225 promax low water pressure at idle

[whipper]

The question is why did it change? It ran one way and now it's different. Something happened. I had the same issue at the beginning of the year but an impeller fixed mine.

ive changed my impeller after running one once or twice because it just wasnt working very good I thought. Same thing as Silverbullet i went and found another one and tryed again and was good for the season? Thats the easyest place to start.

Also if you look at the touque specs for the impeller screws there like 8 or somthing? Real low anyway. If you tighten them up to much that would effect how well they spin also. Get another KIT.The housing impeller all the gaskets,rubber shaft seal the water tube plastic conector thingy and try it again. Dollers to a donut if your good at higher rpm just not idle that would fix it? i hope for ya anway.:big grin Not to mention the gearcase specs also. Always to spec. They are about as tight as you can tighten them though but ya never know. Just the anode one ya have to be carfull with because thats just a cast piece that can break if to tight.

 

[2fast4mom]

Couple of thoughts about pumps and gaskets not necessarily related to this problem.

The specs from Merc on torque for the water pump housing are dead wrong and ridiculous at 20 inch/lbs. This much torque WILL crush the housing and make the studs deflect. Been there; done that years ago. Nowadays I just tighten them real snug. No "monkey grip".

Gaskets: My Dad was a navy chief engineman and taught me young never to put a gasket for a Water pump in dry. I used to coat the pump gaskets with 2-4-C grease, lightly. This makes them seal good and also prevents them from tearing next time you take the pump apart, making for no peeling or shredding or scraping surfaces...

But more recently, a top Merc mechanic told me no sealant or grease was called for or needed, so I've been putting them in dry. This has worked out fine so far.

I have found pieces of gasket missing from various places as shown in the previous pic...grease, sealant, or not. It seems to be the nature of the beast...

Also, somewhere it is written to coat the impeller with 2-4-C grease before installing the housing while twisting the drive shaft. This works BUT the same Merc mechanic told me the grease weakens and compromises the rubber impeller, which makes sense. Use dish soap as a lube instead.

My two cents.

Lou

 

[whipper]

Couple of thoughts about pumps and gaskets not necessarily related to this problem.

The specs from Merc on torque for the water pump housing are dead wrong and ridiculous at 20 inch/lbs. This much torque WILL crush the housing and make the studs deflect. Been there; done that years ago. Nowadays I just tighten them real snug. No "monkey grip".
But more recently, a top Merc mechanic told me no sealant or grease was called for or needed, so I've been putting them in dry. This has worked out fine so far.

I have found pieces of gasket missing from various places as shown in the previous pic...grease, sealant, or not. It seems to be the nature of the beast...
Use dish soap as a lube instead.

My two cents.

Lou

this is what i also do.:big grin

 

[njj502]

Also, somewhere it is written to coat the impeller with 2-4-C grease before installing the housing while twisting the drive shaft. This works BUT the same Merc mechanic told me the grease weakens and compromises the rubber impeller, which makes sense. Use dish soap as a lube instead.

Very good advice here. Never lube up a part with a liquid it never sees. Impellers/grease, Orings/antifreeze, Orings/oil, etc etc.

 

[ROBERT CROSS]

I've followed the service manual,(90-840541), for our 2004 225X PM which states.."Apply a light coat of 2-4-C w/Teflon Marine Lubricant inside of water pump insert".
Has this procedure been up-dated, or am I missing something?

Bob

 

[chad202]

I've been using a tab of grease on the impeller blade for over 20years with no impeller failures so I'm not gonna change now.

 

[njj502]

I don't blame you, to each his own! I've seen way too many failures of rubber products, orings, wear rings etc from being in contact with "foreign" material. I generally install mine dry and on the first fire I'll crank the engine a bit extra before letting it fire. This ensures you don't burn it up when it fires.

 

[xb03]

I've been using a tab of grease on the impeller blade for over 20years with no impeller failures so I'm not gonna change now.

Same here, for 11 years I've used white lithium grease on the impeller and nothing on the gaskets without a single problem.

 

[2fast4mom]

I'm not saying grease will make the impeller fail, but the petroleum will release the nitriles in the rubber causing it to harden prematurely. I have removed plenty of stiff impellers that I had greased.

 

[ROBERT CROSS]

No consensus here....I'll go with Mercury I guess.

I'm not sure just how long the teflon grease sticks around after start-up anywho.... not long I wager. :wink

Bob
:beer:

 

[chad202]

I do general maintenance on our club members outboards and the ones that are hard are because they sat up or ran in salt water frequently. I change my impeller at least once a year but mostly twice a year.

 

[90 5.0]

Maybe something was in there and it freed up now??

Generally mine has under 3 to nothing at idle, and when it's 5-6 at idle i know I have crap in my system and i need to start digging stuff out again..

what is it running, is it abnormally high then too??

 

[SLOmofo]

Having a Bastard Child, OMC/Sports master, I'll weigh in here also!

GLUE the gaskets to the plate ! ! ! ! ! Other wise they will blow out! The pump doesn't do it but the ram effect of speed does. Permatex Weatherstrip Adhesive #81850 otherwise known in my trade as Elephant Snot.

Silicone grease or spray in the impeller housing and on the impeller will help 1. Cramming that impeller into the housing and 2. Give a little lubrication on first start up. If your going to use it right away I don't think other greases will be a problem.

Never ever start the engine without water to the pump. This means water has to be at least 5" above the seam between the lower unit and the mid section.
Reason, I saw 5 psi lower pressure after doing a compression check. I did the compression check twice.
This type pump uses water for lubrication and it needs it also for priming, they don't suck they blow.
If I run the engine in my tank I put the muff on the lower unit and turn on the water, then I start the engine.

 

[allisonjr]

Ive bought a second impeller, checked all gaskets surroundind the impeller inspected the impeller housing, ran water through the gearcase with the gearcase off the boat. Pulled the thermostats out ran water through the heads again to make sure water went through copper tube up to the powerhead. Also changed the water pressure gauge. Still same results

 

[bec]

did you make sure the hose going to water pressure guage was clear?just a thought

 

[ROBERT CROSS]

Did you inspect the poppet valve?

Bob

 

[allisonjr]

I blew the hose going to gauge with compressed air. I havent tackled the poppet valve yet, im not a 100% sure how it comes off.Would the poppet valve effect how the water pisses out the back?

 

[bec]

Just a thought before you go into the poppet take a small piece of known good tubing attach to the water pressure gauge at the engine and see if your pressure rises.i had a small enough piece in mine that you could still get compressed air through it.just a thought to rule out a small piece of trash interupting your w/p gauge.

 

[njj502]

Comes off with (4) 1/2" (socket size) bolts and one hose. Pretty easy once you get it apart. Found a small piece of wood in mine this am.

 

[silverbullet02]

It's not a big deal. Heck, I've done it on the beach before. Only thing is getting it perfectly centered putting it back together, but it's pretty obvious. When it slides in easy, you've got it.