tapping noise on 12ht (1 Viewer)

[rideglobally]

my 12ht has about 400.000 km on it. i know there are other thread about the noise on 12ht. they seem to be different from each other and i did not want to hi jack the other thread.

here is how my engine noise sounds: it sound like a valve need adjustment and it does not go away when the engine is gets hot. it get louder when you step on the right foot pedal and when you release the rigth foot pedal. at idle you can barely hear it, sometimes it even go away.

what i have done; adjusted the valves, crack the fuel line loose to find out from which cylinder it is coming form, the noise does not go away even when the fuel line is crack open.

what i am planning on doing: flush my engine and put synthetic oil on it maybe the 5W 40W (DEO) AMSOIL or the Mobil 1 synthetic oil on it.

what do you think is the problem? i planned to drive 3000 miles over the holiday, i am now thinking that i should not do the drive unless i can figure out where it is coming from or i am able to fix it.

 

[amaurer]

(You always use the smiley face next to your posts, makes me think you're excited to have a tapping noise!! hee)

Sounds like an exhaust leak to me... probe around the manifold, the turbo, and the donut with a piece of tubing and the other end in your ear.

 

[1tontoy]

Seems you've found your problem: its got 400,000KM's. Its not new anymore. Old diesels make noise. I say drive it like you stole it. It won't break b/c of a tapping noise as long as its running cool and has oil pressure. Just my $.02.

 

[rideglobally]

if you notice i am also banging my head by the end of the post. i hope you are correct about an exhaust leak, i will search for that again tomm. if you are correct i will put two smiling faces on my next post.

(You always use the smiley face next to your posts, makes me think you're excited to have a tapping noise!! hee)

Sounds like an exhaust leak to me... probe around the manifold, the turbo, and the donut with a piece of tubing and the other end in your ear.

 

[rideglobally]

all the vital signs seems to be good, oil pressure, water temperature, EGT, you can even hear the turbo and i am not losing oil. all is good except the tapping noise.

Seems you've found your problem: its got 400,000KM's. Its not new anymore. Old diesels make noise. I say drive it like you stole it. It won't break b/c of a tapping noise as long as its running cool and has oil pressure. Just my $.02.

 

[blis]

could be caused by pitting of the rocker arms, it isnt so rare at those km's in these engines... however, long as vitals are good you should be good to go..

 

[gbentink]

At ~400kkm, it could also be a flogged out top ring land and the ring flapping or a piece of ring broken off and floating around the top of the piston. Mine did that and another I pulled apart with 320kkm was showing signs of heading in the same direction.

Due to the hard hitting single spring DI and no steel inserts for the top ring land, it happens to all 12ht's. Great engine but they wear there and also rockers, exhaust valve guides and lifters. Very good otherwise

 

[jb BJ73]

i would be checking for an exhaust leak first as well, around each port.
would a leak down test diagnose those problems with the rings?

 

[rideglobally]

thanks all for all your help. despite all of this i like this engine.
i already pulled it apart and check the rocker arm, lifters, push rods all are in perfect condition showing no wear measured everything with a caliper (pix below). i also pulled the oil pan cover off to clean it out and also take a peak at the camshaft. i saw no wear on the camshaft. it was also very clean, not a lot of carbon deposit on the engine block and the pan was clean no oil gunk. in fact it made me think maybe this engine has been taken apart before.

today i will check for exhaust leak.

i am also thinking of changing to synthetic oil, particularly the AMSOIL (DEO) 5w 40w Diesel oil. what do you all think of this oil? it is getting positive review from the mechanic at the marina.

the next possible step will be to pull the head out and check the pistons. is there another way to check the piston without pulling the head?

At ~400kkm, it could also be a flogged out top ring land and the ring flapping or a piece of ring broken off and floating around the top of the piston. Mine did that and another I pulled apart with 320kkm was showing signs of heading in the same direction.

Due to the hard hitting single spring DI and no steel inserts for the top ring land, it happens to all 12ht's. Great engine but they wear there and also rockers, exhaust valve guides and lifters. Very good otherwise

 

[amaurer]

I really think this sounds like an exhaust leak - I had the exact same thing happen to my 3B after I took the head off; I thought I wrecked something, but really I just did a s***ty job with the exhaust donut.

the next possible step will be to pull the head out and check the pistons. is there another way to check the piston without pulling the head?

I've never seen a 12HT, but being a DI motor do you think you can pull the injectors and get a [borrowed] boroscope in there?

 

[rideglobally]

not an exhaust leak

the bad new is that it is not an exhaust leak, the good news is that when i added about a quart of Lucas oil the noise went down but did not go away.

