Hot engine & rattling noises (far from home) (1 Viewer)

[Tofel]

Hi!

Need your advice badly on this as I´m thousends of miles away from any car mechanic I know and trust. Hope that some of you had similar problem and managed to fix it.

For the last 1800 miles I´ve observed a strange behavior of the engine noises. When the motor is cold everything sounds perfect, but after it warms up, in low RPM range (1300 - 2000) I can hear rattling similar to engine knocking, which gets louder as the engine gets hotter. I doubt it is engine knocking as the sound is there regardles whether I use RON 95 or 98 (US 91 or 94) and my ignition timing is very low - usually around 0*, never more than 3*. I also have the P420 error code, which has been troubling me for 15 000 miles (from Nicaragua?), but if the fuel wasn´t very bad I could get rid of it by keeping the timing between -1* and 3*. Now I have the code regardless of ignition timing advance. What´s even more strange once the engine is hot and knocking sound is there if I retard the timing to say -10* or -15* the knocking dissapears (but can´t countinue driving with this setting without P420 error code).

A friend of mine suggested that excessive valve clearence might be to blame (with hot engine the clearence becomes too big and thus the noises - but if it is that why would the sound disappear when I retard timing significantly?). I´ll be checking clearance in the incoming days. Do you think it might be it? Any other suggestions where to look for causes?

My mpg is quite okay - between 13.5 and 15 on tarmac.

Would greatly appreciate any suggestions as I'm in Cordoba (Argentina) and don´t know any mechanics around (and the FZJ80 isn´t particulary popular here). Some friends are flying in shortly to drive with us to Patagonia and would not like to drive there without fixing the problem (or make them wait too long as I´ll be tearing the engine apart to look for the cause).

Bartek

 

[M0untaineer]

Hey bud- sorry for your trouble...I've had a similar issue with my rig...I'm about 90% sure that you've got nothing to worry about...I think what you're experiencing is probably a heat shield issue on your exhaust or rattling from your catalytic converters...p420 is a catalytic converter efficiency trouble code...I think your fine...check your oil and make sure your coolant level is topped off...

 

[Tofel]

Would love it to be so simple! Did you have it rattling only with hot engine?

 

[M0untaineer]

yes sure do

 

[inkpot]

Is your oil level way low, or is your oil real old?

 

[Qball]

Would love it to be so simple! Did you have it rattling only with hot engine?

Once the engine is hot then do a walk around to isolate if the rattle comes from the engine or other areas.

Also if it's metal rattling sounds then it could be anything as our trucks are getting older. If the rattle is more of a muffled clacking sound then it could be your engine but that usually is always on even when cold.

 

[Tofel]

Thanks for replies, guys!

I cant pinpoint the noise as it is there only when the truck is moving, mostly uphill. When parked even with engine extremaly hot the sounds are perfect. I hit the heatshields (both where exhaust connect to the engine and around converters) both when hot and cold, but they seemed to be holding really well, no loose elements.

My oil has around 1600 miles, level above average. Mobil Delvac 10W-40. I have been running it for last 8000 miles without issues.

The sound is exactly the same for me and is present in similar conditions as engine knocking, but because the fuel I use has good octane number and my ignition timing is very low, I doubt it is the cause. Maybe it is the ignition system going bad? Any chances this could be rod bearings failing?

UPDATE: I've uploaded to YT a video with the sound in question.

Oh, no idea if that can helps, but the sound developed after driving some 2000 miles across Bolivia at high altitude (between 12000 ft and 18000 ft) on s***ty and low octane fuel (impossible to buy better or even know the octane number of what you buy).

 

[inkpot]

You are at extremely high altitude. Find a timing light and drop the advance down to zero to see if that helps. John

 

[Tofel]

0* timing advance is what I used in Bolivia. Now Im back at sea level and with 0* I still have knocks with hot engine. If I retard the ignition timing to -20* knocking disappears, but I have error code from catalytic converters (due to improper fuel combistion/mixture?). Any ideas what might be causing such behavior?

 

[Qball]

You are at extremely high altitude. Find a timing light and drop the advance down to zero to see if that helps. John

That does sounds like knocking, they must have piss in their gas. Drop your timing to -10 or something, who cars about code as long as your engine is running fine.

 

[Rusco]

Quite possibly a severe accumulation of carbon in the combustion chambers/piston tops due to combination of having to retard timing for altitude and different fuel formulations. SeaFoam or another top-cylinder cleaner may be needed.

 

[baldilocks]

At -15 or 20 your intake valve is still open and probably why you got the code.

 

[Tofel]

That does sounds like knocking, they must have piss in their gas. Drop your timing to -10 or something, who cars about code as long as your engine is running fine.

That's what I'm doing right now, but if you ask me the code means that fuel isn't burnt properly, which if ignored might lead to engine damage in the future.

Quite possibly a severe accumulation of carbon in the combustion chambers/piston tops due to combination of having to retard timing for altitude and different fuel formulations. SeaFoam or another top-cylinder cleaner may be needed.

Currently I'm toying with Lucas Fuel Injectors cleaner (one mechanic suggested that the injectors might be dirty, injecting less fuel and thus causing a lean condition). If that won't help I'll try with some top-cylinder cleaner. There is a chance that I'll be able to get something like that in Chile.

Honestly speaking I'm running out of ideas, what could be wrong as I've checked knock sensors, ignition coil, high tension cords, spark plugs and MAF sensor and all of them were fine (according to FSM).

At -15 or 20 your intake valve is still open and probably why you got the code.

Maybe, but...
1) I have the code also when the timing is more or less around -3 or -5.
2) I don't experience noticable loss of power, even when I have the code (and now I have 5 people with luggage in the car)
3) Wouldn't what you describe cause misfires and thus corresponding error code?

 

[baldilocks]

That's what I'm doing right now, but if you ask me the code means that fuel isn't burnt properly, which if ignored might lead to engine damage in the future.



Currently I'm toying with Lucas Fuel Injectors cleaner (one mechanic suggested that the injectors might be dirty, injecting less fuel and thus causing a lean condition). If that won't help I'll try with some top-cylinder cleaner. There is a chance that I'll be able to get something like that in Chile.

Honestly speaking I'm running out of ideas, what could be wrong as I've checked knock sensors, ignition coil, high tension cords, spark plugs and MAF sensor and all of them were fine (according to FSM).



Maybe, but...
1) I have the code also when the timing is more or less around -3 or -5.
2) I don't experience noticable loss of power, even when I have the code (and now I have 5 people with luggage in the car)
3) Wouldn't what you describe cause misfires and thus corresponding error code?

I'm glad you brought this to my attention because I think now that I was mistaken when I made that comment. I will refer to the manual for clarification. I hope it's working out for you.

 

[Tofel]

A follow up for those who might have similar problem in pinning down the cause or finding a solution. In my case pouring 40 oz of fuel injector cleaner during 8 fill ups did the trick and now I neither have rattling nor P0420 error code (that is unless I fill up with poor fuel).

 

[M0untaineer]

Thanks for closing this out...I'm trying some fuel injector cleaner as well...

 

[Tofel]

No problem! Hope it will work in your case as well! I used Lucas Fuel Injector Cleaner mostly as that's what I took from the States with me. Seafoam recommended by many mudders as an ultimate cylinder cleaner doesn't seem to be available neither in Chile nor in Argentina.