KZJ keeps breaking Exhaust?

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Triplefat

Triplefat

Joined
Nov 15, 2020
Threads
21
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73
Location
USA
Does everyone’s KZJ motor move around a lot? I had a 3in exhaust put on with flex pipe and I still keep breaking exhaust hangers. To the point I ripped the front exhaust mount that goes to the frame. I tried installing some new engine and transmission mounts but to be honest I don’t see a big difference. Anyone else have this issue? I’m think of replacing my glow plugs next to try and smooth out start up a little, since that’s when it’s the roughest

Edit- Also wondering if anyone’s done Polly mounts on their truck or if that would make the truck vibrate like hell?
 
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Do you still have the "throttle butterfly" in the intake venturi?
Its a common "modification" to remove the plate for more sound and possible flow.
The most reported negative effects is that there is rough engine shutdown and one or two revolutions extra during start up.

Balance shafts have snapped or bearings failed and a quick solution is "balance shaft delete" also resulting in more vibration or harmonics.
Hard to tell without a deep dive
 
Triplefat said:
Does everyone’s KZJ motor move around a lot? I had a 3in exhaust put on with flex pipe and I still keep breaking exhaust hangers. To the point I ripped the front exhaust mount that goes to the frame. I tried installing some new engine and transmission mounts but to be honest I don’t see a big difference. Anyone else have this issue? I’m think of replacing my glow plugs next to try and smooth out start up a little, since that’s when it’s the roughest

Edit- Also wondering if anyone’s done Polly mounts on their truck or if that would make the truck vibrate like hell?
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If your engine is shaking abnormally, you have engine issues.

You should not be breaking exhaust mounts on a properly operating engine.

Do a compression and leak down tests. I bet you have a blow head gasket/cracked head.
 
I also went through a few flex pipes actually. I spent months trying to track down the source of this strange rough idle and then one day I'm deleting the EGR and it turned out the vacuum line to the MAF sensor (on the intake) had got a bit of residue in it and I guess it was throwing off the maf sensor just enough at low rpms. Quick fix though.
 
Black94Prado said:
I also went through a few flex pipes actually. I spent months trying to track down the source of this strange rough idle and then one day I'm deleting the EGR and it turned out the vacuum line to the MAF sensor (on the intake) had got a bit of residue in it and I guess it was throwing off the maf sensor just enough at low rpms. Quick fix though.
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You know I did the EGR delete last year… let me take a look at that. It’s not so bad that I think it’s a head gasket or anything. Just a tad rough on start up from how it use to be. Takes an extra crank or two to start. Didn’t know this motor has balance shafts so that might be something to check out also. Thanks for the ideas
 
Triplefat said:
You know I did the EGR delete last year… let me take a look at that. It’s not so bad that I think it’s a head gasket or anything. Just a tad rough on start up from how it use to be. Takes an extra crank or two to start. Didn’t know this motor has balance shafts so that might be something to check out also. Thanks for the ideas
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If it started after you did the EGR delete or shortly after I'd also do a bit of a look around for any vacuum leaks. What you're describing (the extra cranks to start) I've had both when there was a small air leak in the fuel system and also with the maf sensor in general, not just when it was blocked up, but years after that I started having this strange rough shut down, like a cummins diesel shutting off. It's like when you just cut fuel to a diesel engine, it kind of shakes to a stop (my old sailboat engine does that). I kind of got used to it but it turned out to be the MAF sensor again (I had replace it) and it wasn't changing values correctly. My point is the these engines should shut off completely smooth, without any shaking. Anyways, that's all I got.
 
Black94Prado said:
If it started after you did the EGR delete or shortly after I'd also do a bit of a look around for any vacuum leaks. What you're describing (the extra cranks to start) I've had both when there was a small air leak in the fuel system and also with the maf sensor in general, not just when it was blocked up, but years after that I started having this strange rough shut down, like a cummins diesel shutting off. It's like when you just cut fuel to a diesel engine, it kind of shakes to a stop (my old sailboat engine does that). I kind of got used to it but it turned out to be the MAF sensor again (I had replace it) and it wasn't changing values correctly. My point is the these engines should shut off completely smooth, without any shaking. Anyways, that's all I got.
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When you say MAF do you mean the MAP sensor? I couldn’t find a MAF sensor for my car
 
As a side note, it is a little surprising how soft the engine mounts are on these trucks. I can grab my down pipe and shack the motor no problem with brand new mounts
 
Black94Prado said:
It's the sensor on your intake manifold, it has a small vacuum line going into it.
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This?

image.webp
 
When I took that hose off the intake it was pretty nasty. Not sure if that’s from before I did the EGR delete or if I got turbo problems (Doesn’t smoke out the exhaust yet) So I’m going to change out that filter for sure. Anyway to clean out the intake manifold? If it was a gas engine I’d seafoam the intake
 
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