Name that engine noise

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Hello all,

I have recently acquired a 1994 FZJ80 that has an engine noise that doesn't sound good. I bought the Cruiser knowing it had an engine noise, but I may have been a bit optimistic. Would anyone be willing to chime in on what may be going or have gone on my engine? I was hoping the valves were just out of adjustment, but the noise seems to have changed from a ticking to a knocking since I bought it. I did drive it from Nebraska to California, and it made that drive with ease but that may not have helped the engine. I'm trying to figure out my next steps on how to diagnose what's wrong and move forward on fixing it. Any help will be appreciated!

The noise seems loudest at idle and I don't hear it all when cruising on the highway.




Thank you,

Craig
 

inkpot

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The great mystery knock. We have pulled apart several of these. All had different problems. Wrist pins. Rod/crank bearings, piston bore damage....no single answer. I have seen several of thesenoise makers run over 15000 miles before they were torn down.
 
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The great mystery knock. We have pulled apart several of these. All had different problems. Wrist pins. Rod/crank bearings, piston bore damage....no single answer. I have seen several of thesenoise makers run over 15000 miles before they were torn down.
Thanks for your insight. In order to figure out the issue is the way forward to pull the engine and start taking it apart?
 
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Sounds like a rod knock but hard to tell. Definitely doesn't sound great. Any way to pinpoint where it's loudest?
It's interesting to me how the noise seems to have changed. But I may just be going crazy from listening to it! I listened with a scope and I hear the noise all over. Are you in Fresno, CA?
 

baldilocks

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It’s power down? Compression verification test? Oil pressure verified using a test gauge?

Get a free oil sampling kit from Blackstone Labs and send them a sample. Their site has info on how to draw the sample and send it in.
 
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It’s power down? Compression verification test? Oil pressure verified using a test gauge?

Get a free oil sampling kit from Blackstone Labs and send them a sample. Their site has info on how to draw the sample and send it in.
Great suggestions on things to check and test. Power seems normal to me, but I've only owned it for a couple months. A buddy has one and I can compare it to his.
I haven't checked compression, will do this.
I will have to research what sort of gauge I need for verifying the oil pressure.
Good idea on the oil sampling kit. I haven't used one of these, what will the test reveal?
 

inkpot

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Thanks for your insight. In order to figure out the issue is the way forward to pull the engine and start taking it apart?
Only way to know for sure is tear it all down. Basically a full rebuild. Some folks just do a build of a spare engine. Others just pick up a good running engine and swap it in, then tear into the original. No easy way to solve the problem.
We had one there we found both halves of the rod bearings stuck to the cap. No serious wear or damage to the block bore or the crank! Go figure. I push the snot out of mine at 242000 miles. It is S C, water/meth injected, Landtanks injectors and MAF kit. And it sees 5000 rpm almost every day. I keep my eyes open for a spare/builder.
 

baldilocks

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Oil analysis can tell you everything about what’s going on inside your engine providing info on wear metals present, dirt (silica), fuel dilution, presence of water and antifreeze, etc.

They can assist you in figuring out what’s going wrong in your engine because they know what metals are used to make what engine parts.

Go to a store like Autozone and rent an oil pressure tester gauge. By removing the factory oil pressure sending unit and then threading the test gauge into the engine block, you will know real time oil pressure.

If you don’t already have a Factory Service Manual (FSM) you should give serious consideration to getting ahold one.
 
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If the power steering pump has been replaced its possible the teeth on the gear that drives the pump were damaged, this can lead to some significant sounds that have been mistaken for rod knock. No idea if this is whats happening here but it's something you could test without pulling the engine out of the truck.
 

ppc

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Try the simple and no cost diagnostics first. Pull one plug wire at a time to see if the knock changes. This will point to a specific cylinder if the noise goes away. Other suggestion is to remove the belts to verify it's not something like a bearing in one of the idlers, water pump etc.
 
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Oil analysis can tell you everything about what’s going on inside your engine providing info on wear metals present, dirt (silica), fuel dilution, presence of water and antifreeze, etc.

They can assist you in figuring out what’s going wrong in your engine because they know what metals are used to make what engine parts.

Go to a store like Autozone and rent an oil pressure tester gauge. By removing the factory oil pressure sending unit and then threading the test gauge into the engine block, you will know real time oil pressure.

If you don’t already have a Factory Service Manual (FSM) you should give serious consideration to getting ahold one.
This information is excellent. I recently changed the oil and I've only put 30 miles on it. Do I need to drive it more before I send in an oil sample? I'm eager to do this now.

I didn't know about the oil pressure gauge rental, thanks.

I have the FSM, it wasn't cheap, but it's full of information!

Thank you for your helpful suggestions. I will keep you all posted what I find out.
 
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Cut your old oil filter open and check for bearing material.There is a series of YouTube vidieos(3) concerning the diagnosis of a knock on an fj80.I think the oil sender is before the last rod bearing leading to a false confidence reading.
 
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Try the simple and no cost diagnostics first. Pull one plug wire at a time to see if the knock changes. This will point to a specific cylinder if the noise goes away. Other suggestion is to remove the belts to verify it's not something like a bearing in one of the idlers, water pump etc.
Wow, you guys are loading me up with great ideas on tests that I can perform. Thank you!
 

baldilocks

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This information is excellent. I recently changed the oil and I've only put 30 miles on it. Do I need to drive it more before I send in an oil sample? I'm eager to do this now.

I didn't know about the oil pressure gauge rental, thanks.

I have the FSM, it wasn't cheap, but it's full of information!

Thank you for your helpful suggestions. I will keep you all posted what I find out.
I don’t really know about how many miles you need to run the oil before sending in a sample but Black Stone Labs can answer all sampling questions. You need to contact them to acquire a sampling kit anyway.
 
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If the power steering pump has been replaced its possible the teeth on the gear that drives the pump were damaged, this can lead to some significant sounds that have been mistaken for rod knock. No idea if this is whats happening here but it's something you could test without pulling the engine out of the truck.
Based on the service records I received the power steering pump has been replaced so this is worth checking.
 

zapatius

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Yes. It was a brand new Aisin. Replaced with another brand new Aisin and no issues. At least if noise is still there you know it's not the water pump. Could easily be power steering.
 

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