Skip to main content ↑ ↓
Topic: Block heater question (Read 1617 times) previous topic - next topic

Re: Block heater question

Reply #25 –
If you don't believe me, take a look at your U300 schematic and try to find a hot screen or glow plug on the 2 cycle. Our Detroit waits about a quarter second after hitting the start postion and then cranks. ECU may be responsible for any delay and current draw. Low enought voltage will cause the engine to die unlike the mechanical Detroits. Even though the entry step is not electric, it still requires a certain amount of voltage/current to trigger the retraction.

Mechanical Detroit 2 cycles have no delay and will normally be running in one tenth of a second after hitting the starter button. I have never had one start slower in thousands of starts in the fire service.

Typical hot screens are found on Diesels like Perkins and others. They may be located before the turbo. Pre-combustion chamber diesels usually have only glow plugs but in some cases, also have heated screens to aid starting. Our diesel generators are pre-combustion chamber designs and have glow plugs. They usually have up to 21:1 compression ratio (may be 4 or 5 points higher than direct injction engines) and are generally about 5 percent less efficient than direct injection engines.

After recommended hours, the turbo should be pulled along with the blower and the aftercooler cleaned. They may build up deposits and not be as efficient in cooling the hot air from the turbo and blower. Would look up hours but sitting in a hotel in Detroit with slow internet and don't want to go to the car for the MiFi card in the rain.

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Block heater question

Reply #26 –
It was a question, not a case of disbelief. I can't come up with an easy answer for why the voltage goes down when I turn the key on and the engine will crank but not start until the red lights go out. It's often up to 20 seconds before the lights go out and the engine will start. If it doesn't have a heater it must be doing something else that takes a lot of time and electricity before it will start.
Scott Cook
1991 U300 36' 6V92TA
Old Town Penobscot 16
1984 Honda VF1100C (V65 Magna)

Re: Block heater question

Reply #27 –
So, in reading your post, your starter motor will operate almost immediately after turning the key but not fire/start until up to 20 seconds later?

The turbo 6V-92TA has a lower compression ratio (16:1) than the non-tubo engines so generates less heat from compression and is slow to get all cylinders firing in cold weather. With the temps in the 60's, our engine will start on one cylinder, pick up another one or two quickly and then the last several a few seconds later. Drop the temperature another ten degrees and the first cylinder to fire will delayed a few more seconds and with the temperature down in the 40's, it may cranks quite a few seconds before the first cylinder fires. A very poor block heater location means several hours of operation before the engine will start reasonably quickly.  The resuling white  smoke is from the unburned fuel in the last cylinders to fire.

Older mechanical engines had a spring loaded cap on the blower housing to allow ether to be sprayed to aid starting. Not used on RVs as one ether application on a hot engine may bend a connecting rod or break a ring from an explosion very early on the compression stroke. This applies to all diesels.

Slow starting in any diesel may be at least partially aided by having clean terminals and good batteries and low voltage drop between the start batteries and the starter motor. Faster cranking means compression heating will be greater in a shorter period of time and the cylinder with the best injector pattern and highest compression will start firing sooner.

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Block heater question

Reply #28 –
It still takes a few seconds to start even when the engine is warm. I've only accidentally done that a couple of times, usually after I just got out of a gasoline powered car and forgot I was starting a diesel and had to wait. I'll crank it immediately the next time I start it just to prove it to myself. As I was thinking about this I realized that the supercharger will make intake heat by compressing the air into the intake, which is why there's an intercooler right beneath the supercharger, to get rid of the heat. It's a law of physics that there's a direct relationship between compression and heat... but that still doesn't answer my question as to what requires electricity and time to start the engine if there isn't an electric heater.
Scott Cook
1991 U300 36' 6V92TA
Old Town Penobscot 16
1984 Honda VF1100C (V65 Magna)

Re: Block heater question

Reply #29 –
Scott,

You either have an injector(s) leaking diesel into the cylinders when turned off, air getting into the loop or low compression. Try using the hand pump for 30 seconds or so. Check O rings on hand pump. Look at the check valve by the primary filter. Ours was cracked.

Absolute best is to pull the fuel return line off the engine, attach a 10 foot line and place it below the surface of a container partially filled with diesel. Turn engine off at night and start in the morning with someone watching for bubbles in the container.

Pierce

ECU will draw quite a bit. You can hear it buzzing if you walk back with the key on.
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Block heater question

Reply #30 –
Quote from: RRadio –
So why won't the engine start if I attempt to crank it before the red lights go out on the dashboard? If there's no heater what is the engine doing for that period of time? Out of curiosity I just turned my ignition key on and watched the voltmeter drop a full volt immediately. There has to be something on the other end of the 23 year old wiring that's drawing a lot of current. It's not the vacuum pump and I don't hear any fuel pump or other pumps running and it's not below 40 degrees so it can't be the heater in the air dryer and it's not the mirror defogger or anything controlled from the instrument panel. Even if it's the 23 year old wiring that still doesn't explain why the engine won't start until after the red lights go out.

