What could have gone wrong here? (switch engines, no compression)

[misterW]

I have a 1991 3.0, which was knocking.

I took the engine from a 1999 3.0 w/ a bad frame but running engine and put it in the 1991. I put the distributor and upper and lower intake from the 1991 on the 1999 engine. To switch the lower intake I had to take out the pushrods and then tighten them back up after.

Truck finally is all back together, I start it, and it is barely running, sounds like running on just a couple cylinders. Compression test on #1 cylinder shows no compression.

What could have gone wrong here? I'm guessing this is a valve issue, since that is the only thing I messed with that I can think could conceivable lead to the compression loss. But as I understand it, the valves on that engine aren't adjustable. The manual had me tighten each one down to 24 ft*lbs, regardless of cam position. Hard to see what could have been screwed up in that process? Any ideas?

 

[rusty ol ranger]

You didnt mess with the timing chain did you?

 

[misterW]

No, nothing w/ the timing chain. I thought I had the answer -- that I had accidentally put the pushrods back in from the old engine (which were longer) instead of the new one. But I just measured a couple of them from the engine I took out and they are in the engine they are supposed to be in. Still searching for the answer.

 

[MikeG]

Valves, rings, or a hole in the piston. You only messed with the valves, so .......

 

[misterW]

Cylinder #1 had no compression when tested. Took the valve cover off and loosened up the rocker arm a bit so that the bolt wasn't bottomed out. When retested, the cylinder had compression. The pushrods for those valves measured 5.29 inches, which is what they should be for that year.

It seems as if the valves were somehow too tight, but I don't understand how to resolve that, because it is my understanding that these hydraulic valves are not adjustable and you are supposed to just bottom out the rocker arm bolt and torque it to specifications, which is what I did originally. Yet that seems to result in a condition where the cylinder gets no compression.

Any ideas?

 

[misterW]

The new engine also sat for quite some time before being started up again. It ran in the early winter of 2019, then sat until yesterday. Could lifters be frozen from sitting or something like that?

 

[pjtoledo]

how much valve lash?

loosen the rockers until the pushrod is easy to spin. slowly tighten until resistance is felt.

then count the revolutions needed on the bolt to get tight,

 

[RonD]

If you have a Rocker Arm Assembly you have a torque setting for the 3 bolts on each head

If you have individual rocker nuts then you don't, you have to do each one with lifter down all the way
Loosen nut until pushrod can spin easily but can't move up or down, thats 0 lash
Then in most engines you turn the nut 1 full turn, then 1/2 a turn more
You should STILL be able to turn pushrod with fingers but need a good grip, lol


With the 3.0l "they" recommend tightening all nuts to 8ft/lb(96in/lb)
Then with its lifter down tighten each to 19ft/lb

The manual had me tighten each one down to 24 ft*lbs, regardless of cam position.

throw away that manual
The 24ft/lb might be OK, but with individual rocker nuts the cam position matters ALOT

 

[pjtoledo]

the 3.0 uses bolts to secure the individual fulcrums. there is no lash adjustment, the lifter just bleeds down to equilibrium between oil pressure and spring pressure.

spec is measured with a collapsed lifter, should be between .085 and .185 valve clearance.

 

[misterW]

Mystery solved.

Some of the lifter plungers do appear to be somewhat stuck (when tightening down the rocker arm bolt, I can see the valve being opened instead of the pushrod going down).
But the reason that some of the cylinders aren't getting any compression is because I'm a dumbass and some of the paper shop towels that I had stuffed into the intake to prevent stuff from getting in there while I worked had gotten pushed down out of sight, and I guess I never verified that the intake was completely clear before putting everything back together and starting it. This occurred to me a couple of days ago, but finally had the time to take things apart and look.

I took off the upper intake and I can see shop towel fibers coating the intakes and just make out bigger pieces further down.

So, after I take the intake out again and clean things... what else is to be done? If paper towel pieces get through a valve, what would happen then? And what can I do about it now?

 

[pjtoledo]

paper towels in cylinder,,, bring piston up to top, stick wire into spark hole and go fishing.
paper is flammable, the problem will be temporary.

lifter plungers,,,,

I'll defer the the real experts instead of telling you how to shoot lifter springs all over the garage.
maybe just leave one under pressure for a couple hours to see if it bleeds down????

 

[misterW]

by leave it under pressure do you mean by tightening down the rocker arm bolt and then leaving it? it should be under pressure then, right? thing is, they've been tightened down for a long time -- i don't have a ton of time to work on the truck and i first tightened them up at least a month or two ago before I got around to putting the rest of the engine together and trying to start the truck. so sitting like that for that long of period didn't seem to unstick them.

I was wondering if getting the truck started (once the intake is clear, I imagine it will run) and letting it get up to operating temperature might free them up by heating up the congealed oil or whatever it is that has them frozen in position?