Timing Chain Rattle on 12HT or Other Problem?

[PeterInSa]

Have a HJ61 done about 350,000Km on cold weather start up have a rattle that sounds like 2 stones in a tin can that you shake up and down, fairly loud at the start and then dies away after a minute or so.

I use nulon with the engine oil.

Is it the timing chain and if so do I need to adjust a tensioner or replace the tensioner whick I hope is a nylon type of tensioner?

Thanks

Peter

[Shaun05]

Well, it's certainly not a timing chain, because 12HT''s don't have one. They have a gear driven cam shaft.

Are you sure it's not just the normal diesel rattle? They do tend to rattle a fair bit when first started in cold conditions.

[dumbdunce]

try a slightly thinner oil, without the additive - it could be that thick oil with thicker goo in it, plus winter time, is making it hard work to pump the oil to the top of the motor on cold starts. a 10W40 is good for winter.

they are a pretty rattly motor anyway, they get a lot of backlash in the timing gears, could even be big ends needing a re-shell if it has never been done. engine noises are notoriously difficult to diagnose via a silent, text based medium

[RED60]

they are a pretty rattly motor anyway, they get a lot of backlash in the timing gears

dd, apart from new timing gears, can the backlash be taken out or minimized in any way...

[CustomTurbos]

I dont want to be the bearer of bad news, but if your 12HT has not been rebuilt in the past, then I fear you have the death rattle which is either the top ring on one or more pistons flapping around due to the extreme top ring groove wear that ALL 12HT's get or one ring has broken and the biots are bouncing around the top of your cylinder.

There are no exceptions on the high km 12HT's, it will happen at some point unless the pistons are replaced by the newer versions with cast in iron based inserts to support the top ring. If gotten early enough, you can usually get away without a rebore (but a pretty serious hone).

Once the failure has occurred, you might be luicky to get away with a 1mm bore oversize, maybe not. May need sleeving on the failed cylinder.

These are a great engine but suffer from only 3 wear issues:

* The pistons top ring land (this is really a bad one and shows up 330kkm onwards (I have seen it as late as 530kkm)
* the lifters (Chrome pits and cracks off on the wear surface where it follows the cam)
* Rocker wear (the rocker arm rod wears, I think these are available new)

If your injector pump is OK, then otherwise these engines are awesome

Have a HJ61 done about 350,000Km on cold weather start up have a rattle that sounds like 2 stones in a tin can that you shake up and down, fairly loud at the start and then dies away after a minute or so.

I use nulon with the engine oil.

Is it the timing chain and if so do I need to adjust a tensioner or replace the tensioner whick I hope is a nylon type of tensioner?

Thanks

Peter

[PeterInSa]

Thanks Custom Turbos for your comment
But how come the noise dissapears after about a minute when the engine oil with Nulon seems to get to the noisy part?

Peter

[dumbdunce]

they are a pretty rattly motor anyway, they get a lot of backlash in the timing gears

dd, apart from new timing gears, can the backlash be taken out or minimized in any way...

use good oil. any noise should only be present at idle and should disappear once oil pressure is up. there is no adjustment, the timing gears are the same as 2H, they are bulletproof but the idler shafts do wear and introduces a bit of slop.

There are plenty of well maintained 12H-T's out there with well over 500k km on them and going strong, like most things automotive the single most influential variable is the driver.

[CustomTurbos]

Well it is hard to say, if that is the case (oil) then I guess it isnt the death rattle.

If you have some $ to throw at the engine, these are a great candidate for doing a cheap "in situ" rebuild (basically big ends, a hone, pistons/rings and head service). Parts in Australia for this job are around the $1000 mark. It eliminates the piston issue and ensures that the engine can in fact do well over 500kkm like Dumdunce said (he's obviously got heaps of experience with them?).