The DDEC/ATEC  parts?
"Riding and rejoicing"
Bob
1997 U320 40' Mid entry, build 5132,  wtbi ce27, 4th owner
2007 Solara convertible
2 prodeco tech outlaw ss electric bikes

1095 watts solar
08 Ls 460 and a sc430
2000 Ford F-250 superduty 4x4

Re: Block heater question

Reply #31 –
The engine starts in a fraction of a second if I wait until the red lights go out before I start cranking. If I start cranking before the red lights go out it just cranks and cranks until the red lights go out, then starts normally. I doubt the computer can draw an 8D battery down a full volt or more. It's not exactly a liquid cooled mainframe computer! :)) I don't think there's anything wrong with my engine so I'm definitely not gonna mess with it. It's been this way the whole time I've owned it. It has very strong performance, especially at high altitude, and much higher fuel efficiency than expected. People are always blown away when I tell them what I get for mileage.
Scott Cook
1991 U300 36' 6V92TA
Old Town Penobscot 16
1984 Honda VF1100C (V65 Magna)

Re: Block heater question

Reply #32 –
Scott,

I just don't have any red lights so can't figure that one out. Perhaps it has an electric fuel pump added as I have seen buses with one. Where are the lights? Do they appear to be added or OEM?
Does the voltage go up after the lights go out?

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Block heater question

Reply #33 –
Quote from: RRadio –
The engine starts in a fraction of a second if I wait until the red lights go out before I start cranking. If I start cranking before the red lights go out it just cranks and cranks until the red lights go out, then starts normally. I doubt the computer can draw an 8D battery down a full volt or more. It's not exactly a liquid cooled mainframe computer! :)) I don't think there's anything wrong with my engine so I'm definitely not gonna mess with it. It's been this way the whole time I've owned it. It has very strong performance, especially at high altitude, and much higher fuel efficiency than expected. People are always blown away when I tell them what I get for mileage.

Not sure of the electrical circuits made ready at the ignition turn on but it seems to be quite a bit.

Second thing I would check is every electrical connection in the engine battery circuit.

Every part new condition then monitor the drop.  In my Foretravel days I would check/remember numerous duplicate coaches to see if I get similar results.
"Riding and rejoicing"
Bob
1997 U320 40' Mid entry, build 5132,  wtbi ce27, 4th owner
2007 Solara convertible
2 prodeco tech outlaw ss electric bikes

1095 watts solar
08 Ls 460 and a sc430
2000 Ford F-250 superduty 4x4

Re: Block heater question

Reply #34 –
Maybe someone added an oil pressure pre lube that will not let the coach until it has oil pressure. That would account for a voltage drop with a motor running a pump.
previous 1984 35 ft ORED 250 HP 3208 Cat       
previous 1998 40 ft U295 CAI 325 hp Cummins
previous 2003 40 Ft u320 build #6140 450 Cummins M11.                                                         
1999 Mazda Miata
Ron, Nancy, Tipper the cat, Max The dog
1997 U 270 36 ft build number 5174 8.3 Cummins

Re: Block heater question

Reply #35 –
The red lights are built into the instrument panel and the same lights were on the 40' 1991 U300 I looked at before I bought my 36' coach. The lights say: "Check Trans", "Stop Engine", and "Check Engine" and they go out after a few seconds, then the engine will start normally. The 40' coach behaved the same way. I remember the seller waiting a few seconds until the lights went out before he started it. I also looked at a Vogue with a 6V92TA and that seller waited a few seconds before starting it. The Vogue didn't have DDEC like the Foretravels though. There are no pumps running. I have excellent hearing and I've never heard anything other than the vacuum pump come on with the ignition key. The wiring is in good condition and the coach cranks and starts just like it always has. There's nothing wrong with it. The next time I'm at a Detroit Diesel service center I'll ask why there's a starting delay and a voltage drop if there supposedly isn't any heater. It's not really a burning question that needs an immediate answer. I've just read that the Detroit doesn't have a heater so many times on this forum but I can't find any evidence either way and mine certainly acts like it has a heater... so that's why I asked if you guys know of any evidence. It's not that I don't believe you. I'm just asking how you know this because I sure can't find any evidence either way.
Scott Cook
1991 U300 36' 6V92TA
Old Town Penobscot 16
1984 Honda VF1100C (V65 Magna)

Re: Block heater question

Reply #36 –
"The red lights are built into the instrument panel and the same lights were on the 40' 1991 U300 I looked at before I bought my 36' coach. The lights say: "Check Trans", "Stop Engine", and "Check Engine" and they go out after a few seconds, then the engine will start normally." That's the way things are on my coach, too. The PO told me to turn the key on, wait for things to settle down, and then start. I turn the key on and after a few seconds those lights go out and then I start the Detroit.

