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6.2L Diesel - Tech Support - Troubleshooting - Performance 1982-93 6.2L Diesel - Welcome to the Internet's first discussion forum for the 6.2L engine.

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  #1  
Old 07-20-2005, 10:48 AM
tomsepe tomsepe is offline
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Hey Friends!

(This might get a little technical for some, but I thought I
  #2  
Old 07-20-2005, 12:26 PM
john8662
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Hmm.. Time for some fun

You should get a pretty nice puff from the cylinder just rotating it over with the starter, Heck I blew out my stuffed in rags accross the garage spinning the engine over by hand.

Before you condemn this engine though I'd suggest getting a Diesel compression tester that uses the glow plug hole. You'll need to re-intall the injectors and use the diesel compression tester. I kind of doubt that you're getting anything close to accurate so far. Matco makes a diesel compression tester thats reasonable on the pocket book and works well.


I'm just curious why you would suddenly have no compresion in the cylinders mentioned.

Those injectors are not going to clean up, it's time to call up Diesel Injection Service www.dieselpage.com and get a new set of reman injectors for putting the engine back. Believe me, they stand by their product and do a good job.

Since you're going to be pulling the engine entirely take note of where everything goes, because it's going to be a while before you get it all ready to put back together. An old trick to this is to take cardboard boxes and cut them up unitl you have pieces (say 6" by 10") to LABEL and poke holes into to hold the bolts.

Take for example the valve cover bolts that you have already removed. some of the bolts are just a bolt, others incorporate a stud on them for allowing another bracket to mount on top of (like the injector line retainer bracket). So you would take a piece of cardboard and poke 8 holes in it, then take a marker and label left side, right side, top, bottom etc and then take the bolts and associated nuts and place them on the cardboard. You'll want to do this for most components on the engine. This technique will allow you to assemble the engine with accuracy and with less frustration. I don't like to take the time to torque all the bolts in place to find out that some bracket required some exact shaped bolt in order to mount. I then would have to remove the bolt and swap it around and then torque it down. So, saving the position saves time!

Another thing that works well is taking digital pictures, which I see you have access to!
  #3  
Old 07-20-2005, 03:44 PM
tomsepe tomsepe is offline
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I'm pretty sure it is the head gasket. cylinders 1,2 and 6 produced almost no compression at all. COmpared to the others that popped the device out of the hole (it has a rubber nozzle, probably designed for gas engines).

I'll try the cardboard idea... before I forget where everything goes!

When I buy new injectors I might get some from this company in europe that retools injectors specifically for the higher viscosity of vegetable oil.

Thanks for the tips!

thomas
  #4  
Old 07-21-2005, 11:45 AM
jcomp jcomp is offline
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You've drained the oil, removed the injectors, replaced the starter, checked the batteries and cables and the engine is still cranking slowly? Why do you think that is? How did you check the batteries?

I suggest pulling the heads since the gaskets are bad anyway and troubleshooting the slow cranking problem before you put it back together. I'm not sure if a cracked piston or bad bearings would cause it but I do know that a blown head gasket by itself won't (especially with the injectors removed).

Anyway, good luck with it. Even if it ends up being a worst case situation (engine rebuild) just think that in 30K miles you've saved about $4000 in fuel (assuming 19MPG and $2.50/gal for diesel vs. free WVO).

I'm curious, how are you heating the oil in your system?
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  #5  
Old 07-21-2005, 08:30 PM
tomsepe tomsepe is offline
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No the engine was only cranking slowly when the injectors were still in and all the fuel lines on. The starter was drawing over 600 amps at that point. But with teh injectors pulled and the fuel lines removed, the engine spins quickly and easily.

still seems a little odd to me the slow cranking issue... Here's my current question; How would no compression in three cylinders slow the cranking speed down? seems odd.
  #6  
Old 07-22-2005, 04:52 AM
john8662
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NO compression in three cylinders would speed up the cranking. Unless those cyliners are taking in water, then it would slow it down or lock.

I agree with the above statements regarding the starting system on the engine, there may be more at fault. Usually it's a starter that tests good on the bench, but with a load, has no torque to do it's job.
  #7  
Old 07-22-2005, 06:17 AM
tomsepe tomsepe is offline
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No its not the starter. That was the first thing I checked. ANd I replaced it just to be sure.

So the engine is cranking fast with all the injectors pulled, but there is little or no compression in cylinders 1,2 and 6.

I still think it is the head gasket. I'm going to pull hte heads this weekend....

but I'm open to other thoughts.

Thanks!
  #8  
Old 07-22-2005, 08:28 AM
Quack_Addict Quack_Addict is offline
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A few thoughts to consider... the one injector in your photo has some rust on it, indicating some water/coolant probably contacted it. That is, assuming the photo was taken right after the injectors came out (they could have rusted from condensation sitting on your garage floor overnight).

