a heck of a lot of carbon buildup in the exhaust manifold of my HZJ81 (1 Viewer)

[John Young]

Hi all. I've written a bit about the Japan market HZJ81 converted to LHD I recently bought it at auction here . Long story short, my regular mechanics are tearing into it pretty good, getting the turbo rebuilt and so on. I've also been asking them to clean everything as much as possible as I will likely be the next guy taking a wrench to it when it is back in the US in a year or so.

Anyways, they found that the main exhaust had a lot of carbon built up in it. It seemed like a REAL LOT to me:

It is back together again. But it is not generating a heck of a lot of power even after the turbo rebuild. My question is, should I be looking at replacing the muffler? Is it likely also to be filled with this stuff? What else should I be asking my mechanics to do?

Probably unrelated, I'm also told that it tends to hunt for gear and revs high at higher speeds. I've asked them to look at this as a transmission issue, but could it be related?

I'd really appreciate any advice on what my next steps should be....

 

[mudgudgeon]

First up, your pic is of the intake manifold.
If it has an EGR system on it, look at deleting it (not legal in some states). EGR recycles exhaust gases back through the engine to reduce emissions. Soot will collect in the intake, near complete blockage is not uncommon

Carbon should mostly burn up in the exhaust. I'd look at other reasons for lack of power.

Hunting for gears may possibly be due to incorrectly adjusted TPS cable(throttle position sensor), but autos aren't my thing

 

[GTSSportCoupe]

What he said ^^

Cleaning all that up will undoubtedly make it run better. Also look in the intake ports of the cylinder head and back of the valves for more EGR soot. This is a common problem on 2LTE's which also have EGR systems. Definitely block it off and/or completely remove the system.

The trans made need adjustment to the kick-down cable too. Also look into getting the trans flushed with fresh Dextron ATF.

 

[John Young]

Thanks MG and GTS,

And 'doh!' re intake vs exhaust manifold. I remember looking at the photo and thinking, 'hey, that's a nice and clean exhaust manifold' without thinking it through.

Anyhoo.... Thanks for the thoughts on the EGR and the Throttle Position Sensor. I've already had them flush the ATF in the transmission as part of the initial go-through, so either its an adjustment or a repair needed most likely. I They have sent the truck out for a comprehensive interior cleaning, which it needed very badly. Hope to drive the truck just before I leave for the US at the end of the week for the Thanksgiving holiday. Is there any engine cleaning product I ought to try? I often find that particular products available in the US and other markets are not available here, so my luggage always is heavier inbound than outbound.

 

[roscoFJ73]

Anyways, they found that the main exhaust had a lot of carbon built up in it. It seemed like a REAL LOT to me:

Yes, the manifold in my shed had almost no carbon at 145000klms. I would be trying to find how it accumulated.
A wrecker in Australia that imports diesels said he recommends running a thin oil through it, then dumping it and running another batch of thin oil through it.
But IMO , once they are running right, they will clean themselves.

 

[John Young]

Yes, the manifold in my shed had almost no carbon at 145000klms. I would be trying to find how it accumulated.
A wrecker in Australia that imports diesels said he recommends running a thin oil through it, then dumping it and running another batch of thin oil through it.
But IMO , once they are running right, they will clean themselves.

Thank you Roscoe. Could you expand a bit? Run a thin oil (5w40?) through what exactly? I'm having a little trouble tracking...

 

[roscoFJ73]

5/30 or something like that. It wont hurt as long as the engine is being used lightly. "Through" the engine with a couple of short mileage oil changes. The lighter oil will dissolve the sludge built up around the engine.

 

[John Young]

Hi again, guys. More advice requested. The guys at my local garage took things apart, cleaned everything and had the turbine rebuilt, and put it all back together. It's very pretty now. And it drives fine and gets to 120 kph without fuss. But despite rebuilding the turbine there appears to be no boost and the turbine is not spinning as near as I can tell.

Are there any simple things I ought to be looking for if the turbine does not spin up at all? Or is it likely to just be a poor job on the rebuild?

One other thing they did was remove the cruise control servo motor from the throttle linkage. I've got a new one and I'm going to put it in in the next day or so. I can't imagine how that would be a factor unless there was something electrical that could prevent the turbine from running--but the turbine seems to be completely independent of anything electrical as far as I can tell. Certainly when I crank the throttle by hand the RPM's are high enough that it seems to me that the turbine ought to have kicked in.

 

[dan1554]

What are you using to measure intake manifold pressure?

 

[John Young]

What are you using to measure intake manifold pressure?

Perhaps duct tape, like Red Green?

