Perkins 4108 Overheating/Steaming

[svHyLyte]

Originally Posted by jlogan

One other thing you might check is the hint mentioned in one of the posts above, the one about disconnecting your water heater from the circuit...for some reasons some installations like this with Perkins cause them to overheat. I don't remember the reason, but I think you can find it on this forum. The basic point is that the hose to the heater screws up the circulation and you get an overheat.

Lines from the engine to a hot water heater typically have a diverter valve that controls the amount of coolant running to the heat exchanger in the water heater. Fully closed, none, fully opened, all of the water from the engine flows through the water heater although that may make the fresh water too hot for safe use. If the water heater has been removed, the diverter valve should be closed or water through the engine's cooling system will be restricted. Further, the thermostat should be replaced with the proper replacement part. Without, the coolant flow through the engine heat exchanger can be too fast to allow the coolant heat to be passed to the raw water. Heat transfer isn't instantaneous. If you have an infrared thermometer, you can easily measure the temperature of the raw water exhaust, which should be substantially greater than the ambient raw water temperature. If not, its not cooling the engine coolant.

FWIW...

[cal 39 guy]

Do you know where diverter valve is located?
On my 4108 set up, 1 hose plumbs at head and the other comes off a y at trans cooler.
doesn't look like all coolant flows through potable heater lines.
Also i checked and someone removed
thermostat. could this be why my engine over heats after an hour or so running.
local waters are 80 deg. even when engine is overheating, raw water is not very hot to touch.

[SkiprJohn]

Let us know what you check and how it works out. If someone changed the water pump and impeller then they have taken the pump off and maybe reversed the gaskets. I'd remove it and check once you've tried everything else.
As was suggested: Give the pump a spin by hand to see if the vanes are moving water. That'll at least tell you if the impeller shaft is spinning the vanes.
I have an old very large Perkins heat exchanger here that I could sell you but it may not be your problem. I'm on the Big Island.
Blockage of the exhaust mixing elbow will sometimes cause overheating as will anything wrapped around your propeller shaft or a stuffing box too tight. Many things can add to the problem. Check everything but make certain that water is pumping out through the exhaust whenever you start the engine.
kind regards,

[cal 39 guy]

thanks
i looked at coolant pump but i couldn't see three layers of: gasket, metal,
gasket. it looks like just one red gasket.

are there different style pumps that only use 1 gasket?


and any recommendations for best way to inspect exhaust elbow?
do i need to remove manifold?

[onestepcsy37]

cal39guy -

i just checked my perkins engine manual. there are two gaskets and a 'backing plate' between the fresh water pump and the engine block.

part number 36866713 is a cork gasket that goes up against the pump.
part number 36866421 is a cork gasket that goes up against the engine block.
part number 36243515 is a metal 'backplate' that goes between the two gaskets.

the installation instructions advise installing the engine gasket, then the backplate, then the pump gasket, in that order, using 'jointing compound'.

so i guess there really are two different cork gaskets used in the assembly. that doesn't mean you've put it on wrong, just that it's different.

as for the thermostat;

the purpose of a thermostat is to bring the engine up to 'operating' temperature quickly. engines run best when run in their correct 'operating' temperature range.

removing the thermostat will slow down the process of warming up. it may even prevent the engine from reaching it's operating temperature range (but not likely). one thing it will NOT do is cause the engine to overheat.

on the other hand, leaving a faulty thermostat in the engine can cause it to overheat, if it fails in the closed position (also not likely).

i removed mine two years ago. i also sail in warm waters (florida/bahamas) and have suffered no adverse consequences.

someone mentioned the exhaust elbow. if this were clogged it would show up quickly in reduced water flow out the exhaust pipe, and would be noticeable to an experienced owner. i get the feeling from your post that this is a new boat/engine to you and so you have no prior experience in what a 'normal' outflow of cooling water is from your exhaust pipe. if so, try to have another 4-108 owner look at it or look at another 4-108 to get a rough idea.

i know it's hard to believe, having been down this road many times, that you (or your expensive mechanic) will eventually find the problem. good luck.

[onestepcsy37]

also should have mentioned this.

if you can only find one gasket - or even two but no metal plate between them, then you have incorrectly installed the fresh water pump. try to find a REAL perkins mechanic or perkins engine dealer and get the right parts, as well as advice on how to install it correctly.

[cal 39 guy]

thanks!
sadly there is no perkins dealer on oahu{honolulu}
but the coolant pump was put on by a marine mechanic recommended by surveyor.
i havent pulled the pump yet but im wondering if this :
gasket, metal plate, gasket can be seen without pulling pump?
btw i have the engine service manual that shows proper installation.

[Jubilee39]

I had the same problem when I went from Virginia to the Caribbean, chased it for years and finally called Sendure for advise on what else was possible. They told me they made a bigger heat exchanger for the 4-108. Installed it several years ago and have not over heated since, always in tropical waters.
Joe

[cal 39 guy]

thanks to all!
capped the water heater lines and installed thermostat and she's running
cool.

[HappyMdRSailor]

Originally Posted by cal 39 guy

thanks to all!
capped the water heater lines and installed thermostat and she's running
cool.

Thanks for posting the resolution!!!!!

My first instinct was to put that T-stat back in, as I have had tons of experience with people taking them out for overheating diagnosis, and leaving them out.... CREATING another DIFFERENT overheat cause...Engines need T-stats to slow the recirculating hot water as well as their warm up function.... There were others with specific experience running without them, so I let that go...

Glad you got it worked out!

[SkiprJohn]

Congratulations! Feels good to have a good running engine. 4-108s are great.
kind regards,

[donradcliffe]

Originally Posted by svHyLyte

Lines from the engine to a hot water heater typically have a diverter valve that controls the amount of coolant running to the heat exchanger in the water heater. Fully closed, none, fully opened, all of the water from the engine flows through the water heater although that may make the fresh water too hot for safe use. If the water heater has been removed, the diverter valve should be closed or water through the engine's cooling system will be restricted. Further, the thermostat should be replaced with the proper replacement part. Without, the coolant flow through the engine heat exchanger can be too fast to allow the coolant heat to be passed to the raw water. Heat transfer isn't instantaneous. If you have an infrared thermometer, you can easily measure the temperature of the raw water exhaust, which should be substantially greater than the ambient raw water temperature. If not, its not cooling the engine coolant.

FWIW...

None of the hot water heater installations I've seen have a diverter valve in the circuit to the engine--they can have one in the circuit to the faucets.

I guess I'll have to give back my degrees in fluid flow and heat transfer, because all the heat exchanger design calculations I know of say the opposite--the more coolant that flows through the heat exchanger, the cooler things get.

[onestepcsy37]

glad to hear things have turned out ok. they usually do, but when you're in the middle of it it's sometimes hard to believe. i'm certain it was the water heater line and not the thermostat, but that's just my opinion.

since you've reinstalled your thermostat and it's working fine i wouldn't take it out now. i've had mine out for a couple of years and have no problems, but like you i'm in a warm climate. if i were in a cold climate i probably would have left it in.