Perkins 4108 Issue

[Cap Morgan]

Hello out there!
I finally purchased a Cruiser after a year of searching, actually a racer cruiser (1980 CAL 39).
Naturally this old lady needs some TLC for which I have her hauled out in Port Canaveral Florida to primarily work on the bottom. The list of todos is quite extensive as you can imagine with a time constraint to get out of the Marina that I’m in. As such I’m seeking some assistance with one particular issue. The Perkins 4108 has a coolant leak which I must locate prior to motoring down the ICW to Miami in a few weeks. The metal coolant reservoir is not leaking and is actually full, however, when filling the plastic reservoir the coolant leaks out under the metal tank and I can see it trickling across the exhaust header. I tested the plastic tank and the output line and they’re not leaking. So, what could I check beneath the metal tank for leaks? With adequate time I would investigate myself, but unfortunately with my monumental list of todos with little time I could certainly use your assistance. Thanks in advance for your assistance!

[rbk]

That’s an expansion or overflow tank, don’t fill it. If the tank on the engine is full you’re good. The plastic tanks are added in case they overhear and boil over. Rather then making a mess of the engine and filling the cabin with coolant and smoke/ steam it goes in the overflow tank.

[CSY Man]

Please show pictures, much easier to comment then.
The 4-108 came in several different versions.
My version did not have an expansion tank for the coolant, but rather a plastic tube from the coolant reservoir's cap flange down to the bilge area.
(I let it bottom out in a plastic bottle, like a Poor Man's Expansion Tank, to avoid a messy bilge. )

[Cap Morgan]

Originally Posted by rbk

That’s an expansion or overflow tank, don’t fill it. If the tank on the engine is full you’re good. The plastic tanks are added in case they overhear and boil over. Rather then making a mess of the engine and filling the cabin with coolant and smoke/ steam it goes in the overflow tank.

Thanks RBK!

Want to know how silly I feel about putting water in the expansion tank?😳

BTW, I’m curious as to the normal operating temp of this engine. Is it between 160 and 180 degrees or is 180 too high?

[Cap Morgan]

Thanks for responding CSY. I think RBK solved the puzzle for me.

[marcjsmith]

My 4108 also had no expansion tank, but like CSy, an old plastic one liter bottle of tonic water serves as my overflow.

Runs happily at 180

[Cap Morgan]

Originally Posted by marcjsmith

My 4108 also had no expansion tank, but like CSy, an old plastic one liter bottle of tonic water serves as my overflow.

Runs happily at 180

Thanks Marc! Much appreciated.