Minimum amount of compression to fire a diesel - Page 2 - SailNet Community
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post #11 of 22 Old 03-05-2010
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Not being a diesel mechanic I don't know if this is possible. When testing a gasoline engine for compression, if I get a abnormally low reading on a particular cylinder I will squirt a small amount (maybe a tablespoon or two) of oil into that cylinder and retest compression. If the compression rises significantly it indicates worn rings. If compression does not increase it would indicate bad valves. It would be instructive if a bonifide diesel mechanic would comment on this.
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post #12 of 22 Old 03-05-2010
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Same principal works with diesel as well.


So I take it you didn't try the ether?...Did you not have any white smoke out the exhaust?

FWIW..I have two machines that came from the factory with auto ether cold start systems on them....This whole never use ether on a Diesel is just a bunch of Back yard urban legend heard someone blew one up once turned mainstream mechanic saw it on You-Tube cover your rear end hog wash.

Its like anything else in life..its not what you use its how you use it.... Put one bullet in a guns chamber at a time it works as designed ..try and put in two and you have problems.

Its your engine through money at it all you want.


Dang I need to get that next video out!...

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post #13 of 22 Old 03-05-2010
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You havenít mentioned any work to confirm that the intake and exhaust paths are unobstructed. If itís getting fuel but no air it will stop combustion. If it canít exhaust, it will stop combustion as well. Excessive time at idle can lead to soot build up in the exhaust elbow that can eventually block it. I saw it once and the engine sounds like itís going to start and just doesnít quite make it. A bit of smoke came out the air filter.

What about the exhaust color? A couple of people have asked and you havenít replied. That is a pretty low level diagnostic tool and it sounds like you are considering pretty drastic measures.
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post #14 of 22 Old 03-07-2010
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Quote:
Originally Posted by Stillraining View Post
Same principal works with diesel as well.


So I take it you didn't try the ether?...Did you not have any white smoke out the exhaust?

FWIW..I have two machines that came from the factory with auto ether cold start systems on them....This whole never use ether on a Diesel is just a bunch of Back yard urban legend heard someone blew one up once turned mainstream mechanic saw it on You-Tube cover your rear end hog wash.

Its like anything else in life..its not what you use its how you use it.... Put one bullet in a guns chamber at a time it works as designed ..try and put in two and you have problems.

Its your engine through money at it all you want.


Dang I need to get that next video out!...
It is not an urban legend. Ether ignites easily burns rapidly and produces high cylinder pressures. Ether can also pre ignite in the cylinder causing all kinds of damage to pistons, rings, connecting rods, etc. If used in large amounts it will also dry the cylinder walls causing premature wear. Starting fluid can be used but for those reasons it should be used in small amounts and only while cranking the engine.
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post #15 of 22 Old 03-10-2010 Thread Starter
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Quote:
Originally Posted by waynemk View Post
You havenít mentioned any work to confirm that the intake and exhaust paths are unobstructed. If itís getting fuel but no air it will stop combustion. If it canít exhaust, it will stop combustion as well. Excessive time at idle can lead to soot build up in the exhaust elbow that can eventually block it. I saw it once and the engine sounds like itís going to start and just doesnít quite make it. A bit of smoke came out the air filter.

What about the exhaust color? A couple of people have asked and you havenít replied. That is a pretty low level diagnostic tool and it sounds like you are considering pretty drastic measures.
A couple of people have have asked but I don't have a really good answer for the exhaust color. When the motor last worked it did seem like it had more smoke than usual but that was thinking about it a month later. The smoke it had did not really seem white or black but more of a greyish. I am color blind as well so my perceptions of color cannot be relied on.

I have checked the intake to make sure it is getting air. The exhaust is a little bit more difficult to get at so I have not tried that yet. That will be one of the things I check before doing anything more major like taking off the high pressure pump to have it checked.

I did buy a compression guage finally and check the compression. It was 280 and 290psi. So the compression is low but it is not horribly low. The starter compression is supposed to be 284 to 355.

It is confirmed that the lift pump is working and the high pressure pump is putting out plenty of fuel but without taking it off I can't really tell if it is at the spec of 2500 some psi.

The weather here is getting better so hopefully I can get into some more. Its been a really wierd winter here in Florida this year with temps abnormally low. Supposed to be in the 70s today so I am going to start on it again.

Thanks for all the help! Any suggestions are appreciated. Theres nothing like a real life problem to get you learning something.

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post #16 of 22 Old 03-10-2010
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Quote:
Originally Posted by CarelessNavigator View Post
It is not an urban legend. Ether ignites easily burns rapidly and produces high cylinder pressures. Ether can also pre ignite in the cylinder causing all kinds of damage to pistons, rings, connecting rods, etc. If used in large amounts it will also dry the cylinder walls causing premature wear. Starting fluid can be used but for those reasons it should be used in small amounts and only while cranking the engine.
Careless...What I meant is this Legend has become so prevalent as to it becoming the "Gospel of Diesel lore"...It is simply untrue.

I can probably find and post 100,000 cases of successful diesel ether starts to your one damaged engine one..I have realistically preformed 10,000 myself over the past 35 years with not one instance of damage.

I have kept diesels running on straight ether shot into the intake until it finds its own stride on Diesel fuel many, many times.

Its like I said the improper use of anything that causes the damage..Over speed your diesel and you will see engine damage as well.

