Leaking head??

[Korishan]

Hey all.

Have a NH TC40D here. Started having a little blueish smoke and an odd knocking sound. So I disconnected each injector to find which one may have fouled out. Cyl #2 when disconnected stopped the knocking sound.

So I ended up taking all the injectors out as when I disconnected the fuel rail it broke due to corrosion. So I wanted to make sure they were all cleaned and all signs of corrosion or buildup were all removed from all connected pieces.

Disassembled the injectors and cleaned them all out. Used a copper brush to remove any problem spots. Reassembled the injectors and cleaned all threads of every connection; injector, fuel lines, ports. I did notice that a couple of the injector nozzles were discolored (included pics)

After getting everything put back together and primed, the tractor cranked up and ran fairly smoothly, like it had before. However, there is still a slight blueish smoke coming out. I also noticed that there was wetness around the injectors; so I super cleaned around them, checked the connections again, wiped everything down dry on the block, injectors, lines. Starting the engine, within seconds, between the block and head there starts to be a wet line the length of the parts.

I recorded the dry gap getting wet while running.

Any idea how it's getting wet or what it is? I can't tell right now if it's oil, diesel, or water. When I wipe it down, it is dark; but I dont know if that's from some grease/dirt from the block.
Could it be a failing head gasket?

Thanks, Kori

 

[Agvg]

Proper testing and torque when reasembly?

 

[Korishan]

Update on work:

I checked each cylinder by disconnecting the pressure line one by one. The same cylinder was having issues as before. I am not sure that I got the injectors back in the same cylinders as they were before; most likely not.

But, when I disconnected cylinder 2, the smoking went away. As did the slight popping at idle.

Also, when I took cylinder 2 injector out, I noticed the nozzle had some oil residue build up on it. Now, the engine had only ran for maybe 10-15 minutes tops after having put everything back together. It wasn't driven, and wasn't ran much higher than idle (the cable is currently disconnected and hand revving). I didn't pull any other injector out as I was testing to see if maybe I had by chance put the same injector in cylinder 2 as was already in there and it was still fouling. After putting the replacement injector in, cylinder 2 was still acting the same way.


Agvg:
I have not taken the head off, so I assume they are torqued correctly. I guess they could have gotten loose over time.
I torqued the injectors down to 70ft-lbs. Not sure if that is to much or not enough. When I took them out, they didn't seem to be in very tight at all. In fact, when I was disconnecting the fuel rail, it stuck so tight that cyl 3 injector came loose. I had to use a wrench to hold it still break everything else loose first.

When you refer to proper testing, what testing are you talking about here? I do have a cylinder compression tester, but I haven't used it yet as I have to go in through the glow plugs with this kit. Should that be the next step to test compression level? What else should I check when doing these checks?


Please forgive me, this is the first diesel tractor I've ever worked on. So I'm going into uncharted territory. Learning new things is definitely required here and I'm not afraid to learn new things. I don't know most of the terminologies or the nomenclatures related to the diesels, so trying to do a search is kinda difficult as I don't know the keywords to use.

Thanks for the help,
Kori

P.S. i guess another question would be, is it safe to still use, albeit not rough like digging holes and knocking over trees?

 

[Agvg]

You usually have to adjust the opening pressure on the injectors, that requires a tester so it's not a diy job.

 

[Korishan]

Somehow my last post was lost. So I will try to recompile it.

Tractor has just a standard pintle style injector. So it only has like 5 pieces to it.
I've seen pictures and videos on how to make an injector tester, so I planned on making one for future use.

However, back to the original question, is it possible that the head gasket is going bad considering that it is weeping between the head and the block? The tractor has approximately 3000 hours on it. Or at least that's what the hour gauge says.

The side of the block had been getting wet with oil or diesel and caked with dirt. We had thought it must have been just a couple leaky injectors that was keeping that side of the block wet, but I guess it is possible that the gasket could have been leaking oil the entire time.

Kori

 

[rScotty]

Update on work:
Please forgive me, this is the first diesel tractor I've ever worked on. So I'm going into uncharted territory. Learning new things is definitely required here and I'm not afraid to learn new things. I don't know most of the terminologies or the nomenclatures related to the diesels, so trying to do a search is kinda difficult as I don't know the keywords to use.

Thanks for the help,
Kori

P.S. i guess another question would be, is it safe to still use, albeit not rough like digging holes and knocking over trees?

Kori, I'm looking forward to learning this right along with you. I've got enough background in gas engines to satisfy most folks, being a long time mechanic, machinist, and mech. engineer. But I don't have good hands-on experience wrenching on diesels. They seem simple; but I just haven't done much with them.