I've only pulled down 3 and had experience with 2 others. 2 died to the point they stopped (460kkm and 530kkm. The 460kkm the owner - see posts by "Rideglobally" http://www.ih8mud.com" onclick="window.open(this.href);return false; - posted a similar noise, I told him the same thing, not 5kkm later the engine was dead), 2, one at ~ 340kkm and other at 440kkm was almost ready to go (ring groove double thickness of ring itself) and due to flapping of ring ends the bores were very worn and a heavy hone only just made it barely acceptable on 2 cylinders. The other engine had been previously rebuilt and have now been built with Custom CrMo 4340 Rods and now is 4.35Litres :-)

Whats the oil pressure like - a minute is a long time for a nasty rattle to dissapear. At the end of the day it may be something altogether unrelated to oil..... When the engine is warm, the idle is smoother so a benign resonance may dissapear after it smooths out?

Thanks Custom Turbos for your comment
But how come the noise dissapears after about a minute when the engine oil with Nulon seems to get to the noisy part?

Peter

[Shadow]

my 2H died with a similar noise.

top ring land broke away and procedded to be smashed into the head by the piston.

makes an aweful noise!. Limped it to my dads place, about 5km when mine let go and he came running out the front as I approached cause he could hear a racket!

mine did not go away though, but the engine rebuilder i used said the noise can be intermitent as the piece of the poiston gets smashed into the head and stops making a noise, and then vibrates lose again etc.

[PeterInSa]

Shadow did you hear the noise for XXXXKm prior to the problem, we have heard the noise for about 2 months and on cold startups for around the last 6000km. Had my mechanic around last night with a stethscope and he could not hear the noise on startup. It was not as cold probably 10deg C as was when we heard the noise last, alternatively when we have heard the noise I have not driven the cruiser for a couple of days.

Will replace the oil ,previousdly used Valvolene and Nulon with Pentrite and Nulon.
Mechanic does not like additives in the engine oil says puts a glaze or such like on the bore. Ok for Gearbox etc.

Re engine do ups his Trade cost for a 12HT $4,300 + GST, then says unless i get new injectors, injector pump checked, radiator cleaned out the engine replacement company will try to get out of honouring their warranty. 2 days to pull the engine out and put back.

Also if I am going this far I should get the Turbo looked at $1,500, new water pump and although the clutch has only done 40,00oKm might as well change that as well.

His verdict if I get out of it for less than $12,000 I would be lucky.

With all the gear I have on this cruiser am loth to change over to an 80 series which may have problems of its own.

We only do about 10,000 Km a year towing the van and the boat otherwise we mainly use SWMBO's car.

I want to find out the cause, otherwise long trips towing our 2450kg tandem van will be tense.

With a Stehascope where do you listen?
Any other way other than taking the head off to confirm, as the noise appears to be at the front of the engine ( Thought it was the fan blade touching something, but no.)

At my age I am passed DIY so need a mechanic to do the job, he will do the job at cost.

Appreciate your advice

Peter

[Shadow]

i did not drive it once it started making the noise. Had it towed straight to the engine rebuilder and he pulled the head off to confirm the piston had let go.

you really need to see inside the bore to be able to rule it out totally. Maybe one of those snake cameras down the injector hole?

Or pull the head off etc. Probably cost you $500-$1000 depending if you get the head rebuilt or not while its off.

I cannot hear the noise you are having so cant say for sure its what mine did, but i would definately say mine sounded like a rock in a tin can!

[PeterInSa]

Rang up a second hand engine shop re price, firm had sold a (2nd Hand 12HT motor this morning for $5,900, it seems they are sought after by 2H owners. Met an 80 series owner in Northern WA 3 weeks ago who had put a 12HT in his vehicle.

Bugga

Peter

[PeterInSa]

Shadoe Re "mine did not go away though, but the engine rebuilder i used said the noise can be intermitent as the piece of the piston gets smashed into the head and stops making a noise, and then vibrates lose again etc."

Mine only makes the "stone noise in a tin", and not that loud when cold and does not come back when the engine is warm.

Peter

[hulsty]

Graeme, whats is the cause of the piston problems in 12HTs? Is it because the top ring is to close to the top of the pistion exposing the ring groove to a harsher enviroment?


To the OP dont jump to conclusions and start ripping it apart, investigate it properly, could a bore scope be used through the injector ports to check the top of the pistons?

