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Discussion Starter · #1 ·
Hey guys,

I’m hoping to get some help on this from those more knowledgable than myself. I bought this FJ (07’, 135k miles) a couple months ago and while doing some future-proofing I noticed a bit of a knock at idle.

The maintenance history is unknown (the owner didn’t go to the dealer for maintenance).

So far, I’ve checked the oil (it was relatively clean) and cut open the filter and didn’t find any metallic particles. The engine internals have some visible shellack under the oil cap but nothing that is outstanding.

New plugs were put in. I have NOT yet checked the timing chain tensioner for timing chain stretch and haven’t yet checked the oil pickup for blockage. I’m running premium fuel.

I DO have P0420 and a P0430 code too. When I bought the FJ and checked the MAF sensor (cleaned) and it looked like it had never been cleaned, and the tailpipe is covered in excess black soot like it had been driven like that for years. So I suspect that the cats might be coated in carbon deposits just like the tailpipe (and it smells a bit when running, like possible bad cats).

I haven’t made the leap into replacing the upstream O2 sensors, but did both down-streams recently.

So now that I’ve covered what’s been checked/done. 1. Do others have this issue? 2. What should I prioritize checking or fixing next?

Thanks
 

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It's extremely unlikely that you are hearing anything related to pre-ignition (spark knock) at idle.

Is is a 'ticking', or a heavier 'knock' from the bottom end of the engine?

At only 135K miles, there should be no significant engine wear IF the engine has had regular maintenence.

First thing I'd do is use a mechanic's stethoscope (or a 3/8" wooden dowel) to try to pinpoint the source of the noise.

If necessary, pull the serpentine belt and run the engine for a minute to make sure the noise is not from any belt-driven accessory.

There is a solenoid-actuated vacuum switching valve near the LH valve cover that can 'clack' pretty noisily when the engine first starts when cold.

A rapping noise from the front of the engine, loudest at the timing cover, is usually a slapping timing chain (elongated chain from poor oil maintenance, or a broken chain guide).

A deeper knock from the lower part of the block can be a bad main or rod bearing, but again, with this low mileage there should be no fundamental problem with the engine.

Excessive valve clearance is another potential top-end noise source, but the early bucket-tappet engines usually go hundreds of thousands of miles without requiring a valve adjustment.
 

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Discussion Starter · #4 · (Edited)
Thank you for the replies. It sounds like a mid-height knock. Not low end and it doesn’t sound like a main. With a stethoscope I narrowed it down to the drivers side cylinder head. But by putting the stethoscope onto the exhaust outlets I can’t tell which cylinder it’s coming from. Nothing coming from the passenger side head.
It’s not the vacuum actuator tick, and I don’t think its coming from the timing cover. No accessories are making noise.

The knock comes and goes and is much less pronounced once I’ve driven it around a bit. I’ll have a video with audio up soon.
 

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Discussion Starter · #5 · (Edited)
Update: I’m leaning towards the engine giving up the ghost.

While filming the engine to post here tonight it seemed that the sound is deeper (cold start @ 48° temp) and knocking more loudly than it had been before. More consistent with a low end rod knock.

I’ve put a ton of work into the truck already, so I may go forward with a replacement engine. Has anyone here rebuilt one of these that could speak to the difficulty? I can would like to hear from others’ experiences before taking the plunge.

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- Update edit (Saturday afternoon 2:00pm)
Here’s a couple videos of the noise.

Engine bay:
Wheel well:

I drained the oil (only 750 miles on Mobil 1 synthetic) strained and found a few fine metal particles around .003-.005 (thousands) thick on the magnet. Zero brass/copper or anything larger than a hair.

I’m going to check the pickup screen and pan for metal later and add Liqui Moly to see if anything changes as far as the noise and will update then.
 

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Based on your video, that sounds more like something originating in the valvetrain rather than a rod/main knock.

With a properly-maintained 1GR-FE, 135K miles is only about 1/3 of the way into its potential service life, and I think that the potential for any problem with rod or main bearings is pretty slim unless the engine was somehow abused (run out of oil, etc.).

I'd pull the timing chain tensioner cover and see how far the plunger is extended; you'll also be able to get some ides of internal engine cleanliness.

Then, pull the valve covers and look for anything unusual in the valve gear, any odd cam lobe wear, check valve clearances, etc.
 

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Discussion Starter · #8 · (Edited)
I really appreciate the feedback, thanks guys. I was sure it sounded deeper last night but there’s nearly zero metal in the oil over 5k miles.

@FJtest I will prioritize pulling the tensioner cover & check the oil pickup screen next and will post an update, and then the valve cover after that for a timing and valve-train check. It is running a touch rough at idle too, like a cylinder is having a hiccup every 10 or so sec of idle time.

@Datajockeys I did after I noticed the knocking. I added Seafoam (1/3rd can I believe) to the oil 125 miles before the last oil change. The last oil change had only 4k miles on it with only a few very fine particles of metal, just like yesterdays’ 750 mile oil check. During that change the oil was very dark but was without sludge. When I peek into the pan & timing cover tonight I’ll check for sludge buildup and update here.
 

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Did you cut open the oil filter at the last oil change and search for particles on the outside of the filter media?

If the engine is generating metal particles, 99.9% of them will be in the oil filter, not in the oil in the sump.

Opening the filter and inspecting the media is SOP with every oil filter change on recip aircraft engines.

There are specialized oil filter cutters made specifically for this purpose that don't generate any metal particles that might be confused with particles originating within the engine.

I'd pull a valve cover to check for sludge (relatively quick and easy) before pulling the oil pan. The first evidence of sludge deposits will be in the heads and not down in the block.
 

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Discussion Starter · #10 · (Edited)
@FJtest I did and I washed down the filter media with acetone into a small container and found only trace amount of material in the 4k mile oil. My family is heavily into aviation and vintage warbirds, so I still have some of the tools we used for those engines like the filter cutter.

I will cut open the 750 mile oil filter and check that one too.

There’s so little metal that it’s like either damage was done more than 5k ago and was unrecorded and no longer producing or the failing part is small or failing gradually.

And roger that re: oil pan. I wasn’t sure if the pump would draw the metal upward with this pan design. I’ll prioritize checking the valve-train and timing.

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- Update edit (Noon on Sunday)

I opened the 750 mile filter and found virtually zero metal. I replaced the oil and added Liqui Moly which reduced the knock by about 30%. I also replaced the PCV valve which was stuck in the open position.

Will update later once I’ve dug into the timing/valvetrain.

Update edit (Monday)
FL weather has put a delay on the FJ until next weekend. Stay tuned!
 

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Unplug the vaccum switch harness that is shown around 6 seconds in on your first video and I bet it stops
 
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