MM GVI engine trouble (continued)

[Anonymous-0]

As discussed in my previous post I am still having trouble with the #1 and #2 cylinders not firing. It seems as if I am just not getting enough compression to ignite the fuel so I decided to remove the injectors and turn over the engine with my thumb over the injector port. I know the cylinder pressure for this engine should be about 450psi and upon holding my finger over the injector ports for cylinders #1 and #2 I did not feel much pressure back on my thumb (at least not what I expected to feel). With at being said here comes the even STRANGER PART, I pulled the injector out of the #3 cylinder to do the same check expecting to feel lots of pressure since I know this cylinder is firing fine but I felt the same amount as the first two which wasn't much pressure at all. Can someone please explain to me why I do not feel that much pressure? If I wasn't getting the proper compression in the cylinder than it won't fire so I must be getting 450psi or somewhere around that but I definitely do not feel that amount of pressure when covering the injector port with my thumb. PLEASE HELP!!!

 

[Alex Blackerby]

ITS BECAUSE THERE IS A GAP BETWEEN THE INJETOR BORE IN THE HEAD THAT OPENS TO THE CRANK CASE SO THE PSI IS JUST GOING TO THE PAN IF THEER IS NO INJ IN THE HOLE THATS WHY THE INJS HAVE O RINGS ON THEM SO YOU DONT LEAK OIL FROM BLOWBY AROUND YOUR INJ. YOU NEED TO MAKE A TESTER OUT OF AN OLD INJ. ALSO TRY HOOKING A GOOD INJ TO YOUR # 1 AND 2 LINES COMING OF YOUR PUMP AND START YOUR ENGINE AND WATCH YOUR INJ TO SEE IF THEY SPRAY FUEL THIS WILL LET YOU KNOW IF YOUR PUMP IS GOOD. WELL HOPE I HELPED GOOD LUCK !

 

[Anonymous-0]

You are very right about the opening to crank case I forgot all about that. Thanks for your help.

 

[molinegb]

Check compression from energy cell. Remove cell cap. The original compression checker threaded into cell.Good compression usually blows cup about 40 feet!

 

[Anonymous-0]

Thanks I will try to check it from the energy cell side as that makes sense and would be easier to do.

 

[MMfan]

Listen to Alex, he knows what he is talking about...Even if the caps are locked on his computer
My thought would be since you re-did the heads, maybe your valves are too tight and leaking compression.

 

[Captainhookerus]

Look closely at #2 nozzle, if the popping pressure is way low then there is no pressure at delivery valve and since #1 fires after #2 it will also kill #1

 

[Anonymous-0]

So are you thinking that this problem I am having may be related to the injection pump/injectors? Also, the firing order is 1-5-3-6-2-4 so #1 does not fire after #2. Could you please explain in a little more detail, what you think the problem is.

Thanks for you help

 

[Anonymous-0]

One other thing I should note is that when we put the new heads back on the engine and reset the valve tappets we did so to spec (0.012 intake and 0.020 exhaust) but when the engine was cold (i.e. before everything ever got up to temperature). I have read that these settings should be down when the engine is HOT, is this correct? Would this make much difference? Could I be losing compression through the valves because when things warm up and expand than the valves may not be seating properly and could cause a loss of compression? Why do the other pistons fire if this is the case?
When the heads were off we tried to move the pistons and they do have a fair bit of play/movement to them but the cylinder walls look and feel fine. Is this typical? Do they need a fair bit of tolerance to expand when hot or are the rings just wore out?
Is there any way to get the lifters/tappets out of the engine without removing the camshaft or engine blocks?

Sorry for all the questions but I am running out of ideas.

 

[Captainhookerus]

I would still check all the nozzles and make sure that an alignment or centering tool was used while tightening the tip nut. I am assuming this has a Roosa pump. You can check camshaft lift at the top end of push rod.

 

[Captainhookerus]

I am also assuming that you are tightening the nuts(plain nuts not lock) no lock washers to 15 ft lbs.