Perkins 4108 coolant replacement

[Roberto]

I have a Perkins 4108 with a Bowman heat exchanger.

The engine runs fine, normal operating temperature, the refrigeration liquid keeps its colour, etc. Usually, I just top up the coolant level from time to time, basically half a glass every 100hrs, I guess that is normal.

I would like to drain it completely, wash the conduits, then fill with new fresh coolant. It can't hurt.

There are two draining bolts: one is on the bottom of the exchanger, the second one is on the engine block, near the lift pump.
The second plug obviously is "behind" the thermostat.
In the past I drained some liquid from the engine block plug just to check it was free flowing and with no sludge, but never emptied it completely.

Suppose I drain all the liquid from this second plug. When I fill the exchanger with new liquid, is there a bypass of the thermostat allowing it to fill the engine block ? Or do I have to remove the thermostat, fill with coolant, then put the thermostat back in ?

I looked at the workshop manual but there are so many different cooling arrangements I could not find a proper answer.


thanks

 

[PlankWalker]

I drain mine from the plug near the back of the block, I poke some wire in it as it drains to help expel rusty sludge.

I refill from the heat exchanger, leave the cap off then start the engine, as it gets warm, level goes down, slowly top up, half a pint or so until you cant get any more in,

Fit cap, job done. I haven't removed my thermostat in 20 years.

Plank

 

[macnorton]

I drain mine from the plug near the back of the block, I poke some wire in it as it drains to help expel rusty sludge.

I refill from the heat exchanger, leave the cap off then start the engine, as it gets warm, level goes down, slowly top up, half a pint or so until you cant get any more in,

Fit cap, job done. I haven't removed my thermostat in 20 years.

Plank

Same as, the factory marine engines have a tap near the lift pump for draining.

 

[Roberto]

thank you