Perkins 4108 overheat and black smoke...

[avazquez]

Here is the situation:

Problem:

Under normal operation engine used to overheat and begin to smoke black after around steady 2900 rpm or more.

Suddenly engine began to overheat and upon investigation found loose belt and after tightening the belt - still overheating at around 2400 rpm.

At 2500 rpm engine will smoke a bit black smoke and slowly overheat above 200F.

Things I've done:

a. Removed heat exchanger and was clean so I cleaned it again.
b. Verified thermostat operation by removing it by checking its opening temperature etc.
c. Adjusted valves.
d. Verified impeller and was ok.
e. Cleaned raw water strainer.
f. Removed and verified the fresh water pump. Reinstalled with proper gaskets and plate etc.
g. Removed and cleaned mixing elbow.
h. Verified cleanliness of air intake screen.

The thing is that this happened suddenly and I have run out of ideas on what to check next.

[Harter]

Originally Posted by avazquez

Here is the situation:

Problem:

Under normal operation engine used to overheat and begin to smoke black after around steady 2900 rpm or more.

Suddenly engine began to overheat and upon investigation found loose belt and after tightening the belt - still overheating at around 2400 rpm.

At 2500 rpm engine will smoke a bit black smoke and slowly overheat above 200F.

Things I've done:

a. Removed heat exchanger and was clean so I cleaned it again.
b. Verified thermostat operation by removing it by checking its opening temperature etc.
c. Adjusted valves.
d. Verified impeller and was ok.
e. Cleaned raw water strainer.
f. Removed and verified the fresh water pump. Reinstalled with proper gaskets and plate etc.
g. Removed and cleaned mixing elbow.
h. Verified cleanliness of air intake screen.

The thing is that this happened suddenly and I have run out of ideas on what to check next.

I have one thought and I am sure others will have thoughts as well.
The impellers on the water pump. Are then in good condition???
i had a water pump eat the impellers down to just part of one left. This caused a slow overheating of the motor, It heated up to 200 degrees, Same as what you are saying, The black smoke is a sign of over fueling, Best I can do for help, I am sure others here have more to add,
Terry

[avazquez]

Both the fresh water (coolant) impeller looks perfect as the pump is a few years old and I just removed it this morning. The raw water impeller is new. The intriguing part of this is that it happened suddenly.

[Harter]

ok here are my next thoughts, something has changed, Is there something restricting the flow of fluid? you heated up suddenly, something is plugged off,
has to be,
cooling to heat exchange, coolant shut off valve threads stripped, hose pinched?
Do you think you might have any thing like that happening?
Terry

[DeepFrz]

Have you read any of the other threads on the 4-108 overheating?

[avazquez]

Its a combination:

Overheating and smoking earlier than it used to. What could cause both things?

[model 10]

It's not a cooling system problem. It's fuel problem, maybe, as in you are getting too much. Diesels like their fuel, like a sailor likes rum. The controls in the pump keeps the rpm constant but the engine is burning too much fuel. Might be time for a fuel pump overhaul.
I once drove a diesel truck with a 3208 Cat. I tried to make go faster up hills by adjusting the fuel flow higher. All it did was make it smoke and get hot.

[avazquez]

Originally Posted by Guy

It's not a cooling system problem. It's fuel problem, maybe, as in you are getting too much. Diesels like their fuel, like a sailor likes rum. The controls in the pump keeps the rpm constant but the engine is burning too much fuel. Might be time for a fuel pump overhaul.
I once drove a diesel truck with a 3208 Cat. I tried to make go faster up hills by adjusting the fuel flow higher. All it did was make it smoke and get hot.

Ha ha ha I love it!

The ribs "hot and smoking" !!!

[onestepcsy37]

I'm sure you checked this but just to mention it.... I always check the volume of water coming out the exhaust pipe so I have an idea about what it should look like. Does your output water stream seem to be less than usual? Is it coming out like steam rather than water? That would indicate a raw water cooling system problem.

I did have an overheat problem on my 4-108 which turned out to be the fresh water pump. The internal vane is press fitted to the shaft that the pulley turns and there was slippage under load. It looks fine when it's running but it's not pumping coolant very well. I could tell because when the engine was running, with the radiator cap removed, you could not see much water movement in the header tank.

I also note you run at what I would consider high rpm, although some think I run at too low an rpm. I normally run at 1700. Highest i've ever had was 2200.

I used to work in Humacao back in the 1970's, in the industrial park just outside of town on the way to the beach. Bet it looks a whole lot different now....

[Lepke]

If your fresh and salt water pumps check out ok, no blockage in your exhaust water stream, you might check your prop. If you picked up some line or other debris on the prop, your injector pump will add fuel to reach the rpm you set. The debris causes drag on the prop and appears to the engine as if you are in an over propped condition. You get black smoke because the injectors are adding fuel and the engine heats because your asking for more hp than normal.

[CSY Man]

. normally run at 1700. Highest i've ever had was 2200.

70% of max continues RPM was recommended to me, on the 4-108 that turns out to be 2100 RPM and what I used for years cruising Florida and the Bahamas.
0,6 gallons per hour and 5,3 knots, no black smoke.
(It would put out a cloud of black smoke if gunned from idle, as in maneuvering in strong current or trying to clear a rogue bridge, black smoke = un-burned fuel)

My 4-108 would also slowly but surely over-heat if ran above 2600 RPM.
Tried everything to find the problem, but could not fix it, concluded that the heat exchanger was to small or the boat's cooling intake was undersized.
No big deal, it worked fine at normal cruise and I had 4000 RPM available when needed, if needed.

[sigmasailor]

Could be as simple as something has caught up in your prop causing extra drag. Does the prop spin easily when in neutral?

[avazquez]

Originally Posted by sigmasailor

Could be as simple as something has caught up in your prop causing extra drag. Does the prop spin easily when in neutral?

I already went down diving. Nothing there. Of all the things I think the next step is to remove the hose between the through-hull to the strainer and check it. If not then I will look into the Injection Pump etc. The fact that it blacksmokes at a lower rev than before is suspicious...

[NakedCity]

Happened suddenly is the key. As suggested previously the prop must be checked. Do not know what kind of prop you have but the pitch can change on some brands of feathering props.
If not a prop issue it could be a wet exhaust hose problem. The large exhaust hose is constructed of multiple layers of material. It is possible for an internal layer to separate at a bend, closing down the internal diameter and restricting the exhaust flow causing excessive engine back pressure. This could create your issues. The exterior of the hose will look fine.

Good Luck

[zeehag]

check your fuel system. first check oil, is it proper level or is there more on the dipstick than should be.
what color is fuel. if it is black, stop running engine..
has a pile of carbonny gook exuded from the exhaust yet? lol seems to be last stage of this all..
mine did not overheat when running, but the smoke was black, exudate was black, fuel was black, there was more oil in crankcase then put in originally, there was black smoke at 2600 ish rpms...oil smelled like diesel fuel.....

then i had runaway diesel.

check fuel system. all of it.

luckily i am not in usa, as my newly rebuilt engine was less than 4000 usd , including my rebuild of injector pump and lift pump and transmission heat exchanger.

good luck.