Diesel cold start problems

**Cerise** · 26th September 2017, 07:35 PM

Hi there,
Over the past year, Tallulah has become harder to start when cold, but runs beautifully once she's running. I just replaced the glo-plugs as the resistance has been increasing, and one finally went open circuit. As the new set has a total resistance of 0.3 ohms, whereas the previous set was nearly 2 ohms, the 30 amp fuse that I'd put in promptly blew. The plugs now work fine with a 50 amp relay and fuse and 54 amps showing on the ammeter...

BUT.. She still won't start when cold. She turns fine, until one cylinder ignites, but the next one doesn't, so the starter motor disengages with its whiny hum, and the engine stops as the starter motor whine slows down. It'll keep doing this until the cows come home, or until the weather is warm enough, a spring sunny afternoon warm, when she'll finally start and happily gallop off. I'm pretty sure she would start fine on a jump start, so that more than one cylinder has a chance to crank and ignite. The problem is it's hard to find a spare hill to carry around to park on all the time...

My next guess is that after the first cylinder ignites, the next one won't ignite because the fuel injector may be spraying in the cylinder, and won't start when cold. As the injectors are spectacularly not cheap, I'm wondering if anyone has any other good ideas for me to explore to work out why it won't start. The engine is smooth and running well, without smoke, without any unusual vibration or noise (beyond the normal), so I don't suspect any leaky exhaust valves or similar, but I'm a bit stumped on looking for the next possible solution to explore.

I'd really appreciate some canned inspiration please!

Thanks, Cerise.

**trout1105** · 26th September 2017, 07:41 PM

I'd really appreciate some canned inspiration please!

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**TimNZ** · 26th September 2017, 07:48 PM

Is the timing ok? Might be worth checking the condition of the cam chain and guides?

Just a thought,

Cheers,

**JDNSW** · 27th September 2017, 05:05 AM

What oil are you using? Should be no thicker than the recommended winter grade for Canberra winters. Also, check for voltage drop anywhere in the starter circuit, most likely in the earth, but could be anywhere including a slightly sick battery. Slow cranking can result in the issues you are seeing, and this engine draws a heavy current for starting - its not that big a diesel, but it is very high compression compared to a lot.

**123rover50** · 27th September 2017, 05:48 AM

Do you keep the glow plugs engaged for a while once it fires or do you stop them straight away.?
Mine are on a push button and I keep them on untill it runs smoothly.

Keith

**Cerise** · 29th September 2017, 06:16 PM

Gosh, thanks for the non-aerosol helpful ideas!.

I've gone through the starter motor twice with a brilliant friend. We did find a little bit of age-related corrosion in one of the high current connections, and it didn't run slower in the winter after fixing that. The relay now looks beautiful inside. I have a new battery, all the volts look good now, and it cranks at normal starting speed.

I keep the glow plugs on as the starter cranks; One cylinder always fires reasonably promptly: just one....

The oil has the right numbers on the bottle.

I hadn't thought about cam timing, I'll go and look that up as I've never played with that before and I don't know if it's a quick or a monster job.

I haven't checked the tappets yet: why didn't I think of that before? d'oh.

It'll b a couple of weeks until I have time to get round to that, too much else to play with!

Cheers, Cerise.

**ian4002000** · 1st October 2017, 06:47 PM

You can check the diesel pump timing ? have you had the injectors checked or cleaned lately ?
Is the fuel fresh as in winter fuel ?
How long do you hold the glow plugs on for ? how long does the handbook suggest to hold the glow plugs ?
Have you done compression check of the engine ?

I have several diesel engines in different machines and they all have their own personalities when it is cold. I had an old tractor that would start first try except under 10 deg C, as such I gave up driving it until the weather was warmer.

Good luck
Ian Bittern

**JDNSW** · 2nd October 2017, 06:16 AM

I wonder if glazed bores could have this effect - low compression when not oily? But should also show oil burning when hot. Low compression for any reason will cause this - worn bores, stuck or damaged rings, valves not sealing due to insufficient clearance, burnt or carboned up sealing surfaces, compression leaks around injectors.

Also, as suggested, poor spray pattern from the injectors, possibly loose or damaged precombustion chambers, although that seems unlikely to me.

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Diesel cold start problems

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