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1982 OMC 800 wont pickup water

D

drewzap

Member
Hey all,
I have an 82ish OMC 800 mechanical shift unit. The engine started to overheat on me..and no water was coming from my pee hole, so I assumed it was the the impellor. Upon disassembly, the old impellor was in good shape..but since i was there and had a new one in my hands.. i replaced it anyways. Shaft looked good, all splines intact.
All reassembled, earmuffs installed...water on, fired the engine up..and no water out the pee hole....rev the engine and it gets better, but not what i would like to see...
suggestions???

thx
DZ
 
Re: OMC 800 wont pickup water

The drive fully down ?

You sealed around the pump with sillycone?

You running on muffs or you have the drive submerged?

You shot the zerk with grease on the front of the drive in the hole ?
 
Re: OMC 800 wont pickup water

yep..all the way down,greased the zirc, pump sealed with sillycone lol, perhaps not well enough? but it also failed before and as i stated, the old impeller looked fine...I am running it on earmuffs..as I usually do before heading to the lake to make sure its working ok...
what exactly is the path from the open water into the impeller?? i cant seem to see any path or tube...
also...I saw some small wear grooves in the housing, but i cannot imagine that it would cause failure...i dont believe its designed to work ONLY on glass smooth housings...
I am going to order up another impeller and housing i guess and try that...unless someone has any other ideas????
 
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Re: OMC 800 wont pickup water

I'm not familiar with the OMC 800, but recently have been playing around with a standard Cobra.

I have been looking for places where air can enter the system and cause a low water flow condition at idle.

When I separated the upper and lower units, I noticed one of the water tube seals had not seated properly and was not properly engaged with the lower unit. It was permanently deformed because it did not seat properly.

I bought new seals and installed them and re-assembled the upper and lower units. I noticed it is very difficult to see if that tube engages properly when putting the units together. So I took it apart again to inspect the new seal. Sure enough, it had not seated properly and was starting to deform like the old seal.

I don't know if the 800 uses a tube or not, but if it does, it is worth looking at as a possible place for an air leak.

Also, the tube in the Cobra is located in an area where it may be under some positive pressure from the exhaust, thus making any air leak worse. But I'm being hypothetical here, just a thought.
 
Re: OMC 800 wont pickup water

cobra is a different dog altogether.

Bear with me as in my own inept way in describing the way the water gets to the motor. Reason i stated motor cause your problem may be a blockage there.

Look at the drive lower unit, see the inlets where the water enters the lower. Is there a blockage there, say you ingested seaweed, or a plastic garbage bag or some other garbage.

With the lower off look down the channels, see there are no tubes as in a cobra or earlier stringer drive. This is one of the reasons i am loath to get rid of my 86' stringer and i am babying it along.

The water enters the lower travels up the channels, and enters the water pump in the upper. You know this already cause you did the water pump. The thru bolts must be sealed on the pump, the water pump as per the manual seloc # 3400 right hand corner would explain it better,see where the pump meets the housing you had to seal that also as well as the lip and the cover of the pump. If you missed any of that then you will loose suction hence no peeing on the ball gears.

You can use a water hose and back flush at this point to see if you can flush out the channels and the inlets.

Water travels up the channels to the pivot caps does a u turn thru the trunnion the starboard side has the pee hole on the ball gear. Water then enters the intermediate channel to the hose inside the transom. That long hose can do one of 2 things, it can go directly to the t-stat housing or go to a heat exchanger. Then to the t-stat housing.

Say it goes to a heat exchanger such as a power steering cooler, it can be clogged up.

So say you got that lower back together and the drive back on and you pulled the cap on the trunnion starboard side, and cleared it of any obstruction "it has 4 screws holding it on " and you pull the long hose off where ever it goes to first and hold it straight up and with water going to the drive you start the motor and have water shooting straight up maybe 10-12 inch's then you know you have good water to whatever point that long hose goes. You need only 3-5 seconds and then quick shut off the motor.

Say you pulled the trunnion cap and are now wondering where to get that large rubber o-ring, and the gasket? Well a garden water hose female rubber washer is a exact fit, and any auto store will have gasket material cheap just make your own gasket. Just make sure you scrap off the old gasket get it clean, use a little sillycone, ( i said a little ) just to hold the rubber washer and the gasket to the cap.

Say it went straight to the t-stat housing, then maybe the t-stat is bad. It's frozen closed maybe ?

Me for now i would pull the t-stat and replace it latter and close up the housing or leave the t-stat out for good.

