Issues running after head gasket job... then full head job.

[TRusselo]

I initially started this at another forum, got nowhere, so there's a bit of catching up to do...

===============

I will admit Im no engine guy, but my best friend who's been a licensed mechanic for 10 years helped me. Just replaced the head gaskets, (whole top end gasket kit), and timing set, plugs wires. Painted everything too.

Got it all back together, fires right up cold, a little rough, almost seems like a missfire, but not horrible by any means, gets warm we revved up to 2500 and starts running like crap, revs all over the place, evens out, kinda, then touch the gas again - the smallest touch - and it dies. Wont run again while warm unless full throttle, and even then it runs like crap.

Let it cool down, and it ran at idle again. touch the throttle, and it dies again. wont start back up at all.

Seems like a timing issue, we are pretty dam sure that the timing set was installed an aligned correctly. old set off, new set on within 3 minutes, no ******* around, 2 people checked the marks in line, then installed.

The old chain had a SURPRISING amount of slack, 1/4 inch! , the engine ran fine before, besides overheating, the only reason we were changing the timing set was because, Why not? 310000km unknown history, and we are 6 small bolts away. change it while we are there.

Never removed, loosed or touched distributor, only changed cap while the intake manifold was off, when it is the absolute easiest on these engines.Through a timing light on just for reference, its 15-20 degrees off at idle...

Please help me work through this. its been 2 days, cant figure anything out, and my mechanic is stumped... at least give me some spit ball ideas.

BTW i have alldata on my computer. yes all 319 GB of it.

==============


i have only owned this truck about 2 weeks, wrapped my last one around a pole, i dont have much of a history on the truck, but looks like it has been taken to dealership for work, fog light wiring harness looks NEW, there is a Dealership Authorized Change sticker on the fuse box under the hood saying that the PCM has been changed out with another unit, date 08-97. truck would have been few months old then,
=================

Someone Suggests checking distributor indexing/cam sensor alignment.

got fuel pressure. got good vacuum. every gasket except oil pan was replaced new, even intake manifold bedpan gasket, and fuel injector o-rings were done.

I'll check the distributor indexing

====================

you mean like this? yup she's off a bit. rotor is sitting just before the mark at TDC.

Ill see if i can get my hand back there after a fresh pot of coffee

Is it worth mentioning that i get no engine codes, i know it hasnt run long to preform any diag, but... wouldnt a bad crank sensor send a code right away? thats what i'm considering tackling next, if the distributor doesnt fix it.

====================

well, adjusted the distributor, its bang on at TDC,

now it wont even start cold. im stumped.

screw it, time to rip off the timing cover to see if we were too tired to see straight that night.

===================
ripped off the timing cover, timing set is good, in line.

any suggestions?
=====================

Someone suggests a bad coil

got spark, compression and fuel.

========================

just noticed my new plugs are burnt and fuel washed (still after 18 hours of not turning over...). probably should have checked them after adjusting the distributor, when the engine stopped starting at all, before ripping my timing cover back off

=======================

pulled the intake, found bent rods, swapping the heads with 5.9 heads and rods i have sitting in the garage. Start from scratch. See if Mopac has a cam in-stock. Might as well at this point.

==========================

Started cleaning up the 5.9 heads to install, and found a crack in the head in the seat of the first valve we removed. Scrap that idea. At least we found it on the first valve and not the 16th.


tore the whole top end apart, inspected all valves (original 5.2 ones), guides, lifters and rods.

Found 4 bent rods intake and exhaust on cylinder 1 and 6. And found impact marks on the pistons 1 and 6 where the valves hit. no cracks in the pistons but 2 nice shiny moon shapes about 5/8 long on 1 and 6. there was also several blown valve guides.

no damage to the valves. lapped the valves, cleaned the heads, re-installed the heads, new rods, inspected movement by rotating engine by hand.

Could not find a reason for the valve impacts/bent rods. Timing was correct. and only on 2 cylinders, running mates, both intake and exhaust.

Did 4 of 16 lobes magically move or change shape? Did cylinders 1 and 6 decided to come up too soon AND stay up too late? (sarcasm) wtf?

