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jim 0010 jim 0010 is offline
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First recorded activity by BoatBanter: Jun 2009
Posts: 27
Default Overheating/Steam - Thermo OK/One exhaust Riser hot - Mercruise5.7 350MAG

Matt wrote:
I've never took off/checked the cooler before... can i just pull the
hoses off each side? take the entire cooler down/off? what's the
norm? and how to flush/check it? Thanks again for all your help!


"jim 0010" wrote in message
...
Matt wrote:
I called the marina that did my drive service (they said it prob
isn't that because both would be overheating) i have never had a prob
w/ them in the past, but i expect them to say that over the phone
becuase there can be 10 other things wrong w/ it too.. There is no
mussles or anything growing (it's dry docked all year long and in
fresh water) manifolds are running about the same the one where the
riser is very hot is a little warmer but i guess that would be as a
result of right?

The flaps sound fine, i hear no clacking...

I can check the cooler, but again, at the end of last season all was
fine, winterized it, then had it serviced few weeks ago, then the
start of my problems...

I pulled the hoses to the risers while the engine was on to check the
flow, the 'hot' riser had a little less flow but nothing major, this
was all while on the earmuffs...

I'm clueless... I am dreading bringing it back to the marina the
TELLING them to redo the impeller or recheck it.. I really don't want
to do it myself, it's such a pain in the ass and i need two people
for it...


"jim 0010" wrote in message
...
Matt wrote:
It was stored with coolant run through (same as i do every year)
There are no metering balls in the housing, and i toolk the entire
housing apart, everything looks good. Hose's are definately not
reversed. Manifolds/Risers are only 3 years old, fresh water use
only. I inspected the riser and looks good.


"jim 0010" wrote in message
...
Matt wrote:
Hi,

I have a 94' Chaparral w/a 5.7L Mercruiser 350MAG. Looking for
some advice on pinpointing a problem. Here's the story:

Last year everything was running fine. Beginning of this season
i had the outdrive/impeller serviced. After dropping it in the
water i noticed that one Riser gets extremely hot. This is def
not the norm. The temp is constant at 160 (thermostat setting).
I took off the entire thermostat housing (everything was fine),
replaced the thermostat, took off the Riser (everything fine),
checked the exhaust flaps (everything fine), and all hoses looked
good. I can't figure out what could be the problem. My two
thoughts, either something happened over the course of the
winter, but what? or when the marina serviced the outdrive
something got screwed up. but if it was an water intake problem
wouldn't both risers get really hot?

Any help troubleshooting is greatly appreciated.

Thanks!!



The first thing to be suspicious of is the work that was just
done. Did you store the engine wet or dry? Dry storage can cause
excessive internal rusting. Rust particles could be clogging a
riser or the riser itself has rusted out and clogged. If your
engine has metering balls in the thermostat housing, they could be
worn or where they seat on the housing could be eroded. Is it
possible that you have 2 hoses reversed.

I would go to the water pump and check it carefully, including the
part the copper tube sticks out, of in the upper unit. It might have
melted during an overheat episode. Also make sure the guy used the
right rebuild kit. Make sure the 3/4 diam water hose in the bell
housing isn't kinked or cracked. Make sure you don't have mussels or
vegatation clogging the water pickup vents. Is one manifold much
hotter than the other? Make sure your timing is set correctly. Make
sure some broken impeller pieces aren't blocking the power steering
cooler. Are your exast shutters clacking noticeably?

As long as you have sufficient water pressure to the muffs and you
arent running the engine more than a fast idle, there's nothing more
to check without pulling the drive off. Check the oil cooler to be
sure there are no blockages. you don't want them sandbagging you when
you bring it in for service. If they come back and say the problem is
something you already checked then you have a problem with your
assessment or the dealership's honesty.
Good luck.


pull both hoses off and run a wooden bbq skewer thru each tube. Catch
anything that comes out the other side and inspect it to see what it is.
Or you could look thru the tubes if you can.