All_at_Sea
Well-Known Member
I have a Nic 38 with a Perkins 4108. Does anyone know what is the correct running temp? It seems to vary between 80 -100 degrees, which seems too hot?
Perkins 4108 running temp
- Thread starter All_at_Sea
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bdsweeting
Well-Known Member
I assume that you are talking °C in which case 100° is a bit hot.
The fact that the temperature is fluctuating it would seem to indicate a dicky thermostat if this is at constant revs.
The fact that the temperature is fluctuating it would seem to indicate a dicky thermostat if this is at constant revs.
Salty John
Well-Known Member
It should run at around 80 degrees, so it is running a little hot. The thermostat will open somewhere between 74 and 82 degrees. I would check the raw water strainer, pump belt tension and heat exchanger.
Roberto
Well-Known Member
on mine, from idle to say 2000 rpm it runs at around 70°, thermostat barely open, from 2000 to 2800rpm it is stable at around 80/85
when I first took the boat it ran at a much higher temperature, at around 90°C whatever rpm: I checked the impeller and there were 6 broken and missing vanes, after replacing it everything runs smoothly (funny though, at first sight it does not seem to make too much difference in the amount of water that comes out of the exhaust)
when I first took the boat it ran at a much higher temperature, at around 90°C whatever rpm: I checked the impeller and there were 6 broken and missing vanes, after replacing it everything runs smoothly (funny though, at first sight it does not seem to make too much difference in the amount of water that comes out of the exhaust)
Stemar
Well-Known Member
My understanding is that it depends on whether the engine is raw water or fresh water cooled.
From the engine's point of view, the closer to 100 degrees C the better, as the hotter the engine, the more efficient it is. Also there's less risk of acids from combustion condensing out. This is why cars usually run around 95 C and the red line's well over 100 C. The pressure in the system keeps the water from boiling.
With a raw water system, if the water temperature goes much above 60 C, the engine will fur up like a kettle. This is a vicious circle, because the fur lines the waterways, reducing the flow, so it gets hotter, so you get more furring...
With a fresh water system, the engine can afford to run hotter, but not as hot as a car, or you're likely to get furring up in the raw water part of the heat exchanger. Once you've checked the pump, strainer and belt, this is the most likely cause of hot running. If so, the cure is a good soak in a mild acid. Vinegar is cheap and, while a bit slow, won't eat the metal A lot of kettle descalers use citric acid, which is more expensive, but stronger. It's also unlikely to damage anything
From the engine's point of view, the closer to 100 degrees C the better, as the hotter the engine, the more efficient it is. Also there's less risk of acids from combustion condensing out. This is why cars usually run around 95 C and the red line's well over 100 C. The pressure in the system keeps the water from boiling.
With a raw water system, if the water temperature goes much above 60 C, the engine will fur up like a kettle. This is a vicious circle, because the fur lines the waterways, reducing the flow, so it gets hotter, so you get more furring...
With a fresh water system, the engine can afford to run hotter, but not as hot as a car, or you're likely to get furring up in the raw water part of the heat exchanger. Once you've checked the pump, strainer and belt, this is the most likely cause of hot running. If so, the cure is a good soak in a mild acid. Vinegar is cheap and, while a bit slow, won't eat the metal A lot of kettle descalers use citric acid, which is more expensive, but stronger. It's also unlikely to damage anything
LeytonC
Well-Known Member
If it it running to high with correct thermostat, you might have (some) blocked tubes in the heat exchanger, my pair of 4108 have the heat exchanger across the front of the engine, combined with the oil cooler - they are dead easy to take apart to clean just a single 3/4 bolt (long though!) holds the lot together.
Check the rubber seals though, but you can get replacements from Bowman in Birmingham.
Check the rubber seals though, but you can get replacements from Bowman in Birmingham.
pappaecho
Well-Known Member
My keel cooled 4108 never gets to working temperature even though there is a working temperature gauge, on the Perkins instrument panel.
With indirect cooled engine the most likely cause is either a damaged Jabsco impellor, or partly blocked heat exchanger.
The Perkins manual shows you how to clean the heat exchanger bundles in situ.
If you need to download a copy ( in PDF format) drop me a PM
With indirect cooled engine the most likely cause is either a damaged Jabsco impellor, or partly blocked heat exchanger.
The Perkins manual shows you how to clean the heat exchanger bundles in situ.
If you need to download a copy ( in PDF format) drop me a PM
All_at_Sea
Well-Known Member
Sorry, new to this game, what's a PM. I'd love a PDF copy if you have one.
Bejasus
Well-Known Member
If you look near the top of your screen next to user options, you will see a flashing envelope icon. Click on this icon and it will take you to your private mailbox and there you will find a PM from me explaining further. /forums/images/graemlins/cool.gif
George
George
scubadud
New Member
hi i am looking for 2 perkins 4108 engines
can eny one help
can eny one help
AndrewB
Well-Known Member
My 4108 runs between 80-83ºC. For years I thought it ran cool, until I fitted a new thermometer. The old one had a slight crack and was misreading. So if the reading is odd but the engine is running normally, check that.
The usual cause of an overheating engine is a stuck thermostat, easy and cheap enough to change on a 4108 just as a precaution.
The usual cause of an overheating engine is a stuck thermostat, easy and cheap enough to change on a 4108 just as a precaution.
AndrewB
Well-Known Member
[ QUOTE ]
hi i am looking for 2 perkins 4108 engines
can eny one help
[/ QUOTE ]Try Marlec Marine at Ramsgate. They had a couple of recon marine 4108's last time I was there. Otherwise they come up fairly regularly on Ebay.
hi i am looking for 2 perkins 4108 engines
can eny one help
[/ QUOTE ]Try Marlec Marine at Ramsgate. They had a couple of recon marine 4108's last time I was there. Otherwise they come up fairly regularly on Ebay.
