Sudden power loss and noise

[mendelmax]

Hi guys, I've posted it also on a Jeepforum.com, because I don't believe it's stroker related problem, but maybe some of you may chime in with some good ideas.

rig is a 4.6 stroker 93 ZJ. It ran fine for over 800 miles until today. Suddenly with no warning, the jeep started to make a horrible grinding noise. The noise was increasing with the engine speed. The rig had problems to reach 70MPH and there are sensible vibes.

Most of you would say that engine died, but:
- engine revvs high, both on D and N positions. It easily reaches 4500 range
- it runs smooth
- after sitting for few minutes it started fine and the noise was gone, but it still felt powerless when running.


So my bet is the original 42RE tranny, probably clutches went out. Especially since gears are changing pretty rough. We were planning to change it for AW4 anyway, but we hoped it will survive till summer.

The oil in the engine is brand new 5W50 at proper level, the tranny oil also looks fresh, and was changed no longer than 2000 miles ago.


Any ideas on what to check to make a sure diagnose? Because I wouldn't like to swap the tranny only to find out that it wasn't the source of problem. Or maybe you guys think it can be an engine related problem?
But how could it be that under no high load, virtually new engine would fail with no earlier symptoms? Could a failed engine rev so smoothly? All broken engines I've seen before were unstable, couldn't rev, smoked, choked...
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[dwg86]

You can't tell if its coming from the engine or trans? (not being rude) Thats kind of strange? Oils look good?...hmm, don't know what to tell you.

[mendelmax]

Well, it's not my jeep, I'm building it with a friend who is few miles from me. I don't have time now to go there and check myself, and he can't locate it for sure- it happened few minutes before my post. I was considering torque converter failure, because this is the borderline of the engine and the trans, so that may make it more difficult to locate.

I know that it's hard to diagnose from these unclear symptoms, I also have this problem, but I thought someone may throw any idea of what and how to check, that I didn't think of.
I told my friend to tryto drive it a bit and check if this power loss occurs on all gears or not. As for now I know that it spinns tires when he hits the gas from stop, that's why I thought about clutches. I can't believe that engine with serious problems could spin the tire, could it?

[mendelmax]

The good news for now are that it appears to be the tranny. Problems with power starts just after applying overdrive, on gears 1-3 it seems to go fine. It is possible, that these noises were from the OD gears smashing and flying around the tranny. Now they probably lay on the bottom of the oil pan, and this may be the reason why it quieted down a bit

So, it's time to swap AW4 in.
Now I learned two things:
a) 42RE is POS transmission
b) 42RE has one really good feature- keeps driving even heavily damaged
c) My stroker must have really nice bottom end if it broke the tranny in 2 weeks, while 4.0 was trying to do it for over 15 years