[C320-list] Another Perkins M30 Overheating Help Thread

[Dan Winsor]

Hey all, this is a good one. So.... now that we have confirmed fresh water
flow via clear hose section (great idea), let's focus on heat transfer. The
fresh water gains heat from circulating around the cylinders and dumps heat
by transferring to the raw water via the heat exchanger and the hot water
heater via a coil located within. Those two circuits are parallel flow and
the hot water heater will get less flow due to smaller hose size. Does the
hot water heater get hot?
The engine heat exchanger is the primary heat dump of course. Although I
have not had cause to open mine, I assume it to be a shell and tube type
exchanger where raw water runs thru tubes from the fwd end to the aft end
of the exchanger and the tubes are surrounded by fresh water being
circulated by your new engine water pump. The radiator cap being on top of
the exchanger shell insures that if the water level is near to the top then
the likelihood of airbound condition is minimal. The expansion tank being
even higher pretty much guarantees it. Have you run with cap removed and
seen flow thru the shell?
The wet exhaust is a good indication of raw water flow but can be somewhat
hard to differentiate good flow from low, especially with the pulses from
the muffler. I would second the suggestion to resort to a contact
thermometer and start tracing the heat. I frequently grip the hose leaving
the raw water pump (cool to touch) and the hose entering the exhaust elbow
(quite warm) during my engine testing prior to launch.
Here are some additional suggestions....
1. monitor the expansion tank and verify that level rises as engine heats
and returns to prior level as engine cools. this will verify proper
operation of the radiator cap and the plumping between the cap and the
tank. should eliminate air concerns.
2. when eng temp starts to climb, try running hot water and see if that
stabilizes or slows the rate of increase.
3. remove the raw water hose from the exhaust elbow and run it overboard.
Cob some plug on the elbow where the hose was attached. This will minimize
back pressure on the raw water pump and create more flow thru the tubes
thereby transferring more heat. This will also eliminate the exhaust line
from being a cause. Of course exhaust flow will be louder and get hotter so
don't run that way too long.
4. remove the large rubber end caps at one or both end of the heat
exchanger and clean the inside of the tubes with a bottle brush. fouled
tubes cant transfer heat well.
5. verify indicated eng water temp with contact thermometer.
Sorry if I repeated any testing you have already done. I also have the
perkins and have a vested interest in your issue. Lets solve this thing and
save your trip!
Dan Winsor
Lucky Devil #109
Mattapoisett, MA

On Fri, Jun 9, 2023 at 1:20 PM Paul Hetherington via C320-list <
c320-list at lists.catalina320.com> wrote:

> Jeff and Dave thanks for your comments.  Thanks for sticking with me on
> this.
>
> Dave, you are correct we are in Salt Water and have replaced the exhaust
> elbow.  It was relatively inexpensive and easy to do so it was high on the
> list.
>
> Jeff, we may very well have air in the system it sounds like.  After other
> fixes we may not have been focusing on getting it all out well enough,
> giving us the impression other fixes didn't work?   Going to play with ways
> to eliminate it.  I'm not sure I understand the funnel method you mention,
> but I am doing some research.  Also looking into whether a pressure tester
> would be of value.  Dave mentioned 7psi.  Gonna chase that down.
>
> We did think perhaps we were over propped (good suggestion), but after
> working with the outfit that built our prop up here in Naniamo (he was very
> helpful) it actually appears we may be under propped which is resulting in
> our not achieving expected speeds and thus wanting to push the revs up.  We
> are working with that as separate issue and will be re-pitching after a
> haul out in 2 weeks.  Hopefully that doesn't exasperat our overheating
> issue, but at least we will be able to achieve a higher speed at the lower
> rpms we are currently forced to operate under.
>
> Will report back.
> ----------------------------------------------------------------
> Paul Hetherington
> Seasun, 1994, Hull #155
>
> On Fri, Jun 9, 2023 at 8:48 AM Jeff Smith via C320-list <
> c320-list at lists.catalina320.com> wrote:
>
> > You might try running the engine without the cap on (apologies if this
> has
> > been suggested). It sounds like air in the coolant. There is also a
> > no-spill funnel that you can use with coolant to make sure there is no
> > trapped air. This involves filling the funnel with coolant and running
> the
> > engine and letting air bubble out. It might be getting into the system
> > through the cap.
> >
> > Is it also possible you are over-propped? I know you just installed a new
> > prop and the problems also just started. Either too much pitch or size? I
> > am sure, based on the list of stuff you have replaced, that this is not
> an
> > issue. But, I have a max prop with adjustable pitch, and the previous
> owner
> > (or me the last time I serviced it) set the pitch too low.
> >
> > Good luck. Let us know if you figure it out.
