twin engine water cooling question/tip

[douglas_be]

Hi,

My boat has 2 x 502 MPI wich are cooled with seawater. On both thermostat housings assy's there is an outlet for hot-water kitchen apliances. Both outlets are blocked with a yellow plastic cap , that is srewed on this outlets. Now totday one of those plastic caps cracked , because it can't coop with the water pressure. All the waster was spraying around over my engine's and I saw my water press gauges that one only had 10psi and the other one +30 psi.
OK I can block it again and replace the yellow plastic srews by two copper screws.
But i was thinking , what if I connected both outlets to eachother by a rubber hose. This means that if one of the seawater pumps or circulation pumps would fail , that both engines will still have cooling. Of course if one of the engine's would leak water , all the pressure would go tru this leak ? So whats is your opinion ?. Let me know.

Thanks

Douglas
Belgium-Europe

[GVL]

You should have an additional hose fitting off of the back of the sea water pump that you can run a hose to from the thermostat housing and just cycle the water that way. Then you don't have to worry about this happening again.

[Griff]

30+ psi is borderline too much water pressure. 20-25 at wot would be better.

[Hell Ya!]

If you are seeing "30+ psi" on the water psi gauges you better look into that. That is to high. I like 18# and 25 MAX.

Glen, I don't think these Raw water pump housings have the port you are talking about. These should be the plastic mercs with only a in and out.

So as for your origional qestion. Install a new plug and get some by-passes on the engines before you push out a head gasket. You must be running shorty IMCO's ??

Jeff

[douglas_be]

How can i reduce the +30psi at W/O/T ? some kinde of pop-off ???or pressure regulator system?
You think you can blow a headgasket with too much water pressure?

[Hell Ya!]

How can i reduce the +30psi at W/O/T ? some kinde of pop-off ???or pressure regulator system?
You think you can blow a headgasket with too much water pressure?


Yes, yes, yes, and a big yes! It sounds like you have imco lowers with the pick up just under the nose cone. Merc makes a water by-pass they used on (i think) 500 HP's This is used to reduce or by-pass excessive water psi at high speed. They will also need to be drained for winterising as they will hold fresh water in the hose that is only dispatched at speed. There is a chance the broken plug was a warning. They ain't cheap but if you continue to run that much pressure you are destin for hose or gasket failure which will be more expensive.

Jeff

[Bajapit]

Jeff: Is it possible that something is clogging the H20 exit building up pressure?

[Hell Ya!]

Jeff: Is it possible that something is clogging the H20 exit building up pressure?


I suppose it is possible. But it sounds like they both usually run up there. I have had to deal with this every time I bolted on IMCO's. It's a common deal..

Jeff

[douglas_be]

Hi Jeff , Thanks for the info/warning . Can you give me a part number or tell me where I can get these pressure regualators. No one arround here knows abuth thiese.

Thanks

Douglas

PS : where is the pressure measured ? at the outlet of the impellor(seawater pump ) ? or someehere eles ?

[Griff]

Pressure is measured at the block drain or at the top of the intake near the T stat housing.

Merc makes a water pressure relief valve to take care of this problem. Don't know the part #. Maybe Brett/Nebraskabaja knows it or can order some.

[Bajapit]

I don't know where you usually boat or where this boat has been, But I do know that some of the peeps who have boated on the River have had everything fill up with sand. Exhaust elbows and everything else. If you have bravo drives, Id go ahead and flush everything out that you can. Getting to the source of the problem is priceless... Just a thought...

[Hell Ya!]

Hi Jeff , Thanks for the info/warning . Can you give me a part number or tell me where I can get these pressure regualators. No one arround here knows abuth thiese.

Thanks

Douglas

PS : where is the pressure measured ? at the outlet of the impellor(seawater pump ) ? or someehere eles ?

Here ya go read this. It also contains the by-pass part number from Merc. I am sure Brett can get them for ya. He got my last set.

http://www.marinepartsman.com/Mercury-Marine-service-bulletins/Race-Sterndrives/2001/EN_01.PDF

You are above and I will guess you have only low water pick-ups and that is good. If you install these by-passes you will have the optimum for cooling and durability..

Jeff

[douglas_be]

OK, thanks for aal help , I ordered two 863208A3. today , because they may cost a lot of money , but I don't want to blow the headgaskets !!!

Anyone can send pics or help on istallatiuon , drawing etc.... is it installed before the rawseawaterpump ?

Thanks for informing me.

Regards

Douglas
Belgium

[Bajapit]

http://www.speedwake.com/upload/showthread.php?postid=300518

[JasonSmith]

BAM wants $275 for the "kit" from mamma Merc!!!!

[douglas_be]

Last friday i ordered two of these from BAM (paid $650.00 shipped to belgium UPS ) , I should have them on monday. Over th eweekend I am doing some gymnastics , try to loose some weight too and work on my figure. all this to make sure I will be able to finde my way between the two engines to install this "POP-OFF" valves......................

[douglas_be]

Where do I install these valves , before the seawaterpunmp ? as you can see , there is not too much space between the engines............ Help wanted : not that you have to come over to Belgium , BUT YOU ARE WELCOME !!, but let me know where I need to install these vales , are they adjustable , or are the set at mercruiser ?

[Griff]

I think they are preset at 25 psi from Merc.

[Hell Ya!]

Where do I install these valves , before the seawaterpunmp ? as you can see , there is not too much space between the engines............ Help wanted : not that you have to come over to Belgium , BUT YOU ARE WELCOME !!, but let me know where I need to install these vales , are they adjustable , or are the set at mercruiser ?

They are set at Merc. You will also need to install a through transom water dump. I locate the dump so it sprays the water on the drive for extra cooling.

