Mercury OptiMax Engine Housing Fills with Water

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Author Topic:   Mercury OptiMax Engine Housing Fills with Water

WT Lee posted 10-07-2008 02:01 PM ET (US)
I am running a pair of 2001 Mercury OptiMax 200-HP motors on my 1989 25 WALKAROUND. I am having water routing problem with one and have no idea where to start looking. As I run, the engine housing fills up with water. First I lose one cylinder and then a second. In order to make it back in the other day, I had to constantly raise the engine to drain the water and continue until it filled again. I tried hooking up a hose but could not replicate the problem, so it may be feeding up from the lower unit. Any ideas where to start?
jimh posted 10-07-2008 02:12 PM ET (US)
If I understand your narrative, the engine cowling is filling with water when underway. I don't know if the common name for this is "water routing" or not. I have never heard that term before.
Is the water that accumulates in the cowling warm or cold?
Fishcop posted 10-07-2008 02:23 PM ET (US)
You might want to check the gasket on your cowling and make sure the seal is tight. If you are pushing a lot of water against the forward cowling while getting on plane or at low speeds, this could be your problem.
WT Lee posted 10-07-2008 04:11 PM ET (US)
we were running in rough water, so i didn't take off the cover. The water was warm but it had been sitting around the engine block for a few minutes befor I dumped it. It would fill at all speeds but quicker when at higher RPMS.
Thanks
L H G posted 10-07-2008 04:45 PM ET (US)
Sounds like a blown out poppet valve.
sosmerc posted 10-08-2008 08:49 PM ET (US)
I suppose it could also be a water pressure line or speedo hose that is leaking. Or a leaking fuel cooler hose.
jimh posted 10-09-2008 11:54 AM ET (US)
To help diagnose the problem, I recommend you remove the cowling from the motor, then operate the motor in the manner which causes the flooding to occur. Without the cowling in place you should be able to see where the water is coming from.
In most outboard motors any water in the cowling can drain to the sea by flowing down the lower leg of the midsection and discharging. You could test this by taking a hose and filling the lower leg of the midsection with water when the engine is not running, and then observe if it drains out or if it accumulates. If the water accumulates there is something blocking a drain path.
If could also be the case that water is being pumped into the cowling faster than it can drain. I asked about the temperature of the water because that will give a clue to its source. If the water is at sea water temperature, it is probably coming right off the water pump. If it is warm, it probably has circulated through the engine. A lot of water is dumped out of the engine into the exhaust. Again, if there is a blockage, it could prevent the water from draining fast enough, and water could accumulate.
phatwhaler posted 10-09-2008 11:57 AM ET (US)
I'm thinking a broken cooling hose or possible the poppit valve. On the 2.5L engines the poppit valve has a bleed hole. I'm not sure about the 3.0L blocks.
Should be a fairly easy fix.
pglein posted 10-09-2008 12:58 PM ET (US)
Jimh's method is the obvious recommendation. You can probably identify the source of the water by simply idling it at the dock. You may have to let it warm up to open the thermostat. If this does not work, take it out and run it. There are a lot of ways water can get into an engine cowling, and only a few ways it can get out. It won't take you long to find the problem.
For future reference, even though you were in rough water, I would recommend removing the cowling if this were to ever happen again. Some water splashing on the engine is a lot safer than submerging the block and it's electronics.
Also, I believe you said you have two motors. If the engine cowling is actually FILLING with water, next time, I strongly recommend running home on just one engine. Submerging the carburetors will cause water to get sucked into the cylinder, and result in hydrolock. This can (and usually DOES) result in an instant catastrophic failure of the engine in the form of either a broken connecting rod or cracked block. At best, you'll only blow the head off the engine. But the end result is the same; the entire motor is toast.
Tohsgib posted 10-09-2008 01:46 PM ET (US)
Engine is DFI, no carbs but good point. Cowls do have drains but are small. It is something that happens under load if idling on a hose does not reproduce the event.I think tied to a dock in gear would imick it under moderate power.
pglein posted 10-09-2008 06:19 PM ET (US)
Even with DFI, there is a throttle body that lets air into the engine.