(
Sounds like an exhaust leak to me... probe around the manifold, the turbo, and the donut with a piece of tubing and the other end in your ear.

this weekend i plan to take out the cylinder head and get it redone if needed as well as cleaning out the fuel injectors. this will also give me a change to see the top of the piston. if gbentink is correct then i am going to a total and complete over all of the engine. while i have the cylinder head out what kind of inspections can i do to the pistons and the crankshaft, like checking for looseness... etc

gbentink and others,
what is a good source for a "steel inserts for the top of the ring land" to be honest i have never heard of them before. is there a link you can send me on the pros and con on the experience with these steel inserts, i assume that the inserts are assembled by a machine shop, pictures would be great. also what is a good source for the 12ht overall kit. if i am going to end up overhauling this engine i want to end with a top of the line product and do not want to take short cut, as long as i can afford them.

the other challenge of course is that i am in los angeles, california. finding a good mechanic who have done many of these engine is a challenge.

thank you all and will keep you posted.

At ~400kkm, it could also be a flogged out top ring land and the ring flapping or a piece of ring broken off and floating around the top of the piston. Mine did that and another I pulled apart with 320kkm was showing signs of heading in the same direction.

Due to the hard hitting single spring DI and no steel inserts for the top ring land, it happens to all 12ht's. Great engine but they wear there and also rockers, exhaust valve guides and lifters. Very good otherwise

 

[gbentink]

The steel inserts are cast into the pistons by the piston manufacturer. It is obvious when the piston is new because the colour of the aluminium alloy and steel is different.

You will not spot the ring land damage without removing the piston, unless a piece of ring has broken off. I doubt that has happened yet and I hope not else a basic hone wont be sufficient to remove the bore wear.

Lifters should be replaced too. The factory items hard chrome plating cracks and starts to come off where it follows the cam.

For rocker arm wear, best measured with a micrometer, but in my opinion (maybe not shared by others) if it looks ok and the ridge is very minor, I would lightly rub it down with 1200 wet and dry and be done with it. be sure to install the shaft the right direction around - the oil flow entry hole is only at one end.

 

[amaurer]

If indeed it is a worn ring land (although its not clear to me that Lucas oil would help with that as you've described) there is a thread here somewhere about that on an H engine...

ah, here it is:
https://forum.ih8mud.com/diesel-tec...2249-stuck-piston-ring-diagnostic-help-h.html

The H doesn't have the steel inserts, but you can see it needs it:

 

[gbentink]

Thanks for the pic. I thought the top ring issue was limited to the direct injection engines.

This shows the idential thing on the precom engines. Simply poor metallurgy in the pistons.

BIGBROWN DOG posted a set of custom pistons. They look great quality, but the steel insert should be visible clearly ~ 1mm above and below the ring groove.

In any case, modern metallurgy may have already fixed the problem.

 

[LenaW]

Big end bearings, maybe?

 

[watrob]

For a start don't run synthetic oil in this motor, as is the 2H they should be run on the old fashion mineral oils. Synthetic oil when it gets hot thins and your oil pressure will drop away to nothing.

I have rebuilt a 2H and put in synthetic, when it reached operating temp the oil pressure fell away, swapped to mineral , all ok again. Even the manuals say if your pressure drops it maybe because of the wrong type of oil used.

I also run one litre of canola with every 100 litres of diesel fuel, also helps quieten down the IP.

Like you, I have adjusted the tappets etc, these motors are a little noisey, but with 400,000 on the clock the last thing you want to do is put a synthetic oil in or a heavy detergent base oil. With the new low sulpher diesel fuel, heavy based engine detergent oils are not required to capture the sulpher as much (which causes the oil to turn black), thats why I add a little canola oil to the fuel which seems to soften the motor noise.

PS. And I change the oil quite often as mineral oil is half the price of synthetic.

 

[PHIL O]

x2 on the big end bearings. the piston might be slapping on the valves creating the noise you hear. so no matter how you adjust valve clearances, they just wont go away.

 

[rideglobally]

strange tapping noise gone away

the tapping noise has gone away, i have not done anything different, except added more lucas oil, but i did that before tapping did not go away. so i do not know what is really going on..... i am not complaining it is a great thing. i had plans to rebuild the engine in May because of the tapping noise now i am wondering whether i should rebuild it? again the engine has 400. km what do you think?

 

[roscoFJ73]

If its got good compression leave it,especailly if the noise has one away.
Most toyota diesels in australia run on 20-50 oil,its also what Toyota sells and recommends for the older diesels.
Maybe this engine has spent its life on 20-50
I would try that and see how it goes. California should be warm enough with summer coming on

 

[rideglobally]

i will have the compression check, what about the fact that the engine have over 400 km on it, i am concern about reliability, but i also want to save that money. thx

If its got good compression leave it,especailly if the noise has one away.
Most toyota diesels in australia run on 20-50 oil,its also what Toyota sells and recommends for the older diesels.
Maybe this engine has spent its life on 20-50
I would try that and see how it goes. California should be warm enough with summer coming on