'98 Engine Noise Diagnosis

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camino70

camino70

10 Year
Joined
Jul 1, 2015
Threads
51
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1,345
Location
Canton, GA


My favorite, online video diagnosis....

This is a 1998 LX470 with 200K. TB done at 190, but a few years ago. Oil change was semi recent, but I plan on doing that too. Even though I don't believe it's a cracked exhaust manifold, I intend on doing some type of smoke test, borrow a buddies smoke machine and strap it to the exhaust or strap my shopvac to the exhaust and use incense? to see where it gets sucked in?

The noise doesn't seem to go away.

I removed the v-belt this morning and was pleasantly surprised (albeit shortlived) that the noise was no longer present. Excitedly, I dragged my wife into the cold (yes 35* is cold in Atlanta) and say "this is a ton quieter than yesterday, no?" The words were barely out of my mouth as the clatter began again....

Can you guys provide some guidance on how to troubleshoot this?
TIA
Ron
 
that it would appear to me is an exhaust leak.... first I'd just take a 4ft piece of rubber hose... fuel line to garden hose.... and put one end to my ear and the other end towards the sound until you pin it down... if it's the manifold to head gasket... I'd bet more towards a cracked manifold... you might need to remove the heat shield to see it...
BUT at night in the dark no lights on... I bet you will see fire or a red glow...

just where I'd look first
 
Thanks ponytl,
I have a mechanical stethoscope, but I have only been able to determine the drivers side is noisy, the passenger side isn't.


Am I OK to drive this? (Once the seat belt is reattached of course).
 
Sound like my 01 with 165k before oil pressure and temp reach normal operation.

If oil pressure good, you should be fine to drive.

With stethoscope, can you isolate further? Valve cover, injector, coil, exhaust etc.,.. Serpentine Belt off won't make any difference to these areas except air pump.

The exhaust issue (my 01 had) was corrected in the 2003 model wasn't it?
When I first heard my exhaust leak it sounded like valves needed adjusting, like your sound. But sound changed (reduced) as I reached operating temp.

Make sure your spark plugs are tight also.
 
Exhaust manifolds were a known issue. For those the hose method mentioned is better. The flanges on the manifolds would warp. First it would make noise only when cold. After time it would be all the time.
 
Thanks guys,
I'm cautiously excited as I was afraid this may be the beginning of a catastrophic top end issue.

I'm going to try running it tonight in the dark, then maybe find a piece of hose for a listen.

Thanks again.
 
ponytl said:
that it would appear to me is an exhaust leak.... first I'd just take a 4ft piece of rubber hose... fuel line to garden hose.... and put one end to my ear and the other end towards the sound until you pin it down... if it's the manifold to head gasket... I'd bet more towards a cracked manifold... you might need to remove the heat shield to see it...
BUT at night in the dark no lights on... I bet you will see fire or a red glow...

just where I'd look first
Click to expand...

My 01 Sequoia (same 4.7L engine) has exhaust manifold crack, and it sounds just like that before we sell the car.
 
I hooked up the shop vac to the exhaust and used some tubing to listen through. I can't find it and feel like an idiot. I tried some incense, but didn't see it get sucked in either....
 
If sound doesn't change when engine hot, then it's a bad leak and should be easy to find. I'm not convinced it's exhaust, but if you've exhausted all other tricks suggested above, I have one more. Some may not like this but it works. Oil squirt can works best but one can use oil dip stick for this. Squirt a little oil on exhaust manifold where you think it's leaking. Oil will smoke and you'll see a stream of smoke where exhaust air is escaping. Oil has a high flashpoint so risk of fire is low, but have grease/oil fire retardant on hand just incase. IIRC baking soda is a retardant but Google that to make sure, it's you a$%.

This well may be lifter(s) need adjusting (not common) or a noisy injector (common).
 
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Started running rough and then CEL came on today, P0300, P0302 and P0305. Any chance this could play into my noises?
I'm thinking of trying the 8 coil packs for 80 on amazon, am I kidding myself thinking they may actually work?
 
It sounds like an engine with no oil, whats the oil level and pressure like? You could swap the coil packs to see if the fault moves cylinders, there is a chance the T belt might of jumped a tooth.
 
Idle RPM sounds high, was video at operating temp or during cold start up. If cold can you give one at Operating Temp.

Also did you disconnect battery for 30 minutes after installs, resets system.
 
It was cold start and it was the initial start after battery reconnection. I left it disconnected overnight.
 
It may be a bad recording, but the engine sounds flat to me, ignoring the tapping noise it sounded more responsive in the first video. Where any of the old plugs fouled up. For the time it takes I would double check valve timing.
 
Spark plugs looks pretty good, a little bit of carbon build-up. You may want to carefully clean carbon off, then check gap of each one just for your records. Gap can give indication of how each cylinders spark has been (clues).

That sounded pretty loud, but it could just be your microphone.
You've checked for the common stuff like exhaust leak, lose/leaking spark plug, remove S-Belt, and have good clean oil, filter & oil pressure. You've been using good fuel, and running a can of fuel system clean like 44K through gas tank now and then to keep fuel injectors clean. Right?

If your still uncomfortable with sound then:
At this point I'd use a stethoscope and check each fuel injector, both side. Starting with least suspect side to get comparison. Upon finding any suspect, pull electrical connection see if noise stops. Keep in mind these guy's get pretty noisy with age. Be very carefully as the plastic of electrical connection will most likely be brittle.

The next suspect would be valve gap, the PM test for this is sound. I'd be very sure it's a valve gap sound by getting a second opinion from a very good Toyota shop, if you find this suspect. But I've not heard of anyone adjusting valve gap in mud, and I've looked. One day I want to do valve gaps just to see, but not until I'm at least in need of new cover gaskets.
 
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