996 starting problem

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Gard
Posts: 244
Joined: Sun Apr 06, 2008 2:25 pm
Location: Fairfax Vermont USA

Re: 996 starting problem

Post by Gard » Thu Sep 27, 2018 11:06 pm

I agree on the issue of not turning fast enough and I do not know if the tractometer is accurate enough to determine cranking speed, I have an independent tack that I put on the PTO shaft and calculate cranking speed from that. New battery, heavier cables and new starter helped me.

On a somewhat related note can someone recommend the best way to verify correct flow and pressure from the lift pump and thru the filters?

Patrick98
Posts: 52
Joined: Thu Aug 02, 2018 7:44 pm
Location: Bt344st

Re: 996 starting problem

Post by Patrick98 » Thu Sep 27, 2018 11:23 pm

I got a new battery for her

philedge
Posts: 240
Joined: Sun Dec 03, 2006 11:27 am
Location: Chester UK

Re: 996 starting problem

Post by philedge » Fri Sep 28, 2018 6:58 am

If its turning over quickly then, as others have suggested, its probably best to check the compression is up to spec before pulling things apart.
If its not turning over quickly then worth checking the battery is the correct capacity and the connections on the thick cables to the starter and earth are clean and tight.
'66 880 Selectamatic rat.

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cobbadog
Posts: 612
Joined: Tue Oct 11, 2011 6:18 am
Location: beautiful Coopernook NSW. near Taree. NSW. Australia

Re: 996 starting problem

Post by cobbadog » Fri Sep 28, 2018 7:38 am

A compression test and leakage test should tell you a lot. Another possibility is the valves may not be seating properly either.
You asked is it worth the expense? To me, YES, it is. It may not be a full time working tractor but you say you want to take it to shows and do a bit of ploughing with it. Non of these things are practical with a bad engine. I bit the bullet on our 30C and did a full rebuild and as you say, pricey, but I am glad that is now done as it starts and runs like a clock at any time we want it to do so. But the decision is yours to make if you find that compression is the issue.

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rid54
Posts: 178
Joined: Mon Oct 13, 2014 8:20 am
Location: Vallentuna, Sweden

Re: 996 starting problem

Post by rid54 » Fri Sep 28, 2018 9:43 am

Engine speed when cranked by starter motor should be around 2-3 turns per second, i think, to achieve reliable, quick starts. Turning speed depends on battery condition, and all the electrical wires and connections involved in the starter motor current path. Battery being new is no guarantee for a full battery - the Ah cost of prolonged startup procedures may be difficult to "repay" with just the tractor's own generator unless it is driven for longer periods.

Patrick98
Posts: 52
Joined: Thu Aug 02, 2018 7:44 pm
Location: Bt344st

Re: 996 starting problem

Post by Patrick98 » Fri Sep 28, 2018 10:27 am

I have drove tractors, diggers and tellyhandlers were the compression of the engine is not good and they started fine.. I will do a compression test but its very odd..

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rid54
Posts: 178
Joined: Mon Oct 13, 2014 8:20 am
Location: Vallentuna, Sweden

Re: 996 starting problem

Post by rid54 » Fri Sep 28, 2018 12:07 pm

Injection timing and less-than-specification max delivery from injection pump may affect starting.

Some DB engines seem to have a tendency to develop a problem with the lift pump drive, a push rod that wears too short, and causes low pressure side flow to be inadequate. Might be worth checking as well...

Gard
Posts: 244
Joined: Sun Apr 06, 2008 2:25 pm
Location: Fairfax Vermont USA

Re: 996 starting problem

Post by Gard » Sun Sep 30, 2018 11:50 pm

Patrick98, I tend to agree, both of my DB have low compression and start fine, if cranking speed is decent I suspect something in fuel delivery (or possibly air filter). It seems like there should be an easy way to measure fuel delivery or pressure like on modern cars but I have not seen one. I usually end up blowing out lines, cleaning and replacing filters and bleeding air until it starts. Let us know how you make out.

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DB780
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Location: Lincolnshire

Re: 996 starting problem

Post by DB780 » Mon Oct 01, 2018 8:52 am

I agree low cranking speed will affect starting as will fuel problems but low compression causes starting problems. The clue is in the way diesels run ' compression ignition'.

Patrick98
Posts: 52
Joined: Thu Aug 02, 2018 7:44 pm
Location: Bt344st

Re: 996 starting problem

Post by Patrick98 » Mon Oct 01, 2018 4:52 pm

Will do thanks. This case is very odd.. a mechanic was a bit confused over the situation.lol

Patrick98
Posts: 52
Joined: Thu Aug 02, 2018 7:44 pm
Location: Bt344st

Re: 996 starting problem

Post by Patrick98 » Mon Oct 01, 2018 5:04 pm

Gard wrote:
Sun Sep 30, 2018 11:50 pm
Patrick98, I tend to agree, both of my DB have low compression and start fine, if cranking speed is decent I suspect something in fuel delivery (or possibly air filter). It seems like there should be an easy way to measure fuel delivery or pressure like on modern cars but I have not seen one. I usually end up blowing out lines, cleaning and replacing filters and bleeding air until it starts. Let us know how you make out.
Just off the phone to the mechanic.. he said that the fuel pump and valves have a bit of wear and there is a wee bit off blow back on the engine.. he said that an engine overhall is needed.

philedge
Posts: 240
Joined: Sun Dec 03, 2006 11:27 am
Location: Chester UK

Re: 996 starting problem

Post by philedge » Mon Oct 01, 2018 9:58 pm

In your first post the mechanic said its not the pump!!

Id be sure youve got a concrete diagnosis before tearing the engine apart and shelling out a load.
'66 880 Selectamatic rat.

Patrick98
Posts: 52
Joined: Thu Aug 02, 2018 7:44 pm
Location: Bt344st

Re: 996 starting problem

Post by Patrick98 » Mon Oct 01, 2018 10:44 pm

Ino. He was only assuming.. it was only a quick diagnosis.. he looked at it properly lately sorry about that

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GeoffDEAL
Posts: 436
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Location: New Zealand

Re: 996 starting problem

Post by GeoffDEAL » Tue Oct 02, 2018 10:12 am

Hi if its getting fuel it will go, injectors tested for spray pattern and pressure would be a good check, i have an old 1494 with over 12000 hrs but always starts unless its real cold one or two cylinders pickup and its away, does not require a lot of winding over on starter,uses heaps of oil and smokes like a train, if its real cold it gets a squirt of starting fluid not much just in air cleaner intake under mushroom and starts no problem but probably has very little compression with age and wear. Valve condition could be a problem with yours starting but the usual problem with valves on later DBs was exhaust valve heads breaking off usually around 3000 to 4000 hrs but replacement valves never did it. What is motor condition like - uses lots of oil -fumes with blow by ect they have to be really sick to be hard to start, try a little starting spray in intake and it should go.

Patrick98
Posts: 52
Joined: Thu Aug 02, 2018 7:44 pm
Location: Bt344st

Re: 996 starting problem

Post by Patrick98 » Tue Oct 02, 2018 11:52 am

Uses no oil. Smoky when she starts but becomes clear.. I did try the spray but it didn't overly help.. it just popped the odd time when it was turning over so I stopped it..

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