1987 OMC Sea Drive -21 Proline W/A Cuddy

[seachest]

My 1987 1.8 L 140HP Sea Drive is causing me some headaches - I am getting quite a bit of water into the pan which vaporizes and chokes the motor out - I found my original post and your gracious replies re OMC Sea Drive Water Flow from Sept 3 - 6 2010. This boat is stern heavy and rides low in the water - I suspect that the water is getting in around some plugs and possibly around the overboard discharge - My Q is can I caulk (3M 5200) all of the plugs in the pan without any adverse effects (eg water retention) - I also want to replace the seal around the cowling & pan - I brought the seal and can't find it so I figure duct tape may help test temporarily. Are there any othe places I should be looking? I checked the siphon hose which lies in the pan and it is working perfectly.

Thanks in advance for your expert advice / recommendations

 

[Solittle]

Re: 1987 OMC Sea Drive -21 Proline W/A Cuddy

A couple of things - First that engine is rated by OMC at 110 hp not 140 even though they have the bubble back - no big deal. OMC manuals were available some time back though I don't know where now. I have a pair of these on my 23' Welcraft CC. I have had no problems with the Seadrives themselves but have had both power-heads rebuilt.

Second do not use 5200 as you will have to use a chisel & sledge if you ever want to remove it. Use 4200 as a sealer. It is a bit more pliable. Water can also get in through the ports for air intake.

The most important thing you can do is to watch your stern wake when coming off of a plane and use your throttle to minimize the backwash over the engine. As you know you can not raise or lower the Seadrive assembly without punching new holes in the transom.

 

[seachest]

Re: 1987 OMC Sea Drive -21 Proline W/A Cuddy

A couple of things - First that engine is rated by OMC at 110 hp not 140 even though they have the bubble back - no big deal. OMC manuals were available some time back though I don't know where now. I have a pair of these on my 23' Welcraft CC. I have had no problems with the Seadrives themselves but have had both power-heads rebuilt.

Second do not use 5200 as you will have to use a chisel & sledge if you ever want to remove it. Use 4200 as a sealer. It is a bit more pliable. Water can also get in through the ports for air intake.

The most important thing you can do is to watch your stern wake when coming off of a plane and use your throttle to minimize the backwash over the engine. As you know you can not raise or lower the Seadrive assembly without punching new holes in the transom.

Thanks you for your advice - I always try to maintain high trim when heading out at slow speed - and gradually lower it when throtling (sp?) up. I do the same thing when coming off plane - SLOWLY -

I have also gotten so many different desrpitions on this motor - One company told me that they didn't make a 1.8L but that the logo on the cowling is how they made their sixes . The tag in the pan clearly shows 1.8L

A local parts dealer found the manual for the 1.8 - and I also have one but for a 1.6L Lots of confusion. I'd like to re-power and was going to go with 150 Merc - but the safety information lable is all but gone & proline was not able to help me other than to send me a sales page - I'll see if I can attach it and send it on. Thanks again for your help - I'll opt for the 4200.

I think I was able to attach what Proline sent me - It is a bad copy of a black & white sheet in PDF format