Now start the boat it still overheating ? You have the idea now ? Keep going down the line till you find the obstruction, risers, heat exchangers ? Maybe a flapper / shutter fell down and is blocking the exhaust ?

Say you don't have good water out of the long hose from the transom, you could use a garden hose to back flush the hose.

Post back and let us know what happened.
 
Re: OMC 800 wont pickup water

at one point... i put the muffs on the lower while i had the upper off to reinspect..and turn the water on to see what happens...
you are saying it comes in the to side ports.then is drawn up thru the lower/upper mating point?? or am i missing the "channels"?
i have a hole drilled in a cap on one of the trunion caps to backflush the drive..it doesnt make pressure there...
grrr..if weather holds im going to take it apart..YET AGAIN this weekend before i end up scrapping the whole boat.
 
Re: OMC 800 wont pickup water

The small grooves don't sound good but I think your right . Make sure the small keyway or 1/2 moon key is in good shape.
 
Re: OMC 800 wont pickup water

when I hook up the muffs to my 800, I turn the hose on full and, water starts running out the exhaust grate and prop before I even crank the engine.
I'm in the country - only 55 psi at my garden hose.
 
Re: OMC 800 wont pickup water

i have plenty of water gushing out the grates and whatnot..but its not getting up into the engine..or for that matter the pee hole. I was invited duck hunting this weekend...so it might sit another week unless the weather holds lol.. blues skies=poor hunting but good fishing
 
Re: OMC 800 wont pickup water

Could it be there is some abnormal back pressure getting into the water jacket? Thus causing the water not to flow at low RPM? Like a slightly leaking head gasket or bad exhaust manifold or riser? A problem that the impeller can overcome with a little RPM?

Is there any difference in flow before and after the t-stat opens?
 
Re: OMC 800 wont pickup water

i covered that in post #5. Remove the t-stat make sure the housing is clear the overflow hole clear.

I also covered the riser issue as well as the flapper / shutter blockage issue.

But, and this is a big but, the water pump must be assembled correctly, and sealed correctly.
 
Re: OMC 800 wont pickup water

drewzap said:
i have plenty of water gushing out the grates and whatnot
Click to expand...
water ONLY exits the exhaust AFTER it has completely circulated through the exhaust manifold cooling path, which is after the engine once the t-stat opens

if water is pouring out there, your entire cooling system is fine, except maybe the thermostat- but you have no way of seeing that unless you have xray vision.
 
Re: OMC 800 wont pickup water

Chiefalen,

flappers??
so in the housing with the grates..is that just a hollow area? no pathways or channels to block up before it enters the upper/impeller?? i replaced the shift cable while i had it open and saw nothing in there, but really dont know what lies beneath that seal and zirc fitting in the lower.
What is that seal called...cause once i open it up AGAIN... i might as well replace it.
I am considering pressurizing the lower from above and seeing if anything flows back to the grates/pickup.
 
Re: OMC 800 wont pickup water

I feel your pain and have read, and re-read this thread again, must be 5 times now.It must be frustrating to you.

What manual you using ? I use the seloc # 3400 upper right hand corner.

With a garden hose putting water to the drive, i find it incredible that no water is making it's way to the long hose that comes in from the transom.

That thru fitting must be clogged up IF the water pump was sealed correctly, and installed correctly, and the fitting was shot with grease. No water peeing on the gears, after the starboard trunnion cap was removed and the holes checked for blockage. If you checked it then i am dumbfounded.

I am in Manalapan nj you near me ? i will for free be willing to take that drive apart myself.
 
Re: OMC 800 wont pickup water

wow thx Cheifalen
,
i'm only around the corner..across the woods past Grandmothers house north of San Fransisco lol....
But i appreciate the offer. Yeah this thing is pissing me off...it has very low flow if any at all*at idle..but does pick up some when above 2000 rpms. It seems to fall off some tho, but the engine gets hot at idle so i run it up..let the engine cool..and shut her down.
It absolutely poured here last night..and I attended a Black Label Society concert.. so although the sun is out, I am not in the best of shape to be re-disassembling the drive, (just not into it today lol).
The manual i have says OMC repair manual with a white and brown runabout on it. Its really old and corners of the cover are tattered, but it has been dead on thus far as to the steps to remove, replace etc. Possibly the Seloc one. Its gotten to the point where i can have the upper/lwr split and the impeller housing removed*in about 1 1/2 hours beer time. I really wish i could get into the grate area and see if anything is moving back and forth in there under pressure and blocking the flow. I've backflushed the upper unit through both ports with the impeller removed, attached the muffs to the lower with the upper removed and checked flow there. Its possible i didnt use enough grease through the zirc. I am assuming that allows a quick prime?? I will again remove the impeller housing..use a sh*tload more silicone on all facings and bolts...and try again. I am half tempted to drag it to the local launch and put it in on the trailer just to see if fully submerged i have a problem..that would put the notion*I did not seal something correctly, although it was doing this before i removed the old impeller.
*

