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DOGBREATH

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Good day all, I am trying to solve a starting from cold problem with my old 6354. The head was rebuilt and injectors serviced 80hrs ago. I did a compression test today and all six cylinders show about 26kgf/cm2. Does anybody know if this is an exceptable figure for this old girl? Many thanks.
 
I do not know if that is a good or bad figure but if all the cylinders are about the same that is much better than having 1 or 2 cylinders lower than the rest.
 
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Good day all, I am trying to solve a starting from cold problem with my old 6354. The head was rebuilt and injectors serviced 80hrs ago. I did a compression test today and all six cylinders show about 26kgf/cm2. Does anybody know if this is an exceptable figure for this old girl? Many thanks.

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If I've got it right [1kg.=2.2 lb., 1 cm2 =0.155 sq.in.] then 26 kgf/cm2 equals 370 psi. which sounds pretty healthy and if all cylinders show the same then it should be OK.
 
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is the cold start working ?

Thanks for reply Mick, Yes, It"s a single flamethrower jobbie in the inlet manifold and was replaced when head was rebuilt
 
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Good day all, I am trying to solve a starting from cold problem with my old 6354. The head was rebuilt and injectors serviced 80hrs ago. I did a compression test today and all six cylinders show about 26kgf/cm2. Does anybody know if this is an exceptable figure for this old girl? Many thanks.

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If I've got it right [1kg.=2.2 lb., 1 cm2 =0.155 sq.in.] then 26 kgf/cm2 equals 370 psi. which sounds pretty healthy and if all cylinders show the same then it should be OK.

[/ QUOTE ] Thanks for that Reeac, Just to add, batteries are fine, smokes well untill warm, then runs like a watch, till next start from cold. Fuel pump timing? running out of ideas! /forums/images/graemlins/confused.gif
 
Has it always been difficult since the rebuild, or has it suddenly become difficult? Pump timing wouldnt slip, but if it was always difficult to start look at camshaft timing as well. If it has happened suddenly or been building up, take a look at the fuel system to see if the fuel is leaking away from the pump when it is stopped for some reason, or a minute air leak that allows the engine to run - if it can be started, but builds up enough air to make it difficult to start while idle.
 
Thanks Harry, When I bought the boat 2 years ago, she started fine from cold on the sea-trial. (owner must have had the knack) I had trouble from day 1 and opinion was head gasket. When head was removed, gasket looked ok, but valves etc needed work. Just seems to be getting worse. I will check out your ideas.
 
No glow plugs, just an element that ignites a fierce flame up the inlet manifold and BOOM!!!! pretty basic stuff! /forums/images/graemlins/shocked.gif
 
Hi. I note you say the thermostart was replaced during rebuild, but have you taken the air cleaner off and actually seen it
"fully ablaze" ? The other thing that they are hyper critical on is cranking speed, try fully charging the batteries and see if that helps. hope you succeed they are a great engine when all is right !
 
I take it the thermo start is still alight while cranking? or do you only pre thermo?

smoke while cold is as I expect you know perfectly acceptable for the period of the engine, as would have done so from new.

if it runs well when warm, wouldnt expect timing to be a problem

at next start, first try pumping the lift pump to pressurise the injection pump,then give it a start.

I assume the air cleaner if fitted is clean.
 
Essexboy has a point - a good cranking speed is vital with these older Perks. Good batteries, all connections 100% (check if any get warm/hot during cranking and dont forget earth return connections), and starter motor in good condition.
 
well if cold starts fine then which oil are you using ? is it slowing down cranking speed ?
I have a 6/354 in my bus which has not long before I got it had the head gasket done
Cant see it being the lift pump or it would air lock and never start untill bled


cheers
Mick
 
Thanks for your help all, quite a few things to check there, not today though-to rough in the harbour! Air filter is clear, thermostart could have failed I suppose. Am using morris oil as recommended, cannot remember the viscosity at the moment. Any idea of what cranking speed is needed?
 
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Thanks for your help all, quite a few things to check there, not today though-to rough in the harbour! Air filter is clear, thermostart could have failed I suppose. Am using morris oil as recommended, cannot remember the viscosity at the moment. Any idea of what cranking speed is needed?

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I have an Adlard Coles book about marine inboard engines which states for a diesel that " cranking speeds, usually in excess of 120 rpm., must be capable of being sustained ..". Incidentally I find that it also states that the combustion chamber pressure needs to be 500 psi. at a temp. in excess of 900 deg.F i.e. rather more than my earlier calculated 370 psi.
 
Have no knowledge of your engine or its characteristics.

But experience over the years says that at this time of year old diesels are always a bit stubborn.My old Bukh certainly is. But in the summer it starts easily.

Does your start well in the summer??

As has been said, a good battery is essential. Never tried it but a hair drier pointed at the air filter is said to improve starting, if you have pontoon lecky.

Another problem might be air in the fuel system Uncoupling the fuel pipe to one of the injectors, then turning the engine might show if the system needs bleeding, thus air leaks.

Good luck
 
If it's cranking speed, a possible test is to cover the inlet (having removed the air cleaner) with your hand (or something else that can't be sucked in!) and cranking. the air will be sucked out and none left to compress, so it will spin up just like a de-compressed engine. Fuel will be injected, when it's up to speed take away your hand and it should burst into life.
 
When starting my elderly Perkins 4108 during the winter, I hold the heater on until it is well alight, and continue until the engine starts. However, I find it better to open the throttle to max, reducing it the instant it starts.

The Perkins manual says that too much flame reduces the available oxygen, but I have not found any evidence to justify this.

There is only a limited amount of fuel available to the heater, it may be worth checking you are not running out too soon.

Some early engines have a small, manually filled, tank.
 
Battery voltage is lower in cold weather, it may be worth checking your batteries are fully charged. One trick I have found useful, if you suspect battery voltage is a bit low, is to pinch power from the domestic batteries. I have in the past used an inverter, to drive a two stage battery charger that charges to 14.5 volts.

This has not been necessary since since fitting a x-split and topping up my sealed batteries.
 
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