> >
> > Jeff Smith, #121
> >
> >
> >
> > On Fri, Jun 9, 2023 at 9:54 AM Dave Hupe via C320-list <
> > c320-list at lists.catalina320.com> wrote:
> >
> > > Looks based on your photos like some minor coolant leak around the
> > > "radiator cap" neck on the heat exchanger tank. The cap looks
> > > original/rusty. So, wouldn’t hurt to replace it (7psi is what is
> spec'd).
> > > However, without seeing a trail of coolant leakage there, I am not sure
> > > that is your problem.
> > > I have heard about blockage in the exhaust elbow causing overheating.
> Any
> > > consideration of that?  I replaced my entire heat exchanger tank
> because
> > > the "radiator cap" neck on the tank had a piece cracked off where the
> cap
> > > should seal.  I had to remove my exhaust elbow attached to the tank and
> > > remount it on the new tank.  I carefully inspected my elbow and it was
> > very
> > > clean and seemed fine to reuse.   My boat has always been in
> > freshwater.  I
> > > don't see on the hull roster or your posts where you are located
> > > (saltwater??). That can make a significant difference related to items
> > like
> > > this.
> > > Dave Hupe
> > > 1994 C320 #32
> > >
> > > Sent from Yahoo Mail on Android
> > >
> > >   On Fri, Jun 9, 2023 at 1:42 AM, Paul Hetherington via C320-list<
> > > c320-list at lists.catalina320.com> wrote:   So still trying various
> > > suggestions here and have ordered a fresh water
> > > pump.  But we put a clear hose on the fresh water loop today and it's
> > very
> > > obviously circulating water.
> > >
> > > We thought we had maybe fixed the overheating after really running at
> > high
> > > revs the other day for testing of the prop (dislodged something?) so
> did
> > > some measurements/testing.  Unfortunately the temp climbed to 200 after
> > > about 30 minutes at 2700.  It dropped back down to 180 after 20 min at
> > > 2000, and then climbed back to 185 after 30 minutes at 2500.  Not sure
> if
> > > it had plateaued because we had to come in.  But clearly still have a
> > > problem.
> > >
> > > Any chance a small leak in the rad cap could cause this?  Here are some
> > > pics.  We can't see  a leak, or water coming out but it looks corroded
> > and
> > > we are trying anything at this point.  What is the best way to test
> this
> > > out?
> > >
> > > Pics here:  https://photos.app.goo.gl/E83NV9cPXe6JFXXZ8
> > >
> > > We are getting pretty discouraged at this point.  The boat is usable,
> but
> > > the month long journey we have planned for this summer is going to be
> > tough
> > > with 4 knots through the water.  Especially because some of the passes
> up
> > > here can be 8 knots (really have to time it!).
> > >
> > > Thanks, Paul.
> > >
> > > ----------------------------------------------------------------
> > > Paul Hetherington
> > > Seasun, 1994, Hull #155
> > >
> > >
> > > On Mon, May 29, 2023 at 7:27 PM Paul Hetherington <paul at heth.ca>
> wrote:
> > >
> > > > Some good thoughts here. Thanks to all.  Will be trying a few things.
> > > >
> > > > One thing that has come up, how would we best confirm the non-raw (so
> > > > fresh) water pump is working well?  There is no impeller that I know
> > of,
> > > so
> > > > not entirely sure how the water is 'pushed' around the circuit. It
> > would
> > > > stand to reason that if this water isn't moving well then the cooling
> > > > transfer won't be efficient and the temp would rise.  I'm just not
> sure
> > > how
> > > > to best test this.
> > > >
> > > > Cheers.
> > > >
> > > > ----------------------------------------------------------------
> > > > Paul Hetherington
> > > > Hull 155, 1994 Seasun.
> > > >
> > > >
> > > > On Mon, May 29, 2023 at 1:08 PM Dan Winsor via C320-list <
> > > > c320-list at lists.catalina320.com> wrote:
> > > >
> > > >> Here's my two cents worth...
> > > >> If the engine can't transfer its heat to the raw water then the raw
> > > water
> > > >> would be cold when it enters the exhaust elbow. If that's the case
> > then
> > > >> swap out your new water pump. I don't believe in coincidences like
> > that.
> > > >> Dan Winsor
> > > >> Lucky Devil #109
> > > >>
> > > >> On Mon, May 29, 2023, 15:41 P.F. Ross via C320-list <
> > > >> c320-list at lists.catalina320.com> wrote:
> > > >>
> > > >> > Paul,
> > > >> >
> > > >> > Your experience sounds very much like mine.  I run at 190 at 2700
> > rpm
> > > >> > cruise (I have an Autoprop) and have done all the things you have,
> > > >> except
> > > >> > for doing the temp testing with a non contact thermometer.  It has
> > > been
> > > >> > this way for many years and over those same many years replacing
> the
> > > >> temp
> > > >> > sender has been on my list.  I figure it is the only thing I have
> > not
> > > >> done.
