I was looking over a boat that I am considering buying and I noticed something
strange with the outboard.
It's a 1995 Johnson 112 HP V4.
We had it running on earmuffs for a few minutes to warm it up so I could do a
compression test. I noticed that the two piston banks had a significant
difference
in temperature. After about 3 or 4 minutes, one side was still cool while the
other
side was very warm.
Anyone have any idea what could cause this? Blocked internal water passage
maybe?

The owner bought the motor new in 95 and has had it professionally winterized
every year. He did not know when or if the water pump was changed so it's
possible that it has never been replaced.
BTW, the compression checked out OK. All four cylinders measured 120 psi.

Thanks in advance,
VI

Chenz759 wrote:

I was looking over a boat that I am considering buying and I noticed something
strange with the outboard.
It's a 1995 Johnson 112 HP V4.
We had it running on earmuffs for a few minutes to warm it up so I could do a
compression test. I noticed that the two piston banks had a significant
difference
in temperature. After about 3 or 4 minutes, one side was still cool while the
other
side was very warm.
Anyone have any idea what could cause this? Blocked internal water passage
maybe?

The owner bought the motor new in 95 and has had it professionally winterized
every year. He did not know when or if the water pump was changed so it's
possible that it has never been replaced.
BTW, the compression checked out OK. All four cylinders measured 120 psi.

Thanks in advance,
VI

I believe each cyl bank has its own thermostat located on the aft side
of the motor at the base of the block and I suspect 1 is stuck.

Chenz759 wrote:

I was looking over a boat that I am considering buying and I noticed
something
strange with the outboard.
It's a 1995 Johnson 112 HP V4.
We had it running on earmuffs for a few minutes to warm it up so I could do
a
compression test. I noticed that the two piston banks had a significant
difference
in temperature. After about 3 or 4 minutes, one side was still cool while
the
other
side was very warm.
Anyone have any idea what could cause this? Blocked internal water passage
maybe?

The owner bought the motor new in 95 and has had it professionally
winterized
every year. He did not know when or if the water pump was changed so it's
possible that it has never been replaced.
BTW, the compression checked out OK. All four cylinders measured 120 psi.

Thanks in advance,
VI

I believe each cyl bank has its own thermostat located on the aft side
of the motor at the base of the block and I suspect 1 is stuck.







I suspect this is normal.The lower cylinder bank will probably get more water
through it and the thermostat will open later than the upper cylinder bank.I
don't know if that's the actual reason but my old Johnson 200 did the same
thing. Maybe just the direction water runs through the cooling chambers.

Barry

"F330 GT" wrote in message
...
Chenz759 wrote:

I was looking over a boat that I am considering buying and I noticed
something
strange with the outboard.
It's a 1995 Johnson 112 HP V4.
We had it running on earmuffs for a few minutes to warm it up so I
could do
a
compression test. I noticed that the two piston banks had a significant
difference
in temperature. After about 3 or 4 minutes, one side was still cool
while
the
other
side was very warm.
Anyone have any idea what could cause this? Blocked internal water
passage
maybe?

The owner bought the motor new in 95 and has had it professionally
winterized
every year. He did not know when or if the water pump was changed so
it's
possible that it has never been replaced.
BTW, the compression checked out OK. All four cylinders measured 120
psi.

Thanks in advance,
VI

I believe each cyl bank has its own thermostat located on the aft side
of the motor at the base of the block and I suspect 1 is stuck.







I suspect this is normal.The lower cylinder bank will probably get more
water
through it and the thermostat will open later than the upper cylinder
bank.I
don't know if that's the actual reason but my old Johnson 200 did the same
thing. Maybe just the direction water runs through the cooling chambers.

Barry

Didn't some of those motors only run on 1/2 the cylinders at idle?

"Calif Bill" wrote in message
ink.net...

"F330 GT" wrote in message
...
Chenz759 wrote:

I was looking over a boat that I am considering buying and I noticed
something
strange with the outboard.
It's a 1995 Johnson 112 HP V4.
We had it running on earmuffs for a few minutes to warm it up so I
could do
a
compression test. I noticed that the two piston banks had a
significant
difference
in temperature. After about 3 or 4 minutes, one side was still cool
while
the
other
side was very warm.
Anyone have any idea what could cause this? Blocked internal water
passage
maybe?

The owner bought the motor new in 95 and has had it professionally
winterized
every year. He did not know when or if the water pump was changed so
it's
possible that it has never been replaced.
BTW, the compression checked out OK. All four cylinders measured 120
psi.

Thanks in advance,
VI

I believe each cyl bank has its own thermostat located on the aft side
of the motor at the base of the block and I suspect 1 is stuck.







I suspect this is normal.The lower cylinder bank will probably get more
water
through it and the thermostat will open later than the upper cylinder
bank.I
don't know if that's the actual reason but my old Johnson 200 did the
same
thing. Maybe just the direction water runs through the cooling chambers.

Barry

Didn't some of those motors only run on 1/2 the cylinders at idle?



Those crossflow V4's had a thermostat for each bank of cylinders located at
the aft top of the exhaust housing, just under the powerhead assembly, which
made it very awkward to service. A hose ran from each head to each
thermostat and pressure relief valve cavity. They always ran on 4 cylinders,
even at idle. There is no comparison with the V6 200 hp cooling system, that
had a thermostat and pressure relief valve at the top of each cylinder
head.

Bill Grannis