Engine block or oil pan heaters?

[Xmeter]

I am in the middle of an in-frame on one of my 671's and was wondering which type of heater I should put back on.
I had a 500 watt silicon pad type oil pan heater that had burned out, and I would think that since heat rises, I should go with the oil pan type.
But, since everything is off the block I can actually see where the internal block style is supposed to mount and now would be the time.
Any suggestions?

 

[Jaxfishgyd]

I stuck on a 250w pan heater on each of my 6-71's several years ago and am very happy with them. Before it would take 15-20 secs for the motors to fire off when cold, now they fire right up, no problem.

 

[Glory]

Since you seem to ne in Jacksonville either should work well. I have in, block, coolant heaters, and in the the north east even in october I headly ever use them.

JM

 

[jim rosenthal]

Owned both, and I think the pan heaters are the way to go. I had Kim Hotstarts, and Wolverine pan heaters on two boats. Wolverines draw less current, too.

 

[rsmith]

FWIW aircraft engines have to be preheated below 20^ before starting. A number of years ago the silicone pad heaters that glue to the oilpan became popular. Avation Consumer (which is like consumer reports) did a study on these heaters and found people who were using them developed rust in the top of the engines. Since in a piston aircraft the crank is on top the rust caused bearing failures. A.C. concluded that heating the oil on the bottom of the motor caused the heated air and moisture to rise and condense on the cooler top portion of the engine. as the air was constantly rising more and more moisture would be drawn into the engine and condense at the top portions causing the rust. Their recomendation was to cover the cowling with blankets to insure the engine heated uniformly. I would think the same situation would apply to marine engines. (except Georges of course)

 

[GJH]

Well George's boat has Zerostart immersion heaters on the main engines as illustrated in pictures on another thread. It is 22 degrees and windy outside as I write this. It was like this all last week, then we had a warm and rainy weekend, then back to this on Monday. I have the engine room vents stuffed with a couple of big towels. The engine room doors have been left open, the mid stateroom A/C turned off and a small ceramic heater left on low in the galley. The master stateroom door has been closed and it's A/c running.

The temperature at the heat exchanger is 105. The cylinder block, measure at the outlet to the exhaust manifolds is 95. The oil pan is 75. Ambient temp in the ER is about 70, mid-low sixties in adjacent spaces (companion way, mid stateroom and head)

I recently added a Wolverine pad to the little 4 cylinder Cummins on my genset. The temp readings there are basically the reverse of those above. 105 on the oil pan, about 70 at the cylinder head and heat exchanger. This engine sits down in separate enclosed room below the galley with the A/C compressors and isolation transformers. BTW, the Wolverine people are about the nicest most helpful folks you would ever want to do business with.

I intuitively like the heat distribution on the mains better, but my diesel intuition is fairly amateur and naive. I leave the main engine block heaters on full time other than the summer months, and even then if there has been a big temperature swing and rain. Of course, when we are on the hook, they only operate when the genset is on, and the engines are still warm the first day after running.

Perhaps one issue is whether the heaters are run consistently, or just the day before someone wants to start an engine. In the aircraft example, is this the case or are they left on all the time? At the Hatteras Owners University, Roger Wetherington also recommended leaving them on all the time, to fight condensation issues.

Thoughts/conclusions of the group?

 

[rsmith]

Imo the the best setup heats the engine uniformly top and bottom so there are no areas that are cooler to start a tropical rain cycle in your engine. IMHO just heating the bottom may be more harmfull than good unless you use your boat everyday and need the oil warm for starting purposes.

 

[Xmeter]

Thanks for all the input.
I think I now realize that there is a lot more to this than I first thought.
What do you think about going with the block heater and a small silicone pad heater on the pan?
It looks like the block heaters are offered in 1000 and 1500 watt versions.
I could go with the 1000 watt block and a 150 watt pad heater.

 

[Glory]

I don't think there is any need for both. I would go for the block heaters. I'm fond of the in block type, there are no hoses to fail and it keeps things simple.

Even on a 20 degree day, and engine that is out doors with a 1500 watt 120V AC the engine would reach 80 to 85 degrees. This would provide an instant start. On a 70 degree day the engines would be as high a 120 degrees.

JM

 

[davidwigler]

What is the brand and model of the 1000 watt block heaters and who carries them? Are they difficult to install? I have 8v71ti's. Does anyone have pictures of the installation?

