2.5 Mercury cooling and other questions

[cocacola]

I am refurbishing a boat/engine I just purchased. I just found out the thermostats aren't installed. Is that gonna hurt me? I heard some folks run without or install washers to restict flow. I am in Texas and it does get hot here during boating season.

question 2...what does the water pressure relief valve do?

question 3...the water dump from one cylinder bank dumps into fitting on other cylinder bank before it goes back into the lake. Is that normal? The lower cowl fitting looks like it has holes for a dump hose on both sides of engine. Just wondering do both outlets need to be joined and exit together.

I can't find the serial number on engine. It's a 1995 steel sleeve carb 2.5... and that's all I know.

[shooter1]

If this is a fishin' motor and not modified I would go ahead and run stats. Question #2. The relief or more commonly called the poppet is there so you don't blow gaskets or hoses. From time to time you might have probems of low water pressure or heating up. Sometimes this is traced back to the poppet having trash under it or a bad diaphram or spring. I had a 96 2.5 200 that has always had lower water pressure than what I wanted that I found that the seat was cut a little too deep so I had to shim the diaphram out a little. If you boat doesn't have a water pressure guage you should get one. The 2 heads are tied together coming off the thermostat ports and then the hose should go down and tee off to the pee hole and the other end goes to port side of the exhaust adapter.

Shooter1

[cocacola]

It's not a fishing motor; 2.5 offshore with CLE gearcase on a Lavey Mod-VP. I fired it up in driveway and never saw water peeing. New pump is now installed, but I want to make sure everything is up to standard before I fire it again and don't burn up a pump. Impeller could have been trash before I fired it as boat was lacking maintenance. It's mildly modified from what I can tell. Yes, there's a water pressure gauge thankfully. My plumbing of the hoses is just as you say.

I took the poppet off to learn a little more about it. Now I need new gaskets (damn it). There is not a hose on it and probably what use to be in that hole that is plugged with a screw. Read here about Cooling Modifications (http://www.biggerhammer.net/mercury/) about half way down the page... I want a good realiable engine with decent cooling. Not sure if I need to do anything with Poppet except put new gaskets on it. With no hose attached, I don't think it's doing anything.


If this is a fishin' motor and not modified I would go ahead and run stats. Question #2. The relief or more commonly called the poppet is there so you don't blow gaskets or hoses. From time to time you might have probems of low water pressure or heating up. Sometimes this is traced back to the poppet having trash under it or a bad diaphram or spring. I had a 96 2.5 200 that has always had lower water pressure than what I wanted that I found that the seat was cut a little too deep so I had to shim the diaphram out a little. If you boat doesn't have a water pressure guage you should get one. The 2 heads are tied together coming off the thermostat ports and then the hose should go down and tee off to the pee hole and the other end goes to port side of the exhaust adapter.

Shooter1

[Jay Smith]

If this is a High Performance Nicom/Nik coated engine you need to install the restrictor discs , I don't suggest running it wide open. Also the hose routing sounds stock ( star. side hose runs to a tee on the port head and then they both go out, that motor does'nt have a poppet valve and the cover should have another hose and that one goes out also ).... Most High Performance "coated" bored engines don't have much of a water "tell tale" stream at idle, thats a normal condition.

Good luck,

[cocacola]

If this is a High Performance Nicom/Nik coated engine you need to install the restrictor discs , I don't suggest running it wide open. Also the hose routing sounds stock ( star. side hose runs to a tee on the port head and then they both go out, that motor does'nt have a poppet valve and the cover should have another hose and that one goes out also ).... Most High Performance "coated" bored engines don't have much of a water "tell tale" stream at idle, thats a normal condition.

Good luck,

this engine is steel sleeved and not coated and it sounds like you say I need thermostats and add the hose back to poppet that is current missing. You say I don't have a poppet? I tool 4 bolts off a plate that had another plate behind with with a spring loaded diaphragm. Isn't that it? I am confused.

[Jay Smith]

No ,

Sorry I misunderstood ( bad reader ! Failed Evelyn Woods 3 times LOL ,) IMO if this is a steel sleeved engine I would put it cooling system back as stock with stock thermostats and poppet valving....

