i have a 87 turbo 4 runner that just started with this problem.

it makes a really loud clicking sound at idle that sounds like its coming from the turbo. when i rev it up to anywhere from 1500-2500 RPM the noise is completely gone.

my question is. what noise can a turbo make at idle, that it couldnt make at 2000 RPM ?

or can it possibly valves?

 

http://www.youtube.com/watch?v=ywCxP1YePkw

http://www.youtube.com/watch?v=ipcLnJUPmrU

 

Dude, when mine was running, it did the same thing!

I think I read where the Turbo would lose oil pressure after it sat for a while and it was the impeller turbine shaft or something that was making the noise.


Sorry I don't have more... Mine have been nothing but major headaches since I've bought them... And I haven't really messed with them a lot.


Kinda makes a tick-tick-tick like the MAF meter door slamming around till oil pressure comes up...

 

How's your shaft play? Mainly in and out ? If there's excess play then when the turbine is spinning at idle then the fins could rub on the housing due to the shaft play, but when you rev it the boost could move/force the turbine and shaft into a different position and stop rubbing. Just a suggestion. That's all I could think of

 

Check the rubber Turbo air intake hose that goes from the air box into the Turbo for cracks where the PCV (IIRC) dumps into it.


They love to crack there.

 

Also wonder about the diaphragm that controls the waste gate...

Wonder if it could be blown?

 

why would a cracked rubber intake tube make that noise?

 

Just a thought. To eliminate a possibility. And b/c there might be less drag for air to get sucked into there, than through the airbox and filter and that might be it making that sound.

 

ok, thanx. just curious there.

anything is possible. just wanted to kno what your opinion was.

 

Has the timing chain been replaced?

 

the engine was completely rebuilt 45,000 ago.

i havent had the time as i work 80hrs a week. (been driving the girlfriends car)

hopefully i will be able to diag the truck tomorrow or the next.

 

okay. so i got to take the valve cover off and when i look down at the chain.

the drivers side guide is broken off. there are wear marks on the side of the cover.

does this mean i need a new chain as well?
or could i get away with fixing just the guide?

 

Definately chain slap on the timing chain cover....the guides are notorious for breaking. You can order a new kit from DOA Racing that comes with metal guides. I personally would replace the cover too. Mine had hair line cracks in it that coolant was leaking through.

 

Depending on how badly worn the cover is, best is to replace it.. its cheap anyways.

the guide has broken due to the chain stretching, id do a timing chain job.

get engnbldrs metal backed guide

 

id personally start with the exhaust manifold and work down sounds like converter shield is rattling

 

You will want to replace the timing chain set. Depending on how warn the front cover is you can re-use it. Hopefully it is still good. You said this engine was rebuilt, if so they would have cut the front cover with the deck. Which would mean a new one would be too tall and would have to be hand filed to fit. A ROYAL PITA !!!

IF yours is bad and has to be replaced, cheep aftermarket front timing chain covers are fine. However the timing chain set is a major component to engine life.

Metal back guides only fix the symptoms not the actual cause of a plastic guide breaking. The cause of a plastic guide breaking is chain stretch combined with wear on the tensioner foot. Neither of wich is addressed by a metal back guide. So either way all timing sets will eventually have to be changed every 100-130K

I also have seen a few metal back guides break wich is far worse than a plastic one breaking.

Long story short, I humbly say I use a FACTORY OEM set in my truck.

Any NAPA can order a Factory OSK set from Altrom for about half what the dealer charges. I pay 54.00 a set from NAPA.

Doa makes a decent aftermarket set
Rock uses an OEM tensioner which is good

 

i was thinking of buying engnbldrs timing set.

i had luck with his rebuild kit on my last motor..

 

So why would the stretched chain only make noises when warm?

 

Just a guess but the oil is thicker when cold, so puts more pressure on the the tensioner. The problem might be with the tensioner. Bad tensioner=loose chain=broken guide.

 

heres a new one.... i ahvent done anything, except let the truck sit for about 3 weeks. and now. the noise is completely gone.