Recap my cooling issue

LaRea

They are air supply hoses for an air-actuated drain valve.  

Somewhere, you should have a little blue device that looks like a miniature bicycle air pump (originally clipped on top of the engine).  There's also an air valve on top of the engine, like on a bicycle tire.  When you attach the pump to the valve and pump it a few times, it opens a valve in the water pump that drains water out of the pump body.  

If the air hose is disconnected or broken, the pump will still work fine. 

rasbury

would the little blue caps on the body of the pump do the same thing? I went to the Merc shop and that line and hardware would have to come from Merc, no one has them so either not a popular option or seldom are replaced. I'm in Orlando and we don't deal with hard freezes and if I can undo those blue caps on the pump and do the same thing, I'm good for now and will cap them off until I do my impeller change next go around and will get them...I do like to keep things the way they came but if I don't get this boat back in the water, the admiral will be looking for a new captain....

Dream_Inn

I imagine it will stay sealed if it is still in tact on the pump.  Little late now, but if I remember correctly, you push on the piece around the hose and then they pull right out.  Took me a little playing before I figured it out.

LaRea

Google "mercruiser water drain system" or look here for details (might be slightly different on your 350):

http://www.boats.net/parts/search/Merc2/Mercruiser/496 Base Mag - (496CID 8.1L V8)/0W650000 THRU 1A066165/Water Drain System/parts.html

I'm not sure whether the blue plugs would completely drain the pump.

rasbury

hmmm...think I will cap off for now....I tried pushing on them and got nothing then I got aggravated and cut the line, not the best move of the day! We seldom get to freezing here in the Orlando area...I picked up the boat in Pensacola where they had a real hard freeze and I'm pretty sure the guy I bought it from , like everything else on the boat, did nothing about it. I need to look at the risers and manifolds next and change the foot oil and I think I will have everything pretty well caught up!

rasbury

http://www.marine-496pump.com/  check this out...

rasbury

well, success? Got it all back together ( sure comes out easier than it goes in ), fired it up not really expecting any good news, but, I was watching for water to come through the back side and was not giving it long and there it was. It seemed to run up high though as it went a little past 175 but running on the muffs may not be getting sufficient water as the strainer did not fill completely. Boat seems to want more water than I can offer at the house so to the ramp in the am. The surveyor noticed when I bought it that the supply line from the foot looked like it had been crushed beneath the motor then pulled back out and left. I did not think much of it being a hose. Now I see this marine hose is a hard wall ID hose, I'm going to replace it chop chop. New rebuilt starter gives me hopes of smooth starting for a while. There is a pretty easy trouble shooting section in the repair guide to determine if its the starter going or bad connections and if followed works like a charm!

rasbury

well, crashed and burned...started at the ramp, took it off the trailer and watched the temp climb over 175...should the sea strainer be filling completely? Also, I took the cover off the sea strainer and turned on the sea valve to the thru hull- should not water be rushing in???

Dream_Inn

I would believe any strainer connected into a seacock should have water rushing in and filling the strainer.  Sounds like something somewhere is clogged.  Maybe it's a hose on the engine (could it be possible one of your impeller pieces clogged something?)

craigswardmtb

Couple comments:

1. I'm not a fan of the air drain system.  I always get more water out of releasing the blue drain plugs.  There are 3 on each of my engines, which are 496's.

2. I would check your water pickup hose that runs from your B3 drive.  Someone else mentioned it earlier, so not sure if you already checked, but it sounds like you are getting bad flow.  Those hoses go bad and after time collapse under pressure.  Even though they include the water pickup hose in most bellows kits many mechanics don't change them because they are a PIA to get in and out.

3. Could impeller chunks be clogging something.  THey have been known to clog the power steering cooler causing an overheat condition.  Also check the thermostat to see if its stuck.

