Mercury XR2 150 high water pressure

[Dukedog]

sorry but no pictures.. with 'em split and no gaskets you should find a coupla slots (on some, not all) and/or a coupla holes right behind tha mount pockets.. there should be either 4 small holes or 2 slightly larger hole right behind tha tuner.. these drain into tha exhaust "can/liner".. opening inside poppet pocket.. should be a discharge on tha port side with a 90* bib also.... it should also drain thru tha tube and water pump.. 99% drains thru tha adapter plates in some way or another.. its a completely "open system"....

 

[sam am I]

So, not exactly sure about your engine, this is a 92 175HP however, I think they are similar enough to get a good idea here.

I was looking at my old just torn down pictures, trying to see the exact path/s and where each is in respect to the pump's output through all the jackets. It does appear that the lower head discharge ports end up with only one (well two) out and that's through the poppet. There is a drain hole (1a) for them but, that's back towards the pump's output....So only when the pump is off, the heads are draining back out the pumps output path.

I think the numbering makes sense, should help to reference to for any discussion anyway .........Anything "1" is just pumped in (pump's output), the yellow square is where the pump's output pipe enters under the plate.

So, if it were me still, I'd pull that poppet and the stats out and run it, go from there.

 

[AFR Engines]

agreed that's all I have been able to find is drains that go back to the pressure side. Im not sure how the pressure will ever be lower unless the poppet or thermostats are open since it doesn't have a path threw the exhaust plate if the poppet is closed. Maybe someone can tell me. thanks

 

[Faztbullet]

Post a pic of your block.....

 

[AFR Engines]

I will have to remove the power head again. I will try to do that this weekend

 

[sam am I]

Im not sure how the pressure will ever be lower unless the poppet or thermostats are open since it doesn't have a path threw the exhaust plate if the poppet is closed.

Agreed as well and perhaps a crazy thought here......... Those "1b" path's are also on the pressure side of the pump, they make up those four holes that look to me like they spray/drain into the open exhaust box.

So what if one or two or all those spraying drain holes are starting or are just plugged up? Can you get or have you got to those to inspect them? I'd think the back pressure on the pump should increase, at least some right? And perhaps just ever so slightly.......You siad your pressure went up just a bit. They're not too big of holes but, they do dictate some (or lack there of) back pressure on the pump non the less.

Also, if they double as they are also "cooling" the exhaust similar the one after the poppet merc has indicated sprays in and cools........If soooo, and if they plug, the pressure should go up some AND, perhaps the running temp should go up as well? Not sure, just a thought since it appears everything else is in order.

 

[Dukedog]

Its an "open" system..no way wll it hold water runnin' or not.. stats have absolutely no bearing on pressure..when first started and/or on hose made up to tube where is all tha water going? out tha down housing and prop.. how does it get there?. it goes thru tha block/heads and out tha divider plates.. 90% goes thru tha exhaust "can" from poppet drain hole in divider plates inside tha down housing no mater poppet position and rest goes thru tha water pump side of down housing... tha diagrams, although correct, are very misleading.. they could of done a better job with routings, intake and exits...

 

[sam am I]

Definitely an open system AFTER the pumped water goes through some sort of restrictions else we'd not get a pressure reading on our gauge, right?.......

And yes, with pump/engine off, everything drains back and out..........it's "open" in that sense as well.

After the pump however, the water is gaining pressure due to restrictions on its way back to freedom (the lake). If no restrictions, no back pressure and the pump must definitely have restrictions else we'd not see pressure on the gauge, right?

Those restrictions as far as I can tell are 3 things............

1) Stats and bypass (meant to reduce restriction) restrict flow and lead back to freedom in the lake through a rubber hose/pee hole,

2) A poppet valve leading to freedom back down through mid unit and a spray port .

3) 4 spray/drain (path 1b) holes leading to freedom back down the mid unit......This one I'm not sure 100% because I can't follow those holes and where they go BUT I sure see 4 of them and they are on the pumps pressure side, where they go, not sure exactly.

They all empty out back to the lake in some way or form, either through hoses and pee tubes, the prop hub and exhaust spray jets.

Each play its own part in adding to or reducing the back pressure readings on our pressure gauges........We can watch as the poppets and stats open and close if we watch the gauge close.

OP states his pressure and temp went up some on his high end, to me, that says a restriction has increased, whatever that may be.........Increased pressure = increased restriction (decreased out freedom) = lower flow through = less cooling = high running temp.

I don't think his engine has suffered some sort of a mechanical failure that is causing his over heating, which can happen, no doubt and I'm sure you've seen it all, some of you have worked/seen a ton more of these black bastards then I ever will BUT, with that subtle increase in water pressure as he states and not draining back as I think he observed, it just makes me think it something happened to restrict water flow through ....JMO

 

[AFR Engines]

thanks for all the info guys I really appreciate everyone trying to help me as much as they can. I have made sure all passages on block heads divider etc are open. Since I can fill the block with the lower unit removed im sure if there is a drain in the exhaust plate it must be blocked or however it goes out the prop. the only way I can get water to drain is out the poppet drain hole or 4 small exhaust exhaust holes when water is coming from the thermostats to the 90 fitting on the plate. If someone can tell me how it goes threw to plate that would be really helpful. thanks everyone

 

[sam am I]

Perhaps this may help here or someone else down the road........


View attachment merc water flow_XXX.pdf

 

[AFR Engines]

Hello all. It has been a year now and i have taken everything off 4-5 times and still cant find a restriction. Thanks for everyones help.