OMC COBRA 4.3. BURNING MY HOSES. GETTING HOT

Pedrocasas

Seaman
Joined
Apr 9, 2016
Messages
54
Lou C. The engine was good temp 160-175. Seems that the exhaust system was the only one hot. So hot that the hose clamps burned thru the gas line.

I did remove the impeller and will replace that. Also ill be replacing the thermostat housing.

What' is the best,way to check the bat wing manifolds???
What do i need to look for??
 

Bondo

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Staff member
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Apr 17, 2002
Messages
70,465
What' is the best,way to check the bat wing manifolds???
What do i need to look for??

Ayuh,.... Toss 'em in the water,... if they sink, replace 'em,....

Seriously,... Scrap 'em, Right Now, before yer scrappin' the motor, along with the manifolds,...

Lou has been Lucky,.... one of few that have been,....

Get a conversion kit to traditional manifolds, 'n risers,...
 

Lou C

Supreme Mariner
Joined
Nov 10, 2002
Messages
11,802
Yes I have been. Even checked em with acetone for leaks every few years.
What to check?
Take em off and look in the outlets. There is one center exhaust opening and 4 water passages. Those 4 passages are prone to clogging up you can rod em out. All so the feed nipples on the thermo housing must be open . Those "4.3" stickers tell me these are original never replaced. I've bought 2 sets of these and non of them had those stickers. So it's tine to get rid of them and up grade to the 2 piece.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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47,297
Dont even bother trying to test bat wing manifolds. Most killed the motors years ago, the fact that you still have them is a miracle. If you have been using them at all in salt, consider them junk and replace
 

Pedrocasas

Seaman
Joined
Apr 9, 2016
Messages
54
Burned Hoses. 4.3 OMC.

Hello Guys. I have posted 2 topics in the previous months. Asking about my boats engine. I had the chance to remove all the parts Related to the "water system". Here it goes.
I took the boat out. Rammed up the engine up to 35 mph in the bay. Boat had been sitting for months. Previous owner didn't do much with it but take out for like 10 minutes. Boat was running good for the first hour. Nothing bad was notice at low speeds. 30 minutes after ramming the engine and going 35mph, we started smelling burned rubber. Again we had no IDEA, this is MY FIRST BOAT ever.

Here are some pictures. I do not want to bore you guys with my stories.

first group:
I decided to remove the Port Side Manifold. Hoses attached to a pipe going to the Transom of the boat. SORRY I DONT KNOW many parts names. but I will attach pictures. Port Side did not smell like burned.


UPDATE*** I attached all the pictures from all the stuff that I removed. As you can see a lot of it is really bad damaged. I will be buying all new water hoses all of them.

*** NOTE THAT ALOT OF THE DAMAGE IS ON STARBOARD SIDE.***

What can be causing my boat to heat up the way it did?
Where can I start to start fixing it up.

I appreciate all your guys time. The more info the better. Im glad to part of this Forum.

Thank you guys!!!!!!



I've been told that maybe its the Raw water pump, and I believe there is more hoses or parts in the outdrive. Any suggestions?

Thank you
 

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Pedrocasas

Seaman
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Messages
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No Title

Here is the Starboard Side pictures. NOTICE, Starboard side had more damage, hose from manifold to pipe was BURNT completely. The hose clamp was so hot it burnt thru the RED GAS FUME HOSE, it burned thru the RED POWER CABLE. The damage to the pipe is a lot also the Manifold on the starboard side is more damaged. see pictures please.

I noticed the PIPE going to the rear of the boat DOES NOT HAVE the flap inside, like the PIPE on the PORT SIDE. is that suppose to be like that? See picture, it just had a stick but no FLAP.

Thank you.
 

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Pedrocasas

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this are more pictures showing all the DAMAGE TO THE STARBOARD SIDE OF THE ENGINE.
 

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Pedrocasas

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This is the Thermostat housing. Im not sure if that looks ok or not.. IM NOT FAMILIAR WITH MARINE PARTS.
 

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Pedrocasas

Seaman
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I took a picture of this part, it has a hose CONNECTED TO THE Thermostat housing.
 

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Pedrocasas

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This is my Impeller. I also removed. it.
 

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GA_Boater

Honorary Moderator Emeritus
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We always say that a new to you boat should have a new impeller installed. You impeller probably had enough life for low speed, but not for high speed operation.

You need a new impeller and it's a good idea to replace the wear plate and cup because the soft rubber impeller is now hard as a rock. All the rubber exhaust parts need replaced and you need a shutter for the starboard side. I can't tell if the battery cable is beyond repair.

Most likely all of the damage would have been avoided by replacing the impeller before using the boat for the first time, but that's water under the bridge now. Cobra drive impellers are a snap to change unlike most other sterndrives.
 