Modern Diesel ether's do have a upper cylinder lube in them already.

I have two machines that I start daily on the job with ether for years...They run like a tops...Should I crank on a 600.00 starter for 60 seconds every morning when a shot of ether makes it 2?..Or should I tear down a perfectly running dependable money making machine off line just because its low on compression and just needs a little helping hand every morning?

Real world is where its at for me..Not theory and heard it happened somewhere. once

Your opinion is what it is and it is shared by many others..I respect that but my experience and those of many others has proven this a false phobia...

But back it up with a video showing one blowing up and I will show you improper use of ether in that video as well...

I have a .50 caliber black power rifle...It is my choice as to the amount of powder I load into it...I can under load it to the point of the ball failing to exit the barrel...I can over load it to the point of breach failure and risk bodily harm.

I will never win this argument with the mass over this issue and that is fine...I just put my money where my mouth is and owing 1/2 a mill. worth of heavy equipment with a replacment cost today of over 2 mill. that Id rather not destroy, would seem to me to pull a little more weight on this matter then most...

Take it for what it is worth to you...Its given freely

"Go Simple...Go Large"

Relationships are everything to me..everything else in life are just tools to enhance them.


The purchase price of a boat is just the admittance fee to the dance...you still have to spend money on the girl...so court one with something going for her with pleasing and desirable character traits others desire as well... or you could find yourself in a disillusioned relationship contemplating an expensive divorce.

Last edited by Stillraining; 03-10-2010 at 11:43 AM.
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post #17 of 22 Old 03-10-2010 Thread Starter
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W00t! Got the engine going. I put a space heater in the engine compartment for about 3 hours and got it toasty warm. Its been running just fine for about the last half hour. It fired almost immediately and surprised the heck out of me!

For those who asked about the smoke I had my girlfriend look at it and she said it looked bluish white. It looks bluish grey to me so my perception is off. It is not putting out too much smoke though so that is a good thing.

The oil in the water did not return after running it so it was likely caused by the water coming back up the elbow. Once the wind dies down I will take it out and put it under some load to see how it acts then. I put it in reverse and it seemed to work just fine pushing against the wind but I could not really throttle it up too much.

If anyone would like to speculate about things that I could change or fix on the engine so I can get it start when the temperature is below 100 degrees or so I would gladly take that advice.

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post #18 of 22 Old 03-10-2010
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Your compression is low- unless you solve that problem, it is always going to be hard to start, and it is always going to smoke. Do the easy stuff first. Since you have the manual, I'd check the valve clearances, check torque and retorquethe head as needed, and check your numbers again. if no change in comp, then you might need to pull the head and re-ring at a minimum.
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post #19 of 22 Old 03-11-2010
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Quote:
Originally Posted by Stillraining View Post
Careless...What I meant is this Legend has become so prevalent as to it becoming the "Gospel of Diesel lore"...It is simply untrue.

I can probably find and post 100,000 cases of successful diesel ether starts to your one damaged engine one..I have realistically preformed 10,000 myself over the past 35 years with not one instance of damage.

I have kept diesels running on straight ether shot into the intake until it finds its own stride on Diesel fuel many, many times.

Its like I said the improper use of anything that causes the damage..Over speed your diesel and you will see engine damage as well.

Modern Diesel ether's do have a upper cylinder lube in them already.

I have two machines that I start daily on the job with ether for years...They run like a tops...Should I crank on a 600.00 starter for 60 seconds every morning when a shot of ether makes it 2?..Or should I tear down a perfectly running dependable money making machine off line just because its low on compression and just needs a little helping hand every morning?

Real world is where its at for me..Not theory and heard it happened somewhere. once

Your opinion is what it is and it is shared by many others..I respect that but my experience and those of many others has proven this a false phobia...

But back it up with a video showing one blowing up and I will show you improper use of ether in that video as well...

I have a .50 caliber black power rifle...It is my choice as to the amount of powder I load into it...I can under load it to the point of the ball failing to exit the barrel...I can over load it to the point of breach failure and risk bodily harm.

I will never win this argument with the mass over this issue and that is fine...I just put my money where my mouth is and owing 1/2 a mill. worth of heavy equipment with a replacment cost today of over 2 mill. that Id rather not destroy, would seem to me to pull a little more weight on this matter then most...

Take it for what it is worth to you...Its given freely
I am an advocate of proper use of starting fluid. To say that nothing will happen if it is used on a diesel engine is misleading to someone who is unaware. Chances are nothing will happen when you use ether but there is the possibility of damage happening albeit slim.

I have always been warned of tires exploding when filling them with air. It took eight years and hundreds if not well over a thousand of times topping of tires with air after I started working as a mechanic to see it happen with my own eyes and it's been several years since I have seen it. Does that mean it will never happen, no it just means the possibility is there and to be aware that it can happen.
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post #20 of 22 Old 03-11-2010
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Agreed.....My comments are to those that say never to be used.


To The OP:
Glad you got it running...I knew you would..You already have my opinion as to what to do.

"Go Simple...Go Large"

Relationships are everything to me..everything else in life are just tools to enhance them.


The purchase price of a boat is just the admittance fee to the dance...you still have to spend money on the girl...so court one with something going for her with pleasing and desirable character traits others desire as well... or you could find yourself in a disillusioned relationship contemplating an expensive divorce.

Last edited by Stillraining; 03-11-2010 at 02:29 PM.
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