4.3 omc cobra started running hot at idle speeds.....

[Brijoe00]

Hi all-

I was out fishing this weekend and noticed after trolling at idle speed, about 1-1.5mph, the temp was maxed out. This only happens at slow speeds like that, when I am at cruising speeds it is fine. Any ideas what this could be? Water pump? Impellor? Any help would be appreciated.

Thanks
Brian

 

[Don S]

Re: 4.3 omc cobra started running hot at idle speeds.....

The raw water pump impeller is the FIRST thing you check with any kind of overheat problem. They should be replaced every couple of years, how old is yours?

 

[Brijoe00]

Re: 4.3 omc cobra started running hot at idle speeds.....

It is an 86 Seaswirl. This is a new boat to me this year, so I am not sure if it has been replaced. Is it a involved proccess?

 

[Don S]

Re: 4.3 omc cobra started running hot at idle speeds.....

Is it a involved proccess?

If you haven't done it before, and don't have a manual, yea, it's an involved process that can be screwed up by the un-knowing.

 

[bruceb58]

Re: 4.3 omc cobra started running hot at idle speeds.....

On a Cobra it is very easy to change. Take the 3 bolts holding on the rear cover of the drive. You will see the impeller housing under it. You take that housing off to replace the impeller.

I would still buy a service manual. Try to find an OMC manual. Stay away from after market manuals.

 

[Brijoe00]

Re: 4.3 omc cobra started running hot at idle speeds.....

Thanks for the help Don and Bruce. I am heading out today to buy a manual. The local shop caries Seloc manuals, I am unable to find the OMC manual. Is there a reason why stay away from aftermarket amnuals?

 

[bruceb58]

Re: 4.3 omc cobra started running hot at idle speeds.....

They often have incorrect info in them.

Seloc would be my second choice to the factory manual.

This is also a handy site to look at and have bookmarked:

Hastings Site

 

[Boatin Bob]

Re: 4.3 omc cobra started running hot at idle speeds.....

Try to get an original OMC one, eBay is a good place to check like this one even if it is a little used 1986 Cobra Manual

 

[Brijoe00]

Re: 4.3 omc cobra started running hot at idle speeds.....

Ok after further review I have discovered that this is not a cobra. I am new to boating and this is a new boat to me. I assumed it was a cobra because I read that this was the first year for cobra. It is a 1986 4.3L stern drive. I have been told that on this model aparently I need to take the outdrive off of the boat to get to the impellor. Is that true? I bought a manual, but after looking at it, it does not cover my model. grrr!! I know I could do this if I had some sort of direction but I am having trouble finding that in a manual.

Also could this problem where it overheats at idle speed maybe be caused from a worn belt, or thermostat? Maybe something other than impellor? I am trying to avoid spending $500+ dollars by figuring this out myself.

Thanks

 

[Gary H NC]

Re: 4.3 omc cobra started running hot at idle speeds.....

What manual did you buy? i may take it off your hands..

best to find the engine and drive serial and model numbers and post them.
We need to know exactly what you have to be able to help.

Or at least post some pics...

 

[Gary H NC]

Re: 4.3 omc cobra started running hot at idle speeds.....

does it look anything like this?

http://i83.photobucket.com/albums/j299/garyh38/boat7.jpg

 

[bruceb58]

Re: 4.3 omc cobra started running hot at idle speeds.....

If you have the big black boot around the drive, you have the Stringer drive which precedes the Cobra.

Cobra drives have hydraulic rams which lift the drive and have rubber bellows for the u-joints and the exhaust. Stringers have ball gears instead of u-joints.

No matter what drive you have, the symptoms you state point to the impeller. You should replace it every two years anyway so time to bite the bullet.

 

[cobra 3.0]

Re: 4.3 omc cobra started running hot at idle speeds.....

You'll be able to determine your type of drive from the schematics shown here:

http://www.sterndrive.info/omc_help_page.html

 

[Boatin Bob]

Re: 4.3 omc cobra started running hot at idle speeds.....

See if you can find the engine model # on a plate on the rocker cover or t-stat housing, if your boat is a 1986 then it's possible you could have a 1985 engine/drive setup as some dealers have year old stock hanging around that they use up first. 1985 was the last yr for Stringers and 1986 was the first yr for Cobra's.

 

[Brijoe00]

Re: 4.3 omc cobra started running hot at idle speeds.....

Thanks for all your help. What I have is a 4.3L 400/800 outdrive, I am sure of that now. I am a little mad at myself as when I bought the boat I was told if the outdrive was silver it was a cobra...which I know now is not true. I would not have bought the boat if I knew it was a stringer, but I didnt know the differance at that time.

Anyway, I am going to replace the inpellor. But, if I have to pull the outdrive completly off the boat I probably will not do that myslef. Doese anyone know if this is for sure how you go about replacing the impellor on a stringer?

Thanks