Searched and still confused ; hard starting

[Blacksheep1974]

Well I was referred to this site .... I heard and since I have been lurking there are a lot of educated oil burners here.  I have an issue with my 81 Caddy.  I will give you some history, the diesel is OEM and a little tired but compression is strong.  The truck ran fine all summer and winters before.  This winter has been rough on it yet it hasn't been really cold.  It started hard starting about a month ago, at the same time as maybe a bad tank of diesel?  I replaced the tired glow plugs with new Bosch and they are relayed each so they are getting roughly 11.5 when on.  I checked today and again they all turn on strong and the relays good, and they will run for 50 seconds with the sender unplugged.  I have new diesel in and only fill at Shell, plus I added a booster for cetane and varnish etc.  The cold start lever seems to work, the motion of travel is 100 percent and it will run smoother when started with the cold start out.  It starts but rough and real rough if you try to rev it up to smooth it out, yet once it is warm a few minutes it runs smooth.  It also runs smooth with the truck plugged in so I am at a lost.  Glow plugs good, relays good, block heater good, diesel good, compression good and air flow good with a KNN, so any ideas as to why it would run rough right at start? The only thing I can think of it something in the pump, any ideas for me?  And great to be part of this forum.

[theman53]

sounds normal

[TylerDurden]

... It starts but rough and real rough if you try to rev it up to smooth it out, yet once it is warm a few minutes it runs smooth.  It also runs smooth with the truck plugged in so I am at a lost.  Glow plugs good, relays good, block heater good, diesel good, compression good and air flow good with a KNN, so any ideas as to why it would run rough right at start? The only thing I can think of it something in the pump, any ideas for me?

When the block heater makes a significant difference, the compression is low. Some hard numbers would be good to know.

Could possibly be a bit of air getting into in the lines. I'd put clear lines on the in and out ports of the IP and see if bubbles are present in the out-line during startup. Can't hurt.

[Blacksheep1974]

... It starts but rough and real rough if you try to rev it up to smooth it out, yet once it is warm a few minutes it runs smooth.  It also runs smooth with the truck plugged in so I am at a lost.  Glow plugs good, relays good, block heater good, diesel good, compression good and air flow good with a KNN, so any ideas as to why it would run rough right at start? The only thing I can think of it something in the pump, any ideas for me?

When the block heater makes a significant difference, the compression is low. Some hard numbers would be good to know.

Could possibly be a bit of air getting into in the lines. I'd put clear lines on the in and out ports of the IP and see if bubbles are present in the out-line during startup. Can't hurt.

Once warm it starts great ... I agree it might be normal, I should redo the compression test.  It did run warm once this winter when a rad hose split but not for long.  Might try a "restore" product or something, running 10W30 Diesel oil which may be too thin I read for older oil burners.

[burn_your_money]

Switch to a 0w30 or 0w40 synthetic for the winter. It will make starting much easier and probably smoother. I wouldn't run it a full 10k, especially the first few changes.

[ORCoaster]

Time to check the timing.  IF it starts and runs better on the cold lever then you may be off just enough to cause it to start and run rough initially.

All else seems aligned with the moon and the stars. 

[Blacksheep1974]

Well this weekend was a great test ... it has been approx -30C all weekend.  Plugged in it starts easy as usual, then in the unheated garage where it is about -10 if I cycle the plugs for abut four times it starts fair and if it was outside all day I know it wouldn't go for sure.  So I think I will either wire in a toggle switch to run the glow plugs the full fifty seconds then start, or I have a timer similar to a turbo timer but it is adjustable to a minute to run the plugs. 

How is the cold treating everyone else's oil burners?

[steevz]

I had a similar condition on my Vanagon diesel, and I advanced the timing and now she fires no problem. Engine might be starting to get tired and running more advanced should help the cold start condition.

[Blacksheep1974]

Hey Tyler thanks I am running 10W30 right now diesel oil and it seems good.  It does seem to maybe be burning a bit so I will try some of that 'restore' maybe it will help over winter.  And the timing are you guys just talking pump timing or as a whole? What is the easiest way to advance it just the little needed?  Thanks for all the help guys. 