You can still hydrolock the engine if it becomes submerged.
aussiejake posted 10-09-2008 06:28 PM ET (US)
Check the [aspirator or confidence stream] hose. If it is split the water will leak and squirt out of there once [engine speed is] brought up. It won't do it while idling as there isn't much pressure. Cheers, Jake
jross036 posted 10-12-2008 06:52 PM ET (US)
I've seen the flush hose on the back of lower cowl with a worn hole in it from the lines etc. rubbing on it. It should have a check valve on the engine side but ours didn't have the plug screwed in and water would come in under following seas.
deepwater posted 10-12-2008 08:14 PM ET (US)
what do you meen you loose a cylender,,do you meen the plugs short out from all the water on them
martyn1075 posted 08-17-2009 11:06 AM ET (US)
I had this same problem with my 1999 Optimax and thought I was the only one. It is an odd problem but in my case after finding no major problem with the engine I found a screw that fell out from who knows where that was stuck below the seal at the bottom of the cowling. It was such a minor gab between the screw and seal but with the amount of pressure/back-spray that was being put on the engine was enough to fill the cowling. Can't say for sure that your engine has a lose screw but I would take real good look. It may also not be obvious so you may need to remove the whole bottom cowling to find it, at least I had to. I also noticed with certain speeds that the water was entering and filling the cowling which would explain the water pressure into the engine. Lower speeds was worse then cruising or (wot)
RevengeFamily posted 08-18-2009 04:31 PM ET (US)
My 1999 225 port side Opti had a similar problem. Would run fine for a while and then start missing. Pulled the engine cowl off and discovered water right up to the lower cowling. Trimmed the engine up to pour water out. Lowered the engine back down, started it up and saw nothing. Had my buddy throttle her up and eventually found the culprit.
On the port side of the block down low is a diaphram for the cooling system. The diaphram got tired and eventually had a tear in it. It would only leak at higher engine speeds. The water was warm because it had already passed through the engine and picked up engine heat. Of course it was a pain in the neck to get to but it was not expensive for the replacement diaphram.
Hope this helps,
Norm

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Author	Topic: Mercury OptiMax Engine Housing Fills with Water
WT Lee	posted 10-07-2008 02:01 PM ET (US) I am running a pair of 2001 Mercury OptiMax 200-HP motors on my 1989 25 WALKAROUND. I am having water routing problem with one and have no idea where to start looking. As I run, the engine housing fills up with water. First I lose one cylinder and then a second. In order to make it back in the other day, I had to constantly raise the engine to drain the water and continue until it filled again. I tried hooking up a hose but could not replicate the problem, so it may be feeding up from the lower unit. Any ideas where to start?
jimh	posted 10-07-2008 02:12 PM ET (US) If I understand your narrative, the engine cowling is filling with water when underway. I don't know if the common name for this is "water routing" or not. I have never heard that term before. Is the water that accumulates in the cowling warm or cold?
Fishcop	posted 10-07-2008 02:23 PM ET (US) You might want to check the gasket on your cowling and make sure the seal is tight. If you are pushing a lot of water against the forward cowling while getting on plane or at low speeds, this could be your problem.
WT Lee	posted 10-07-2008 04:11 PM ET (US) we were running in rough water, so i didn't take off the cover. The water was warm but it had been sitting around the engine block for a few minutes befor I dumped it. It would fill at all speeds but quicker when at higher RPMS. Thanks
L H G	posted 10-07-2008 04:45 PM ET (US) Sounds like a blown out poppet valve.
sosmerc	posted 10-08-2008 08:49 PM ET (US) I suppose it could also be a water pressure line or speedo hose that is leaking. Or a leaking fuel cooler hose.
