1990 Chevy/ OMC won't start - water in plugs

[boatgrunt]

I have a 1990 Chevy 4.3 v6 with a OMC Cobra I/O. She won't start and when I pulled the plugs, the left side were fine but the right side plugs were wet and had some water in them. What does this mean and what do I do? <br /><br />Thanks

 

[Laddies]

Re: 1990 Chevy/ OMC won't start - water in plugs

Sounds like a bad manifold or elbow lot of the elbows are giving out, so I would remove it first and ck it

 

[boatgrunt]

Re: 1990 Chevy/ OMC won't start - water in plugs

Thanks Laddies. I actually just removed the manifold to replace the elbow and the manifod looked pretty clean. I put on a new gasket but maybe I didn't put it back together right? I have driven the boat pretty hard about five times since I last had the manifold off. <br /><br />The manifold was held in place by bolts with threads on both sides. I couldn't get one of the bolts back in, so I just used a bolt with a thread on one side instead of the two sided bolt. Do you think that could have made a difference?

 

[boatgrunt]

Re: 1990 Chevy/ OMC won't start - water in plugs

1. Removed the plugs and turned the engine over a few times to blow out any water/condensation. <br /><br />2. Removed the hose going from the thermostat to the manifold/side that appeared to be leaking and pointed the hose down towards the bilge. <br /><br />3. Finally got the engine running but shut it down after 5-10 seconds to avoid damaging the engine since I was preventing water flow to the starboard side. <br /><br />I will probably remove the manifold and valve cover next and check for cracks. Any more suggestions would be appreciated. My boat mechanic told me that the OMC "bat wing" manifolds required a skilled technician to install properly, so I may take it in.

 

[Bondo]

Re: 1990 Chevy/ OMC won't start - water in plugs

OMC "bat wing" manifolds required a skilled technician to install properly,

Are these the 1 pc. casting, Riser/Manifold Combination Things,..???........<br />Merc. used them for a rather Short run as well,.....<br /><br />It's not that you put it On Wrong,....That's Almost Impossible... It's Probably Cracked,+ Needs Replacing...........<br />They're a poorly designed Idea,.. That doesn't work as planned..........<br />I've seen conversations available for Merc.s,.... I don't know about OMCs..........

 

[boatgrunt]

Re: 1990 Chevy/ OMC won't start - water in plugs

Bondo - yes, I belive they are the 1 pc. casting things to which you referred. I have heard boat technicians also refer to them as "star track" manifolds. There is a picture on page 6/3 of this .pdf:<br /><br /> http://www.marysvillemarine.com/catalog/cat_p611-616.pdf <br /><br />The "putting it on wrong" line seemed wierd to me too, since you basically slap on the gasket, line up the 3 studs and bolt the manifold onto the engine block. That being said, I really trust my mechanic, so maybe I explained it wrong. I have seen OMC to Merc Manifold conversion kits, so I may check that option out. <br /><br />Do you know how to pressure test the manifold? I searched for a posting on that topic but couldn't find any with sufficient detail.

 

[Lou C]

Re: 1990 Chevy/ OMC won't start - water in plugs

The one piece OMC manifold is actually a good design and quite durable. I took my OE ones off at 14 years old and they still looked good but I put new OE ones on then since I didn't know how long they were used in salt and didn't want to take a chance. I got a spare set from doug russell in Mass last winter. Pricey yes but I think they last longer and there is no riser/manifold joint to leak. That is were a lot of failures start, at that gasket. Even if the manifold and riser have not failed, if that gasket leaks internally you can get water sucked in. <br />Sea Way Marine www.sea-way.com is selling a conversion kit to use Merc parts if you want to go that route, but because of the extra parts needed it is not really cheaper than the high priced OE.

 

[Bondo]

Re: 1990 Chevy/ OMC won't start - water in plugs

I Still Think your Wrench is "Pulling your Leg",....... There's No Water Gaskets,... Just the Exhaust gasket,.... Maybe some pipe threads sealant,... Hose Clamps,.....<br /><br />I've only ran across the Single Castings once,.... The Adaptability of the Center-rise manifold just worked out Better.........<br />We Switched......<br /><br />And,..... There's really No way to Pressure Test them,...... The Center-rise manifolds can be Capped,+ Plugged,+ Pressurized........