4.  I would then check the risers and manifolds for being corroded.  The drain check valve on the bottom of the manifolds can scale up from corrosion.  You are low hours so I wouldn't think it would be corrosion related.  Salt can certainly corrode quickly though.  Unlikely in my opinion.

rasbury

thanks Craig- I think I'm convinced I have something blocking my thru hull pick up- if I run it with the muffs on I can get enough water to the engine so it will run about at temp but at the river with no pressure not. I pulled the cover off the sea strainer and opened the sea valve and get nothing.  I think that is my culprit, I hope, but will have to wait until the weekend to get it back to the house and take another look at that. Also the pickup hose from the foot looks like it was crushed perhaps when the motor was installed- I don't think is is collapsing completely as that inner wall is very hard, almost PVC like but I'm concerned it is either restricting the flow or will continue to crack and cause a problem. It is restricted about 25% I would guess and with no other water source I think just not enough. I have all the impeller pieces so was very fortunate there...I was thinking the impeller started all the problem but perhaps blocage of the thru hull started this chain of events, just very lucky it happened at the dock and not while I was roaring down the river. I do need to check those risors as it set on a lift- might have been better off in the water as at least it would not have gotten as much oxygen in there to corrode. I am quickly becoming a Merc expert! 

JC290

Ras that strainer should be filling with water your blocked up some where. The seacock might be part of the way restricted. Have you cycled the handle open and closed? 

rasbury

yep, I'm thinking the same...don't have enough experience yet but that;s what I figure as well...

TikiHut2

Sorry I'm late to this one but that picture of your pump scoring means it's toast. No further discussion. Sorry.

A new impeller won't sit on those grooves but will only cavitate. I couldn't get mine to draw water even when I force fed it with 60lbs of hose pressure. Put a whole new pump on it (kissing 5 boat units goodbye) and, baring anything you haven't disclosed, it'll work right away.

One last shortcut: Re-read my saga on the water pump impeller issue. There was a link in there to a replacement SS backing plate available on Ebay that would've been my last resort if Mercruiser hadn't stepped in and gave me a whole pump as compensation for the defective impellers left on their suppliers shelves that I endured.

Good luck dude.  Those water pump removal times at 10mins were dead on. Not a skill I really wanted. Rum was ALWAYS involved after the fact.
Mike

rasbury

Tiki! With all your pump issues I was really waiting for you to chime in...also, I thought I may have solved the bad impeller issue as it did not make sense to me that there would be "shorter" impellers out there by accident. I have worked in/around manufacturing a good part of my life and a part made that way is on purpose not by accident. Somewhere up above is a post to a company that offers a "shorter" impeller along with two "wear plates" of sorts to make up for scouring on both ends of the pump. Perhaps those impellers come from the same supplier that Merc uses and they got mixed up? I am not convinced my pump is done- it was pumping just fine before the impeller came apart and I blame that part on me as I had the new one in hand. I need to bring the boat home as mentioned above, but I think I have a blockage of sorts through the thru hull raw water pick up. I will bring it home this weekend and look at that. If I still have a problem, I will look back at the parts that company offers as that is less that half the cost of a new pump and other than the areas that are scoured, not much else to go wrong with the pump until the bearing implodes....

luckydog

WOW, I've been watching this thread, sorry I can't help. Man o man you do have some patience, good luck and keep going

rasbury

I have to have patience, I'm poor!

rasbury

Tiki- does your sea strainer fill when you put the boat in the water or have you noticed either way???

howardrams

Ras, make sure the outdrive is in the full down position.  Not up in trailer mode, because some hoses separate at the transom when drive pivots up.  

TikiHut2

I don't have a strainer on my raw water intake for the seawater pump. It goes directly from the sterndrive foot to the raw water pump, and then out to the engine circulating pump(etc), and out of the engine through the exhaust headers.

Most importantly! **** If you put muffs on my sterndrive and take the intake hose off the RW pump it flows in like a river. If I reconnect the hose (almost)nothing will go through the pump until it's drawing water correctly.

It was the most confounding thing to understand but your pump body is obviously scored and a new impeller simply will not seat correctly to form a suction with those old grooves allowing it to suck air from the output side.

Try the replacement backing plate I mentioned if funds are tight.

After a brief but critically important mention by AlSwagg about a Merc impeller recall I checked mine carefully. The (VERY)slightly shorter impellers I got from the dealer were NOT made that way on purpose. The factory had a recall and those were actually checked and incorrectly found to be within spec and put back on the shelf. In reality the compound WAS defective and didn't maintain spec size. I was the lucky guy to disclose it to Mercruiser and documented my experience in that thread. They were good for it and I gained my NASCAR speedy water pump changing experience.

