Perkins 4108 Overheating

[jacob30]

I would not put a weld bead down as a premptiv measure. I would consider building up a worn adaptor fitting but I beleieve the shaft on the pump size is brass. I will have to double check the pump I have (which is a JABSCO). My plan for long term cruising is periodic inspection and always have one of each on board.

[Silence]

I'm not sure I am being clear. The "tip" or part that looks like a screw driver head is not worn down and has plenty of space to drive the pump shaft so that is not the problem. The problem is that the shaft shown, when plugged back into the gear simply spins freely. There is no key. Possibly it was pressed into the gear and came undone??? So what happens is the engine runs but does not move the shaft at all. Does this make sense?

[Davwu]

Check out page 28 of this. Me thinks you are missing a key

[Chief Engineer]

dEPCO pUMP

[Blue Stocking]

Have no Perkins experience, but am curious.

Post #10 photo shows female spline housing adjacent to pump drive fitting.
Does a short male spline connect them, otherwise, how does pump get driven.?

[donradcliffe]

This one has me stumped--it looks like the drive coupling has sheared off, but the seawater pump coupling in the Perkins parts manual doesn't look at all like your picture or what I can remember. They must have more than one design. Time for you to talk tot a real mechanic.

[Chief Engineer]

iS THE bLACK hORSE OR THE GUNPOWDER CAVERN STILL OPEN?

[perchance]

Originally Posted by Silence

I am attaching a picture.

I see what looks like an internal spline where the drive lug goes. Is there a corresponding spline in the drive coupler?

[Blue Stocking]

Originally Posted by Chief Engineer

iS THE bLACK hORSE OR THE GUNPOWDER CAVERN STILL OPEN?

The Black Horse is alive and well, jumpin 'n pumpin, still belongs to 'Burp' Lambe. Cavern closed up some time back.

[Chief Engineer]

I liked the Cavern........I was there in off season some years back....the lady that ran it took us on a private tour almost a;; the way to Fort ST Catherine

[Seman]

Originally Posted by CSY Man

Numerous threads on 4-108s over-heating, do a search.

The engine is rated for 51 HP at 4000 RPM

Max continous RPM is 3000.

My 1979 4-108 will slowly but surely over heat if I run it over 2400 RPM.

Some folks may be over-propped, or running too high RPM to get the "goods".

First thing to check is impeller. Second is heat exchanger. (Clean in acid bath)

Third is to flush and overhaul cooling system including sea water strainer.

These are old engines in old boats and lots of deferred maintenance is going on.

Recommended RPM for cruise is 70% of max continous, or 2100.

If your 4-108 still over heat heats after you checked the cooling system including impeller/heat exchanger and running 2100 RPM, then you are possibly over-propped or the boat is too big for the engine...Or the engine too small for the boat.

I've battled with a similar overheating problem on my 4108 for years, until I replaced the Bowman heat exchanger.
The holes in the Heat Exchanger, where the bronce saltwater pipe fit through, were worn & the water was by-passing the cooling pipe.
These holes should be a tight fit.

[gulfstar37]

Just went through a overheating issue on our 4-108 last week. Started out with the simple stuff, impellers, ect and found it was just the thermostat. Don't know if this was put out before but "Gates thermostat #33008" at 180F was cross referenced at local auto store as a direct replacemnt.

[Jesse]

Originally Posted by Blue Stocking

Have no Perkins experience, but am curious.

Post #10 photo shows female spline housing adjacent to pump drive fitting.
Does a short male spline connect them, otherwise, how does pump get driven.?

Yes a short adapter spline conects the the whole shebang. Without it nothing turns. If memory serves there is a flat on one side so it only fits one way.