My guess, is that it is a headgasket beginning to leak...and my experience is that heads leak from either a head gasket not designed right, or a bout with overheating....or both. And headgaskets leak in different ways. Most of the ones I've seen are leaking internally - usually from the water passages to the cylinder or vice versa. I rarely see on that leaks to the outside unless it is leaking water out - and that shouldn't cause a problem with running.

Hmmm....if it is leaking water out....AND you have a problem with the way it runs on one cylinder close to where the water is coming out then it is beginning to sound like either a warped head due to overheating or maybe the head bolts there have somehow lost their torque. That would be rare, but might be worth a check. I'd check them by seeing if I could get 10% over factory torque or somewhat less than one flat - whichever comes first. And I'd do that in the normal torque pattern right across the whole head. If it is warped, well....flattening (milling) a head is pretty normal machine shop work and no biggie as long as there isn't erosion of the metal along the leak path.

Another thing with internal leakage is you may see white exhaust smoke (probably steam), some missed firing strokes particularly at idle, and sometimes (rarely) the coolant looks to have fuel or oil floating in it. That would be a giveaway of course...but you can't usually see that unless you suck some of the coolant up through the radiator cap - fuel being lighter than water - and put it into a glass jar to sit for awhile. Probably worth doing, though.

As for using it....yes, I don't see a problem with that. Keep a real close eye on the temperature and oil pressure. But I've seen motors with head gasket leaks go for a long time without extra damage. Obviously What will eventually happen is that the leak will erode the metal where the leak is. If that goes on long enough then you can't mill the head.
Keep us posted,
luck, rScotty

 

[Korishan]

Thanks for the input, Scotty.

I've been doing a lot of reading on diesel heads and trying to figure this stuff out. From what I can gather, there is a small leak from the oil passage that runs through the block near that cylinder. So I'm getting some oil sucked (during down stroke) into the chamber, though it be very little. It's not bad enough to cause the whole gasket to blow out, yet.

What I'm really worried about when using the diesel, is that, unlike gas engines, they operate at a much higher compression ration. Gas engines are typically 8-10:1, whereas this diesel (I believe; we dont have an operators manual) is closer to 16:1. So I was wondering if that higher compression would cause it to malfunction sooner.

As far as the color of the exhaust, it's blueish. So I know water isn't getting into the cylinder. It's gotta be burning oil in that cylinder. The only way to fully test to see if oil is leaking into the chamber during running, is to pull the injector or glow plug out (probably do the glow plug as it's easier) and see if the blue smoke goes away. I'll have to try that. Might do that this afternoon or tomorrow.

Thanks for the reply, Scotty.

Kori

 

[Agvg]

The opening pressure and correct diesel spray pattern is very important for a 100% working engine, serious damage can occur over time when this is not in order.

 

[Korishan]

I'm getting together the tools needed to be able to properly test thing out. It hasn't been fully serviced in over 5 yrs. So I'm having to collect the tools needed. It'd be easy to just take it to a shop, but then I'd not really learn anything that way.

 

[rScotty]

I'm getting together the tools needed to be able to properly test thing out. It hasn't been fully serviced in over 5 yrs. So I'm having to collect the tools needed. It'd be easy to just take it to a shop, but then I'd not really learn anything that way.

That's what I do too - collect the tools and knowledge. It not only costs about the same the first time, but it means that I get to have all the fun.

I agree that what you are probably seeing is an oil leak as you describe. But if that is the case, what are we looking at in the video you posted?
Do not give up on it being a defective injector. The spray pattern is critical - spray vaporization affects the ability of the CR to crack the long chain diesel fuel molecules. It's a long shot, but a malfunctioning injector could actually be helping to manufacture the difficult-to-burn oil you are seeing.

Easy test is to swap injectors.

Most gassers run a static compression ratio between 7 and 14 to 1. Static pressure is real close to what you typically measure on a compression gauge. Diesels like to run between 18 and 23 to 1. To get psi from compression ratio, just multiply the compression ratio by your local atmospheric pressure. (typ. 14.7 lbs/sq inch)

Looking at my good screw-in compression gauge for gas engines, the scale goes to 250 psi...so it should measure CR of up to 250/14.7 = a CR of 17 and change.
Any good diesel is literally going to blow up that gauge.

Oddball notes: Dynamic compression pressure is different because it depends on things like gaseous flow and valve timing. Think of 2-strokes and expansion chambers...or supercharged engines.... for an example of the real world effects of compression ratio measured dynamically. Dynamic measurements are always the tough ones to do. They are also the ones that count...
Still, using static pressure will tell us all we need to know to fix this tractor.
Hmm.... another oddball thing....I see by the stats that some of the cylinder JDs ran an amazingly high static compression ratio. Those were very long stroke, cool running, low RPM engines & maybe that's how they got away with ratios of 12:1 on cheap low octane gasoline without knocking. I'm only guessing on that & haven't yet thought it though.
Luck,
rScotty