Cheers 

[Blacksheep1974]

I guess after reading more, I am looking to advance pump timing by one tooth? Right?  I have been reading tips and tricks to not lose base timing.

[ORCoaster]

Not one tooth, Just loosen the bolts and nuts holding the pump secure and give a slight push towards the engine block.  Mark the pump across from the line on the pump bracket or someplace on top where you can see it.  Do this before loosening the pump.  The amount of advance we are suggesting is like the width of a pencil mark. 

Seriously, Just that fraction more towards the engine will change the base timing enough for you I think.  Then lock everything down tight on the IP but you are not done yet...

Now take a 17mm wrench to the back of the IP and loosen all four of the nuts on the injectors lines.  Don't back them all the way off just enough so that they loose their tension.  Get them all loose then tighten them back up.  Failure to do this may end in vibrations cracking a line or just more shake than the IP needs to run smooth.

That should get your pump a few more degrees advance.  If it makes it totally wrong you have the index mark you made and you can go the other way with it.  Loosen nuts on pump and pull the IP towards the front of the engine to retard it.  Lock it all down, relax the back end nuts and reset.  Good to try again.

Hope that helps ya. 

[Blacksheep1974]

Not one tooth, Just loosen the bolts and nuts holding the pump secure and give a slight push towards the engine block.  Mark the pump across from the line on the pump bracket or someplace on top where you can see it.  Do this before loosening the pump.  The amount of advance we are suggesting is like the width of a pencil mark. 

Seriously, Just that fraction more towards the engine will change the base timing enough for you I think.  Then lock everything down tight on the IP but you are not done yet...

Now take a 17mm wrench to the back of the IP and loosen all four of the nuts on the injectors lines.  Don't back them all the way off just enough so that they loose their tension.  Get them all loose then tighten them back up.  Failure to do this may end in vibrations cracking a line or just more shake than the IP needs to run smooth.

That should get your pump a few more degrees advance.  If it makes it totally wrong you have the index mark you made and you can go the other way with it.  Loosen nuts on pump and pull the IP towards the front of the engine to retard it.  Lock it all down, relax the back end nuts and reset.  Good to try again.

Hope that helps ya.

I am going to try this .... so after the mark when the pump is pushed back the mark should just disappear right?  I guess a scribe might be best?  The movement only changes timing not tension on the tbelt right looking at the bolt pattern

Thanks for the input ... I really appreciate it 

[TylerDurden]

... so after the mark when the pump is pushed back the mark should just disappear right? 

Nah, just scratch the IP and bracket close to the front-most bolt, so when you turn the IP, you can see how much you are turning.

[Blacksheep1974]

I loosened the bolts off and tried to rotate the IP.  I didn't realize that the bottom bolt is a pivot, so it was a learning experience.  I guess it loosens the timing belt or tensions it depending on what way you turn.  I was only able to move it maybe a pencil lead width towards the back and I am impressed it started easier, ran smoother and the test will be the morning to see how it starts.  The only thing that concerned me is that the pump is maxed adjusted now so I guess it must be off a tooth.  Thanks for all the input, I will keep you posted.

[ORCoaster]

The belt tension is changed another way.  By loosening the three bolts around the shaft of the IP you are just allowing it to rotate on the center shaft.  To advance or to retard it.  If you are maxed out then you need to check from step one on timing. 

That would be to break the cam pulley loose and then set the plate in the cam shaft at the back to be sure you are TDC on the head, then look where the pointer is at the back of the engine just before the transmission. Yeah that big plastic plug.  You may just need to Pin the IP with a socket and loosen the tensioner and retighten it all once you line up the bottom end on the pointer. 

There is a right and a wrong way to swing the tensioner, you want to tighten it so it brings the slack over the top of the IP and Cam pulley without moving the lower end.   Once you have the slack out, about a 45 degree twist on the timing belt between the two top pulleys, then tighten the cam pulley back down.  Pull keepers at the cam and IP and rotate the engine over a couple of times with a ratchet or box end wrench and check position of cam and IP Pulley to see how they may have changed with pointer is at mark on TDC of flywheel.