However, I had pretty much the same exact problem with the 6.5L in my Suburban last week - it would crank but wouldn't start. Fuel was getting to the injection pump (so the lift pump was pushing the fuel fine), but nothing came out with injector lines cracked/removed. I then pulled the pink wire of the IP and checked it with a light - with the 'ignition' on, the test light came on. I put the pink wire back on the IP - again, no fuel. Then I took a piece of Scotch-brite and cleaned the oxide off the terminal on the IP that the pink wire hooks to, reinstalled the wire, turned the key and VROOM - the engine started right up and it purrs like a kitten.

I have to question whether the rubber on the compression tester you used was seated fully when you did your compression test. This could have been why you were reading low on cylinders 1, 2 and 6. IF the problem is a head gasket, this would indicate 2 BAD head gaskets as #1 is on the left side of the engine and #'s 2&6 are on the right side. It's unlikely for two head gaskets to go bad simultaneously. Even so, the engine should start, sputter, run or at least try to fire on 5 of 8 cylinders - if you're getting fuel. With a blown head gasket (or gaskets) on 3 cylinders, you should have seen a very noticeable cloud of steam coming out of your tail pipe(s) before the engine quit running. No fuel = no VROOM.
  #9  
Old 07-22-2005, 05:22 PM
NH2112
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I agree with John8662 and Quack_Addict, disregard any info the gasser compression tester might have given you and use a diesel tester. I bought the complete Matco diesel set for about $150, but the 6.2l/6.5l adapter is $15.70 (CT152) and the gauge (CT15) is $58.10. With the engine in the truck pulling the heads is kind of a PITA, so if I was in the same situation (and had the diesel tester, obviously) I'd put the injectors back in and get some good numbers.

Next, I'd try to figure out the slow cranking speed problem before continuing (like jcomp said), because if you're not cranking fast enough the engine won't start. Don't count on a new (rebuilt?) starter being good, generally 10% or so of rebuilt electrical components are bad right out of the box.

What I like to do any time I'm having a fuel delivery problem is use temporarily hook up an electric fuel pump to an ignition-hot source and bypass the mechanical pump. The nice thing is you can undo the return line on the pump and see if fuel's making it that far. If not, work your way backward till you find the blockage.

So, to restate everything, I think your priorities should be 1) find & repair cranking speed problem, 2) ensure fuel's getting to the pump and squirting out the disconnected return line, and making it to the injector fittings, and 3) test compression and repair if necessary.
  #10  
Old 07-24-2005, 06:07 AM
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HANK1948 HANK1948 is offline
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Tomsepe, I see you are running WVO Iam currently collecting parts for my conversion how did you set yours up? Iam going to run a tank in the bed I have dual tanks but its a PITA to set up a stock tank for all the heated pickups and tank heaters, what kind of filters are you running? and also how are you prefiltering? whats your process just curious
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  #11  
Old 07-24-2005, 09:36 AM
tomsepe tomsepe is offline
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Wow thanks everyone for all the advice and thoughts and experience. Today I'm going to work on it and see.

so to answer questions:

You can find out more about my veggieoil system and the big trip I took last year to mexico here:

http://tomsepe.com/vegoil_adventure/

because I'm in california I did not bother with a tank heater at all. I put my tanks on the roof to take advantage of gracity and painted them black to take advantage of passive solar heating, which does nothing for me in the early mornings, but as long as I run long enough on biodiesel or diesel first and pre-heat the Vormax filter with the hot coolant, then I've been fine. You can install an electric hot-pad style heater to the outside of your stock tank, but you have to make sure that your alternator can handle the extra electrical output. You can also run a blend of diesel (or biodiesel) and veggie oil which will reduce the viscosity of you oil, reducing the need to heat you tank. But it really depends on you climate and if the WVO you use is liquid at room temp.


Mechanical fuel pump is definitely working.

I checked the batteries by fully charging them with a digital battery charger overnight, and then checked all the connections.

I put an amp meter on the positive cable to the starter (when the injectors and everything was still on) and the starter was pulling 600amp... way to much! So I know the batteries are good and the connections are good. The starter was just working way to hard.

Also, when I removed the injection pump it is necessary to manualy turn the engine to reach the bolts that connect the injection pump to the gear that runs it. And at one point I couldn't turn the engine by hand - there was some serious physical resistance - but I could bump it with the starter to get the pump out.

Once the pump was out it spinned freely so the problem doesn't seem to be there.

I had checked the voltage at the pump and also at the solenoid, but I didn't try cleaning the terminals... seems unlikely that that would be it, but the possibility of a combo of problems is always there. However I was not getting fuel leaking out of the lines... so perhaps there is something wrong with the pump? I'll try reconnecting the supply line and seeing if fuel comes out when I crank it today.

Somehow I think the cylyders have water in them 'cause the radiator is low. I did have a leak that I fixed with some overthecounter copper solution... but perhaps that is why my radiator keept getting holes, was from excess pressure from a blown gasket!? Maybe I've only been running on 7 cylinders for a while and it was just as the gasket got worse that it manifested?

But this issue with the resistance in the engine is concerning me... what could that be? I wonder if some of that radiator product got into the cylinder?

