1993 OMC Cobra 5.0 l EFI, almost sunk it...

[holgo123]

I just finished up a lengthy transom repair... I had everything ready to go... Primed the oil pump, hitched her up and took it to the boat ramp... I backed her in and decided to run it a bit on the trailer. Before I turned the key, I opened up the engine compartment to see if it was dry. Holy crap, water was rushing in... Dissapointed, I drove home. Come to find out that it is the exhaust Y-Pipe not matching up to the replacement transom mount (I pulled the foot and put a hose in the exhaust and water ran straight in to the bilge). I didn't look close enough, but it seems there is a gap along the bottom. The Y-Pipe opening is a little different than the transom mount opening only along the bottom. The bolt holes were the same and it bolted up easily... I used the original Y-Pipe and a transom mount that was supposed to be off a 5.0 L OMC... When I looked up the part numbers on Doug Russell, they are all the same for the transom bracket, and Y-Pipe (even across multiple years...). I am pulling the motor to get to it... The transom bracket that came with the replacement mount has the OMC part # of 986680. I can't find that number listed on Doug Russell... Does anyone have a parts catalog that can cross reference this number? Is there a couple of y-pipes that were used on V-8's? I am wondering if I can find the right Y-Pipe for this mount... My old transom mount is corroded pretty bad and this one is pristine, looks brand new... What's weird is that everything bolted up fine while putting it back together. The only thing different is that a bolt hole was missing on top of the steering arm for a ground strap connection and the pin holding the steering arm to the steering rod was to big big and the hole had to be enlarged a little... I am bummed out a little... When I get it back aprt, I will take a few pictures...

 

[Don S]

Re: 1993 OMC Cobra 5.0 l EFI, almost sunk it...

I have seen this happen on new boats also, the transom could be too thick or the stringer in the way of the Y pipe when it's bolted in place. This will hold the pipe away from the transom shield.
There are specific dimensions in the installation manual for makeing the proper clearance.

 

[holgo123]

Re: 1993 OMC Cobra 5.0 l EFI, almost sunk it...

Thanks Don. I am going to pull the engine tonight when I get home from work and try to figure out the next step... I looked around with a mirror and can't see the pipe interfering with anything, who knows...

I did write the part number I was trying to look up from the previuos post incorrectly, it should be 985680... I was thinking if I could figure out which model this belonged to, I could determine if I had a wrong part on my boat...

Thanks! I'll update later on...

 

[holgo123]

Re: 1993 OMC Cobra 5.0 l EFI, almost sunk it... Update

Re: 1993 OMC Cobra 5.0 l EFI, almost sunk it... Update

I pulled the engine and took off the Y-Pipe... The transom mount and the Y-Pipe are a little different where they mate together... Take a look. Also, the outlet for the exhaust on the bottom of the exhaust right before it enters the bellows is two holes on the "new" one vs. one oblong hole on the old one... I have tried to look up both part number on the Bombardier site and Doug Rousell, but they are invalid. Part # 914037 (Transom Mount), part # 985680 (Transom Bracket). Everything fits fine except this... I am thinking of taking the Y-Pipe to a machine shop and having them weld in a piece of metal and machine it flush to match the "new" exhaust hole. Do you think the amount of change would be too much restriction for the exhaust? The area that would change is fairly small, but sure lets in a bunch of water... Any ideas? What's really weird is that most of the part numbers are the same for the V-8/V-6 on the Y-Pipe, Transom Bracket, Transom Mount...

The gasket on the left fits the transom bracket exhaust opening, the gasket on the right fits the original Y-Pipe opening...

 

[Robj]

Re: 1993 OMC Cobra 5.0 l EFI, almost sunk it...

If it was mine, I would just weld it up. If you buy another one, it will have that opening blocked, so what is the difference if you weld it?? Hopefully others will chime in soon.

Have a great day,

Rob.

 

[Don S]

Re: 1993 OMC Cobra 5.0 l EFI, almost sunk it...

Now I see what the problem is. The 94 and newer OMC was also during the Volvo/OMC joint venture. You have a Y pipe for the 94 and newer OMC/Volvo SX style Cobra, not a 93 OMC and earlier Cobra.

Go to the Bombardier site and look at the differences in the Y pipe seal ring between the 93 and 94 models. I think you will find your differnce.

 

[holgo123]

Re: 1993 OMC Cobra 5.0 l EFI, almost sunk it...

That explains it... I thought it was a 1993 model, maybe it was produced late in 1993 and got some 1994 parts on it...

Do you see any problem with welding in a piece of metal and machining it to match the transom mount?

 

[Don S]

Re: 1993 OMC Cobra 5.0 l EFI, almost sunk it...

Get the right Y pipe and you won't have any problems. The transom shield is 93, the Y pipe is 94.

Do you see any problem with welding in a piece of metal and machining it to match the transom mount?

Anything is possible for a price. How much do you trust the welder and machine shop to do it right?
How much do you enjoy pulling the engine if they don't do it properly?????

 

[holgo123]

Re: 1993 OMC Cobra 5.0 l EFI, almost sunk it...

You are probably right... I do have to say that I have gotten pretty good at removing the engine. I am not sure that is a good thing... Thanks again!

 

[holgo123]

Re: 1993 OMC Cobra 5.0 l EFI, almost sunk it...

Well, it was a long time coming, but I am finally done... I ended up getting the correct Y-Pipe. I couldn't be comfortable out on the lake wondering if the weld would hold or corrode away and leak. I Have spent a fortune of time repairing this boat, but I felt pretty good when I backed it in and cranked it up and everything worked without any leaks at all. It started and ran great! It shifts great. It doesn't leak... It is clean as a pin... The brightside white paint makes the engine compartment sparkle... Unfortunately, it is winter and the lake is suffering from the drought in our area... I hope we get a better weather pattern and fill the lake back up soon... I am going to try my hand a upohlstery this winter. I got a 1960 circa Singer industrial sewing machine from a friend and am going to try and learn the skills. It is about the last thing I can do to the boat. I'll post pictures on the restoration forum if I get anywhere... This is a great website for the "do it your selfer", thanks for the input that helped me along...