98 225 Pro Max Cooling on 260 plate

[crankbearing]

Hey All,

Not too re-hash this, I know there are several threads I have read most of them I think. I have a 98 225 A17 box, mounted on a 260 smoothback mid assemble this for the client in the spring. I blocked the poppet and installed washer in the heads. Motor will not pull past 5900 and sluggish out of the hole on his V-king. Motor has 131-2 a hole and less than 75 hours on this thing since new it pulled 6300-6400 easy in Sept last year on my Virage on the stock plate and mid. In the threads I have read some say mount it on a BP plate port matching the exhaust, I can do that I have one here or the guys with the 225SS one piece plate said the motors had a poppet and t-stats on the one piece plate. The way it is now, the temp gauge never sees more than 120 degrees which is way to cold and I can only assume the computer is dumping fuel trying to compensate.

Should I Just re-install the stock cooling on his 260 plate or pop the head and install the BP plate I want to go the right way here as he likely puts a ton of hours on his boat a year. It will be run under 7K.

Thanks,

Dave

[Coupe427]

The poppet shouldn't be blocked. It should have a dump hose coming out of it. What is your pressure?

[crankbearing]

No it should be blocked this is a steel sleeve motor not nic. no pressure at idle 5-7 at 5900.

[h2oskiier30]

Did you put diverters into the cylinder water jackets? If not, the block might be damaged. If you didn't install diverters, the cyliders can warp from all the water going in on one side of the cylinder. It won't cause the motor to blow, but power will suffer.

Not saying that's what happened here, but it's a very real possibility.

[crankbearing]

It's 130-132 per hole with a 3-4% leakdown this mod was only done a couple weeks ago. I am just trying to figure out the best way to remedy it, put it on a bp plate or leave it on the 260 plate with stock cooling which is what the 225ss seemed to have, but no diverters yet. I really do not want to ruin a 260 plate when I have a BP plate I can port match here for him. He can then at least recoup some money from the good 260 plate.

rgds,

Dave

[h2oskiier30]

Go here, and follow Marles' directions to the "t". It works.

http://www.us1.cc/racingcoolingsystem.html

[wired247]

I dont see higher than 120 head temp either unless I'm idling in gear for extended periods and it drops from 145 to 120 immediately once I take off. I have no problem winding it up to 7K with a 28 pitch prop. Bone stock 225 promax ( except for a spacer and brucatto box) with 2 piece plate , 143 thermostats and poppet. I dont think the RPM issue is temp related.

[Varmint]

I think what Dave is saying,is the motor ran perfectly fine and ran strong,and was factory setup w/2 pc. tuner,for all the years he owned it,even tho' he didn't use it alot,until he sold it a few weeks ago,the new owner added an offshore mid/260 1 pc. plate,and they removed the poppit and replaced t stats w/washers,,the question is,what happened to the performance after this change?, the only promax 225's that came with 1pc plates were the 15" SS,so,how did Mercury plumb those ? did the SS have a poppit,and t stats? or was it plumbed like a bridgeport ?, Is the motor actually under performing now,due to not being able to reach a proper internal temperature ?,is the computer reading that it is too cold, and dumping a rich mixture ?,

[tlwjkw]

Just something I've seen as far as manuals, parts on a ss pm. No where does it list or say anything about removing poppet, T-stats, on tha one piece. It looks like ya don't change anything with tha "stock" coolin' stuff along with tha efi head temp sensor on either type plate. Just an observation with tha "paper work". I've never laid eyes ona factory stock 15" pm..........As most on here know there are several ways ta build heat with tha one piece. but also know tha some of tha 260 plates need several changes that tha "factory" missed in order ta do it. He may have one of those plates. Justa comment on tha temp part.

But we all also know tha when ya turn tha key one day alls well. Turn it again 5 minutes after ya shut it off and it all goes ta ****..........jmo

[silverbullet02]

Why not throw a set of 2 piece plates on?

[Coupe427]

Maybe we have different plates but this was the result of running with a blocked poppet and tstats on my 225 with a 260 plate.


http://youtu.be/pIOUdB8RfCE

[wired247]

Maybe we have different plates but this was the result of running with a blocked poppet and tstats on my 225 with a 260 plate.


http://youtu.be/pIOUdB8RfCE

Your pressure is high but your temps look fine.

[crankbearing]

Yep we are going to install the stats and poppet and then run it on the dyno if that does not do it then swapping to BP plate. one way or the other it's fixed tomorrow. Thanks for the replies.

[tlwjkw]

While ya got it apart check tha holes, number of and size. Tha 260's were all over place......

[Coupe427]

Your pressure is high but your temps look fine.

Hence the reason we added the dump hose to the poppet plate.

[wired247]

Hence the reason we added the dump hose to the poppet plate.

Oh... Explain further if you dont mind. My pressures are the same way. Even with motor up as high as she goes ( in ch over the pad ) and two of the four inlet holes plugged I still peg 30+ WOT mid 80's-low 90's.


Wait never mind. Your'e using a 260 plate. Mine a 2 piece 2.5.

[crankbearing]

We have a 260 plate here as well, pressure is low at 5900 rpm and temps are 118 to 120 at best at that rpm also it has the big water tube. will try to get some video tomorrow of it on the dyno.

[mach1magnum]

Go here, and follow Marles' directions to the "t". It works.

http://www.us1.cc/racingcoolingsystem.html

i am also running steel sleeve with 260 plates i put valves on the poppet valve hose to control the flow out of it cold water keep it closed running hard in warm water i can open them i followed the link above but do not understand number 7 the last step can anyone explain what he is talking about?