[Tim HJ61]

Graeme, whats is the cause of the piston problems in 12HTs? Is it because the top ring is to close to the top of the pistion exposing the ring groove to a harsher enviroment?

To the OP dont jump to conclusions and start ripping it apart, investigate it properly, could a bore scope be used through the injector ports to check the top of the pistons?

I understand it is simply metal quality or design issues. This was the first DI Toyota put into Landcruisers, maybe it was a design issue. I agree with a borescope to check. the link to rideglobally's posting on IH8MUD where he shows a picture of the damaged head is at http://forum.ih8mud.com/diesel-tech-24- ... ost6290974" onclick="window.open(this.href);return false;

PeterinSA - have you checked out the fan clutch and or movement in the water pump?
The reason I ask is that on start up the fan clutch engages and runs at full power for a bit, then turns off. If you are only noticing this noise on a cold startup, maybe this is the problem. I'm just trying to think of something else that changes after start up.

Tim

[PeterInSa]

Tim , Thanks for your comments, hopefully have a mechanic with a stehscope, do an engine checkout early tomorrow morning

Custom Turbo, Thanks for the IHMud site its great for the 60 series.

Shadow, CT, all
Re the stone in the tin noise, mine is not repreative like a tappet noise, its more irrugular.
eg tappet noise, 1 sec quiet, Tappet noise,1 sec quiet, Tappet noise, 1 sec quiet.
My SITN noise, 1 sec quiet, my SITN, 2sec quiet, my SITN .5sec quiet.

Were your Land/ring noises of a repetitive nature or more irregular.

Thanks

[CustomTurbos]

Tim , Thanks for your comments, hopefully have a mechanic with a stehscope, do an engine checkout early tomorrow morning

Custom Turbo, Thanks for the IHMud site its great for the 60 series.

Shadow, CT, all
Re the stone in the tin noise, mine is not repreative like a tappet noise, its more irrugular.
eg tappet noise, 1 sec quiet, Tappet noise,1 sec quiet, Tappet noise, 1 sec quiet.
My SITN noise, 1 sec quiet, my SITN, 2sec quiet, my SITN .5sec quiet.

Were your Land/ring noises of a repetitive nature or more irregular.

Thanks

Maybe best to ask "Rideglobally" regarding his interpretation of the noise that he heard.

Noises are such a hard thing to quantify - almost like describing art.....

I really hate even making mention of this issue with the engines because of the concern that it gives the owners - the only reason I do (and at my own peril as far as making friends is concerned...) is because it is cheaper to fix early (if indeed that is the problem).

I hope that it is the fan like HJ61Tim suggested

[CustomTurbos]

Graeme, whats is the cause of the piston problems in 12HTs? Is it because the top ring is to close to the top of the pistion exposing the ring groove to a harsher enviroment?


To the OP dont jump to conclusions and start ripping it apart, investigate it properly, could a bore scope be used through the injector ports to check the top of the pistons?

It is the metallurgy of the pistons. It's either poor metal selection by Piston supplier or bad spec from Toyota. The metal seems to soften with the thermal cycling. Either way its wrong and the problem is prevalent in high mileage 2H as well. I wondered for a while if in fact it was limited to the 12HT being DI and the higher peak cylinder pressures but then saw people having the issues with 2H as well. SOme of the 2H seem to fair a bit better with over 600kkm, but I havent heard of a stock 12HT getting to 600kkm without piston failure.

It is a strange thing, but whilst a bit OT, I have heard numerous reports from 12HT owners that have 400kkm engines that they get 10km/L and then after being rebuilt, they are off at least 10%. I have postulated (I do that alot...) that, other than frictional matters, owners get injectors done at the same time and while the spray pattern is superior, the lower cracking pressure of the old injectors (down to 180Bar when old) causes the timing to advance over std which may improve economy

[PeterInSa]

Mechanic, rocked up this morning, no noise....................
Suggested I have the Tappets checked, Check for cracked Rocker arms do a compression check ( ie ring check...but will not check ringlands) and the end float on the cranksaft.

Comment.... No worries.........

Thanks for your comments

Tim HJ61, Rideglobally answered my PM, also was told no worries before the big bang/fix

Thanks