Hard starting detroit 471

[Rand900]

I have a 1955 detroit diesel 471 runs fine it just doesn't want to start ( you have to crank it for quite some time, or use starting fluid ).
It has H80 injectors, I have tried putting a fuel line to the secondary fuel filter with an electric pump to be sure there is fuel to the injectors.
The injectors only have a few hours since a rebuild.

Thank you

Randall

 

[tiltrider1]

Sounds like low compression.

 

[Lepke]

Get a block heater, don't use too much ether and your engine can run for many more years.

If the engine runs fine after starting, the issue is as tiltrider1 says: low compression.
Each time the piston travels up the cylinder it heats the air and the metal. Having long cranking times means the engine is having trouble reaching diesel ignition temperature.

With a block heater, even a very old worn out Detroit will start.

Too much ether can raise pressures to extremes, breaking rings, and then requiring even more ether to start.

 

[Ken E.]

Agree with what Lepke said on engine heat to help starting Detroits. Mine were old, tired and low compression but with block heaters, they'd start easily. Otherwise, I'd have to grind them, especially in cold weather. Also greatly reduces smoke at startup.

 

[Mischief Managed]

Another trick instead of a block heater is to spin the engine over for 20 to 30 seconds with the fuel shut off. This will heat up the cylinders but they won't be cooled by any fuel that does not ignite. Doing this will also dramatically reduce smoking when it does start.

 

[78puget-trawler]

GMC- gotta mechanic coming.

I know they are mostly good engines, but I always remember when I worked on a tug my dad was skipper on when I was a kid of 14 in 1967. We were on our way to Alaska from Seattle with a barge and didnt make it to Bellingham without one side breaking down.
Had to have the mechanics drive up and work on the engines for a day or so and I heard of lot disparaging remarks made about Jimmys.

The tug was a converted USCG cutter called the Polar Star, (cutter Bonham), 125' long with two 500 Jimmys, dont remember the proper number of the engine model, but I sure remember the colorful language associated with them.

 

[Island Cessna]

Another trick instead of a block heater is to spin the engine over for 20 to 30 seconds with the fuel shut off. This will heat up the cylinders but they won't be cooled by any fuel that does not ignite. Doing this will also dramatically reduce smoking when it does start.

+1 this works.

 

[Lepke]

GMC- gotta mechanic coming.

I know they are mostly good engines, but I always remember when I worked on a tug my dad was skipper on when I was a kid of 14 in 1967. We were on our way to Alaska from Seattle with a barge and didnt make it to Bellingham without one side breaking down.
Had to have the mechanics drive up and work on the engines for a day or so and I heard of lot disparaging remarks made about Jimmys.
The tug was a converted USCG cutter called the Polar Star, (cutter Bonham), 125' long with two 500 Jimmys, dont remember the proper number of the engine mode.

Not Jimmys. That class (Active Class Patrol Boat) was built with Winton 300 hp engines and changed to a later version under the Cleveland Diesel name (owned by GM) or Cooper-Bessemer engines and about the size of WWII submarine engines. The engines were 8-10' long.
Jimmy originally referred to the 671 and later all 71 series diesels. Long before the 53, 92 110, or 149 existed. GM bought Winton Diesel in the 1930s and made it the Cleveland Diesel Division. Lots of Active class still around. The namesake of the Alert class sank in Portland last year near the I80 bridge.
Engines pictured are probably the engine that tug had, maybe with a couple less cylinders. A 671 jimmy won't turn over those props, I know someone that tried.

 

[78puget-trawler]

We called any engine made by GMC a Jimmy, not just the 71's. Jimmy was short for GMC. My dad owned lots of tugs and fish boats and some had GMC engines and he called them all Jimmys.
As far as what model they were, like I said I dont remember, too many years ago and I was just a dumb kid, but I absolutely do remember a lot of disparaging remarks about Jimmys, and they were for certain not C-B's.
You probably know the guys that came up to work on them. Dave Updike and Jim Humphries.
Updike was a well known hard hat diver from Seattle and also a mechanic, Humphries if I remember was primarily a diesel mechanic.
Updike was a huge man, over 6'6" and hands like baseball mits, strong as an ox.
Fortunately he was good natured.
I remember that Humphries always wore one of the little welder type brimless caps and a stogie always sticking out of his mouth, a real character.

 

[78puget-trawler]

What the Polar Star/Bonham looked like recently as a derelict.
One of the easiest riding boats I ever sailed on. Wonderful sea boat.