Sorry you're having the issue but you'll get past it and will have valuable water pump experience too. Try the plates.
Mike

RussRuss

I have the dual pickup - one from the transom and one to a seacock.  With the boat in the water it comes up to the top of the strainer and stops since that is the water level.  I need to be careful since if I get me and another fat guy on the stbd side it will overflow the strainer and start flooding the boat.  But the water doesn't gush in the boat if that was your question.

rasbury

might want to put a cover on that strainer!

rasbury

ok, back to this..one last thing I want to check before I jump back to the pump is the thermostat...I see from the manual to put it in water and the temp on the therm is 160, manual states to check temp at initial opening, at full and to check the valve lift but really gives no specs as to measure any of this by, what should I see and how di I verify? I'm thinking I have to replace the gasket I assume when I take it out so just replacing the therm at this stage is the way to go but would like to know this was a problem or not other than trial an error...

rasbury

wow, did not see that coming .....got the thermostat out ok but did not think this through apparently and need to go back to the manual. I have a 1/2 closed loop system so as near as I can tell, I have no thermostat on the raw water side and it cools the manifold (Heads?)and the heat exchanger while the closed side cools the block. The thermostat I have and the only one in the manual is on the closed side, and, it's bad. I have a temp sensor at the thermostat, and, what looks like another on back on what is called the trans cooler? Oh MY. So I don't know which side is overheating......

rasbury

I rechecked the thermostat and it did start to open around 180 about 1/8th inch or so...as the temp climbed up to around boiling, it was up around 1/4 to 3/16 open...at 165 the book says it should be "open" but I don't see the details of that per above. I'm going to replace it but would like to know for the future. I will do a little surfing as well but if anyone knows....this thermostat has nothing to do with my raw water pump.....

rasbury

and the other sensor is on the power steering cooler at the back of the motor which is also the raw water inlet to the motor...

rowboat212

Thermostats have seriously slipped over the last decade, or so... It's likely safe to blame Chinese production and saving an entire penny over the next thousand out the door... 

They should start to open around ten degrees under their rating and be wide open at or around their rating... The issue is the Chinese decided a fifteen degree window is close enough.  

Test them every one before installing, no matter the brand or the cost.  Let them cycle open and closed several times.  Seriously, two out of every five are bad out of the box.  Also, if you're so inclined, drilling a tiny hole in the blade isn't a bad idea either.

rasbury

so, I assume you are confirming this one is bad...I used a hand held laser type temp sensor which was at a little over 200 when it came to boil so I assume I am getting good temp readings. My problem started with a raw water impeller problem and was running 175 prior so very puzzled I have this issue. So since I have it out I will replace it but this does not solve the raw water pump. I was thinking that perhaps when the impeller broke and jammed the pump could it have bent the impeller shaft causing an air leak to the system? I think I will order the kit with the wear plates and shorter impeller I put the link up to. If it is still bad they offer a rebuilt one for 200 bucks I think it was and I will get that and will then have parts for next season. These parts will allow a rebuild of the pump if it gets the grooves from wear in it. I will try just the new therm first. The raw water pump moves 30 GPM at 4000 RPM, maybe at idle it just does not move much water.

rasbury

I am also a bit puzzled that if I have two temp sensors on two completely separate systems for the most part, why is there only one gauge? The audible temp warning went off when the impeller broke so have to assume the temp sensor and gauge are accurate but would seem like you would have two gauges so you know which side you have the problem on...and the raw water side sensor is right where the water goes into the power steering cooler, what is that measuring other than the water temp coming into the motor? Confusing......is there possibly another thermostat there I a not picking up on??? 

rasbury

Well, success sort of!  I got the parts in for the pump and got it all back together. I tested at the house and had water flow through the motor and put the boat in the water on Saturday and it ran and cooled perfectly. I think I'm going to go ahead and order another kit just in case they would not be available in the future. Also, the water impeller is about a 1/16th shorter than a standard one to make up for the added material.