water flow/volume test?

rolandt

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Aug 16, 2012
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im having overheating problem with my 73 gm 250 in line 6 165hp, with alpha 1 drive unit. ive read some threads about checking how much water you get from stern drive. i get 3 quarts in 15 secs at 800 rpm. thats from the hose disconnected from thermostat housing. is this good? should i have more flow? does anyone have a formula for correct testing. thanks in advance for any help.
Roland
 

Bob_VT

Moderator & Unofficial iBoats Historian
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Re: water flow/volume test?

Welcome to iboats.

Go to the adults only sticky at the top of this section and look at the mercruiser information and read what the manual has to say.

I would just ask how old is the impeller?
 

rolandt

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Aug 16, 2012
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Re: water flow/volume test?

Welcome to iboats.

Go to the adults only sticky at the top of this section and look at the mercruiser information and read what the manual has to say.

I would just ask how old is the impeller?

the impeller is new. was carfull installig.
 

rolandt

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Re: water flow/volume test?

Thank you Fun Times for the flow chart. I will figure out my gear ratio today and retest. Sorry for the delay of my reply. Im not only new to iboat but to forums as well. had trouble responding last night. Also in response to Bob_VT. new pump. I have 2 manuals, a seloc and a clymer, but i did check the thread you suggested. Thank you. i will post test results later today. Hopefully!
Roland
 

ktbarrentine

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Re: water flow/volume test?

Thank you Fun Times for the flow chart. I will figure out my gear ratio today and retest. Sorry for the delay of my reply. Im not only new to iboat but to forums as well. had trouble responding last night. Also in response to Bob_VT. new pump. I have 2 manuals, a seloc and a clymer, but i did check the thread you suggested. Thank you. i will post test results later today. Hopefully!
Roland

Gee! a Seloc AND a Clymer! Nothing like adding insult to injury! recommend you get the "good" book (on-line, here, free!!)! Oh, but keep the others to use as knee-pads when you are in the shop working on the boat!:D
 

rolandt

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Aug 16, 2012
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Re: water flow/volume test?

Test results are dead on. I have a gear ratio of 1.65:1. according to Fun Times chart i should get 3.6 quarts. It couldnt have been more spot on. Before I ask what to do next let me tell what I've already done. NEW, manifold,riser,impeller,thermostat, circulation pump. Tests preformed-compression test,#1-115, #2-120, #3-114, #4-110, #5-105, #6-105. While doing flow test I checked to see and feel any air surge or pulsing of water at the hose from thermostat housing to manifold, all good there. With a pot of boiling water and a thermometer for making candy i checked thermo. and gauge and sending unit. at 140 degrees thermo opens gauge reads dead center of green. at 200 gauge is just in the red. checked exauhst bellows and flapper,ok. installed clear hose from stern to thermo housing. There is a stream of small air bubbles using the muffs but on the river there is no air at any time or any rpm. On the river i removed the thermostat and it ran barely in the green. Purged air at thermo. many times. no luck there. Rigged thermostat to stay open and went out again. Just took longer to over heat. 7 to 10 minutes at 2800 rpm or more. use to take less than a minute. I even called MC customer support,(920-929-5040) the guy was stumped. redid flow test catching water at prop, that wasnt easy but but it was dead on. I had a full head of hair a month ago. Dont know what to try next. Suggestions? What am I missing. Again, thanks in advance for any, and I mean any ideas. Roland
 

rolandt

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Re: water flow/volume test?

I know my manuals are not great. Thats why Im here. I aint that dumb. :)
 

Don S

Honorary Moderator Emeritus
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Aug 31, 2004
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62,321
Re: water flow/volume test?

Those numbers are "MINIMUM" amounts, a brand new pump and impeller should have more than that.
You do not use muffs to do the test. You also use a bucket to catch the water from the output hose from the transom shield.

Are you actually having an overheat problem? If so, when, Idle? WOT, under load, on muffs ????????????