Lou C

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Messages
11,802
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OK basically you need a new exhaust system, your starboard manifold is all clogged up with rust, that's what happens to them after about 5-6 years in salt water. You are also missing the exhaust flapper on the starboard side, it is probably vaporized in the bottom of the Y pipe (metal pipe behind the engine that each side connects to behind the engine). Your port side is not as bad, the manifold exit ports are not completely clogged and the exhaust flapper is still there. Its a rubber flap at the top of the Y pipe. The thing you are pointing to asking what it is, that's the power steering cooler. The pic of the engine looks good, I don't see rust in the exhaust ports.
Now, this is not going to be cheap. You need a conversion 2 piece exhaust system to replace the now discontinued OMC one piece units. Do a search, there are a few versions out there. I prefer using OSCO parts vs GLM. Figure about 700 in parts. And I'd also replace the thermo housing, it looks like the cooling ports have necked down. Here is a pic of what those ex manifolds look like when cleaned out after 5-6 years in salt. From my last replacement. Next one I am going to the 2 piece system....
 

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Lou C

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Here is the Starboard Side pictures. NOTICE, Starboard side had more damage, hose from manifold to pipe was BURNT completely. The hose clamp was so hot it burnt thru the RED GAS FUME HOSE, it burned thru the RED POWER CABLE. The damage to the pipe is a lot also the Manifold on the starboard side is more damaged. see pictures please.

I noticed the PIPE going to the rear of the boat DOES NOT HAVE the flap inside, like the PIPE on the PORT SIDE. is that suppose to be like that? See picture, it just had a stick but no FLAP.

Thank you.
Your flapper is vaporized because the 4 cooling ports on the starboard exhaust were all clogged up. Even if the impeller was ok, no water was flowing there.
 

Lou C

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I took a picture of this part, it has a hose CONNECTED TO THE Thermostat housing.


Power steering cooler. Make sure the hose clamps on each end of it are tight and the hoses are in good shape. One goes to the thermo housing the other to the transom mount, which takes water from the impeller and sends it up to the thermo housing.
 

Lou C

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Messages
11,802
This is the Thermostat housing. Im not sure if that looks ok or not.. IM NOT FAMILIAR WITH MARINE PARTS.


Doesn't look too bad, you can ream out the smaller holes that feed the manifolds, but if you find chunks of cast iron peeling off inside replace it. You can still get these.
 

Lou C

Supreme Mariner
Joined
Nov 10, 2002
Messages
11,802
Here is the Starboard Side pictures. NOTICE, Starboard side had more damage, hose from manifold to pipe was BURNT completely. The hose clamp was so hot it burnt thru the RED GAS FUME HOSE, it burned thru the RED POWER CABLE. The damage to the pipe is a lot also the Manifold on the starboard side is more damaged. see pictures please.

I noticed the PIPE going to the rear of the boat DOES NOT HAVE the flap inside, like the PIPE on the PORT SIDE. is that suppose to be like that? See picture, it just had a stick but no FLAP.

Thank you.
Manifold is probably all rotted out and the rust flakes clogged up the 4 water ports that are supposed to keep the exhaust cool. These manifolds usually do not get hotter than 135*. At idle mine were usually at about 100 or so.
 

Lou C

Supreme Mariner
Joined
Nov 10, 2002
Messages
11,802
Hello Guys. I have posted 2 topics in the previous months. Asking about my boats engine. I had the chance to remove all the parts Related to the "water system". Here it goes.
I took the boat out. Rammed up the engine up to 35 mph in the bay. Boat had been sitting for months. Previous owner didn't do much with it but take out for like 10 minutes. Boat was running good for the first hour. Nothing bad was notice at low speeds. 30 minutes after ramming the engine and going 35mph, we started smelling burned rubber. Again we had no IDEA, this is MY FIRST BOAT ever.

Here are some pictures. I do not want to bore you guys with my stories.

first group:
I decided to remove the Port Side Manifold. Hoses attached to a pipe going to the Transom of the boat. SORRY I DONT KNOW many parts names. but I will attach pictures. Port Side did not smell like burned.


UPDATE*** I attached all the pictures from all the stuff that I removed. As you can see a lot of it is really bad damaged. I will be buying all new water hoses all of them.

*** NOTE THAT ALOT OF THE DAMAGE IS ON STARBOARD SIDE.***

What can be causing my boat to heat up the way it did?
Where can I start to start fixing it up.

I appreciate all your guys time. The more info the better. Im glad to part of this Forum.

Thank you guys!!!!!!



I've been told that maybe its the Raw water pump, and I believe there is more hoses or parts in the outdrive. Any suggestions?

Thank you


OK on this side, 3 of the 4 water ports are open, that's why the flapper was still there. But both manifolds are shot, and need to be replaced. Forget about re-using these.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
47,297
You may want to PM a mod to link this to your other thread.

You had the bat wing manifolds, they need to go. Your boat needed a new exhaust system before you bought it.

You had zero water flow to the exhaust, thats why everything burned up

Your thermostat looks to need changing.

I would get a complete raw waterpump kit
 
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Pedrocasas

Seaman
Joined
Apr 9, 2016
Messages
54
Thanks guys!!!

I ordered the new 2 piece exhaust conversion kit. the raw water pump, impeller, and thermostat with new housing.
all the hoses are being replaced too.


I HAVE NOT INSTALLED ANYTHING YET..

HOW CAN I DO A BACK FLUSH... WHERE DO CONNECT THE HOSE TOO?

JUST WANT TO REMOVE ALL THE STUFF THAT COULD BE CLOGGING OR BLOCKING ANYTHING.
 
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