I would like to get a diesel compression tester, but I don't have any money this month. I don't think that I need accuracy at this moment. But I think I can borrow one and I think I will try putting the injectors back in today and checking it out. However with my basic test there was an EXTREME difference in pressure between the cylinders - like night and day. SO the variance of whether it is 200lbs or 400lbs is not important to me at the moment because it is really more like a difference of compression or no compression.

Thanks everyone!
  #12  
Old 07-25-2005, 06:54 AM
jcomp jcomp is offline
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Quote:
Originally posted by tomsepe:

I put an amp meter on the positive cable to the starter (when the injectors and everything was still on) and the starter was pulling 600amp... way to much! So I know the batteries are good and the connections are good. The starter was just working way to hard.
600 amps is about normal to crank over a 6.2. It takes a lot of power to spin an engine with such high compression. My old tired 6.2 took 650 amps. I haven't tested my new engine yet.

Also, the glowplugs draw about 150 amps.
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  #13  
Old 07-25-2005, 07:22 AM
tomsepe tomsepe is offline
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Ok here's the update...

I used a screw in type compression tester (but the dial ended at 300lbs) in cylinder 1 and put the injector in and spun the engine, and got up to 300lbs. I tested cylinder 3 and the dail went past the 300lbs mark... but don't know exact. I'll try again with a proper tester today.

The injection pump has sime kind of blockage or a short. I know the mechanical lift pump is working but when I hook the line up the the IP, no fuel comes out the return side. And nothing comes out the lines - with or without the fuel cut-off soleniod engaged. I know that line is hot but I need to check the electrical on the rest.

I'm still pretty certain it is the head gasket... but now looks like something is not right with the IP...

still wondering about the cranking issue... guess I may return the starter just to be sure...
  #14  
Old 07-26-2005, 09:14 AM
tomsepe tomsepe is offline
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I dissasembled the injection pump and found that the pump had siezed and the main shaft was broken. Don't ever get water in your fuel is all I can say about that!

So I'm bidding on a rebuilt injection pump on ebay from dieselcare. Any other advice on replacing the injection pump?

Today I'm going to start removing components so that I can replace the head gaskets.... I feel a little daunted by this next step...
  #15  
Old 07-26-2005, 02:58 PM
NH2112
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Before removing the heads I'd remove the inner fenders at a minimum, and maybe even the outer fenders. It'll give you much easier access and you won't have to support those heavy SOBs at arm's length.
  #16  
Old 07-26-2005, 07:56 PM
john8662
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Run a real compression test before doing anything else, that way you know exactly what cylinders to pay close attention to, which you already have an idea. This helps so that you can look at the gaskets carefully, and pay close attention to the piston, cylinder wear etc.

As far as the Head gasket R&R, I vote to remove the engine completly and bolt it to an engine stand.

This of course, is determined by what you have access to, if you don't have an engine stand or access to a good engine hoist then this is harder.

Some points for removing the engine would be to remove the oil pan and inspect the main webbing for cracks, and to replace the rear main seal, since you're there. Having the engine on the stand will also make working with the heads much easier, I've done the head gasket replacement on the engine stand, it was enough work. It is possible to do the repair in chassis though, just not as easy to keep things clean.

Glad you found the injection pump failure, you are exactly right in that the water will cause the head to seize, as the tolerance is REAL tight. Water also cause the internals to rust, and in the head/rotor of the pump will pit and ruin the head quickly.
  #17  
Old 07-26-2005, 08:13 PM
tomsepe tomsepe is offline
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well I pulled the heads today... wish I had run a real compression test, but I had to move forward and felt like it need to done cause I have limited time.

but where can I order new gaskets and head bolts online and get here it here in california by the weekend?

the gaskets don't look too bad... but I guess it doesn't take much. THere is definitely corrosioin in some of the cylinders so I'm sure the gaskets are blown. I will get the heads cleaned up and magna-fluxed and pressure treated tomorrow and I'll try to post some pics in the next couple days too.
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Old 07-27-2005, 07:59 AM
Quack_Addict Quack_Addict is offline
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Corrosion in the cylinders may have been from water in the fuel. It should have been very obvious if the head gaskets were bad - holes, gaps/cracks in the rings around the cylinders, pieces of the gasket missing or falling apart, etc). A bad head gasket can also allow gasses to 'vapor hone' the head and/or deck locally.
  #19  
Old 07-27-2005, 11:16 AM
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Peter J. Bierman Peter J. Bierman is offline
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Since you run on something else then top quality diesel fuel, I'd look for a milspec IP.
Those militairy pumps have harder inside components and resist poor fuel far better then regular pumps.

Look for one from a CUCV or Humvee.

Peter
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Old 07-29-2005, 10:00 PM
tomsepe tomsepe is offline
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The heads cleaned up and checked out good. Got the right gaskets, and will pop test injectors tomorrow and begin cleaning the block.

Any suggestions on block cleaning? On person I spoke to at the machine shop (who also runs on veggie oil) says start with a razor blade, then use 160 grit sand paper on a block of flat wood. But don't touch the pistons. Diesels like thier carbon. Maybe a wipe but it is not worth risking scratching the metal or the cylinder if you are not going to do a full rebuild.

any thoughts?
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