I like to install the valves after the sea pump just after the oil cooler. Keep in mind the small hoses will need to be removed and drained for winterizing.

I do think they come with some instructions..

Jeff

[douglas_be]

Thanks for the info , any pics of the installation ? Both of my drives have a stainless coolers.

[douglas_be]

Hi,

I got my two pressure valves from BAM , quick shipping to Belgium !!!

So I checked out where I can easly install the valves , since there is very little space around the two engines. So for me the most easy (and most accessible) is just after the first oilcooler wich is located horizonalt on the back of the engine. The hose at the outlate of the engine cooler makes a 60° bend and then there is a 4 inch straight down , just before the hose dissapears onder the exhaust manifod.
Would this be a good location ? Aslo i can install it here without removing the boat out of the water.
Would it be possible to use only ONE dump , an put a T on both valve outlets

Please let me know !

Thanks

Douglas

[Griff]

That is where I would install the valves. After the oil cooler and before the engines.

I would use two dumps and install them above the drives and angled to dump the water onto the drives. It will help keep them cooler and cleaner.

Something like this
http://www.cpperformance.com/detail.aspx?ID=680

[douglas_be]

Thanks for the confirmation , now I will use two dumps , but I will use regular dumps , the one you're posting is looking good . I have two drive coolers mounted on the drives.

I do not understand , the boat has 125 hours on the clock's , and this boat makes +35psi at speeds above 50 mph ? Why wasn't it installed when they build the boat ? The boat is made late 1999 and registered in early 2000 ???

Strange it didn't come with these valves installed . I am happy that i mentioned this to the people here on the forum .[smilie=appl]

[Hell Ya!]

my 1998 scarab 33 avs had 502 mags and it never got over 25 pounds till I installed the imco lowers. If you have stock bravo lowers with low water pick ups, I don't know why it was so high. But for sure it will be right now.

Jeff

[douglas_be]

Hi,

The drives I have are the Bravo performance/sport units (similar to IMCO) , the have one waterinlet in the front cone. The lower units is exactly the same as mine , only mine is a bravo one. The props I have are : mercury racing labbed BRAVO ONE 4-blade 30p

[douglas_be]

Hi Friends,

Totay I installed the two valves , and now at 3.500 RPM I have 20PSI and at 5.000 RPM I have 25PSI.

This is giving me a much better feeling after beeing told that +30 PSI will blow the Head gaskets ...................................

Thanks to all of you who pointed me out on this !!!!

Regards From Belgium

Douglas

[douglas_be]

Now I had it, I put new distributor , new rotor and still engine going full poser one moment and then it immediately cuts out and won't reve more than 1500/1800 revs. Tomorrow I will change the fuel filter and maybee swap the module in the ignition distributer from one engine to the other. My other engine is running OK , but there I will have to chage the thermostat , watertemperature is going from 100 to 210 al the time !!! and when I opened the oil fill cap , it was all white sludge . I HOPE I DO NOT HAVE A BLOWN HEADGASKET !!! Because of the fact that I have been running for 10 hours with +40 psi cooilgwater pressure.
I hope It is because of the engine getting too cold ??? It could alos be the oilcooler (but I doubt that )..............I feel like.........[smilie=106.gif] [smilie=106.gif] [smilie=106.gif] [smilie=106.gif] [smilie=106.gif]

[BDM]

If the oil is white sludge, you've got internal problems.

My .02 anyway.

[dwtinc]

Milky oil is not good at all. A friend is going through this right now and found his exhaust manifolds are leaking.

[douglas_be]

I will have to check , everywhere coolingwater could go into the engine oil..........:(

[Griff]

Sorry to here you are still having problems. Water in the oil can only come from a few places.

Bad exhaust riser gaskets
Bad intake manifold gasket(pushed out by high water pressure)
Cracked oil cooler
Blown head gasket

Cracked oil cooler is unlikely. The oil pressure is always higher than the water pressure and would most likely be pushing oil out and mixing it with the exhaust water.

Change the oil NOW and get the moisture out.

[Hell Ya!]

It does not sound good my friend. If you haven't pulled ALL the plugs, I would get them out and do a compression or cylinder leak test.

Jeff

[douglas_be]

Bab Bab BAD , I hope I blew my intakebaniford headgasket ?? I hope this is the weakest , weaker than the headgaskets ???

I dont' get it , the boat had 140 hours on the clocks , when at WOT the waterpressure was WAY+35psi. I got the boat at 148 hours with NO problems , now 15 hours later I blew a gasket? Maybee the previous owner never ran at WOT ?
When HELL YEAH told me that I would blow a gasket , i quickly installed the Pressure relieve valves , and with peace in my haert I ran the boat WOT........ only a few hours later , one of the engines turned into a whipped cream machine (water+oil).................. I hope ithe engine will be fixed SOON , since summer is on its way over here !!! I hope that the other engine doesn blow its gaskets too after a few hours..................................

If We finde a faulty/blwn intake manifold gasket , sould we take of the heads then ?????

[douglas_be]

Help Help , where can I get (buy) the chroom exhaust 's that are mounted on mu Scarab. One set is coroded and water goes into my engine. Over here in Europe I cant get them, anyone can help me please. thanks
Douglas
Belgim

[Griff]

Help Help , where can I get (buy) the chroom exhaust 's that are mounted on mu Scarab. One set is coroded and water goes into my engine. Over here in Europe I cant get them, anyone can help me please. thanks
Douglas
Belgim


I just looked at the earlier pics in this thread. I'm pretty sure you have Gil Marine exhaust. It looks like you have the short risers that allow for silent choice/switchable to thru prop exhaust.

Are you sure its the stainless risers leaking. Almost all of the time, the manifolds crack long before the risers go bad.