*
DZ
 
Re: OMC 800 wont pickup water

Miss me I'm BAA_ACK lol...
Holidays are over, trout season is onfire and I am still landlocked.
So I've been pondering bypassing the outdrive altogether with a raw water pump, drilling a hole in the hull and running it to the T-stat housing. Would make impeller changes alot easier...
Has anyone done this before i go drilling unnecessary holes on the bottom of my boat???
Pros??/ Cons????
Once again, thanks for your time peeps..

DZ
 
Re: OMC 800 wont pickup water

drewzap said:
i have plenty of water gushing out the grates and whatnot..but its not getting up into the engine.
Click to expand...
it comes out the grate AFTER it circulates through the manifolds (after the tstat housing)

that's the ONLY WAY water gets out

I don't see where you have described anything that would indicate you have any problem with the raw water system
 
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Re: OMC 800 wont pickup water

drewzap said:
pondering bypassing the outdrive altogether with a raw water pump, ....
Has anyone done this before....
Cons????
Click to expand...
upper gearcase requires that raw water flow through it for cooling. - bypassing that will cause outdrive failure
 
Hystat...
the water is not being picked up into the engine... no water out the "pee hole"..so the engine overheats..
bummer about the raw water needing to go thru the upper....would have made the repair easy.
guess I'll send it in and let someone else play with the damned thing... i cant be bothered anymore
 
pee hole? you mean the ball gear spray hole? Not all units have that hole. Yours might just be plugged. Regardless, that's no reliable indication of water getting to the engine- If it's dumping out the exhaust, you have plenty of water to your engine.
If it isn't, replace the impeller.
You have to go into the impeller housing every 3 to 5 years anyway to grease the water pump shaft splines. If you don't they will fail.

It's not a scary job. Just time consuming the first time - but after you have done it a couple of times, it's a 1.5 hour job.
 
it has the ball gear spray hole... its just not pumping water up there...i replaced the impeller...2x...lubed the hell outta the bushing and shaft...used a ton of silicone to seal it all up...even went as far as trading upper units with one known to be good and theres no water making its way into the engine overheating it.
I must be missing a clog somewhere...i dunno. i cant submerge the whole unit in my driveway to see if mebbe below waterline, it works, without great time and effort to tow to the lake, launch..tie up and inspect. Earmuffs have always worked before...pissing me off lol..
The book shows a hose from the inlet of the lower unit to the impeller housing.. but i cant see it...Im wondering if there is one.. and if its collapsed or sucked up into the passage???
 
Your garden hose should be able to fully fill the entire engine and cooling system BEFORE you even start the engine. Doesn't matter what shape the impeller is in...could take it out and throw it away and still run on muffs.

I don't hit the key until I see water pouring out the prop.

If muffs no good, spend $10 on a radiator flush kit and hook the water up at the supply to the thermostat.
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I wouldn't focus on the ball gear spray hole. I've honestly never even thought to look at mine. If the engine has water, go boating.
 
UN FRIGGIN BELIEVEABLE!!!!

So after sitting there in a state of flux since January, I decided to have another crack at finding the problem. I actually purchased another outdrive to swap and see if it was an internal issue or not. It turns out.. it was not in the drive. I disconnected every hose coming to and from the cooling system and backflushed the inlet once again. This time, i removed the two outer tranfer block and sealed the garden hose into the engine side of the inlet. After turning the water on,,it just trickled out the cavity's for 5 seconds or so..when all the sudden POP!!!
Water started pouring through unubstructed. I saw a wad of something come shooting out and found it...turns out there were some busy wasps that somehow made their way into the cooling system and made a nest in the inlet. I fugure it was loose in there and moved back a forward depending on RPM and pressure....
On the good side.. everything is working and i can get the outdrive off my boat blindfolded ni like 20 minutes ..
Happy boating peeps..and thanks for al the help!!!

DZ
 
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