 

[saltshaker]

All DDEC Detroits require block heaters to start. Detroit uses immersion heaters on all these engines. I had the Kim Hot Start immersion heaters and loved them. Engines fire right up even when the air temps are in the 20's. Really keep the ER warm and the condensation down, not just in the engine but the whole ER. The pad heaters seem to work fine and as stated draw a lot less power. They do heat the oil better than an immersion heater but not really sure if that would be better than heating the entire block. For me up north the immersion heaters work better in heating the entire engine and ER compared to pad heaters.

 

[MikeP]

My 8v71TIs have block heaters, installed when the boat was new, by Hatteras of Lauderdale. They seem to work very well; I have no experience with pan heaters so I can't really comment on which is "better." Only thing I would sort of relate it to is that cars purchased in cold climates - like AK - come with block heaters dealer-installed so it seems to be pretty much a "standard" sort of set up.

 

[GJH]

Rambling further thoughts..

I have immersions, and as stated earlier really like them for reasons Jack explains. I put a Wolverine (wonderful company to do business with, by the way) on my genset, which is in a different room than the engines. about a month ago. Here is my issue:

The Detroits read 90-105 through out the mechanical section of the engine; hotter on the top since that is heater and T-Stat are. The oil sump reads about 70. So it is not like the oil is cold. This is when exterior temps are in the 20's and interior temps in the 50s when we are away from the boat. I leave the ER doors open and the master SR Ac set to 55. If I close the ER doors, the ERs get to about 65 degrees with the vents blocked up with towels.As noted, the engines start flawlessly regardless of exterior temp.

The genset is exactly the reverse. The sum reads 105, but the upper block 65 at most. The only other heat sources in the genset room, if any, are the iso transformers and the AC compressors. The genset starts like it did when ambient temps were in the 50's. Typical ambient temp in the genset room is now about 55 degrees. Not up appreciably from pre-pad heater days, maybe 5 degrees.

Perhaps the pad heaters are best in circumstances when the engine is more exposed to the elements?

I have been toying with the idea of adding pad heaters to the transmissions. They are cheap and it would be an easy install. But most external thermostat rigs for them have a 50 degree max temp shut off, and my ERs are almost always warmer than that. I would want a T-Stat because unplugging them or switching them off, as I have to do on the genset, is kind of a PITA.

Like i said, rambling...

 

[GJH]

What is the brand and model of the 1000 watt block heaters and who carries them? Are they difficult to install? I have 8v71ti's. Does anyone have pictures of the installation?

Dave, search back a few pages. There was a thread on this and I posted pix. Go to zerostart.com and their catalog has them listed by engine.

http://www.zerostart.com/UserFiles/File/2009_Zerostart_Application_Guide_and_Product_catalog.pdf

If you can, get the type with a thermostat pigtail, it is really slick. it may require an additional tap. I have the zerostarts and they are really nice.

(http://www.zerostart.com/UserFiles/File/Thermostatically_Controlled_Engine_Immersion_Heater.pdf)

Edit: I have 8v92s.

 

[REBrueckner]

Unless your boat is cold inside and intake vents are open to winter air and humiodity it's very unlikely any engine pad, oil or coolant heaters or combination could possibly cause unwanted condensation anywhere. Further differential temperatures around different parts of the engine are minor due to any heating element.

In other words if your ambient temps inside a boat are, say 40 degrees or higher, to pick an arbitrary number, and an engine heater of some kind is on, you could not get condensation if you wanted to.

In an airplane engine open to the outside temps, sure it could happen...seems likely it would in fact.

You can also use some 150 watt (for example) radiant heat lamps or a household heater, say 1500 watt....A larger power heater will warm an engine faster and a direct contact type heater (oil,coolant or engine pan) will be faster than a device that heats air first (as a room heater).

I had what my mechanic told me were 1200 watt coolant heaters on each of my 8V71TI's and these were on for 11 years I owned the boat and were not recent when I got the boat....because I had a diesel heater in the engine room it was usually over 50 degrees during real cold weather and a half hour to 45 minutes with the block heaters on resulted in a virtually instant engine start.

 

[Timeout]

I'm very happy with Kim Hotstart (Zerostart is the same). Even though they recommended the 1500W, I didn't want to dedicate 3000W for block heaters so I bought the 750W heaters and they are just fine. If you're sitting in 32+ degree water, there is no need for 1500W on each engine.