[tlwjkw]

If you look at tha base of tha block you will see what he's talkin' about. Pretty sure there are some pictures in some of his post. Ya might do a little search ta see 'zactly what he means. I'm to lazy.............

[crankbearing]

I am pretty sure this plate had 4 holes in it, at least .200 - .250" 2 in the front and 1 in each rear corner. I found a pic of a 225 plate on here somewhere without a stack and it looks a whole lot just like a 260 plate at least the dumps looked the same. I like the idea of just sticking a 2 piece plate on the offshore housing but I am shy on solid upper mounts right now.

[tux974]

If you look at tha base of tha block you will see what he's talkin' about. Pretty sure there are some pictures in some of his post. Ya might do a little search ta see 'zactly what he means. I'm to lazy.............

This is what he is talking about doing. It is to prevent the cold water coming up and hitting the lower bores. The new holes location are so they line up with the drain channel on the plate to properly drain the block.
http://i61.tinypic.com/ibdp3s.jpg

[tux974]

Crankbering, that plate with the 4 holes is a good plate and it can be done but it will take some patience and tweaking to get it right, how much?? it all depends on the water temp in your area. I have found up north is a bit harder then down south. It sounds like 2pc is a better choice for you guys especially if not spinning above 7000! GL

[mach1magnum]

This is what he is talking about doing. It is to prevent the cold water coming up and hitting the lower bores. The new holes location are so they line up with the drain channel on the plate to properly drain the block.
http://i61.tinypic.com/ibdp3s.jpg
thanks i get it now ,i believe the only reason i have these plates on this new to me boat is for strength on a skater with twins i

[crankbearing]

I will get him to take pictures of the plate. The water inlet hole was almost 3/4" the two holes in the front were nearly 3/8" and none at the rear. I installed the 2 piece plate on the offshore housing, lots of water pressure proper temps and lots of rpm. I also found the wrong plugs were installed someone told him to install BR9HS plugs so not only was the motor running cold, that is a colder plug with resistance. I installed new BU8H's and the instant I started it he could hear the difference. Tried the poppet and stats on that one piece plate for the fun of it what a nightmare block never got over 100 degress in a bucket not on flushtool no water pressure at all period nada. He is out to run it tomorrow and I will hear how it went. I also re-synced it all, set the idle timing and idle. It was day and night a quick shot of the hot foot now rocks the boat on the trailer.

[transomstand]

I installed the 2 piece plate on the offshore housing,

Good choice:thumbsup:

[crankbearing]

yep he should see the 100 mph club, I sold him a real nice 30 Spinelli last year, I did not want to I love that prop but I am all fatshafts now it turned 7K on my 280 in a blink of an eye on my V-king and he has a restored CDN edition version should rock his world pretty nicely. Ok enuff, I have to get the virage re-rigged and back on the water so I can get some water time in it, my talon is getting a complete resto and paint so I have to get the hipo 250xs together for it ASAP.

[tux974]

That is a late 2.5, 3/4 water tube one piece plate and those 2 loose 3/8" holes needed to be modded/closed up some.
I thought you said the plate had 4 smaller holes? That would have been an early 2.5 1/2 water tube and is the better plate, no mods.
The correct plug for that motor if you are running an OEM ECU like a A32 are BUZHW.
Either way sound like you did the better thing going with 2 pc plate. GL

[crankbearing]

it's a A17 box, I thought about the BUZHW, but the serial group for that mota was calling for Bu8H, I did not want any Z or R in the plug spec until I know it's 100%. it's got the NGK wires on it which I thought already have a resistor in the cap. I talked to Clark at Rapair on Friday and we talked a little about plugs and that box. I saw oil on the Bu8H's after a few minutes of idling which made me happy as his BR9's were completely dry and the color of the inside of your forearm to lean IMHO.

[crankbearing]

Customer is happy, he had the boat out yesterday hit the limiter on his 28 and it's a rocket out of the hole. thanks for all the input on the subject I know it's an old one.

[Greg G]

Customer is happy, he had the boat out yesterday hit the limiter on his 28 and it's a rocket out of the hole. thanks for all the input on the subject I know it's an old one.

Did he run it all season with no issues? Curious on pressure and temps.

[crankbearing]

Yes he did with no trouble, no overheating, played with a lot of props, he was on the rev limiter at times, water pressures were in the 10-15 psi all the time temp was 130 - 140 consistently. His boat and motor height was an issue, the motor is here now for some mods over the winter and the boat is at Ronny's Marine getting blueprinted and we will start fresh in the spring for new numbers.

[Greg G]

Thanks, curious did you end up using 120 degree thermostats or 143's when you went back to a 2 piece plate?

[crankbearing]

143's

[Greg G]

Yes he did with no trouble, no overheating, played with a lot of props, he was on the rev limiter at times, water pressures were in the 10-15 psi all the time temp was 130 - 140 consistently. His boat and motor height was an issue, the motor is here now for some mods over the winter and the boat is at Ronny's Marine getting blueprinted and we will start fresh in the spring for new numbers.

I guess it's not Spring just yet up North? Good luck with the 143s

[Greg G]

Yes he did with no trouble, no overheating, played with a lot of props, he was on the rev limiter at times, water pressures were in the 10-15 psi all the time temp was 130 - 140 consistently. His boat and motor height was an issue, the motor is here now for some mods over the winter and the boat is at Ronny's Marine getting blueprinted and we will start fresh in the spring for new numbers.

Curious what mods your customer ended up doing on the Promax 225 and how they worked out for him over the course of this past season? Thanks