So i just got done replacing the cracked timing case after the kdp walked out and had a shop weld 5th gear back on. While the mechanic was in there i had him turn my timing up to 16.5.

So after all that I was pulling my jeep from Idaho to Minnesota and somewhere in Montana, suddenly i had no heat coming out of the vent. Its -10 F outside. I look at my temp. Gauge and it slowly starts rising untill in the red. I pull over, pop the hood and I'm pushing anti-freese out through the passenger side of the block through the head gasket. I checked the oil and it was not contaminated. So i filled the radiator with water and pushed on. There was no oil in the antifreese either. So now on my way to minnesota i have to stop every 75 miles and fill the radiator. then somewhere in North Dakota 5th gear fell off again for the second time in 2000 miles. I was so mad I just downshifted and kept going.

So after all that i took it to my buddies shop, he is a GM mechanic but works on dodges as well. He replaces the NV4500 and puts in a new head gasket. Buttons everthing back up and I'm back on the road for the return trip to Idaho or so i thought. I tested the truck for a day before i left and everything seemed fine however when i put on my empty trailer for the return trip i only made it about 20 miles. The truck lost heat to the cab again and i was thinking here we go again. I looked at the temp. gauge and it was fine. But out of nowhere the truck stalled. I kicked in the clutch and refired it. Went about 2 miles and it started to get warm again. I pulled over, popped the hood and it was the head gasket again dumping coolant at the same point just in front of the rearmost exhaust port on the passenger side. I got back in the truck to push onto a parking lot about 1 mile away. On the way, the truck stalled again, and again I refired it. I got the the lot and shut it down. I refilled the radiator like last time, only this time there was oil in the radiator so I called my buddy to come pull me back to the shop.

We pulled the head off the truck again. The gasket failed on the drivers side pushing oil out and on the passenger side pushing coolaint out. We checked the head at the dealership to make sure it wasnt warped or cracked. The block was in prestine condition as well. We installed a new head gasket as well as new head bolts even though the old ones were not stretched. We started the engine and everything was holding except we could hear a knock to the engine. It sounded like a valve adjustment problem so we checked all the valves and they were within spec. We started the engine and drove it for a bit. The knock was getting louder as the engine warmed.

I didn't have time to deal with the truck so i told my buddy to hold onto it for a few months and i bought a GMC with a gasser for the trip back to idaho.

So any thoughts on why the head gasket failed the first time. The fire ring was intact so i dont think it had anything to do with pumping up the engine or timing which are all moderate. Any thoughts on why the gasket failed the second time. All the fire rings had failed and pushed oil and coolant gasket was pushed through as well on the passenger side. After a head gasket install, does it take awhile to break in the gasket and get it to seat. Should i have detuned the truck abit. And finally an thoughts on why the motor has a knock to it now. I did not run it while it was hot and the engine oil was not contaminated with coolant. any thoughts are appreciated, i'm wondering if the truck is worth saving with all the trouble its having. But driving that little 5.3 liter GMC is pathetic and I want my Turbo back.

 

I almost bet that the bolts really were stretched... could be anything, Could be the install, Bad gasket.. the list isn't short of possibilities!

But in some sense from your post it sounds to be a few good possiblities....

to hot to fast on factory gasket
timing way off of 16.5, some on here think 16.5 is to high, I dont really agree but you might try 16 or 15.5

In that respect, You could have a piston problem causing the knock? Any Blow By? If not, You might have a valve out of adjustment, rocker didnt get set just right on the PR side ... bent push rod... anything really

 

no there isn't any blow by and the valves were all in correct adjustment. Before i tear this thing down again, i want to check all the easy things. Could it be bad fuel??? To low on Cetain. I just filled up before the gasket went and it started knocking. Would too low of cetain cause a knock that sounds like the knock a gas motor gets with too low octain???

 

Not to be the bearer of bad news, but it sounds like somthing a little more major, Of course it could be somthing as simple as a FlexPlate bolt if auto, or anything for that matter. I dont think i would lean on bad fuel.

 

im not thinking its bad fuel either, these trucks will run on almost anything, so i think you can rule out the bad fuel, just to make sure try changing your fuel filter, as for the headgasket your really not pushing that much fuel through it you should be fine, as for the timing bump it back down to about 15.5 that should be good for you

 

I'm thinking you should reset the timing. It could be way off or right on but it isn't expensive to check. Since you have to change the oil anyway you might as well drop the pan and take a look at the bottom end, no sense in chancing a spun bearing. You might also consider pulling the pushrods or having the springs tested.

my $.02

 

I had the exact same problem with my 97, timed to 16.5* running a 0 plate, and an NV4500 (which is now toast as well). Here's how it went with me.

Lost the head gasket the first time, did the same thing you did, drove on it til I could get it home. Had Cummins NE replace the gasket, they said the head was within spec, and put it back together with new bolts and a Marine HG. When they fired it up to flush the coolant they blew the gasket again. They replaced it again under the first gaskets warranty, but they decked the head this time to make it flat for sure. Then they discovered they had blown the oil cooler...so they replaced that for free as well. I finally got the truck back and after just 2 days the gasket blew again. I was starting to get pissed. Took it back to them that Monday (I picked it up on a Friday) and they didn't look at it for a week. They pulled it apart again, couldn't find the leak, but replaced it with a .020 over Marine Gasket. I got it back again, and its been fine since. Words of wisdom though... It takes some time to get the gasket seated properly, and I don't care what the shop manual says, over-torque the bolts to at least 135 ft-lb. Make sure you warm it up, and re-torque them again. Drive on it for a hundred miles and re-torque. If you don't get any movement out of them your good, if you get even a touch re-torque them at your next oil change. TAKE IT EASY for a while, make sure the engine is warmed before you go giving it more than 10-15lbs of boost, cylinder pressures kill gaskets. I would avoid anything over 20lbs until the head bolts don't move on re-torques.

The knock could be a spun bearing, but its unlikely... The coolant wears the low friction metal off the bearings, but it takes time. Its worth looking at, although I didn't when I blew mine. The oil pressure will tell you a lot about main bearing condition, if its low, your mains are shot. If its high you have a blockage somewhere, or a badly damaged bearing, but you'd know that by now.