White smoke at start up....

[1994ch]

My 94 has started running rough and chugging white smoke after starting for about five to eight seconds. It does this on hot or cold starts...so I don't think it is the glow plugs. Also I checked for voltage at each wire and pulled them out and bench tested them and they all glowed. So I have been starting to suspect the IP... However... Yesterday when starting it sounded like it locked up on something for a second (like hydro locked or hit a valve or something) but then cleared and started. After the eight seconds or so of smoke and rough running, when I accelerated I looked back and saw a huge cloud of white smoke which cleared after about one hundred yards. From there it ran great... I had to start it one more time before I got it back to the house and it did the same thing again. I am taking the injectors in today to get tested to see if one is leaking after shut down.... any other ideas on what would cause this?

 

[1994ch]

Just to make sure it is clear...while accelerating with the white smoke the engine was running smoothly at that point.

 

[Will L.]

Smell the smoke.
Check your coolant level. Possible seep of coolant into a cylinder.
Other than that, checking your injectors is on track. Fuel is most likely culprit.
Keep them in order to id which cylinder.
When pulling all them, pulling the glowplugs just to see if any are burning away differently from the rest.

Check oil level. You could have valve guide seal letting oil into a (or multiple) cylinder(s). The burning oil will produce smoke and make it hard for the cylinder to fire properly at first. Usually oil wont give white smoke, but if it is keeping the fuel from igniting st first until there is a bit too much, the excess fuel could be your smoke.

With injectors pulled, you could maybe scope the cylinder and see any liquid ontop the pistons after sitting overnight for oil/coolant.

 

[WarWagon]

How long did it sit outside before it went back in?

I would spin it over with the glow plugs out and see if any holes shoot coolant out. The engine coming to a stop while cranking is a bad starter/battery/cable connection or indeed rod bending hydro lock. Seen some places like a (now closed) mine back east that just insisted on throwing the jumper cables on to crank the engine making a cracked head require a new rod and starters on yellow iron. (Yes, the electric drive mine haul truck engines in question had more than one starter. No, stupid stuff like this means unprofitable and justly put the morons out of work all the way up to the CEO as the company folded.)

I don't recommend starting this engine till you eliminate the hydro lock question. You are better off with a cooling system pressure tester than risk starting an engine that wants to hydrolock. Next to double check the pressure tester's negative results (if it shows a leak fix it without further testing) of a coolant leak is removing the T-Stat crossover and fan belt to see if and what side produces bubbles from combustion.

It's possible cranking slow can wet stack the engine till it lights off and then smokes out the unburned fuel.

IMO an injector stuck wide open will not hydro lock this engine due to the distributor design of the injection pump. It will ruin the overun clutch in the starter as compression forces the IP to reprime the system and the engine hits, stalls, hits, stalls while cranking. Low mile Chinese knock off injectors here were all sticking:

 

[1994ch]

Thanks for the great input. All the injectors tested ok. They were Badger diesel rebuilds and were installed about a year or two ago. I am going to checkout my batteries.... They are not very old but that makes sense about the slow cranking flooding the cylinders with diesel before it lights off. I think it spins pretty fast...but I could have just gotten used to a slower speed.

 

[1994ch]

The starter is also only about a year or two old......... And I recently upgraded my battery cables to a larger size.

 

[THEFERMANATOR]

Mine was doing this before I pulled it out. I had bad head gaskets, but they only leaked under boost(could disconnect the vacuum line to the wastegate, and it would barely use any), but it was the injectors in mine were shot. Be carefull, that white smoke could very well be raw droplets or puddled fuel which doesn't ignite(diesel needs to be misted to ignite well under pressure), but when those droplets do ignite, it can blow torch the crowns of your pistons blowing holes in them. Or worse, seen some actually crack the pistons through the ring land from it. So find out what it is ASAP!

