Block Heater When Needed

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Block Heater When Needed

February 14, 2014, 09:18:14 am

Being here in Texas it has gotten cold this winter so I like to go over once a month and take the coach out for about a 10 mile hike to keep it ready to go. Be at Foretravel Tuesday 19th for my get ready oil change etc. At what temp should I turn the block heater on before cranking the engine. If it cranks OK at 32 degrees is it OK to crank it? Never used the block heater yet. Is the heater just to assist the cranking or to keep some parts from being damaged from being cold? DAN

Re: Block Heater When Needed

Reply #1 – February 14, 2014, 09:25:45 am

Dan,

This can be looked at two ways:

1. Will I need the block heater so that the engine to even start?

2. Will it be easier on the engine (oil flow faster, shorter warm up time) to use it.

For #2, between roughly 30 and 40F, block heater on for one hour. Longer if colder.

Temperatures for #1 vary by engine and how they cope with cold starts (ether injection on older ones, intake heaters on newer ones).

Re: Block Heater When Needed

Reply #2 – February 14, 2014, 09:37:37 am

Wolfe: I will start turning it on when the temp is 40 or lower. Your point of warmer oil makes the case for me. Cold oil does not move easily. Tks DAN

Re: Block Heater When Needed

Reply #3 – February 14, 2014, 10:05:29 am

The problem is the block heater is in the block and while the warmer coolant will bring the cylinder heads and cast iron block up to starting temperatures, it does little for the oil down below the block at the bottom of the oil pan. 99.9% of the oil is down in the pan, not in the main part of the engine. While conduction will warm the block, it won't warm the pan.

Pierce

Re: Block Heater When Needed

Reply #4 – February 14, 2014, 10:19:56 am

Pierce is correct about a block heater not warming oil in the pan.

But, immediately on start up, the oil is pumped through the passages in the warm block, so it warms up very quickly.

Re: Block Heater When Needed

Reply #5 – February 14, 2014, 10:20:38 am

Good point! Easy to add a heat pad to oil pan, common on light aircraft in cold climates. Tanis and Reiff both make products

Re: Block Heater When Needed

Reply #6 – February 14, 2014, 10:29:43 am

We warm the oil on aircraft so that engine spins Faster with less resistance During the start, And the oil flows immediately to lubricate the top end of the end if the engine (cam and valves)

Re: Block Heater When Needed

Reply #7 – February 14, 2014, 10:51:32 am

The block heater and wait to start heaters if you have them are really designed to warm combustion chambers to get the fuel to burn. Without them it would take many cranks to get a few cylinders warm enough to keep on firing until the other cylinders get warm enough, so you can get power to drive off. White exhaust smoke is unburned fuel, and can be present if the block is not hot enough.

We turn on our block heater about 12 hours before starting at cold temps. We cycle our wait to start intake manifold heater several times before cranking in cold weather.

Re: Block Heater When Needed

Reply #8 – February 14, 2014, 11:02:23 am

With a tin oil pan you can use a magnetic heater. Think they are about 500 watts. Not much good on aluminum though. Other folks have used a heated dip stick but would have to be a long one on most of our engines but are probably available. Other solutions for aluminum sumps are also available.

A lot of engine wear occurs in the first few seconds of a cold start. The oil pump driveshaft has failed on some automotive engines because of the cold oil viscosity. Multi viscosity oils have a cold start advantage but the 2-cycle Detroits can't use them. And, with multi viscosity oils, only a part is oil, the rest are viscosity improvers. Good short read at: Oil Viscosity

Pierce

Re: Block Heater When Needed

Reply #9 – February 14, 2014, 11:37:13 am

Just to add a couple things not mentioned above:
1. Turn-off block heater before you start your engine and don't turn it on while running.
2. On Foretravels, the power chord of the heater is plugged into an outlet in the engine enclosure under the bed. Sometimes previous owners unplug them to make sure the heater is off because the switch down by the bed can get accidently turned on by someone's shoe toe. A better solution is to turn it off on the breaker panel. That way when you do want it on you will notice the switch does not illuminate and you'll check the breaker - and you don't have to lift the bed either.
3. If leaving the next morning (and you know it will get cold) most people turn the switch on when they go to bed. I know I remember better the night before than I do in the early morning. Other than power usage there's no downside to leaving it on longer than necessary. I think mine uses about 1800 watts.
4. When you turn it on, it's good to verify it's working. I have a different engine (Detroit), but I can see the temperature change on the dash gauge within 30 minutes of being on. After a couple of hours (or less) you should be able to feel around the engine or on the coolant pipes and sense the temperature change with your hand. Trace the power chord to find out exactly where the heater is on your engine - it will obviously start to get warmer there first.
5. There is no thermostat control on the heater. The engine temperature will continue to increase until the heat dissipates from the engine as fast as the heater puts it in. The time it takes to do that varies with the engine, outside temps and where the heater is on the engine. I would guess it's generally about 12 hours.