 

[78puget-trawler]

My brother who worked as asst engineer on this boat when my dad ran it had to rattle his noodle quite a bit but we finally figured out the engines were Cleveland 8-268A models and probably turbo because they were rated at 500HP each whereas it was rated at 350HP standard.
As you noted above, Cleveland was a division of GMC, thus it became a Jimmy, at least to us. Dad called them Gawdawful Mess of Crap! LOL.

 

[oscar]

My 8-71-TI's start in half a second with minimal smoke...... if I use pre-heat. Otherwise it takes 10-15 and there's some smoke. The 20-30 secs of dry cranking works too, but it's a lot of work for the batteries. It does however distribute some oil which is a good thing if it's been sitting for a while.

 

[fgarriso]

Dry cranking also runs the cylinder walls dry, and that will wear the rings and pistons

 

[Mischief Managed]

Dry cranking also runs the cylinder walls dry, and that will wear the rings and pistons

Dry cranking does not affect the oiling system, only the fuel. When the engine is running, that fuel adds zero lubrication to the cylinder walls because it's on fire the instant it enters the combustion chamber.

 

[Lepke]

Detroits like the 471 that started this post always have fuel at the injectors. Unless you hold the stop button while cranking, or hold the governor linkage in the stop position, the governor is in the idle position. That means fuel is being sprayed. A cold engine with low compression won't cause the fuel to ignite until the air temps get above diesel ignition temp (about 500°F depending on the grade). When the engine finally fires, the excess diesel is burned off as smoke.

Since most engine wear happens at startup, dry cranking causes additional wear. A block heater is a good investment for longer engine life.
Depending on the exhaust system, dry cranking can flood a cylinder with salt water.

 

[fgarriso]

Dry cranking does not affect the oiling system, only the fuel. When the engine is running, that fuel adds zero lubrication to the cylinder walls because it's on fire the instant it enters the combustion chamber.

Dave,

I hate to disagree with you, but in this case I have to.
Do you know why diesel fuel is called "fuel oil", that's because it is OIL.
Do you know how difficult it is to light up fuel oil?
It takes a lot of compression and heat 6-800 degrees just to get it smoking in a cylinder. The oiling system in a 2 stroke 4-71 DD only adds oil to the cam and bearings. The oil rings on the pistons are designed to scrape oil off of the cylinder walls hence dry walls. If a engine is hard starting and must be cranked for extended periods of time the cylinders and pistons become dry which in turn causes on do wear on the rings, cylinders, and pistons.

 

[jungpeter]

I have a 1955 detroit diesel 471 runs fine it just doesn't want to start ( you have to crank it for quite some time, or use starting fluid ).
It has H80 injectors, I have tried putting a fuel line to the secondary fuel filter with an electric pump to be sure there is fuel to the injectors.
The injectors only have a few hours since a rebuild.

Thank you

Randall

Hi Randall. As others have said, sounds like low compression. Often an issue in the winter months with ALL diesel engines when the ambient temperature is low. And, as Lemke (and others) have suggested, a block heater is your friend, particularly in the winter. However, I'm not a fan of ether or other starting fluid aids, as that's an easy way to put a hole in a piston or other traumatic issue. And, long cranking can also (as mentioned by others) easily hydrolock the engine. Bad berries for sure.

You might check that your stop solenoid is fully open at startup, as if it has stuck partially closed, you can crank until the cows come home to no effect. If you need to crack the throttle to enable engine start, that's a clue the solenoid is sticking. Try some WD40 on the shaft, or better yet-replace it.

A well-tuned and healthy 4-71, particularly with block heat, should start on the first roll. If yours doesn't, time to call a competent mechanic.

Regards,

Pete

 

[Mischief Managed]

Dave,

I hate to disagree with you, but in this case I have to.

<snip>

The oiling system in a 2 stroke 4-71 DD only adds oil to the cam and bearings. The oil rings on the pistons are designed to scrape oil off of the cylinder walls hence dry walls. If a engine is hard starting and must be cranked for extended periods of time the cylinders and pistons become dry which in turn causes on do wear on the rings, cylinders, and pistons.

If that's the case, where do the cylinders and pistons get lubrication from while the engine is running? The fuel oil is injected at the top of the combustion chamber when the piston is at or near TDC, and it ignites instantly. I know diesel is a decent lubricant in liquid form, but I am reasonably sure it's a terrible lubricant when it's burning.