Seriously, I'm really a newbie on all this with no prior experience with diesels or diesel turbochargers. Not even sure where I would get an appropriate gauge here in Dubai, or the fitting to go with it. I can get a regular pressure gauge and some generic fittings at dragon mart most likely, but what else do I need? And is there a handy reference for the fitting sizes somewhere? I've read through the 1HZ-FT FSM without much sinking in I'm afraid.

I'm just learning as I go along on this...

 

[GTSSportCoupe]

I don't think a 1HZ gets easily up to 120km/h in a heavy 80 series without a working turbo. So I'd say you're probably boosting ok. A boost gauge is a pretty easy thing to get a hold of and connect. If you have doubts; that's definitely the way to go.

Which leads me to: Are you sure it's a turbocharged 1HZ? Not a 1HDT? Have you any pictures of the engine bay and motor?

 

[MonsterCruiser]

I don't think a 1HZ gets easily up to 120km/h in a heavy 80 series without a working turbo. So I'd say you're probably boosting ok. A boost gauge is a pretty easy thing to get a hold of and connect. If you have doubts; that's definitely the way to go.

Which leads me to: Are you sure it's a turbocharged 1HZ? Not a 1HDT? Have you any pictures of the engine bay and motor?

Photos in his other thread here:

Builds - spinning the roulette wheel (twice) on a 1996 Middle East HDJ81 at auction

I have this terrible habit of having a glass of something and then looking at local adverts and auctions. Back when I was married I would self-regulate to some degree and if things got out of hand, well the spouse would let me know. Now... well the governors are off. A few days ago I saw an...

forum.ih8mud.com

1HD-FT

 

[GTSSportCoupe]

1HD-FT

 

[dan1554]

Dubai would strike me as a place to easily find a boost gauge. I have mine hooked up to a t-fitting between the turbo and waste gate actuator. But you could probably tap in to any vacuum line coming off the intake manifold if thats too hard to get to. As @GTSSportCoupe said if if feels good up to 120kph you are probably ok, but I'd want a gauge all the same.

 

[John Young]

I was just down in the garage pulling the cruise control actuator and took the opportunity to poke around, and I did find something--an open vacuum line in the EGR system:

That I think is supposed to connect here:

Hoping for a quick fix, I started the coal burner and put my finger over the open line and juiced it. No joy. No appreciable vacuum either.

I went through the FSM for the 1HZ-FE (I will eventually get that right) again and see a lot of diagrams, but no real theory of operation which would be very helpful indeed.

They are not the clearest diagrams...

Any suggestions for next steps? Is this vacuum hose likely to be part of the problem do you think?

 

[dan1554]

No 1hd-ft guru but my guess is someone disabled the egr. Probably wouldn't get any vacuum or pressure as that part of the system is no longer connected to anything. Again just a huge guess. If thats the case I don't think its a problem per se. Might be related to your carbon issues. Likely makes no difference regarding the turbo though.

 

[MonsterCruiser]

That definitely looks like the source of the problem to me. In the last photo that line is directly off the intake that would be pressurized by the turbo. I don't know for sure, but I'm guessing it's possibly supposed to connect to the diaphagm on the fuel pump (if the -FT has that like the -T does).

 

[MonsterCruiser]

I didn't read though this in detail, but this thread may help as well:

1HD-FT EGR parts identification

Hi. New here, but reading since some years. It would be nice if you can help me to identify all parts of the EGR system on my engine. I want to remove it as i don't need it :) Is there some trouble with the ECU? Will it throw the check engine light? The solenoids near the two EGR valves are...

forum.ih8mud.com

 

[John Young]

That definitely looks like the source of the problem to me. In the last photo that line is directly off the intake that would be pressurized by the turbo. I don't know for sure, but I'm guessing it's possibly supposed to connect to the diaphagm on the fuel pump (if the -FT has that like the -T does).

Thank you MC. I sure wish there was a theory of operation written up for this somewhere. The weekend starts tomorrow afternoon here. I am going to go try to get a pressure gauge and spend some time with this cranky thing. The engine itself sounds very good--it only appears to have 190K km on it, near as I can tell.

 

[mudgudgeon]

Hoping for a quick fix, I started the coal burner and put my finger over the open line and juiced it. No joy. No appreciable vacuum either

A diesel engine typically has no throttle body, so you won't see any vacuum on hoses connected to the intake.

If the EGR system uses vacuum servos (not sure if does) the vacuum comes from an engine driven vacuum pump and vacuum reservoir.

In regards to boost, with the stock turbo you won't hear a lot of real evidence of the turbo building boost just by revving the engine while in the shop.
Boost is dependent on engine load, you can't load the engine in a workshop without a dyno.
On road, depending on the state of tune, boost from a stock turbo and stock tune can come on kind of subtle.
Boost gauge is cheap and will give you definite information