 1...
                    The 93 BBC is well beyond the Alpha,...
                    It Probably doesn't&#39;t have the check-balls in the T-stat housing....


                    Of course, the rest of Richard&#39;s description makes very little to No sense, as far as the cooling system,...
                    My translation of it indicates,...
                    I just Might be Right on this 1....

                    If Richard comes back, maybe We&#39;ll find out..."


                    Last edited by Fun Times; April 19th, 2015, 01:06 PM.
                    OEM Quality Gear Lubes And Greases Available @ iboats.com 'By Bel-Ray Marine Lubricants -- BOAT SPECS -- FORUM GUIDELINES -- Volvo, OMC & Merc Stern Drive Technical Information For DIYers. -- OEM VOLVO PARTS POWERED BY iBOATS.COM -- All OEM Parts / Parts Lookup Now Available Through iboats.com --

                    Comment


                    • #11
                      Originally posted by Fun Times View Post
                      What circulating water pump did you buy and install? type, brand, part number?
                      I dont know brand or modle number, of the engine water pump. It is the pump that was on the engine when i baught the boat a few years ago. I will have to look and see if i can find a number on it.

                      Oh yea, i run in fresh water.

                      Ok, need just a little claifying. After reading the post on the SEC site, the poster said that he had to swap tstat housings to cure the over heat. He sid that he had to swap to the check ball style. he had a pic of the two diferent ones, but i cant view it for some reason.

                      Is this what you, Fun Times, are saying i need or the one like i have, just for an Alpha. After reading, isnt the Alpa one like mine, for a gen 2 Alpha and not a alpha1 or MC1?
                      Last edited by holorinhal; April 19th, 2015, 02:24 PM.

                      Comment


                      • #12
                        So, Fun Times, are you saying that the Sierra Tstat housing is not specifically for the Alpha drive and they dont make one for that aplication?

                        If the Tstat housing is the overheat problem, i will buy one that is specifically for it.

                        I am just stumped by what i was sseeing with the hose diconected from the tstat house to the water pump, with a lot of water comming out the pump and very little out of the tstat hose. i would have thought that it would be oposite?

                        Not sure if i said, but with the water pump hose disconected, the temp stayed steady at 150, after a minute of running, but not much water out the exhaust tips. once i reconected the hose, temp climed rapidly and there was a lot of water out the tips.

                        Comment


                        • #13
                          Originally posted by holorinhal View Post
                          So, Fun Times, are you saying that the Sierra Tstat housing is not specifically for the Alpha drive and they dont make one for that application?
                          Yes that is correct. It will be one of your main problems You need Merc part number 860256A 3860256A 4 Thermostat Housing. USE ONLY ON Bravo Sterndrive, ski or inboard V6 or V8 (350 cid) engines. (No name cast on top. P/N 860256C1 or 860256C4 on bottom).
                          Sierra Thermostat Housing #18-3530-1 OEM Interchange:
                          MERCURY MARINE: 860256A4
                          http://www.firstchoicemarine.com/p-2...18-3530-1.aspx

                          I have searched and can't locate a Sierra part number to match the 860256A 3 number from a reputable online source.

                          I am just stumped by what i was sseeing with the hose diconected from the tstat house to the water pump, with a lot of water comming out the pump and very little out of the tstat hose. i would have thought that it would be oposite?

                          Not sure if i said, but with the water pump hose disconected, the temp stayed steady at 150, after a minute of running, but not much water out the exhaust tips. once i reconected the hose, temp climed rapidly and there was a lot of water out the tips.
                          The pump seems polished so it's possible it not the right direction.


                          OEM Quality Gear Lubes And Greases Available @ iboats.com 'By Bel-Ray Marine Lubricants -- BOAT SPECS -- FORUM GUIDELINES -- Volvo, OMC & Merc Stern Drive Technical Information For DIYers. -- OEM VOLVO PARTS POWERED BY iBOATS.COM -- All OEM Parts / Parts Lookup Now Available Through iboats.com --

                          Comment


                          • #14
                            Originally posted by Fun Times View Post
                            Yes that is correct. It will be one of your main problems You need Merc part number 860256A 3860256A 4 Thermostat Housing. USE ONLY ON Bravo Sterndrive, ski or inboard V6 or V8 (350 cid) engines. (No name cast on top. P/N 860256C1 or 860256C4 on bottom).
                            Sierra Thermostat Housing #18-3530-1 OEM Interchange:
                            MERCURY MARINE: 860256A4
                            http://www.firstchoicemarine.com/p-2...18-3530-1.aspx

                            I have searched and can't locate a Sierra part number to match the 860256A 3 number from a reputable online source.

                            The pump seems polished so it's possible it not the right direction.

                            No the water pump is only painted aluminum color. it was black before and is the same pump that ran with the logs for a couple of years before i did the upgrade and restore on the boat.. Still it is possible that it may be wrong. How do i check the rotation direction? Iknow the engine is standard rotation. It is possible also that it may be an auto water pump by the previous owner, Irealy dont knoe for sure, untill i find a number.


                            Ok, sorry to be redudant, but i want to be absoloutly clear, before i buy another $300 thermostat housing. The only reason i ask is because both look exactly the same on the outside.

                            The part # 860256A 3 for Alpha drive, is for or will work with a Alpha 1 or MC1 and is not specificly for an Alpha gen II. I have read that the water pump in the Alpha gen II is different and similar to the Bravo.
                            In the SEC article above, the guy had to switch to the check valve type Tstat house, like this one in this picture by Dennis Moore.
                            I would rather not have to use the check ball style if possible. The one like i have is much cleaner, with less hose and fittings.
                            Thanks for the help.
                            Last edited by holorinhal; April 20th, 2015, 09:43 AM.

                            Comment


                            • #15
                              Sign up today
                              I did a conversion to my '88 5.7. I don't run those manifolds though. I've only run it on muffs and it stays just under 160. Besides the different hose configuration, I just made 2 more openings in my riser gaskets to be 4 holes instead of just 2.

                              http://forums.iboats.com/forum/engin...t-housing-swap
                              1988 Imperial V220, 260/5.7 Alpha One
                              https://forums.iboats.com/forum/boat...220-low-budget

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