 

[Island Cessna]

If that's the case, where do the cylinders and pistons get lubrication from while the engine is running? The fuel oil is injected at the top of the combustion chamber when the piston is at or near TDC, and it ignites instantly. I know diesel is a decent lubricant in liquid form, but I am reasonably sure it's a terrible lubricant when it's burning.

Let’s not forget that the “trick” of holding the stop button or Governor link during cranking to shorten the cranking time is only necessary for a worn engine with already low compression.

I disagree with the theory that cranking without adding fuel accelerates wear. The goal of cranking without fuel is to shorten the total crank time, and improve lubrication.

The source of lubrication between the rings, piston and liners is oil from the sump, forced out of the rod and wrist pin bearing, or even in some cases an oil cooling nozzle spraying onto the underside of the piston. In the good old days we called the “oil rings” oil control rings. Their job is not to scrape all the oil off, but to leave a controlled film on the cylinder bore.

The wear causing contact pressure between the ring and cylinder bore is created by the combustion chamber pressure, and spring effect of the ring. During cranking before ignition this pressure is minimal compared to after ignition.

The primary reason to block fuel until compression builds heat is to avoid the cooling effect of the latent heat of evaporating the fuel, but another positive effect is not diluting the minimal oil film at the top of the cylinder with the unburned fuel. The oil film might even be restored by some oil circulation while you crank without fuel to wash the oil off.

If your 4-71 is worn and hard to start when cold, go ahead and crank it with the fuel cut off until it has got its combustion chamber warm enough to fire. It won’t heal your worn engine, but if it has any effect on the rate of continuing cylinder wear it is more likely to be positive than negative.

 

[fgarriso]

If that's the case, where do the cylinders and pistons get lubrication from while the engine is running? The fuel oil is injected at the top of the combustion chamber when the piston is at or near TDC, and it ignites instantly. I know diesel is a decent lubricant in liquid form, but I am reasonably sure it's a terrible lubricant when it's burning.

The lower part of the pistons has what is known as splash lubricating. That is when the crank and rods are at their lowest part of the stroke, and then splash oil up onto bottom of the pistons and cylinders. That is why you need to be carful with excessive cranking due to the splash oiling not being very good with cold oil at crank speeds.

 

[Mischief Managed]

The lower part of the pistons has what is known as splash lubricating. That is when the crank and rods are at their lowest part of the stroke, and then splash oil up onto bottom of the pistons and cylinders. That is why you need to be carful with excessive cranking due to the splash oiling not being very good with cold oil at crank speeds.

There's some splash for sure and much of it comes out of the rod journals (so it would be squirting out even while cranking the engine over), but the majority of cylinder wall and piston skirt lube oil in a 71 series is delivered through the crankshaft to the rod journal, around the rod journal, up the rod, around the wrist pin, and out the 4 nozzles on the top of the rod under the crown of the piston. This oil is primarily for cooling, but there's an awful lot of it and it runs down the inside walls of the piston and onto the cylinder walls when the piston is high enough in the cylinder. The oil pump is a positive displacement design so the oil temperature only affects the parasitic loss of pumping oil, not the volume. Thus, there's plenty of lube oil present in the cylinders when the engine is cranking over "dry".

 

[psneeld]

From a marine diesel expert....

"The latent heat of vaporization of diesel fuel is around 100 BTUs per pound. How many pounds of fuel do you think are injected during a cranking period? That's an easy one, the injector in a 4-71 cylinder only injects around 50 cc's of fuel for every 1000 revolutions of the engine. That means if the operator cranks for 100 revolutions the fuel would absorb a whopping 18 or 19 BTUs of heat - that is if all the fuel was vaporized, not just atomized.

The fuel that is injected is never fully vaporized anyway, I doubt that more than a few percent is vaporized. That white smoke you see when cranking is not vapor, it is atomized fuel droplets."

Also, considering that fuel is injected close to the end of the compression stroke, the time available to transfer heat to the fuel is minimal before the heat of compression is removed by expansion of air on the downstroke.

 

[Mischief Managed]

From a marine diesel expert....

"The latent heat of vaporization of diesel fuel is around 100 BTUs per pound. How many pounds of fuel do you think are injected during a cranking period? That's an easy one, the injector in a 4-71 cylinder only injects around 50 cc's of fuel for every 1000 revolutions of the engine. That means if the operator cranks for 100 revolutions the fuel would absorb a whopping 18 or 19 BTUs of heat - that is if all the fuel was vaporized, not just atomized.

