Hole in side of OMC drive

[ccmarine]

There is an open 1" hole in the port side of the upper case on my 1990 OMC drive. When hooked to water hose water pours out of this hole. Does it need to be pluged? If so what part do I need? Thanks

 

[seahorse5]

Re: Hole in side of OMC drive

It's not a "freeze" plug but a cover for a drilled passageway for cooling water. It was a large diameter screw that was fastened to a threaded plate inside the water passage, accessable with the outdrive removed. Originally the screw was hidden under a Cobra medallion on the port side of the outdrive.<br /><br />If I remember correctly, the early parts books do not list these parts but the '92 on up books do.

 

[lrlima]

Re: Hole in side of OMC drive

Like a lot of people on this forum, I just made the dreaded cobra mistake - didnt know what this plug was for, unscrewed it, and the backing fell off in the drive. Going to have to pull the drive this weekend to retrieve it...<br /><br />But here's a question - what steps are necessary to winterize this section? I know I dont want water sitting in this section of the drive. How do you get the water out without removing the drive every time? Once I get that plug back in, I'm not messing with it again....

 

[Ron Everson]

Re: Hole in side of OMC drive

I believe the drain plug on that side of the drive drains that area. It's a little forward from the screw you removed on the port side (at least it is on my 1989 460 OMC King Cobra). I used both the official drain plug and the no-no screw to drain the outdrive. It was apparent to me that the no-no screw has been used to drain the outdrive before, so I just unscrewed it a little and the water runs out. As long as you don't turn it far enough to loose the backing plate, you can screw it back in just fine. Of course, if you don't like the risky method you can rely on the official drain plugs on both sides of the outdrive. The starboard side has two plugs and the port side has one.

 

[Lou C]

Re: Hole in side of OMC drive

Ron the 3 drains you speak of are for draining the pivot housing, not the drive itself, which is self draining in the down position. Those large screws in the middle of the upper gearcase were not meant to be removed, there is a hole used in the casting process there, there is a threaded plate inside that the large screw threads into. If you remove screw the plate falls down and you have to pull the drive off to get it out.

 

[lrlima]

Re: Hole in side of OMC drive

Lou C, my drive was in the down position when I accidentially took the plug out. The pivot housing was still filled with water...<br /><br />I imagine the self draining you are talking about is not happening for me. Is there an area I can check to see if its clogged? I'm getting ready to pull the drive to retrieve the lost threaded plate and replace a drive shaft seal where I'm leaking lube.

 

[Ron Everson]

Re: Hole in side of OMC drive

I'm with lrlima. The upper part of the outdrive doesn't drain out in the vertical position. The screw with the backing plate drains an area that holds quite a bit of water. I guess I need to study the castings a little more when I have the outdrive off to understand why it doesn't drain.

 

[Darkhorse1201]

Re: Hole in side of OMC drive

Sorta the same problem. I just bought a used 1988 OMC outdrive and the screw thing in the side is missing. I too thought it must be a freeze plug. The screw part is missing. If the backing plate did indeed fall inside, where should I look for it? Would it be in the water pump area ar do I need to take the top cover off where the top gears are? What could I use to replace the screw thing? Thanks for any help in advance!

 

[Darkhorse1201]

Re: Hole in side of OMC drive

Also - maybe it is possible to convert this hole to a hose fitting to allow the engine to run without the earmuffs? Any ideas? Thanks

 

[lrlima]

Re: Hole in side of OMC drive

You can do a search on this site, as some people were able to retrieve the screw backing without removing the drive. But most people have to remove it. Not sure about the water circulation. I'd just use the muffs.<br /><br />My biggest concern is that if the water doesnt drain out of there completely, it may freeze and crack the case...Even with the plug out of there, some water still sits in that cavity...

 

[marunr]

Re: Hole in side of OMC drive

Originally posted by lrlima:<br /> Lou C, my drive was in the down position when I accidentially took the plug out. The pivot housing was still filled with water...<br /><br />I imagine the self draining you are talking about is not happening for me. Is there an area I can check to see if its clogged? I'm getting ready to pull the drive to retrieve the lost threaded plate and replace a drive shaft seal where I'm leaking lube.

The pivot housing is not self draining. The drive drains in the down position, the pivot housing is drained by the 3 screws.

 

[lakelivin]

Re: Hole in side of OMC drive

I have an '89 4.3L Cobra on a lift. To drain the drive I've just raised and lowered it several times (pausing for a minute or so each time) without even pulling the water drain plugs on it. I live in northern NC, but temps occasionally get down to the single digits. <br /><br />I haven't had any problems over the 10 years I've had the boat. Don't know if my method is sufficient, or if I've just been lucky (perhaps most of the water evaporated before I hit freezing temps?). <br /><br />Anyone have an informed idea (not just speculation) as to whether this should be sufficient for a cobra drive? Obviously I wouldn't recommend this to anyone else unless there is some verification from some of our 'pro' contributers that it's highly likely to be ok.<br /><br />EDIT: didn't see marunr's post before submitting this one. Looked at my parts manual, & he's right. I imagine I've been ok because my lift is tilted so stern is lowered. I bet most water in my pivot housing flows back into the drive due to gravity, where it self-drains after I put the drive up & down once or twice.

 

[seahorse5]

Re: Hole in side of OMC drive

Originally posted by swsidlo:<br /> Sorta the same problem. I just bought a used 1988 OMC outdrive and the screw thing in the side is missing. I too thought it must be a freeze plug. The screw part is missing. If the backing plate did indeed fall inside, where should I look for it?

To get to the "fallen" threaded plate, you have to remove the outdrive and look inside the water passageway. Use long needlenose pliers to hold it in place as you thread a new screw onto it from the outside. Use a 1992 or later Cobra parts list to find the part numbers of the screw and the plate. They were not listed in early parts books.

 

[Ron Everson]

Re: Hole in side of OMC drive

The owners manual says to drain the pivot housing with the outdrive in the fully raised position. In that position, any water in the area behind the mystery screw will move towards the pivot housing drain screw and will drain out through it. Reviewing the parts diagrams in the parts manual confirms this. So, just drain it like the owners manual says and it'll be ok. By the way, we're probably getting confused by terminology. The lower part of the outdrive will gravity drain. The upper part of the outdrive apparently has pockets that will not gravity drain, but they will drain into the pivot housing to which the outdrive is connected, so the pivot housing drain screws will drain the upper part of the outdrive when the drive is in the raised position.