Re: Block heater question

Reply #37 –
Quote from: JohnFitz –
Well I have pulled my blower to inspect the intercooler (pic attached) which is directly below the blower.  There is no electric heater in there and I think I can tell you why:  It's a very oily space.  The element would get coated with oil when the engine is running.

John,

How long did it take you to pull the aftercooler to clean it? How dirty was it? If dirty, any improvement after doing it? Any problems with the turbo clamps? Parts/gaskets ahead of time?

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Block heater question

Reply #38 –
Quote from: Pierce & Gaylie Stewart –
John,
How long did it take you to pull the aftercooler to clean it? How dirty was it? If dirty, any improvement after doing it? Any problems with the turbo clamps? Parts/gaskets ahead of time?
Pierce
I did it 10 years ago so it's a bit of a faded memory.  A mechanic suggest checking the intercooler for clogging; thought it might be the cause of overheating.  Intercool was clean when I pulled it.  I don't remember how long it took, but I do remember it was a pretty straight forward operation and wouldn't hesitate to do it again if I needed to.  One exception is the exhaust ring that is between the turbo outlet and the exhaust flex that goes to the muffler.  That attachment joint between the turbo and the ring was very difficult to separate:  hours of propane torch heating, beating with wedge and hammer,  applying diesel to joint, repeat, etc. etc. over several days.  I even consulted the Bus Nuts forum and they confirmed yes, it's difficult but perseverance is the key - and they were right.  I managed to not damage either half of joint.  Reused all the original band clamps.  I brought in the turbo, blower and intercooler to the parts guys at the Tucson Williams Detroit Diesel for them to evaluate and they said they all looked good and didn't need to be replaced or repaired.
I remember using new gaskets but I don't remember any details about that - it seemed like Williams had it all in stock.  That might be different today - these engines are getting more rare.  Coach ran just the same once it was back together.
John Fitzgerald
1991 U300 (SAI) Side Aisle Island Bed 40'
Detroit 6V92 with Allison Retarder
Meridian (Boise), Idaho

Re: Block heater question

Reply #39 –
Not to change the tone of the subject, but I have a question regarding replacing my block heater.  I have a 92 Grand Villa with the B5.9 Cummins, my block heater is located in a freeze plug on the drivers side of the engine.  It no longer works.  I have tested the electrical cord and that is good.  Does anyone have a suggestion as to a brand or seller that carries a high quality block heater.  Do not want to put in a cheap heater after having to replace all the anti-freeze.  Also is there any reason I should not use ES complete oat anti freeze?  As always thank to the knowledgeable foretravel owners for your help.

Howard Reinhardt
Howard & Rose
92 U225 GV - 36'  - Build # 3989
2003 Honda Civic
95 Jeep Wrangler
2018 Winnebago Travato 59K
4 Chihuahuas

Re: Block heater question

Reply #40 –
Quote from: hjrein –
Not to change the tone of the subject, but I have a question regarding replacing my block heater.
You and I have pretty much the same coach. When I turn my block heater on the switch at the bottom of the bed on the co-pilot side has a light that comes on inside it. Is that the way yours works? Have you tested to make sure that there is 120vac at the receptacle where the block heater plugs in? You should also be able to check the resistance of the heater (measure from prong-to-prong on the electrical plug). It should be 4 or 5 ohms I think. If it's infinity then the unit is open.

I would contact Cummins. You will need your EID (engine ID) number because if you don't have it they'll tell you that every engine is different. But I suspect any block heater for any Dodge in the early 90s would do the job.

Craig
1993 U225 36' Unihome GV with PACBRAKE exhaust retarder, Banks Stinger and Solar Panels.
Toad: 1999 Jeep Wrangler 2-door soft-top.

"No one has ever had to evacuate a city because the solar panels broke."

Re: Block heater question

Reply #41 –
Hey Craig.  Yes we do have pretty much the same coach.  I do have the block heater switch at the bottom of the bed, but the red light on just means the outlet in the engine compartment that the block heater plugs into is working (on).  Unplugged the heater and tested the plug - got OL - no resistance whatsoever.  Plugged it back in and unhooked from the block and tested cord for voltage - 120 volts.  could not get my tester to touch the actual prongs of the heater to check for resistance but I believe testing the electrical plugs prongs (as you suggested) was sufficient to test for resistance.  I will probably contact cummins tomorrow - just don't want to buy a cheapo (poor quality)heater.  Thanks.  Did you ever put in a resonator.

Howard
Howard & Rose
92 U225 GV - 36'  - Build # 3989
2003 Honda Civic
95 Jeep Wrangler
2018 Winnebago Travato 59K
4 Chihuahuas

Re: Block heater question

Reply #42 –
Thanks Craig - Cummins did have the block heaters and cord.  They even had it in stock.
Howard
Howard & Rose
92 U225 GV - 36'  - Build # 3989
2003 Honda Civic
95 Jeep Wrangler
2018 Winnebago Travato 59K
4 Chihuahuas