[C320-list] Another Perkins M30 Overheating Help Thread

[Dave Hupe]

The only other things I can think of is the actual engine water pump that  circulates coolant may be bad (i got a replacement from parts4engines)  and/or the belt slipping on the water pump pulley??  Did you change the engine's coolant when you removed the heat exchanger tank, etc.?Another possibility is a bad head gasket (are you losing engine coolant?).

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