head change and now it has a miss

[jb carver]

I have a 1995 sub 2500 135000 miles.I had air in the cooling system and it would run hot,so i figured it had a head gasket leak,NOT it was cracked heads yes both but it did run fine.so put two new heads on put it back together and cranked it up and it had a knock knock sound so I cracked the inj lines at the inj and the knock went away but it still is not right it has a mis that makes a thunk thunk thunk sound in the intake of the turbo with each thunk the motor shakes,has new filters air and fuel ,have put a clear line on the fuel return and it has no air bubbles .how about some other ideas of things to try also it has no power and dosnt smoke???

[charliepeterson]

All the Injector lines went on good? You can't bend to make them fit. All the bends are part of the fuel delivery for timing.
Try to get hold of a good scanner and look for any hidden codes and try to retime the engine.
It can sometimes take a while for a new head and/or injectors to really seat into place. Take it for a nice easy ride to warm everything up. Let it cool down and see how it runs then. In a few days everything might be ok.
That was a very good idea to crack the Injectors. Now just let the oil go where it's supposed to go. I bet it's nothing too serious.

Good Luck

[jb carver]

help please give ideas on what to try

[ucdavis]

1) I'm not getting a good picture of symptoms. Maybe listen again (might try a stethoscope available @ any parts store) & redescribe below.
2) pull codes & post (see Members Area, Reference Section @ bottom of page for instructions; its simple on your rig)
3) Cracked heads is almost certainly heat; both is for sure heat. The closest I can discern from your description is likeness to cracked main cap or main cap shoulder in block which is either also heat or overboost, but I have no experience with this- only what I've read here. And my only theory why you'd hear it suddenly is that good compression would initiate or exacerbate it. Hopefully somebody else can debunk this!
Is the miss regular or intermittent? Harmonic damper rubber failure can cause engine noise/shake.
Anybody know if improper EGR reassembly could cause these symptoms? That might be in intake area (my rig no-gots EGR so I don't know).
If it ran fine B4, chances are you can isolate trouble & correct it.

[rustypig]

Others have had this same type symptom posted before, also coming from the turbo area because it's rather tight around there. It's known that a noise came from components rubbing together....apparently it can get rather loud and annoying.

Look for a/c lines, heat shields and glow plug conduits touching things they should not. I'd suspect the vibration/shudder as another problem which could possibly be exacerbating the rubbing/thumping noise. Did the injection pump timing get moved at all while doing the head r@r (I wouldn't think so)? I'd have to agree with Mr. Peterson above so far...try and break it in nice and gentle and see if it doesn't clear itself up.

[cruzer]

How much research/testing to come up w/head gasket
or cracked head? I believe you state "just figured". The majority of these heads crack on the end cyldrs and it is not detremntal to the function. You can have them repaired by sleeving
the water jacket between the valves.
Did it have a miss b4?

Maybe to find miss crack injector lines(1 at a time) to cause a miss. When you find no change in idle, that would be suspect cyld. Compression check maybe advised. Another place to look for noise would be, make sure inj lines where bolted down in holders,w/the rubber insulators around them. I've read some where that metal high pressure lines when in contact w/metal will make noise. Just a thought.

[ 08-01-2003, 11:42 AM: Message edited by: cruzer ]

[jb carver]

thanks for the posts guys,I am thinking that i mite have a bad injector or some trash in one from the head change it did run very good before takeing the heads off,it seams to have one cyl missing as it runs like just one is not fireing and i cannot get to the back two turbo side injectors to crack them its tight back there it also sounds like the turbo side has the miss going to try to get codes tomorow.keep giveing me your feedback ,thanks
john

[EWC]

I had a similar noise when I replaced both heads on my truck with 177,000 miles . It did sound like a thunk but only for a few times and then disappeared .

I actually removed both motor mounts to lower the engine for easier access to the rear cylinders . Are you sure the push rods on number 8 are seated correctly ? Especially the intake ? Mine were a PIA with the AC housing being that close .

How good are the heads that you put on ? Any chance they are the problem ?

[jb carver]

I tryed to get codes but it did nothing, I grounded the two leeds like it says to do with the ign off but nothing, should i do it with the ign on??also the injector three back on turbo side didn't change tune when i cracked it to bleed off pressure so i am going to move it to front driver side cyl and pull off the valve cover have a look and if it look good put it back togather and see if it moves to that cyl with the injecter moved maybe its cloged or something is wrong with it??jbcarver

[whatnot]

You need to short the two pins together with the key off then turn it to the run position to read the codes. You shouldn't connect or disconnect it with the key on.

[jb carver]

do you leave the pins shorted and turn the ign on, or short it then take it out then turn it on

[rustypig]

Short it, leave in place, turn key to run position, read codes, turn ignition off, remove short wire...scratch noggin at mysterious codes.. tongue.gif

[charliepeterson]

I wouldn't pull a valve cover untill you can eliminate the Injectors, too much work for now. It's a good idea to swap the injector to another hole. Take a real good look at the big copper washer on the bottom of the injector itself. This is a crush washer and is really only supposed to be used one time. If it looks good then go ahead and reuse it. Hopefully you only have a bad injector.


Good Luck

[jb carver]

FIXED,FIXED.it was a bad engine builder {ME} I found that i didnt tork the r rear rocker bar .thats all it was runs fine now.