BTW: To my knowledge, there is no such thing as a steel sleeved High Performance 2.5 STOCK in OEM form.Even the 245 HP carbed motors ( Only High Performance carbed 2.5 ever produced ) were a aluminum coated sleeved engine and NOT steel from Mercury...

[cocacola]

thanks for the clarification Jay. Unfortunately, I am finding "truths" about this boat the longer I own it. So far, I feel I got quite a deal...but I only have the word from prior owner on engine specs. Lavey said it came with a 2.4 240hp engine. Externally, it looks like what came with it, but wouldn't know it's a steel sleever or 2.5 since I don't know what I am looking for. Boat is 1989...engine is supposed to be 1995 2.5 steel sleeve and possibly big rods.

Thanks for the cooling system tips. Sounds like I need some hose, thermostats and a right angle fitting for poppet...and the gaskets of course.

David


No ,

Sorry I misunderstood ( bad reader ! Failed Evelyn Woods 3 times LOL ,) IMO if this is a steel sleeved engine I would put it cooling system back as stock with stock thermostats and poppet valving....

BTW: To my knowledge, there is no such thing as a steel sleeved High Performance 2.5 STOCK in OEM form.Even the 245 HP carbed motors ( Only High Performance carbed 2.5 ever produced ) were a aluminum coated sleeved engine and NOT steel from Mercury...

[cocacola]

Jay
Just got cooling system back to stock condition with new thermostats, hoses and new poppet gasket. Old gaskets did not resemble those I took off. New ones are much thicker. The 90* fitting on poppet plate is missing, so I must get one. Previous owner pluged it. I assume this is the same 90* fitting I see on port side thermostat housing. Do you have a part number or know the thread size?

Question: when engine is first started and not up to operating temperature, I assume water will route through engine and exit at poppet outlet and not from thermostats. Is this true? When up to operating temperature, will water exit from BOTH tubes?

what color wire should be connected to temp sensor shown in pics on my link above? I assume this goes to temp horn under the dash.

Thanks again.




No ,

Sorry I misunderstood ( bad reader ! Failed Evelyn Woods 3 times LOL ,) IMO if this is a steel sleeved engine I would put it cooling system back as stock with stock thermostats and poppet valving....

BTW: To my knowledge, there is no such thing as a steel sleeved High Performance 2.5 STOCK in OEM form.Even the 245 HP carbed motors ( Only High Performance carbed 2.5 ever produced ) were a aluminum coated sleeved engine and NOT steel from Mercury...

[Fish]

David,
a few pics of the motor might help. If it is around the same age as your boat then it could be a 2.4, if newer, then it could be a 2.5. The reason I mention this is that I had a 2.4 midsection re-powered with a 2.5. I began having some of the same cooling concerns and started reading a lot of threads, messing with washers, thermostats in, thermostats out, blocked poppet, ...etc. I finally got it straight with help from some friends here on S&F, and ended up putting it back the way it came from the factory to get it to work right. it was a fishing 2,5 200, on a 2.4 2 piece mid- a lot of the mods I read about really were not for my application.

The short version from what I learned is that the merc guys are not totally dumb, and when they configured the cooling system for different motors, they had a reason for it. I kept taking bits and pieces from different threads about 2.5 cooling and that is a mistake since what works for a 2.5 nic motor, is different than with a 2.5 steel motor, what works with a 1 piece divider may not with a 2 piece.. etc.

First find out exactly what you have 2.4, 2.5 (if the power head really is a 95, then it is a 2.5) and whether you have a 1 piece or 2 piece exhaust divider. Also, here are some links from cooling threads I saved and a diagram that should also help a bit.

fish

http://i5.photobucket.com/albums/y174/makulaf/Coolingdiagmercv689andnewerv1a.jpg

http://forums.screamandfly.com/forums/showthread.php?s=&threadid=44348&highlight=temperature+cold

http://forums.screamandfly.com/forums/showthread.php?s=&threadid=24895&highlight=temperature+cold

http://forums.screamandfly.com/forums/showthread.php?s=&threadid=42995&highlight=Cooling+mods

http://forums.screamandfly.com/forums/showthread.php?s=&threadid=43866&highlight=cold+sieze

http://forums.screamandfly.com/forums/showthread.php?s=&threadid=49364&highlight=temperature+cold