If you are overheating, what is the condition of the hose from the bellhousing to the gimbal housing. Any kinks?
What shape is the water pocket cover in (the water tube from the pump connects to this in the upper gear housing.
 

rolandt

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Aug 16, 2012
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Re: water flow/volume test?

I will repeat flow test on the river. Should i be under load or is tied to the dock ok?. It over heats under load. Doesnt over heat with muffs, and doesnt over heat under load when rpm is lower than 2800. Under load at 2800 or more it will over heat in about 7 to ten minutes. I dont see any kinks in that hose from the bell housing. It looks kind of old. The water cover looks good. Very clean. I think i will remove out drive to check hose and water passages. Hopefully will get that done today and get on the river tomorrow. Will post results soon. Thank you everone for your help and support. Wish me luck, Roland.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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Re: water flow/volume test?

you replaced the impeller and pump, however did you flush out the old impeller pieces?
 

rolandt

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Aug 16, 2012
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Re: water flow/volume test?

I did not flush out old impeller pieces as the old impeller was in one piece.
 

Don S

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Re: water flow/volume test?

When you do your on the water test, hook up a clear hose between the hose coming from the transom and the thermostat housing. Then watch for bubbles at low speed and then at higher rpm. If the water pocket cover is leaking, you will get air into the water flow and cause bubbles and an overheat. or maybe there are holes in the tube between the pump and the upper housing, or the seals in the pump are no good or ...................
 

rolandt

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Aug 16, 2012
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Re: water flow/volume test?

? for Ktbarrentine. You said i should get the"GOOD" book here online free. Cant find it. Where do I look? Im better with a wrench than using a cumputer.
 

rolandt

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Aug 16, 2012
Messages
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Re: water flow/volume test?

I think Ive got it folks. After a THOROUGH inspection of the out drive, because im getting ready to remove it. I found a slit or a cut in the hose from the bell housing to the gimball houseing. It is way up inside and hope no one faults for not catching this sooner. This only the second MC I/O that i have ever worked on. BIG thanks to Don S,-(oracle by the sea) and everyone for taking the time to help. I will post results probably next week monday as i plan to be fishing this weekend. Already thinking of fishing lies to post.:) Roland
 

ktbarrentine

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Re: water flow/volume test?

? for Ktbarrentine. You said i should get the"GOOD" book here online free. Cant find it. Where do I look? Im better with a wrench than using a cumputer.

This is a link to one of the information "stickys" at the top of the mercruiser forum (where you are at now). This sticky has a ton of info that is good to know and review when needed. Look for "mercruiser information", click on it and look for "service manuals" These are the OEM manuals for the engines and drives. You cant download the whole manual, but you can search inside of them for critical info, and I believe you can print out selected pages.
http://forums.iboats.com/showthread.php?t=342393

(Post #2 in your thread also gave advice to do this):D

Looks like you will be looking in manual #1: http://boatinfo.no/lib/mercruiser/manuals/mercruiser1.html#/4

So I take it this is not the original outdrive?

If you provide the ser numbers for your engine and your drive, others here (like Don S., "oracle" that he is!) can provide actual downloadable PDF manuals for your drive and motor. They did that for me, so now I have them on my computer for ready reference.
 

rolandt

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Joined
Aug 16, 2012
Messages
10
Re: water flow/volume test?

exallent









Thank you Ktbarrentine. Looks like Ill need them. Managed to remove hose without removeing any of the outdrive. Dont know if I can get anew hose in that way but it doesnt matter. After testing hose with compressed air it did NOT leak even though there is a chafe spot that looks like an old tire with cords showing. Im going to try and snake in a new one cause it needs it. checked it good looking for weakness where a possible kink may have been accurring. As old and ugly as it is its integrety is good. No soft spots nor can i easily twist it to cause it to collapse. As far as i can see inside its clean and has no rot or any sign of comming apart from the inside. What to do. What to do? roland
 
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