 

[1994ch]

I cranked it with the injectors out and it shot coolant out the #3 hole..... looks like it will be a while before I'm back on the road. Not sure what I am going to do... I am almost done rebuilding the 6.2 for the tahoe protect but I still have all of the swap to do... Which ever way I go looks like I will be looking for something to drive. (Can't borrow my friends car forever....)

 

[1994ch]

So...looking for opinions. With 230000 on the clock would you go for a rebuild or just fix the head? Or drive a car for a while and save up for a D'max? I like the idea of a newer truck but in my opinion the older ones are easier to work on...

 

[Will L.]

I pull it apart to see before making decisions unless you are positive you are keeping the rig for a few more years and you know you can afford the investment up front and was planning on it anyways.

I would pull both heads and examine them and the cylinders for cracks. You might have just popped a gasket. If you have to pull engine afterwards, its no biggie to do it without the heads.

 

[ak diesel driver]

if it ran good with no issues before I'd pop the head off and check piston height to see if it bent the rod, if not new head gasket and go

 

[1994ch]

Well I got it down to just needing to pull the head bolts last night. Will hopefully have some help tonight to lift the thing off.....

 

[Twisted Steel Performance]

Where in my state are you?? I have a spare motor here that has nearly everything on it still...

 

[1994ch]

Where in my state are you?? I have a spare motor here that has nearly everything on it still...

I am in Greenville... I also have a parts truck... but it has over 300,000 miles on it so the chances of the heads not being cracked are probably slim to none.

I got the head off and it has a long crack running towards the pre-cup from the intake valve in #3. The piston still looks like it makes it all the way to the top of the block, so hopefully nothing is bent.

All the cylinders have little cracks between the intake and exhaust valves.

I will take this head to a head shop near by and have them look at it, but if they say it's scrap or really expensive to fix I will be shopping for one or two heads most likely.

 

[Twisted Steel Performance]

I'm in the Spartanburg area.. if you can see a crack don't bother with the machine shop, they aren't fixable... if ya need any help I may be able to help just let me know..

 

[1994ch]

I'm in the Spartanburg area.. if you can see a crack don't bother with the machine shop, they aren't fixable... if ya need any help I may be able to help just let me know..

Dover Cylinder Head does some pretty amazing work... not sure if they would be able to weld up one that is this bad but I plan on swinging by there tomorrow just to see.... I think you are right though...

If I pull the other head how likely is it that it will be cracked as well?

 

[THEFERMANATOR]

All 6.5 heads seem to have cracks between the 2 valves, it's other cracks that are cause for concern. I thought my heads were good until I took some brake cleaner and wire brush to them, and found 3 cracks between the valves.

 

[1994ch]

Well I got the engine pulled out of my parts truck and pulled the heads off. One head showed why I was able to by the truck so cheap... was cracked way worse than my truck. The other head only has the little cracks between the valves... If I take it to a machine shop and it pressure checks good..... would you run it? or hold out for one with no cracks?

Long term plans..... My engine has 230,000 on it. It has been running ok... kinda what I am thinking right now is if I can fix it easily for cheap I will and keep running it. If it is going to be several hundred to just fix the one head I am thinking about holding off and later going through the engine and fixing everything right.

 

[1994ch]

Where in my state are you?? I have a spare motor here that has nearly everything on it still...

Looks like I could use a set of rocker arms (for my 6.2 diesel build)....... and most likely a head... I took the heads off of my parts engine and one was badly cracked, the other is at the shop waiting for them to clean it up and see if it is any good, but judging from the shape of the rest of the engine I do not have high hopes. If you are still interested in selling any parts, let me know.

 

[Twisted Steel Performance]

Looks like I could use a set of rocker arms (for my 6.2 diesel build)....... and most likely a head... I took the heads off of my parts engine and one was badly cracked, the other is at the shop waiting for them to clean it up and see if it is any good, but judging from the shape of the rest of the engine I do not have high hopes. If you are still interested in selling any parts, let me know.

I have a new set of rockers for sure, I don't have the heads off the spare motor at this point so I'm not sure what kind of shape they are in as of now... might be able to let the whole motor go cheap enough...