http://forums.screamandfly.com/forums/showthread.php?s=&threadid=35278&highlight=2.5+200

http://forums.screamandfly.com/forums/showthread.php?s=&threadid=36060&highlight=temperature+cold

http://forums.screamandfly.com/forums/showthread.php?t=44994&pp=15&highlight=temperature+cold

http://forums.screamandfly.com/forums/showthread.php?s=&threadid=20855&highlight=2.5+200

http://forums.screamandfly.com/forums/showthread.php?s=&threadid=34861&highlight=temperature+cold

http://forums.screamandfly.com/forums/showthread.php?s=&threadid=21413&highlight=2.5+200

http://forums.screamandfly.com/forums/showthread.php?t=54277&pp=15

[cocacola]

Thanks Fish. Your engine and mine sound EXACTLY the same. This boat did come with a 2.4 when new. It's supposed to be a 2.5 steel sleeve now. Previous owner suspected 225 hp with tuner added. I think it's the original everything except powerhead. It sounds like we have followed the same path....gotta read all the links you sent.

not sure what a 1-2 piece mid is. What am I looking for? Does this help you? (http://home.flash.net/~davidsan/2.5%20Mercury/IMG_4314.JPG)

David



David,
a few pics of the motor might help. If it is around the same age as your boat then it could be a 2.4, if newer, then it could be a 2.5. The reason I mention this is that I had a 2.4 midsection re-powered with a 2.5. I began having some of the same cooling concerns and started reading a lot of threads, messing with washers, thermostats in, thermostats out, blocked poppet, ...etc. I finally got it straight with help from some friends here on S&F, and ended up putting it back the way it came from the factory to get it to work right. it was a fishing 2,5 200, on a 2.4 2 piece mid- a lot of the mods I read about really were not for my application.

The short version from what I learned is that the merc guys are not totally dumb, and when they configured the cooling system for different motors, they had a reason for it. I kept taking bits and pieces from different threads about 2.5 cooling and that is a mistake since what works for a 2.5 nic motor, is different than with a 2.5 steel motor, what works with a 1 piece divider may not with a 2 piece.. etc.

First find out exactly what you have 2.4, 2.5 (if the power head really is a 95, then it is a 2.5) and whether you have a 1 piece or 2 piece exhaust divider. Also, here are some links from cooling threads I saved and a diagram that should also help a bit.

fish

http://i5.photobucket.com/albums/y174/makulaf/Coolingdiagmercv689andnewerv1a.jpg

http://forums.screamandfly.com/forums/showthread.php?s=&threadid=44348&highlight=temperature+cold

http://forums.screamandfly.com/forums/showthread.php?s=&threadid=24895&highlight=temperature+cold

http://forums.screamandfly.com/forums/showthread.php?s=&threadid=42995&highlight=Cooling+mods

http://forums.screamandfly.com/forums/showthread.php?s=&threadid=43866&highlight=cold+sieze

http://forums.screamandfly.com/forums/showthread.php?s=&threadid=49364&highlight=temperature+cold

http://forums.screamandfly.com/forums/showthread.php?s=&threadid=35278&highlight=2.5+200

http://forums.screamandfly.com/forums/showthread.php?s=&threadid=36060&highlight=temperature+cold

http://forums.screamandfly.com/forums/showthread.php?t=44994&pp=15&highlight=temperature+cold

http://forums.screamandfly.com/forums/showthread.php?s=&threadid=20855&highlight=2.5+200

http://forums.screamandfly.com/forums/showthread.php?s=&threadid=34861&highlight=temperature+cold

http://forums.screamandfly.com/forums/showthread.php?s=&threadid=21413&highlight=2.5+200

http://forums.screamandfly.com/forums/showthread.php?t=54277&pp=15

[cocacola]

Update.... I finally ran the Lavey Mod-Vp boat today. Started up just fine and absolutely no peeing from poppet or heads. Cooling system is stock just as Jay recommended. I let her idle on the trailer while backed into lake. Since I made sure everything was back to stock condition; water pressure gauge hooked up along with temperature horn, I didn't worry. Eventually, I turned engine off, pulled the cowl and felt the heads... Mildly warm. Its was a 50* day in a North Texas lake. Probably water temp was about 45-50. Eventually, I thought lets back it off the trailer and run it slowly. All seemed well and I did this for about an hour. Still, no peeing out the hoses. Where is the cooling water going? It did appear to me that water was coming out around where powerhead bolts to rest of engine, but this is when I looked back at engine while at WOT (6700rpm). This is speculation as I saw water coming out of lower cowl pan and it appear steamy. It might have been exhaust, but I doubt it. I pulled the cowl and did not see any water leaks. What's going on?

