no water *%# D@*% pressure..... still

[illMATTic]

so last week i installed a bobs low water pickup. the install went pretty well. after i put it all together and dropped it in the water i was only building 5 psi max. so i took it all apart and called the guys over at bobs. they told me from what i told them the LWPU was installed correctly. so now i changed the impellor and upper pump housing. i am still only getting 2-3 psi now. the water coming out of the pisser is all spuratic like there is air in the system.

when i step on the gas the psi will run up to 10-12 and then drop right back down.

i am going crazy at this point. anything would help. i have a lower pump base on order. this will make the pump all NEW.

 

[xsive]

I had the same thing happen once when I replaced the upper pump body. Took the lower unit off 5 times before I looked into the pump body where the water tube goes and there was no rubber grommet for the tube to seal too. I had assumed there would be.

have you changed anything else since you put the nosecone on?

Not saying that is the problem but it's worth a look.

 

[illMATTic]

the rubber is there. i made sure of that.

originally i only installed the cone and put the LU back on with the old pump. it did the same thing as it is now. i think i warped the pump housing by tightening it too much. i am hoping the lower piece will solve my problems.

 

[Chris E]

ok Matt, step back for a second - the problem is simple and damn frustrating. first thing i'd do is crack a beer and go backwards through the process. i've never installed one of these before but if everything was working ok before, so we no where the problem is. i'm thinking that you have a water leak because of the drop in psi, either that or you have an obstruction in the water line. i' don't know if where you started your diagnosis but lets start here:

are you running the boat in water or on land? they do make a low water pickup set of muffs to run on land. get a pair and run this thing on land. while your at it grab some beer. just remember that city water runs about 60psi so your water pressure gauge may start playing tricks on you. you really interested in water leaks at this point and beer - don't forget the beer.

you need to find out where the water is going - is it leaking down through the original pickups? is that supposed to be sealed off? is it leaking anywhere else - is the joint where the lower unit attaches leaking? is water coming out exhaust through the prop? checked out ok - have another beer.

hows the engine temperature? higher or lower than nomal?

on a lot of mercs there is a white plastic tube that joins the lower unit pickup tube to the engine tube - check it sometimes it sticks - it may have slid off during installation. checked out? - beer time.

this one is a long shot - but on some mercs there is a little quad ring at the base of the powerhead - it may have melted blocking the water passage - if this is the case its 6 pack time.

hope this gives you a few ideas (and a slight hangover). remeber the 2 most important things stepping back to isoloate the problem and beer. it always ends up being something simple in the end. i've run into these problems countless times before and ive found if you leave it for a day and go back the solution usually appears almost instantly. i really think you have a water leak somewhere that is shooting water where it shouldn't be going. either that or an obstruction in the water system - pickup or outlet side. good luck - while your at it have a beer for me!!!!

 

[illMATTic]

thanks chris,

I have checked for obstructions through out the system. none were found. i have tested this is the river. fully submerged.

the only thing I may have done wrong was over tighten the water pump. i noticed the upper pump housing was all tweeked and warped. i replaced it and the imlellor but did not cure the problem. so now i am replacing the lower pump housing.

i have confirmed the upper pump outlet is mated to the pickup tube inside the mid section.

i have not run it on land yet. i think i will mess with that tonight with a beer in hand.

 

[Chris E]

just another thought, (a few scotches helped bring this on) is it possible that the water flow from the low water pick up is less than the original? it now has to travel a further distance and make 2 90 degree bends. how many holes are in the new pickup compared to the old? have you done a pass with the low water pickup at say 30mph compared with the old set up - how was the temperature?

 

[jkeiper]

Chris,

I love your post! I can identify with the part about opening a beer before you try to diagnose the problem.


Matt,

You may have checked this and I'm not familiar with the install of a Bob's cone kit, but is it possible the the 2-90 deg. elbows could be threaded in so far that the inside distance between them and the inner part of the housing/casting of the lower unit or cone kit could be causing a restriction of the water flow in that area? I don't think at this point it has anything to do with the water pump. Like I said, it may be a long shot, but it was the only thing that came to mind.

Jim

 

[illMATTic]

i should have mentioned that after the first three days of screwing with this i unblocked the factory inlets. this leaves all kinds of room for water to get sucked up.

even when i was running at 3000 rpm at about 30mph i was only seeing 5 psi. i got on a couple times and the pressure never rose above 5 psi.

i have let it sit for a week now so i actualy forgot how it acted before. i will have to take it out to the river and see what it does.

 

[jkeiper]

Matt,

Does the water from the low water pickup just go through that hose and then dump into the same cavity as the original water pickups are in?

Jim

 

[illMATTic]

yes, it goes right into the top of that cavity. the guys at bobs said it should make no difference if i have the factory holes pluged or not as long as the whole LU is in the water.

i have tested with either the factory inlets pluged or with the LWPU pluged. still the same. this is leading me to believe it has to do with the pumping system.

the old upper pump housing was tweeked pretty good. it was warped leaving about a 1/8" gap. now im thinking with the new upper it still has this gap using the old pump base.

 

[Blizz]

Are you sure your copper pick up is seated well at both ends in the grommets.

 

[jrogers]

Let see if I can assist

What type of water pump did you buy. Hopefully it was a quicksilver kit for your merc. I have a factory low water pick-up and use only quicksilver water pump kits, which means it comes with replacements for everything (gaskets, housing, pipe, key, and housing).

The only thing I can recommend is ensuring you put the key on the impeller. The key is a small piece of metal that fits in between the impeller and shaft (small notch on the shaft). If you have the key on, all proper gaskets, and the 2" white pipe in place, you should be good to go.

One thing that would prevent pressure (if everything worked before) would be a clogged water pressure gauge pipe. Try pulling the pipe off of the back of the gauge and shooting compressed air down the pipe to clear it. Just shoot it into the cooling system.

I have seen weak pissing at low throutle. Once you give it some throutle (in gear) and go back to idle you should have a stream pissing out.

Don't run the motor unless you are getting above 17 psi at throutle (in the water).

If in doubt, buy the quicksilver kit and redo it. I'd be worried if I did not have a solid stream at 3500rpm. Make sure your over temp alarm is working.

See ya,

 

[illMATTic]

thanks for all the tips guys,


i do have a quick silver pump and the key is in the impellor. i pick up the lower pump base today so i hope this takes care of it. its got to

 

[Blizz]

Just one other guess and i know you probably checked twice but are the impellor blades in the right direction. If so i hope you get it figured out summer is ending quickly..

 

[Roberts Marine]

Matt:
It sounds to me that you have an air leak as opposed to a water leak. The water pump base could very well be the problem. Check the gaskets. I also had one instance where one of the water pump studs was screwed out a ways and when you tightened it down it didn't pull the housing down tight. Remember that ares is full of exhaust. There is a divider between the exhaust housing and the water pump area that you are supposed to put a bead of sealer on before you install the LU.
Good Luck
Bob

 

[illMATTic]

all is well. the lower pump base fixed it.

 

[orangecrush]

water pickup

Matt glad to hear you solved the problem. ijust ordered a bob's low water pickup for my 3.0 250 whats it like to install thanks Paul

 

[Chris E]

yeaaahhhhh - did the beer help?

 

[illMATTic]

chris, the beer did help. :cheers then i helped myself to a couple more once i saw that psi guage hit 15.

 

[JW]

Now for more engine height and testing!