jamesgangnc wrote:
On Jun 1, 11:08 am, Jim Rojas wrote:
I was under the impression that the seawater helped to cool the
antifreeze, since there is no fan. That's why I said heat exchanger. I
will check to see if the thermostat is opening, and if i can see the
water pump flow.

Can I run the engine with the valve cover off? I don't want oil shooting
up at me while I check and see if the oil is pumping through to the
front end.

Thank you for the reply.

Jim Rojas



Tim wrote:
On May 31, 9:28 pm, Jim Rojas wrote:
I have a 1986 fresh water cooled Mercruiser 170HP 4 cylinder engine,
that I am trying to get repaired. I have some questions.
I am getting some tapping sounds from the front top end. How do I tell
if the oil is flowing throughout the engine? The oil gauge shows pressure.
My lower unit shows no sign of circulating water into the heat
exchanger. Does anyone know how to add a weep hole so i can visually see
the flow?
Thank you
Jim Rojas
Heat exchanger? Jim I think you have an enclosed water system, But if
it IS truely a raw water system, you should be able to put it on a
water hose with "muffs" and when runnning, you should have water
splattering out the exhause (directly under the Gimbal bering housing)
and though the propeller.
comcerning the "tap" noise, It's possible that you have a rocker arm
needing adjusting, or replacing. interesting that witht he oil pump
located at the back of the engine, it has to pump oil through the back
to the front, and the rocker arm is at the very top, in the front, and
is the last item to be lubricated. Therefore it's not the case of
starving for lubrication, but rather, a point that the lubrication is
at it's least pressure. It's not uncommon especially an engine that
may have several hr's on it.- Hide quoted text -
- Show quoted text -

Many boat engines simply pump the lake/sea water through the engine in
place of antifreeze. A few do have a real heat exchanger that would
be the equivilent of a radiator.

The '86 era 165/170 Mercruiser is a closed cooling system(this is a
later version of the infamous 470).

Rob


Usually you can tell pretty easily
as the heat exchanger is pretty big and has a number of hoses going to
it. You can't add a weep hole. There is a rubber impeller pump in
the lower unit that should be checked regularly. Merc recomends
yearly but most people do not as it is a pain to remove the bottom
half of the drive to check it. Every couple years is more common.
Unless you really use the boat a lot.

It will spray some oil when running with the valve cover off. I'd
save that as a last resort. If it did no thave oil pressure then it
would have locked up by now. The mains do not survive for more than
an few minutes without oil. You may be able to tell if you have a
loose rocker arm without it running by physically examining them.
They are hydralic so there should be zero lash. A manual will have
the correct adjustment procedure if they are adjustable. In any case
a manual would be a good idea if you plan on doing your own work.
There are clymers manuals for that year engine. The manuals are
engine specific, not boat specific, as a 4 cylinder merc is the same
no matter what the boat brand is.