At idle, I don't see much water pressure, but at speed, it just about pegs the meter.

when I bought this boat, poppet did not have a hose on it and was plugged. Both thermostats were missing. By the way...doesn't the rubber gasket on thermostats go between block and thermostat? I want to make sure I installed them right.

[drasticplastic]

Oh No, the rubber gaskets for the thermose stats go/wrap around the t/stats. Look at the seals and you will see that they have a slot in them, this is were you place the t/stat in. When you instal them like this they will be "wrapped" around the edge of the t/stats an will seal to the pocket in the head and also to the t/stat housing surface.

[cocacola]

thermostats gaskets installed correctly now. Not sure if this will make the vent groove operate correctly (or at all) now. I am about ready to toss the 'stats and go to washers. At least those will pee.

What am I looking for on 1 or 2 pieced exhaust plates? If looking at rear of engine, the plated under power trim soleniods looks like 2 plates sandwiched together with common bolts through both.

I saw no water peeing from Poppet either.




Oh No, the rubber gaskets for the thermose stats go/wrap around the t/stats. Look at the seals and you will see that they have a slot in them, this is were you place the t/stat in. When you instal them like this they will be "wrapped" around the edge of the t/stats an will seal to the pocket in the head and also to the t/stat housing surface.

[cocacola]

thermostats gaskets installed correctly now. Not sure if this will make the vent groove operate correctly (or at all) now. I am about ready to toss the 'stats and go to washers. At least those will pee.
<O:p
What am I looking for on 1 or 2 pieced exhaust plates? If looking at rear of engine, the plated under power trim soleniods looks like 2 plates sandwiched together with common bolts through both.<O:p
<O:p
I saw no water peeing from Poppet either




Oh No, the rubber gaskets for the thermose stats go/wrap around the t/stats. Look at the seals and you will see that they have a slot in them, this is were you place the t/stat in. When you instal them like this they will be "wrapped" around the edge of the t/stats an will seal to the pocket in the head and also to the t/stat housing surface.

[The Big Al]

I would not run the washers.
I would opt for a 120 degree thermstat (pro marine this is one of those item's that might be cheeper at dealer)
Mercury part # 804540
<TABLE id=SearchTemplate13_DataGrid1__ctl3_ProductInfoTable width="100%"><TBODY><TR><TD class=Content>18-3549 (http://www.promarineusa.com/detail.aspx?ID=3786) </TD><TD rowSpan=2><TABLE id=SearchTemplate13_DataGrid1__ctl3_RightDisplay align=right><TBODY></TBODY></TABLE></TD></TR><TR id=SearchTemplate13_DataGrid1__ctl3_ProductNameRow><TD class=Content vAlign=top>Thermostat (http://www.promarineusa.com/detail.aspx?ID=3786) </TD></TR><TR id=SearchTemplate13_DataGrid1__ctl3_DisplayShortDescription><TD class=Content vAlign=top>120º thermostat for many late model 2, 3 and 4 cylinder Mercury engines</TD></TR><TR class=Content id=SearchTemplate13_DataGrid1__ctl3_trRegularPrice><TD class=Content align=left>$18.47 </TD></TR></TBODY></TABLE>

Same design just lower temp.

Popit valve
http://img88.imageshack.us/img88/176/popitvalve25ru5.png<SCRIPT type=text/javascript>setImgWidth();</SCRIPT>

[The Big Al]

http://img258.imageshack.us/img258/7416/coolingproblemcauseslz7.jpg<SCRIPT type=text/javascript>setImgWidth();</SCRIPT>

[cocacola]

good information guys

should have time to work on it this weekend

tell me what you think of this (http://home.flash.net/~davidsan/poppet.pdf)

[The Big Al]

Purchase kit for popit and rebuild it, do it correctly.