Re: Block Heater When Needed

Reply #10 – February 14, 2014, 11:41:07 am

Mine is on now for a departure time of about 7pm. Temp here now is 25 but it was 7 overnight.

Re: Block Heater When Needed

Reply #11 – February 14, 2014, 01:06:57 pm

I do not worry unless it gets really cold. Colder then Texas gets usually. I had had to start and move the coach with no warning at 5 degrees and colder. The block heater is only the coolant and not the oil. Living in the past in cold country we needed to heat the oil and put on a lower viscosity too. At any of the temps talked about you should be fine to start and wait a bit then go. If you want to turn on the block heater that is fine.

Re: Block Heater When Needed

Reply #12 – February 14, 2014, 06:34:17 pm

yup.... I started all my coaches in single digits or worse.

Re: Block Heater When Needed

Reply #13 – February 14, 2014, 10:30:22 pm

RE "switch down by the bed can get accidently turned on by someone's shoe toe"

RE "crank 5 seconds, rest 5 seconds, on third attempt"

We put a shallow small clear cover over our lighted engine heater switch, to prevent accidental turn ons. Cover is hinged with packing tape on one edge, so to turn on we lift cover.

We turn off block heater before we start and disconnect shore cable, but why is it recommended to turn off before starting?

Our coolant dash gauge never moves off zero, no matter how long our block heater is on. We have verified that heater is working with our Kill-o-Watt meter. And engine starts on 1st crank when cold, so heater is doing its job.

Instead of cranking a cold C8.3 engine several times to get it to start, turn key on without starting, turn key off after 'wait-to-start' goes off, and then back on without starting, and repeat as necessary before cranking engine. This is necessary to turn on the two high-amperage 12-volt intake manifold heaters, which also squirt in a little diesel fuel. These heaters turn themselves off after a short cycle based upon how cold it is, so turning the ignition on & off increases combustion air temperature.

Re: Block Heater When Needed

Reply #14 – February 14, 2014, 10:45:04 pm

Heater probe may be exposed to an air bubble allowing instant overheating and damage when the coolant makes contact. You may also forget to switch it off after the engine starts and you unplug from shore or shut down the generator. Next time you plug in, it would come on and could run up a huge bill.

Our temp gauge never moves. Plus, a Detroit block heater is in a poor location and takes forever to reach the engine block.

Pierce

Re: Block Heater When Needed

Reply #15 – February 14, 2014, 10:51:29 pm

Yup..Did that a week ago. Cost me $100 on my utility bill.

Re: Block Heater When Needed

Reply #16 – February 15, 2014, 11:13:05 am

I intend to add an oil pan heater before next winter. My 2 cycle Detroit Diesel with straight 40 weight oil cranks slowly even with the block heater on and the boost solenoid closed. The radiator and block are warmed by the heater but the oil is still cold and makes the engine very difficult to crank. I'm kinda surprised Foretravel overlooked something like this. I presume I have a steel oil pan and a magnetic heater will stick to it but I'll verify this before I purchase it. I also presume the circuit under the bed will handle another 300 watts, but even if it won't I'll add a new circuit and switch.

Re: Block Heater When Needed

Reply #17 – February 15, 2014, 11:38:20 am

I have an aluminum pan.

Re: Block Heater When Needed

Reply #18 – February 15, 2014, 12:10:50 pm

@Scott I bought a magnetic oil pan heater a couple of years ago after having trouble starting in some 17˚ weather in Tiger Run RV Resort at Breckinridge, CO. I paid $30 or $40 on ebay for mine. There are some things you need to be aware of.

The oil pan is not flat. It is sloped and contoured. Mine is steel and I'm pretty sure yours is too. The best place to put the heater is at the bottom but that is where the oil plug is and that area is pretty small. The next best place to put it may be the side. It probably won't be as effective there. Check your oil pan and plan accordingly.