The fuel that is injected is never fully vaporized anyway, I doubt that more than a few percent is vaporized. That white smoke you see when cranking is not vapor, it is atomized fuel droplets."

Also, considering that fuel is injected close to the end of the compression stroke, the time available to transfer heat to the fuel is minimal before the heat of compression is removed by expansion of air on the downstroke.

I live by and keep my boat in a harbor with a ton of commercial lobster boats, many of which operate year round here in New Hampshire. Many of them have old DDs and keep their boats on moorings so they don't have a way to power a block heater. When it's really cold, they have excellent results using the dry crank method to heat up the combustion chambers a bit before they turn on the fuel. Maybe it's only a slight advantage, but it works great.

 

[psneeld]

Lots of myths people swear by.

 

[Lepke]

At one time, Detroits came with an air heater that took the place of one of the air box covers. a hand pump supplied fuel at about 10psi and a second button for the igniter was placed near the starter button so both could be pressed at the same time.
Sometimes you'll find one on ebay.

 

[slymeso44]

I have a 1955 detroit diesel 471 runs fine it just doesn't want to start ( you have to crank it for quite some time, or use starting fluid ).
It has H80 injectors, I have tried putting a fuel line to the secondary fuel filter with an electric pump to be sure there is fuel to the injectors.
The injectors only have a few hours since a rebuild.

Thank you

Randall

air getting in your fuel system might also be a issue

 

[Capn Bob]

I worked on a boat of the same (Active) class; we called them a “buck-and-a-quarter” since they measured 125’ long. Our boat was the former USCG Cutter “Agassiz”. These boats were originally built as medium endurance cutters, and patrolled the “Rum Line” 3 miles offshore during the Prohibition. Despite the fact that they were built as near-coastal boats, they were extremely hardy and seaworthy boats, and the longest-serving vessels of the USCG, the last one decommed in 1978: that’s over 60 I years! The boats originally had 300 hp Winton diesels, but many of these were replaced by GM 8-268-A diesels at 800 hp just before WW2. She also had dual 2-71 gensets. She gained 2 knots (from 12 to 14) with the engine upgrade. That’s Agassiz in the photo.

They were beautiful vessels indeed, very graceful with a bit of old-world style. BTW, the term “Screamin’ Jimmies” refers to the 2-stroke GM diesels such as the 71 and 52 series due to the loud roar they make when running. I worked on the NY waterfront for years, and have also heard that name used to refer only to the 2-stage GMs. Just sayin’ !

 

[Mischief Managed]

From a marine diesel expert....

"The latent heat of vaporization of diesel fuel is around 100 BTUs per pound. How many pounds of fuel do you think are injected during a cranking period? That's an easy one, the injector in a 4-71 cylinder only injects around 50 cc's of fuel for every 1000 revolutions of the engine. That means if the operator cranks for 100 revolutions the fuel would absorb a whopping 18 or 19 BTUs of heat - that is if all the fuel was vaporized, not just atomized.

The fuel that is injected is never fully vaporized anyway, I doubt that more than a few percent is vaporized. That white smoke you see when cranking is not vapor, it is atomized fuel droplets."

Also, considering that fuel is injected close to the end of the compression stroke, the time available to transfer heat to the fuel is minimal before the heat of compression is removed by expansion of air on the downstroke.

It requires 5.3 BTUs to bring 71 cubic inches of air from 70 degrees F to the flame point of diesel vapor. It requires 8.2 BTUs to bring the same amount of air up to the flame point from 0 degrees F. Let's say the unburned fuel robs 2.9 BTUs of heat, a tiny percentage of the 18-19 BTUs that are theoretically possible, that's the difference between starting at 70 degrees and 0 degrees. Seems pretty plausible to me. Plus it works in the real world, not just on paper, so there's that...

 

[psneeld]

It requires 5.3 BTUs to bring 71 cubic inches of air from 70 degrees F to the flame point of diesel vapor. It requires 8.2 BTUs to bring the same amount of air up to the flame point from 0 degrees F. Let's say the unburned fuel robs 2.9 BTUs of heat, a tiny percentage of the 18-19 BTUs that are theoretically possible, that's the difference between starting at 70 degrees and 0 degrees. Seems pretty plausible to me. Plus it works in the real world, not just on paper, so there's that...

Just relaying information from from a guy who has patents on clean genset exhaust. Not a stranger to diesel engine performance.

He's not a drafting table engineer but someone with real world field experience on many levels.

His advice hasn't let me down yet.....I don't know the answer to this issue..... but I trust his knowledge and experience to back it up.