[cocacola]

Purchase kit for popit and rebuild it, do it correctly.

Thanks Al. I assume the kit has instructions on how to do it right as I am not sure what's wrong with it now.

[cocacola]

does anyone have a pictures (not diagram) of a poppet like the one shown below?

installed and removed pics


I would not run the washers.
I would opt for a 120 degree thermstat (pro marine this is one of those item's that might be cheeper at dealer)
Mercury part # 804540
<TABLE id=SearchTemplate13_DataGrid1__ctl3_ProductInfoTable width="100%"><TBODY><TR><TD class=Content>18-3549 (http://www.promarineusa.com/detail.aspx?ID=3786) </TD><TD rowSpan=2><TABLE id=SearchTemplate13_DataGrid1__ctl3_RightDisplay align=right><TBODY></TBODY></TABLE></TD></TR><TR id=SearchTemplate13_DataGrid1__ctl3_ProductNameRow><TD class=Content vAlign=top>Thermostat (http://www.promarineusa.com/detail.aspx?ID=3786) </TD></TR><TR id=SearchTemplate13_DataGrid1__ctl3_DisplayShortDescription><TD class=Content vAlign=top>120º thermostat for many late model 2, 3 and 4 cylinder Mercury engines</TD></TR><TR class=Content id=SearchTemplate13_DataGrid1__ctl3_trRegularPrice><TD class=Content align=left>$18.47 </TD></TR></TBODY></TABLE>

Same design just lower temp.

Popit valve
http://img88.imageshack.us/img88/176/popitvalve25ru5.png<SCRIPT type=text/javascript>setImgWidth();</SCRIPT>

[cocacola]

Took the boat out since swapping washers for thermostats. It was damn nice to see water peeing. Boat seems to run about the same, but holeshot still a little is sluggish. I think the needle valves in bottom carb isn’t seating and allowing excess fuel. Also it’s flooding if I activate enrichment solenoid on cold start up. Possibly too much water being dumped into exhaust…. But that’s another story. Water pressure gauge reads a maximum of 16psi at full throttle and 2 at idle. Much better than the 25psi before Being new to CLE drives and low water pickups leaves me a little baffled. I did not see water peeing until the first time I put engine in forward. Do low water (bottom) pickups work better when boat is moving forward?

Still have not done a compression check and wonder do I need to do this before sending to Jay Smith. I guess I will see if diverters are in (proper) place when heads are removed. I will pull exhaust plate when I do the heads to see what’s been done there.
<O:p
Overall, it ran good. I did something I was unsure of. Boat has two batteries. One was too dead to crank engine, so I started with one and switched to dead one to charge it while engine was running. Nothing bad happened and I noted voltage of that battery was real low on the gauge. Eventually, it did come up and was able to start engine after a short while of running on that battery.
<O:p
I have a 3 way manual valve connecting both tanks to Holley fuel pump. My guess was it was Left/Right/Off. Well, I forgot to change the position from the “off” position, but engine still ran. So…. The middle position must draw from both tanks simultaneously as that’s the way the gauge appeared to read. I thought maybe the valve leaked by and was able to draw fuel anyway. Comments?
<O:p
When I got home, I noted lower unit oil from a little hole I did not know existed. It’s a tiny vertical hole that is a few inches from Vent plug, but closer to Transom. What’s going on and what is that for?
<O:p
I like the foot throttle, but it does not pull engine idle speed back to where it should unless I pull back on it. I see there’s a spring adjustment and will probably increase tension.

Since I have never had an engine with one of these lightweight cowls, I am amazed at how noisy the engine is. Reminds me of my Inline 6 115 when cowl was removed.

[cocacola]

does anyone have a pictures (not diagram) of a poppet like the one shown below?

installed and removed pics

I think my poppet is missing items 11 & 12. Can the spring have too much pre-load on the diaphragm? Need to rebuild the poppet. Since this appears to be a Frankenstein motor, does anyone know the part number of poppet kit that works with illustrations above?

[Prof. O/B]

I am refurbishing a boat/engine I just purchased. I just found out the thermostats aren't installed. Is that gonna hurt me? I heard some folks run without or install washers to restict flow. I am in Texas and it does get hot here during boating season.

question 2...what does the water pressure relief valve do?

question 3...the water dump from one cylinder bank dumps into fitting on other cylinder bank before it goes back into the lake. Is that normal? The lower cowl fitting looks like it has holes for a dump hose on both sides of engine. Just wondering do both outlets need to be joined and exit together.

