New to me 1995 4.3 OMC Cobra in Chris Craft

Alaboat

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I need some input on my recent purchase. It's a 1995 Chris Craft with 4.3 OMC. Previous owner discouraged me from running on hose with muffs; something about over pressurizing seals or something. He said he always ran in drum of water. Is there any truth to that? I have always run my outboards with muffs with no problem, what is different with I/O?
Also, the shift control has a button in the center of shift lever pivot point. He said that it was a choke button and to push it several times when starting. I could never get it started this way and actually drained the already weak battery. Put in a new battery and did some research in the manual and found out depressing this button disengages the shift mechanism and acts like a high idle lever. Wow, Really? Previous owner totally oblivious on how to start the engine properly. I will try this out later today to see if it works this way if I get some feedback on running in driveway on muffs.
Thanks.
 

bruceb58

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Use muffs. Don't use a drum or you will wipe out the impeller. Also, turn on full. You won't wipe out seals.
 

Alaboat

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Use muffs. Don't use a drum or you will wipe out the impeller. Also, turn on full. You won't wipe out seals.

Thanks for the response. Any other comments or thoughts on using muffs on this particular engine? How can I tell is water is circulating properly through the engine? I have never owned an inboard/outboard engine, only outboards.
 

bruceb58

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Should be coming out the idle relief ports near the transom. I also put my hands on the risers after I start up to make sure they stay cool.
 

Alaboat

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Should be coming out the idle relief ports near the transom. I also put my hands on the risers after I start up to make sure they stay cool.

Okay, so I was able to start up the engine yesterday with muffs using full water pressure. Temp gauge stayed below 150 while idling around 1k.(closer to 120-130) The port riser was cool to the touch but the starboard riser was almost too hot to touch. Is that normal when running on muffs?
 

bruceb58

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One will always be warmer than the other. Could be as much as 20 degrees warmer. Should not be hot to the touch though.

First thing I would be doing is changing the impeller especially since he was running in a drum. Likely ruined the impeller. This will also give you a baseline of when it has been chnged since you don't know how long it has been in there. Needs to be changed every 2 years.

Has this boat been run in salt water?
 
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HT32BSX115

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I need some input on my recent purchase. It's a 1995 Chris Craft with 4.3 OMC. Previous owner discouraged me from running on hose with muffs; something about over pressurizing seals or something. He said he always ran in drum of water. Is there any truth to that? I have always run my outboards with muffs with no problem, what is different with I/O?
Also, the shift control has a button in the center of shift lever pivot point. He said that it was a choke button and to push it several times when starting. I could never get it started this way and actually drained the already weak battery. Put in a new battery and did some research in the manual and found out depressing this button disengages the shift mechanism and acts like a high idle lever. Wow, Really? Previous owner totally oblivious on how to start the engine properly. I will try this out later today to see if it works this way if I get some feedback on running in driveway on muffs.
Thanks.

Yeah. An I/O IS quite different from an outboard here. Most outboards have the raw water pump in the lower unit such that it would be submerged in water if you used a "drum" or other water source with the LU in it.

OMC I/O's either have the pump at the back of the drive or on the engine depending on the model. In either case, you won't likely get the water level high enough on the drive to get it as high as the pump.

Also, you might indicate your engine/drive model. If it is indeed a 1995 4.3L OMC I/O [43APHUB 1995] the impeller is listed as:
0825940 IMPELLER replaced by 3862281 (superceded by others) costing about $20-50...... and it's on the engine. ( a Volvo SX)

If it's a 1994 model, (which is common in 1995 model boats) It could be one of the following:
432ACMMDA 1994
432ACPMDA 1994
432AGMMDA 1994
432AGPMDA 1994

and the pump is mounted to the engine and it's probably a Volvo SX drive
Using OMC/Volvo 3854286 which can be replaced with Sierra 18-3060 available right here on iBoats.


When you get the model number, go to http://epc.brp.com/ for parts diagrams. (email address field can be left blank)

Yeah, the PO was mistaken (flat WRONG). I probably wouldn't believe him on other "stuff" either............... Like when the impeller was replaced last!

You should should probably replace the impeller before running it any amount on the water!


Cheers,


RIck
 
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bruceb58

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Also, you might indicate your engine/drive model. If it is indeed a 1995 4.3L OMC I/O [43APHUB 1995] the impeller is listed as:
0825940 IMPELLER replaced by 3862281 (superceded by others) costing about $20-50...... and it's on the back of the drive. (NOT a Volvo SX)
A HU drive is a SX. Pump will be at the engine.

