Engine Block Heaters question

My guess is that oil is like water and expands when warmed.

This man understands physics.

CskipR

Your engine heaters are probably thermostatically controlled, mine shut off at 110. Aside from expansion, the viscosity of the oil changed a bit and more may have flowed back to the pan, particularly from the canister filters if you have them. Suggestion, run the engines, then do your normal oil level check.

I did some training courses with MTU a while back. There feelings with block heaters was that you should not use them untill (forget the number) close to 40f and below. Reason is the heated block drains the oil down to the pan so when the engine starts there is no luberication. Prelube pumps are suppose to correct that issue.
I do not trust block heaters as I have had a lot of malfunctions with them after I turned my back. One almost caught on fire after it unexpectedly became air locked, fortunately I found it just in time.

CSkipR, Are your heaters the immersion type that heat the coolant, or the pad type that is glued to the oil pan and heats the oil? I'm thinking of installing the pad type and was wondering what the experience has been with both.

I've used my immersed heaters from late Fall thru the Winter into early Spring without event even when one element burned out about 6 years ago. For those of you who have had fires, what was the cause and were did it start?

The wire that the heaters comes with can get really brittle fast if laid close to the engine, it should be sleeved for total protection.

In one situation where the system became air locked, the heater barrel that would pass the engine coolant through had no coolant to heat and the thermostat sensed no tempeture keeping the elements on. There was deck carpet near by that almost ignited and the barrel burned off all it's paint. Second time, loose wire connection in control box causing burn smell in ER for me to get excited about. I can go on about many of other issues that where just plain iratating like the unbalanced electrical load issues and bla bla bla.
In warmer weather (above 40f) besides cleaner looking exhaust for the first few minutes of engine run time, I just don't see the need or benifiet to run the risk of using the heaters. Maybe someone can tell me more that I do not know?

C4ENG

For me it's a measure of protection in the Winter. I have a nice warm engine room and all those expensive seals, hydraulics, batteries, etc don't freeze. Also provides a bit of warmth to the salon above. I do agree that like any other item the heaters require periodic inspections, same way you check your batteries during the Winter to be sure they are not boiling off.

Switched all immersion heaters to the pad type years ago. Have used them on everything from car blocks to Lycomings in aircraft, and a wide range of Cat diesels. A single 4x6" pad on a pushcat fuel tank did wonders when things dropped to -35C. Just keep them clean and prep the surface properly before installing and Bob's your uncle. Have also used a few coolant circulation heaters and they worked well.

Like Codger, I have used block heaters on marine diesels in Alaska and the PNW (and aircraft engines in the Rocky Mountains) for years with no problems whatsoever. As a matter of fact the only block temperature trouble I ever had with an engine is when a large EMD dumped the coolant into the pan because it cooled too quickly. A block heater would have saved me a huge amount of work.

As far as the wiring comment, a proper block heater doesn't use zip cord for power and a proper installation will be made with cabling that withstands the relatively mild temperatures surrounding an engine. If you install a block heater from Pep Boys or some other auto parts store all bets are off.

If you think its OK have carpeting around your engine, you have to expect a few problems, block heaters are probably among the least of them.

The advantages of maintaining a constant (warm) engine far exceed any percieved threats. I am surprised to hear of an MTU tech claiming it is harmful to keep an MTU warm.

Anyone who runs 120 v a/c wiring around an engine without encasing it is asking for trouble, an engine running at operating temps is not giving off "mild" temperatures, potential damage in case of a direct short is catastrophic. The best application is to keep the HV away from the engine except at the final connection. YMMV

Just to clarify. The ones that we pulled and no longer use are the heater element type that are mounted in the block, sometimes by removing a frost plug. Those did cause some problems and when removed were found to have all sorts of nasty burned on cake that was as much as half an inch thick. The externally mounted heat pads on the oil pans work like a charm. On some larger blocks the pads can are actually on the block as well, but if the pan is kept warm the block is kept up to a reasonable temp in most situations.

Just to add a note: We never leave block heaters on unmonitored unless it's below -25C, and even then someone checks every 4 hours. Using multiple pads on different circuits and only powering those that are required in the conditions is our practice. If the oil dipstick takes two hands to pull out, turn on another pad. Timers are on all of them as well.

CSkipR - being in NSB, your block heaters really shouldn't be necessary at all. Even if, during the winter, the ambient air temp drops into the 20's (as you know, not often), the water temp under your boat is still in the 40-50º range. I have found it more than sufficient to run the engines up to operating temp and then shutting down. This gets the ER pretty cozy, usually in the 70º range. I've even gone as far asopening the salon hatches afterward and allowing the cabin heat/AC to help keep the interior warm. Just a thought.

BTW, how are those coaming pads working out?

The only "unfortunate" part I can see is you had to pay for the electricity. As far as the engine is concerned, it was the best thing you could do for it.

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Just to add a note: We never leave block heaters on unmonitored unless it's below -25C, and even then someone checks every 4 hours. .[/QUOTE]

Good quality immersion engine heaters are really nothing more than hot water heaters. Does anyone check their hot water heater for the fresh water system every four hours? Maintenance, maintenance. Fortunately I have used mine on this boat for the last 12 years without incident. If they are installed properly they should not air lock. If proper maintenance is performed wires should not come loose, and briitle ones replaced. IMO with a proper breaker in line, engine heaters are like any other 110v electrical system aboard. Just my 2 cents

Hi,

I currently run the Block Heaters on my Main Engines, Gensets and Emergency Genset 24/7 most of the time.

That said the boat is never left without an Engineer onboard and I do not recall ever having had any problem caused by doing this other than making the engines uncomfortably warm if you are doing the valve and Injector settings if you do not turn them off the day before.

There is less smoke on startup and especially in the case of the gensets they can be put to heavy load so much quicker.