I can't find the serial number on engine. It's a 1995 steel sleeve carb 2.5... and that's all I know.

What kinda motor is this? Does it have a horn, Laser-style injection or Carbs, 240 HP steel-sleeve, Umnnnnnnnnn?

[cocacola]

What kinda motor is this? Does it have a horn, Laser-style injection or Carbs, 240 HP steel-sleeve, Umnnnnnnnnn?

Finally have all that information. Powerhead is a steel sleeve 2.5 carb fishin motor. The rest of it is from a 240hp 2.4. Runs 6500rpm

[cocacola]

Pics added (http://home.flash.net/~davidsan/poppet.pdf)

looks like I am missing items 11 & 12 from poppet

Comments

[cocacola]

Question.... where does poppet have water pressure on it? On item 5 or item 11 & 12? I am assuming on item 5, then water passes by items 11 & 12 into spent water cavity and into exhaust housing. Sound correct?

Popit valve
http://img88.imageshack.us/img88/176/popitvalve25ru5.png<SCRIPT type=text/javascript>setImgWidth();</SCRIPT>[/quote]

[cocacola]

Now that my education is starting to stick (with Merc outboards), it seems to me that the thermostats will never pee with a malfunctioning or disabled poppet (like mine). No pressure and possibly no consistent water supply to them....right?

[cocacola]

Alright... it's been slow going, but I now have all parts to my poppet installed along with thermostats. I understand the tell tale on this engine is the water that comes out of thermostats. Do they allow "some" water to pass them before reaching operating temp? Seems to me that they should or I would see no water flow and might have air pocket in the head. My understanding is that the poppet won't open until a give rpm (2500rpm?).

about how long does it take for thermostats to open? I am a little nervous about this until I get a fully functional cooling system. Diverters were installed when heads were removed and new waterpump.

until poppet opens, where does water that pours on tuner come from?

[Fish]

you will have some water flow out the tell tale whether the t-stats are open of not. The t-stats open at around 140 degrees. They are designed like a car to allow the motor to warm up quicker and then when it reaches around 140, they open and allow cooling water to keep the engin temps down.

[cocacola]

you will have some water flow out the tell tale whether the t-stats are open of not. The t-stats open at around 140 degrees. They are designed like a car to allow the motor to warm up quicker and then when it reaches around 140, they open and allow cooling water to keep the engin temps down.

thanks Fish. I noted tstats had a V cut in the end.... I assume this is where water trickles through before stats start opening.

[j_martin]

Alright... it's been slow going, but I now have all parts to my poppet installed along with thermostats. I understand the tell tale on this engine is the water that comes out of thermostats. Do they allow "some" water to pass them before reaching operating temp? Seems to me that they should or I would see no water flow and might have air pocket in the head. My understanding is that the poppet won't open until a give rpm (2500rpm?).

about how long does it take for thermostats to open? I am a little nervous about this until I get a fully functional cooling system. Diverters were installed when heads were removed and new waterpump.

until poppet opens, where does water that pours on tuner come from?

Mine usually pees a little after about 15 - 30 seconds. In a couple of minutes it'll be steady at idle and uncomfortably warm.

The water in the lower comes from both the thermostats and the poppit valve.

[cocacola]

why not have each tstat have it's own discharge hose overboard? for the life of me, I cannot see why one side needs to go to the other, then overboard together

[j_martin]

So the discharge water cools the mid, instead of washing the dock.

[tlwjkw]

It doesn't have to................
production motors only need "one" pee hole cause most boaters nowdays can't cope with watchin' "two" pee holes...less their in a tit bar :D .......T

[cocacola]

I knew there was an underlying reason I love this site:) .... guys here just like me:eek:

Question: If the poppet never opened, would the water pump burn up from exhaust on it?



It doesn't have to................
production motors only need "one" pee hole cause most boaters nowdays can't cope with watchin' "two" pee holes...less their in a tit bar :D .......T

[j_martin]

NO

Fish put up a diagram earlier in this topic that should answer most if not all of these questions.