Timing and movement of crank, cam, distributor, rods, valves ALL IN SYNC.

Re-assemble engine, starts right up, runs for 15 minutes, touched the throttle and DIES. No noises no nothing just died. Ran fine. dies.

Will not start back up.

Towing to dealership tomorrow.
======================

Anyone here have any ideas what the hell is going on?

The most confusing part is all 4 valves on only 1 and 6... and no evidence of why... plus why it wont run.

 

[Johnn123]

I unfortunatly have no idea what to suggest to you, but I did want to comment on the timing chain, those are actually known to stretch in these trucks as you saw. Just about all them do it. Also hope ya replaced the plenum plate while you were that far in... another big problem on these trucks.

Sorry I have no idea otherwise, hopefully someone will chime in and have an idea. Hope ya get er fixed man.

 

[TRusselo]

Plenum plate got a new gasket

 

[Johnn123]

Plenum plate got a new gasket

No not the gasket, I meant the plate itself. Read the plenum sticky at the top of thread.

 

[Merc225hp]

At this time I can say to bend the push rods your timing was out at some point and caused mech interference between parts. Going by your pix of the dizy and the rotor you were one tooth out with the cam and dizy drive gear, but you never touched that nor would that cause the damage.

So your not the first I have helped with this kind of problem but as it's going to a shop do you want help still or???

Edit: IF you still have the truck go do a fast comp test on it see whats going on, might have bent the pushrods again.

 

[TRusselo]

After the bent push rods we tore apart the engine reinspected timing, took it off, put it back on reinspected again, it is all good.

Also if timing was out enough for the valve to impact the piston, would it not happen on all cylinders, not just one and six? also if it was timing off one tooth would it not be only intake or only exhaust, not both?

And a compression test won't tell me if I have bent rods only bent valves. A rod can be bent and the spring will keep the valve closed

The truck is still at my house for the next couple hours

 

[Merc225hp]

No it won't happen on all the cylds, and yep I was thinking bent valves sorry.

So have you now moved the dizzy? If yes reset the fuel sync with a drb scanner.

One tidbit of info

timing gear and chain setting

Dots @ 6 and 12 the rotor will be pointing to cyld 6

Dots @ 12 and 12 will be the rotor will be pointing at cyld one.

 

[TRusselo]

No it won't happen on all the cylds, and yep I was thinking bent valves sorry.

So have you now moved the dizzy? If yes reset the fuel sync with a drb scanner.

One tidbit of info

timing gear and chain setting

Dots @ 6 and 12 the rotor will be pointing to cyld 6

Dots @ 12 and 12 will be the rotor will be pointing at cyld one.

Yeah we got the timing down, all data lists it incorrectly. But it never fooled us, not even the first time around.

Yeah we are thinking that there may be a cam/crank sensor or fuel timing sensor that does need to be re-synced with a DRB scanner. Hence the dealership.

If the DRB scanner fixes it, while he has it plugged in i'll have him mash the keypad and hope for some better settings! Lol

 

[TRusselo]

Had AMA tow it to the dealership few nights ago, went in and talked to them, told a tech what happened, blah blah. I gave them 2 hours of diag max.

They agreed that if the timing gears were off one tooth, if it was it would be ONLY intake or ONLY exhaust, not both.

They called me back the next day, said that 2 techs looked at it, one was the "boss", they are pretty sure that it was distributor timing. I told them that it had been done, but if they can do it and it work, ok, but if it doesnt work, im not paying for the time and labor. OK. 150$ to reset distributor timing. (plus the 2 hours diag @129/hr). $498 tax in.

They finally get back around to my truck later the next day. Call me back and guess what? wasnt distributor timing. They had their electrical guy do some more diag for free, found the issue....

Scroll down for answer
.
..
...
....
.....
......
.......
........
.........
..........
...........
............
.............
..............
...............
................
...............
..............
.............
............
...........
..........
.........
........
.......
......
.....
....
...
..
.



a "broken" coolant temperature sensor 
was telling the engine -40 deg Celcius / -10 F

doesnt explain the bent rods but... engine runs now.