Not a huge Sierra fan. I would stick with the Volvo one.
 
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HT32BSX115

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A HU drive is a SX. Pump will be at the engine.
YES! MY MISTAKE!.....Both the 1994 and 1995 [4.3L]drives are ENGINE driven pumps (according to BRP's parts site)..........

Funny though, the 7.4L 'HUB drive (744DPHUB 1995) is an OMC "interim" (nightmare) drive (according to the BRP parts site) with the NON-available impeller pump on the drive................ go figure!

I wonder how many other mistakes there are in those 20 year old parts diagrams!
 
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Alaboat

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One will always be warmer than the other. Could be as much as 20 degrees warmer. Should not be hot to the touch though.

First thing I would be doing is changing the impeller especially since he was running in a drum. Likely ruined the impeller. This will also give you a baseline of when it has been chnged since you don't know how long it has been in there. Needs to be changed every 2 years.

Has this boat been run in salt water?

The impeller was changed last week when thermostat went out. Never run in salt water and supposedly only about 250 hours on engine. I went over engine yesterday and 2 of the belts were loose and tightened them up. Looked at all exhaust hoses on risers and several clamps were loose, some were loose enough to spin around the hose. Of course, I tightened them all up. Could running with the loose exhaust hoses cause any issues?
 

Alaboat

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Messages
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Yeah. An I/O IS quite different from an outboard here. Most outboards have the raw water pump in the lower unit such that it would be submerged in water if you used a "drum" or other water source with the LU in it.

OMC I/O's either have the pump at the back of the drive or on the engine depending on the model. In either case, you won't likely get the water level high enough on the drive to get it as high as the pump.

Also, you might indicate your engine/drive model. If it is indeed a 1995 4.3L OMC I/O [43APHUB 1995] the impeller is listed as:
0825940 IMPELLER replaced by 3862281 (superceded by others) costing about $20-50...... and it's on the engine. ( a Volvo SX)

If it's a 1994 model, (which is common in 1995 model boats) It could be one of the following:
432ACMMDA 1994
432ACPMDA 1994
432AGMMDA 1994
432AGPMDA 1994

and the pump is mounted to the engine and it's probably a Volvo SX drive
Using OMC/Volvo 3854286 which can be replaced with Sierra 18-3060 available right here on iBoats.


When you get the model number, go to http://epc.brp.com/ for parts diagrams. (email address field can be left blank)

Yeah, the PO was mistaken (flat WRONG). I probably wouldn't believe him on other "stuff" either............... Like when the impeller was replaced last!

You should should probably replace the impeller before running it any amount on the water!


Cheers,


RIck

Yes, After verifying several things PO told me, several don't line up exactly. The model of my engine is 432APHU. The impeller on the engine was P/N 3862281 and was replaced last week.
 
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bruceb58

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Funny though, the 7.4L 'HUB drive (744DPHUB 1995) is an OMC "interim" (nightmare) drive (according to the BRP parts site) with the NON-available impeller pump on the drive................ go figure!

I wonder how many other mistakes there are in those 20 year old parts diagrams!
Yep, 7.4L changed over later.
 

bruceb58

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You happen to have an IR gun to measure the temps of the risers?
 

Alaboat

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Weather didn't cooperate for water run today so decided to pull the exhaust elbows to look around to see what the condition was.After pulling the big hose between elbow and exhaust pipe, I observed a pin that runs across the diameter of the opening on port and starboard exhaust pipes. Anybody know what the function of this pin is? It's probably .1 dia and looks like something you would see on a butterfly valve but there is no butterfly. It is positioned in 2 holes in pipe and the only thing that keeps it there is the hose when its installed. One fell into pipe when I removed hose.
 
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bruceb58

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Those pins hold the exhaust flappers. That may explain things if those flappers burnt up and fell down into the exhaust pipe.

Later, Volvo decided those flappers weren't needed so newer engines won't have them. Yours did assuming no one took them off.
 

Lou C

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Exhaust flapper minus the rubber flapper; he may have overheated it and melted the flappers. They might be in the bottom of the Y pipe...
 

Alaboat

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Okay, I looked it up in BRP part catalog and found out there should be a exhaust seal assembly there but only the pin is there. Is it okay to run without the seal assy and what function does it serve?
 

Alaboat

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Would this service bulletin apply to this engine? Its the same parts as the OMC. I'm guessing somebody already removed the "flapper" and left the pin like the bulletin describes.
Google: P-25-1 2 01
 
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