jimh	posted 10-09-2008 11:54 AM ET (US) To help diagnose the problem, I recommend you remove the cowling from the motor, then operate the motor in the manner which causes the flooding to occur. Without the cowling in place you should be able to see where the water is coming from. In most outboard motors any water in the cowling can drain to the sea by flowing down the lower leg of the midsection and discharging. You could test this by taking a hose and filling the lower leg of the midsection with water when the engine is not running, and then observe if it drains out or if it accumulates. If the water accumulates there is something blocking a drain path. If could also be the case that water is being pumped into the cowling faster than it can drain. I asked about the temperature of the water because that will give a clue to its source. If the water is at sea water temperature, it is probably coming right off the water pump. If it is warm, it probably has circulated through the engine. A lot of water is dumped out of the engine into the exhaust. Again, if there is a blockage, it could prevent the water from draining fast enough, and water could accumulate.
phatwhaler	posted 10-09-2008 11:57 AM ET (US) I'm thinking a broken cooling hose or possible the poppit valve. On the 2.5L engines the poppit valve has a bleed hole. I'm not sure about the 3.0L blocks. Should be a fairly easy fix.
pglein	posted 10-09-2008 12:58 PM ET (US) Jimh's method is the obvious recommendation. You can probably identify the source of the water by simply idling it at the dock. You may have to let it warm up to open the thermostat. If this does not work, take it out and run it. There are a lot of ways water can get into an engine cowling, and only a few ways it can get out. It won't take you long to find the problem. For future reference, even though you were in rough water, I would recommend removing the cowling if this were to ever happen again. Some water splashing on the engine is a lot safer than submerging the block and it's electronics. Also, I believe you said you have two motors. If the engine cowling is actually FILLING with water, next time, I strongly recommend running home on just one engine. Submerging the carburetors will cause water to get sucked into the cylinder, and result in hydrolock. This can (and usually DOES) result in an instant catastrophic failure of the engine in the form of either a broken connecting rod or cracked block. At best, you'll only blow the head off the engine. But the end result is the same; the entire motor is toast.
Tohsgib	posted 10-09-2008 01:46 PM ET (US) Engine is DFI, no carbs but good point. Cowls do have drains but are small. It is something that happens under load if idling on a hose does not reproduce the event.I think tied to a dock in gear would imick it under moderate power.
pglein	posted 10-09-2008 06:19 PM ET (US) Even with DFI, there is a throttle body that lets air into the engine. You can still hydrolock the engine if it becomes submerged.
aussiejake	posted 10-09-2008 06:28 PM ET (US) Check the [aspirator or confidence stream] hose. If it is split the water will leak and squirt out of there once [engine speed is] brought up. It won't do it while idling as there isn't much pressure. Cheers, Jake
jross036	posted 10-12-2008 06:52 PM ET (US) I've seen the flush hose on the back of lower cowl with a worn hole in it from the lines etc. rubbing on it. It should have a check valve on the engine side but ours didn't have the plug screwed in and water would come in under following seas.
deepwater	posted 10-12-2008 08:14 PM ET (US) what do you meen you loose a cylender,,do you meen the plugs short out from all the water on them
martyn1075	posted 08-17-2009 11:06 AM ET (US) I had this same problem with my 1999 Optimax and thought I was the only one. It is an odd problem but in my case after finding no major problem with the engine I found a screw that fell out from who knows where that was stuck below the seal at the bottom of the cowling. It was such a minor gab between the screw and seal but with the amount of pressure/back-spray that was being put on the engine was enough to fill the cowling. Can't say for sure that your engine has a lose screw but I would take real good look. It may also not be obvious so you may need to remove the whole bottom cowling to find it, at least I had to. I also noticed with certain speeds that the water was entering and filling the cowling which would explain the water pressure into the engine. Lower speeds was worse then cruising or (wot)
RevengeFamily	posted 08-18-2009 04:31 PM ET (US) My 1999 225 port side Opti had a similar problem. Would run fine for a while and then start missing. Pulled the engine cowl off and discovered water right up to the lower cowling. Trimmed the engine up to pour water out. Lowered the engine back down, started it up and saw nothing. Had my buddy throttle her up and eventually found the culprit. On the port side of the block down low is a diaphram for the cooling system. The diaphram got tired and eventually had a tear in it. It would only leak at higher engine speeds. The water was warm because it had already passed through the engine and picked up engine heat. Of course it was a pain in the neck to get to but it was not expensive for the replacement diaphram. Hope this helps, Norm