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Head Swap Issues - Need Help Troubleshooting

J

jls095

NAXJA Forum User
Location
MA
Hi all,

I just put the engine back together after replacing my 0331 head with a replacement from Promaxx (formerly Alabama Cylinder). I started it and let it run for about 10 seconds before deciding that something wasn't right. It shook and sounded really uneven. Maybe a cylinder (or two) isn't firing or something is wrong with the valves? I'm not sure how to diagnose what the issue is.

In addition, even after 10 seconds, there was a little white smoke hovering above the engine. Could this be the coating burning off my new exhaust manifolds and painted exhaust downpipes (again, after only 10 seconds)?

Some other potentially relevant facts:
1. New NGK plugs
2. Old injectors (worked perfectly before)
3. New exhaust manifolds (Borla)
4. Promaxx head, with original rocker arms and lifters; all replaced in original order and torqued down per FSM
 
the smoke is normal on break in.

can you take a short video of it running and post it, with audio?
 
Or if you don't want to run it again before finding out whats up..


pop the valve cover, have someone turn the engine over with a ratchet (KEY OFF!) and make sure none of your pushrods or rockers are loose. Most likely scenario for what you described after a head swap is something not reassembled correctly, or a lifter hasnt inflated yet.
 
RedHeep said:
Check your plug wires. The shaking and knocking could be two cylinders firing out of order.
Click to expand...

I would assume that if he's replacing a 0331 head, he's probably got the coil rail ignition.... not that it would be impossible to miss a plug or two with the boots.
 
Shorty said:
I would assume that if he's replacing a 0331 head, he's probably got the coil rail ignition.... not that it would be impossible to miss a plug or two with the boots.
Click to expand...

Yes, exactly. And the injectors are all plugged in the right order. I'd like to investigate no spark / fuel in one or more cylinders or the possibility that there's a valve issue.

When I pull the valve cover and investigate what should I be looking for aside from making sure something isn't loose? E.g., how do I know the valves, which were preinstalled, are right?
 
jls095 said:
Yes, exactly. And the injectors are all plugged in the right order. I'd like to investigate no spark / fuel in one or more cylinders or the possibility that there's a valve issue.

When I pull the valve cover and investigate what should I be looking for aside from making sure something isn't loose? E.g., how do I know the valves, which were preinstalled, are right?
Click to expand...

I think you're trying to solve a whole lot of problems that you might not have based on watching your engine run for 10 seconds.

You might want to consider starting it again and trying to narrow down the possibilities. If you installed pushrods and rocker arms, you should already know what to look for in a valve, a valve spring and a retainer.

You might have missed a lifter when you put the pushrod in or you might have bent one when the engine started up. Other than the obvious, if you really think that you have a cylinder head assembled incorrectly, you're going to do a lot of disassembly to investigate. I would start with the basics and make sure the spark plugs work, the injectors work and there's nothing else that would cause it to run bad.

I just did a head gasket replacement twice because I refused to admit that I had a clogged core in a new radiator. I wouldn't want anyone else to do all that work for something simple like I did.
 
Smoke will be normal as stuff burns off the exhaust manifold. As for the rough running it might just be that the lifters had uncompressed when you had the head off and have not yet fully compressed.

If it doesn't clear up after further running you should start by checking the preload.
 
It is not uncommon to have injectors get sticky after they have been removed for even a short period of time and allowed to dry out. The new additives in the fuel make this even more common. A can of BG44K in the gas cleaned up the hassles I was having with my stroker when I first built it. The injectors had dried out and were sticking. Within 5 miles it ran smooth as silk.
 
Thanks guys, much appreciated. Before I ran it again I wanted to double check that everything was properly situated under the valve cover. When I popped it off, I found that many of the rocker arms had some front to back play despite being torqued properly (21lb-ft). I have a picture in the link below. When I say "front to back" I mean from the front of the Jeep to the back, not left to right...hope that makes sense.

I figured I'd loosen the rocker arms and reseat the bridges and arms on the valve springs and tighten down again. This didn't help with the front to back play. In some cases when I tightened down, there was no play but after a few minutes there was again.

What's going on? Is this normal?

fbytle.jpg


8
 
With the lifter on the heel of the cam lobe how much preload or pushrod depression into
the lifter do you have? 1/4 to 3/4 of a turn would be what you want.

It's not uncommon for lifters to bleed down over night and that may contribute to your
rocker side movement.
 
A few people have suggested that you run the engine and let it settle out to gather more data. At this point if you don't see anything wrong you kind of have to put your purse down and take that advice.
 
Totally agree with you, it needs to be run. Before I run it again, I want to make sure that the rocker arm "play" I mentioned two posts back isn't what's causing the rough running...hence why I asked.
 
Could you spin your oil pump with a drill and slotted head screw drive? On the later model engines you'd remove the cam position sensor for access? Wouldn't that pressurize the lifters? Also you'd be able to see oil reaching the head itself with the cover off.
 
There's oil in the head and on top of each of the rocker arms, so I don't think oil circulation is an issue (at least in the 10 seconds it's been running). I'm going to put it back together and run it later.

Russ - I was under the impression that lifter preload didn't need to be adjusted, especially given that I haven't changed anything but the head.

Also, let me add...I apologize for coming off as overly nervous / tentative. I'm new to this and learning. I appreciate all of the help thus far.
 
Last edited:
Just ran it. Before I started it, I primed it a few times. The first time it ran for about 15 seconds then stalled out. While it was running it sounded mechanically fine (no knocking, tapping, etc.). Then I waited a minute and started it again. It started but almost immediately stalled out.

I actually think this is encouraging and points the way to a fuel delivery issue (either injectors or fuel rail). Do you guys agree? How do I go about confirming this?

For what it's worth, the injectors were exposed for about 2 months while I was poking along at this. Maybe, like old_man mentioned, they dried out?
 
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