Where do I start?
 

I've got a 94 chevy 6.5 I rescued and am just trying to get it running good before I start trying to do any mods. It started making this noise and I don't know where to go to find and fix it. :humm: Thanks in advance.

Appears to have some blowby. Sounds like its missing on one cylinder. Try breaking loose one injector at a time til the noise quiets down. Is there any pressure in the cooling system? They are known for cracked heads. I've seen many fill the cylinder with coolant and bend push rods. Figure out which side it is and time to pull valve cover. Does it get worse with RPMs? If your luck is anything like mine it's going to be the turbo side. Are all the glow plugs tight? Just a thought.


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I'll have to check the GP's as I did just change them. Being new to diesel I treated them like spark plugs and changed all but one which I couldn't find, so a loose one is possible. It does get worse with RPMs. Changing injectors was the next thing on my list when it started making this noise. And it does seem to be worse on the turbo side. Just changed the T-Stat and did a coolant flush but haven't checked to see what kind of pressure I'm getting.

If you loosen the injection line at each injector one at a time with engine running fuel will spray, not terribly bad, and it kills that cylinder similar to pulling plug wire off gas engine. Listen for the noise to go away or get less. You will see and hear the difference if that cylinder is firing like it should. After you verify that cylinder is working tighten line back down and then move to the next. Repeat until you find the cylinder that has no change when loosening fuel line. That's your dead or weak cylinder. Could also do this with a heat gun pointed at each exhaust runner but cutting fuel to cylinder is the best method. Only takes a 3/4" wrench and about 15 minutes to do all. Good luck and let me know if you find one not firing or no change.


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If you loosen the injection line at each injector one at a time with engine running fuel will spray, not terribly bad, and it kills that cylinder similar to pulling plug wire off gas engine. Listen for the noise to go away or get less. You will see and hear the difference if that cylinder is firing like it should. After you verify that cylinder is working tighten line back down and then move to the next. Repeat until you find the cylinder that has no change when loosening fuel line. That's your dead or weak cylinder. Could also do this with a heat gun pointed at each exhaust runner but cutting fuel to cylinder is the best method. Only takes a 3/4" wrench and about 15 minutes to do all. Good luck and let me know if you find one not firing or no change.


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I got down the drivers side and 1 at the front of the passenger side but the rest are under a heat shield behind the turbo which was quite warm by the time I got to it. Do I need to remove the blower to get in there or is there another way?

Take off plastic cover between frame and inner finder and you can get to them.:c:

I always break lines loose then barely tighten them while the engine is cold and not running. Then after starting it, it's a lot easier to break loose and cut the fuel to that cylinder. You should be able to get to them without going thru wheel well opening.


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I tried going through the wheel well as I could see no other way to reach them from above and I can't even see them for the steel heat shield. From on top I could reach one if I had a long and skinny wrench but not the other. I can see no other way but to remove the blower. What considerations should I make before beginning this?

Can't you take that heat shield off? I swear I had no prob getting to injectors on my engine. Can't think of anything I had to remove to do so. Buddy of mine has a 97 dually that I'm going to go look at here shortly to jog my memory on what I'm missing. I'll take some pics and hopefully be a little more help to you. Maybe I'm just not remembering something right. But I swear I could break the lines loose fairly easy. I remember I had a couple jumper return hoses that were leaking and I had to pull a couple off and cut them down and they were on the passenger side. And I did that in a Home Depot parking lot. I'll get back to you.


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Ok I got to see what your dealing with. You are better off removing that heat shield. I didn't have one of them on my 6.5. I would take that off and you don't really need it but if the bolts somehow don't break off you could put it back on. Getting to it from underneath looks like it would be a pain if even possible.


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Ok, I'll try again tomorrow. I found the 2 itty bitty bolts on top of the shield but ran out of time looking for where else it's attached. It won't be going back on.

Even see if you can take them 2 bolts out and bend that thing up and out of your way. Then just bolt it back down if you don't wanna try to get the other bolts.


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That worked. Unfortunately the engine reacted the same way on all of them. Bogged down as a gas engine would with the spark plug removed.

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Also I checked the GPs except the one I can't find, thinking it's behind the starter or something like that. They are all tight.

That thing sounds like one cylinder is just pumping air like an air compressor. I thought for sure it would have a dead cylinder. That thing has a vacuum pump on it that controls the EGR valve. Pull the line off the EGR valve and see if it has constant vacuum. I would make a blocker plate and get rid of that EGR altogether. To me it sounds like a major leak like GP or exhaust manifold or even a dead cylinder. If you can't find any leaks my next step would be a compression test. It's driving me nuts that I can't stand there and look and listen in person. Can you tell which side it sounds more dominant on? High or low?


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Right side/ Passenger. It gets louder if I take the air filter cover off too. Wish I could bring it to you. I've always had someone who could tell me what is what and what to do on gas engines but for some reason I can't find anyone for the diesel.

Louder with air cover off? See that tells me that it has to be a cylinder compression noise. That's why I was thinking a valve, and the cylinder cut out would have shown you that. Maybe EGR stuck open? But I see a lot of blowby. Compression test bud. Gotta see what's going on with the cylinders. The only way to get a test is from the glow plug holes. Maybe you can rent a tester but it has to be for a diesel cuz your compression is up near 400PSI or at least you should hope it is. You could take off valve covers to see if anything looks wrong but doing so requires removal of intake to get fuel lines off. Gets in depth without knowing what your really going after. I'm suspecting a bad intake valve on one cylinder. And after thinking about that cutting fuel to that cylinder wouldn't stop the compression noise coming out the intake like that. Everything points to doing a compression test.


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Yay fun. Something I've never done before. So do you go with all the GPs at once or one at a time. Where is the missing GP?

It's less draw on your starter and batteries if you remove all GP then test. Or you can do one at a time so you don't have to go around more than once. But either do one or the other. It has to stay constant. For example: if you pulled number one GP and did your test you would come up with number X. Then if you not put that GP in and pulled number 2, do your test, not put number 2 in and went to 3, your test is now inconclusive because with every GP removed its less compression on the engine and it would turn faster. Hope you can understand what I'm saying.

As far as the missing GP, they are evenly spaced so if they are lets say 4" apart, then missing one is 4" away from the last or the first one. Going thru the wheel wells are the best way to get to them. Your gonna need the correct adapter to thread into the GP hole and then connect your compression gauge to that. Also crank engine the same amount for every hole to keep variables at a constant. It's best to disconnect the fuel shut off solenoid so the engine doesn't start while cranking.


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Under stand completely. I did go through the wheel well but could only find 3 starting at the front going back. I noticed that they are lined up with the injectors so that last one must be straight under the last injector I just can't find it for all the shielding. Thanks for the input. I'll see what I can do about the compression test.

I would check with local parts stores and see if they can rent you a compression tester. If not go to a local shop and ask them if they would be willing to rent one to you if you leave them some kind of collateral. Or maybe see what they would charge just to do the test. Either way, its gonna tell you a lot about the engine and what kinda shape it's in. Good luck. Please let me know what you find. Couple cans of engine degreaser and a water hose goes a long ways to be sure no dirt and grime gets pushed into the GP hole upon reinstalling GP. Be patient, stay safe. Hope we can get thru this even without me being there to help. Lol


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LOL
Thanks, I'll let you know...