> > > >> >
> > > >> > I watch the temp gauge like a hawk, but it has always held steady
> at
> > > 190
> > > >> > except for once when I sucked a plastic bag into the raw water
> > intake.
> > > >> So
> > > >> > at least I know my temp gauge moves!
> > > >> >
> > > >> > Frank Ross
> > > >> > Beta Wave #206
> > > >> > Naples, FL  34102
> > > >> >
> > > >> > On Mon, May 29, 2023 at 2:26 PM Dave Hupe via C320-list <
> > > >> > c320-list at lists.catalina320.com> wrote:
> > > >> >
> > > >> > >
> > > >> > > https://www.parts4engines.com/perkins-perama-m30-water-pump/
> > > >> > > This would be the engine water pump.
> > > >> > > Dave Hupe
> > > >> > > 1994 C320 #32
> > > >> > >
> > > >> > > Sent from Yahoo Mail on Android
> > > >> > >
> > > >> > >  On Mon, May 29, 2023 at 3:02 PM, Paul Hetherington via
> C320-list<
> > > >> > > c320-list at lists.catalina320.com> wrote:  Yes our M30 is running
> > > hot.
> > > >> > > 2500 rpm = 190, much over that and it pushes
> > > >> > > over 200.  Haven't had the guts to push it right into triggering
> > the
> > > >> > > overheating alarm (203? - not totally sure it's functioning).
> But
> > > we
> > > >> > used
> > > >> > > to be able to run at 2700 with no overheating (185-190) and now
> it
> > > >> heats
> > > >> > up
> > > >> > > very quickly.
> > > >> > >
> > > >> > > I am pretty sure I have read all the previous threads and tried
> > many
> > > >> of
> > > >> > the
> > > >> > > suggestions but we are still stuck, so posting our detailed
> > approach
> > > >> is
> > > >> > > only to clarify it to myself, but hoping to get some
> insight/ideas
> > > >> from
> > > >> > > your experience.
> > > >> > >
> > > >> > > Here is what we have tried:
> > > >> > >
> > > >> > >  - Checked the raw water intake and all was clear.
> > > >> > >  - Removed hose between seacock and water filter and confirmed
> > good
> > > >> > water
> > > >> > >  intake flow through seacock
> > > >> > >  - Diver conformed no obstruction from below at the entrance of
> > the
> > > >> > >  seakcock
> > > >> > >  - Topped up the coolant
> > > >> > >  - Replaced the impeller
> > > >> > >  - Replaced the thermostat (Even though the old thermostat was
> > > >> working
> > > >> > >  fine when I tested both of them in boiling water)
> > > >> > >  - Took out the heat changer and cleaned in a bath of muriatic
> > acid.
> > > >> It
> > > >> > >  was then very clear.  It was not that clogged up to begin with
> > > >> though
> > > >> > >  - Replaced the exhaust elbow (after ordering one with current
> > > >> > downstream
> > > >> > >  tube diameter)
> > > >> > >  - Replaced the raw water hoses between the intake seacock,
> > between
> > > >> the
> > > >> > >  raw water filter and the water pump with new reinforced hoses
> to
> > > >> make
> > > >> > > sure
> > > >> > >  that they are not collapsing
> > > >> > >  - Kept testing the engine in forward gear, tied to the dock,
> and
> > > >> > >  measured temperature with heat gun all over engine block, to
> > > >> confirm it
> > > >> > >  wasn't a gauge issue.
> > > >> > >  - When engine was ran at 2500 rpm or higher, measuring
> > temperatures
> > > >> > >  between 195 and 200 around the coolant pump
> > > >> > >  - Always seemed to have good water flow coming out of the boat
> > > >> > >
> > > >> > > Right around the time we started to have overheating issues two
> > > other
> > > >> > > events happened that may or may not be related.  We switch from
> a
> > > >> tired
> > > >> > and
> > > >> > > chipped 2 blade prop to a 3 blade Campbell Sailer prop AND the
> > water
> > > >> pump
> > > >> > > was leaking so we replaced it with this one from parts4engines:
> > > >> > >
> https://www.parts4engines.com/perkins-perama-m30-raw-water-pump/
> > > >> > >
> > > >> > > Any help is appreciated.
> > > >> > >
> > > >> > > Cheers.
> > > >> > >
> > > >> > > ----------------------------------------------------------------
> > > >> > > Paul Hetherington
> > > >> > > Hull 155, 1994 C320
> > > >> > >
> > > >> > >
> > > >> >
> > > >>
> > > >
> > >
> > >
> >
>