You will need to plan ahead. To reach the oil pan you need to crawl under the coach. That means you will need to insert your safety stands first which means you will need to attach the heater when you set up camp so that you have air to raise and lower the coach. This also means you will be crawling around on the ground in the snow/ice/wind/cold or all of the above.

You don't want to leave it attached permanently. The magnet is not that strong and it will fall off with a big enough bump. You can use a heavy duty extension cord to plug it into the pedestal if you are in a campground.

Disclaimer: I haven't used mine yet. Have managed to stay away from any temps that might require it so far. It is nice to have just in case.

see ya
ken

Re: Block Heater When Needed

Reply #19 – February 15, 2014, 12:38:22 pm

Interesting that yours is steel must be the DD is different.

Re: Block Heater When Needed

Reply #20 – February 15, 2014, 12:44:31 pm

Quote from: John S – February 15, 2014, 12:38:22 pm

Interesting that yours is steel must be the DD is different.

I would think that the inline six m11 block is much taller than the v6 Detroit.

Bob

Re: Block Heater When Needed

Reply #21 – February 16, 2014, 12:16:17 am

Quote from: RRadio – February 15, 2014, 11:13:05 am

I intend to add an oil pan heater before next winter. My 2 cycle Detroit Diesel with straight 40 weight oil cranks slowly even with the block heater on and the boost solenoid closed. The radiator and block are warmed by the heater but the oil is still cold and makes the engine very difficult to crank. I'm kinda surprised Foretravel overlooked something like this. I presume I have a steel oil pan and a magnetic heater will stick to it but I'll verify this before I purchase it. I also presume the circuit under the bed will handle another 300 watts, but even if it won't I'll add a new circuit and switch.

Scott,

You have a terminal, cable or battery problem if you crank slowly. I have three 4 year old Autozone Duralast batteries and they spin the engine like a top down in the teens. Search and review what I did to my connections as well as the extra ground cable. Here are some photos of before and after and the result of starting a Detroit at 13 degrees at high altitude in Yellowstone after the block heater went out. Started but sure smoked like a train for 5 minutes.

Pierce

Re: Block Heater When Needed

Reply #22 – February 16, 2014, 07:17:26 am

I am with Pierce on this one. I put in a new ground and a cable directly to the starter right behind the one FT put in. It avoids the splitter box that is there too. It will turn the M11 over in 5 degrees no boost or heat and start it. Much faster starting then before too in regular weather too.

Re: Block Heater When Needed

Reply #23 – February 16, 2014, 11:20:16 am

The faster the engine turns over relates directly into combustion chamber pressure. Along with pressure comes it's buddy, temperature. As the piston comes up to compress the air, some is lost past the compression rings. The longer it takes to compress (talking about thousands of a second) the more is lost. Since higher cranking RPM means more frequent compression strokes, more residual heat is left over from the last stroke to bring the temperature up further and shorten the time needed for a cold start.

Back in the early 1980's, I bought a nice 200D Mercedes to ship home for a customer. It badly needed an engine overhaul and would not start at all unless the engine was warm the compression was so low. Before the overhaul, we put the dealer plates on it and headed south for a few days R&R. We chose a hotel well up on the side of a mountain outside of Műnchen. Every morning, I would clear off the snow, put it in second gear and coast down the side of the mountain until it started about 30 seconds later. Once running, it was an easy start for the next 2 hours. I did have to remember when in the city to come back to the car and start it before the two hour window was up.

Pierce

Re: Block Heater When Needed

Reply #24 – February 16, 2014, 01:28:08 pm

I think it's the oil temperature that causes the slow cranking. I have new batteries, new alternator, new boost solenoid, and they're all working well and the batteries are fully charged with clean terminals. The block and radiator are warm to the touch so I know the block heater is working. The straight 40 weight oil in the pan is still cold even with the block heater running and the oil pump has to move the thick oil through the galleries to the bearings while the engine is cranking. The oil pressure is at least 60 psi or more after a cold start. It would normally be as low as 20 psi with warm oil. I never experience slow cranking when the oil is warm. I have a small radiant propane heater I can put near the engine to heat the oil pan. I'll try that next time I do a really cold start to verify that it's cold oil that's causing the slow cranking. I've never had the engine fail to start as long as I run the block heater for a couple of hours and close the boost solenoid, but I think it would be a lot better for the engine if it had warm oil when it started up... I wasn't aware the magnetic heaters won't stay on the engine because the magnet isn't strong enough. I want a permanently attached oil heater if possible.

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