I have a 175 hp V6 Mercury problem...

Striper Rig

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1979 175 hp V6 cyl

This motor has good compression and runs, but I only have 4 cyl's firing...

On the left side the top cyl is not firing...

On the right side the middle cyl is not firing...

I see water seeping from the bottom of those two plug holes that are not firing...when u take plug out after running engine steam comes out....:eek:

Do u think I have a blown head gasket on each side, or what would you look for?

I know this don't sound too good...:(
 

j_martin

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Re: I have a 175 hp V6 Mercury problem...

Could be head gaskets, or could be coming from the exhaust divider. The divider is easier and cheaper to pull, so pull that first.

hope it helps
John
 

CharlieB

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Re: I have a 175 hp V6 Mercury problem...

Do you have spark on all cyl''s or are those two wetted with water and shorting the spark plug out?

Look thru the spark plug holes at the piston domes and see what color they all are.

Repost with the info
 

Striper Rig

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Re: I have a 175 hp V6 Mercury problem...

Could be head gaskets, or could be coming from the exhaust divider. The divider is easier and cheaper to pull, so pull that first.

hope it helps
John


John where is exhaust divider located?
 

Striper Rig

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Re: I have a 175 hp V6 Mercury problem...

Do you have spark on all cyl''s or are those two wetted with water and shorting the spark plug out?

Look thru the spark plug holes at the piston domes and see what color they all are.

Repost with the info



Charlie, I will check that out and let u know what I find in a day or two....Thanks
 

j_martin

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Re: I have a 175 hp V6 Mercury problem...

John where is exhaust divider located?

On the back of the engine, between the banks. There's a cover, then a gasket, then the divider, then a gasket, then the block.

Sometimes they crack and spray water into the cylinders through the exhaust port.

hope it helps
John
 

Striper Rig

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Re: I have a 175 hp V6 Mercury problem...

Do you have spark on all cyl''s or are those two wetted with water and shorting the spark plug out?

Look thru the spark plug holes at the piston domes and see what color they all are.

Repost with the info

Charlie I finally got back to my boat motor, the piston domes look black in color...

What does that mean?
 

Striper Rig

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Re: I have a 175 hp V6 Mercury problem...

On the back of the engine, between the banks. There's a cover, then a gasket, then the divider, then a gasket, then the block.

Sometimes they crack and spray water into the cylinders through the exhaust port.

hope it helps
John

John, the seal in the middle of the exhaust divider where it fits into the slot at the back was cracked some, I wonder if this would let water through, the gaskets look rough, but I couldn't see any cracks, only the skinny tube like rubber seal that splits the middle of the exhaust divider had little cracks in it....

Do u think this could cause water to get in a cyl. on each side of the bank?

By the way this is a great site for learning, thanks John!:)
 

j_martin

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Re: I have a 175 hp V6 Mercury problem...

The metal "blade" is hollow and is cooled by water. The silicone seal could cause somewhat of a tune or misfire condition, but does not allow water to get anywhere. Replace it as long as yer in there.

How did the gaskets look. They could also be the problem.

If all is good here, head gaskets is the next inquiry.

hope it helps
John
 

Striper Rig

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Re: I have a 175 hp V6 Mercury problem...

The metal "blade" is hollow and is cooled by water. The silicone seal could cause somewhat of a tune or misfire condition, but does not allow water to get anywhere. Replace it as long as yer in there.

How did the gaskets look. They could also be the problem.

If all is good here, head gaskets is the next inquiry.

hope it helps
John

The gaskets looked a little old, but not sure if they were bad enough for this problem...I will replace gaskets and silicone seal and fire it up to see if it cures the problem...

If not cured I will take a look at the head gaskets and cross my fingers...

Thanks for your help John M.....I will keep u informed....
 

CharlieB

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Re: I have a 175 hp V6 Mercury problem...

possible that you have TWO head gasket leaks, but.........

Basic troubleshooting includes a SPARK TEST to ensure the ignition is working correctly.

Loosing TWO cyl on opposite banks is very suspicious of an ignition trigger problem, before taking things apart, check spark.
 

Striper Rig

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Re: I have a 175 hp V6 Mercury problem...

I finally got back to working on my motor..

I found I had a gasket blowed on the left side of the motor. It fixed the #2 piston from leaking water...

On the right side of the motor the #3 piston is still getting water, head was warped and I had it shaved, but it did not help.

There seems to be a fine hair line crack in the cyl wall that I really did'nt think was anything, looked more like a scratch, but there must be water seeping through...

I was wondering will it hurt the motor if you run it like this?

John or charlie or anyone please help with comment..Thanks....
 
Last edited:

Dukedog

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Oct 6, 2009
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3,235
Re: I have a 175 hp V6 Mercury problem...

If your gettin' water in a clyinder, no mater how small tha amount, its gonna lead ta a lotta damage. So no, don't run it till ya get tha water problem fixed.............
 
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