1HDT turbo rebuild/replace??, light smoke and oil consumption (1 Viewer)

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Hi all,

I have been working on going through my 1991 hdj81 and could use some advice. Short story is i suspect that my turbo seals are leaking (long story below). I want to know what else I should check before rebuilding/replacing the turbo and also advice on turbo rebuild/upgrades.

It generally runs great, but has some minor white smoke (most noticeable when warm after a long highway run or when merging onto the freeway at night and looking back in rearview mirror. I am not sure if the smoke is white-grey (burnt oil) or white (raw diesel in exhaust). Smells like diesel to me. It also has consumed ~1.5 quarts of oil in 5000km. No leaks that i know of. Some blowby present when warm and removing the oil fill cap (it does not make the cap dance or blow like a steam engine). Mileage has been lower than i expect (17-20 mpg on freeway, running 60-70 mph). So i have been checking everything over.

Checked the turbine while on truck:
No signs of damage to the compressor wheel or housing. Some noticeable play in the shaft (more radial then axial). I tried to measure it on the truck using a dial indicator for axial and feeler gauges (measure the change in gap between the wheel and housing). Both measurements were suspect and real reliable but i got:
Axial ~4-6 mils (FSM spec <5.1 mils)
Radial ~10-12mils (FSM spec <7.1 mils)
I am not sure if it really is this far out of spec or if it is just my bad measurement setup. I would need to get it on the bench with access to both ends of the shaft and a dial indicator through the oil port to do any better.

Performed a compression check:
Cold: 1- 505psi, 2 - 500psi, 3 - 500psi, 4 - 505psi, 5- 510psi, 6 - 510psi
Cold test looked good (it can be a better sign of problems), ran out of time but will redo it warm when i get time. It is a pita because the adapter hose is a pain to get on and i have to remove the crosser pipe, glow plug rail, and injector return piping.
FSM spec:
Nominal Compression pressure: > 498 psi
Minimum pressure: 356 psi or more
Difference between each cylinder: 71 psi or less

Checked for oil in the intake. It was fairly wet between the air cleaner and turbo inlet, starting at the breather fitting from the valve cover. The crossover pipe also had some oil present (mostly around the turbo outlet/flex coupling and some at the manifold gasket. The breather tabs inside the valve cover were open to ~15mm, so bend them down to ~4mm gap and I removed breather and vented it into a open bottle temporarily. I cleaned the air intake and crossover pipe up with parts cleaner and wiped them dry as possible, put it back together and drove it to see if the smoke/oil in intake was coming from the breather. In the past 10 days since doing this i drove it maybe 5 times and the smoke did not change. when i re-opened the crossover pipe it again had some oil present (although less than before).

Also checked valve clearances (have not ordered new shims yet): A couple were outside the fsm specification range by 1-3 mils. Not sure how much of an effect this might have. My measurements may be 1 mil thin as i did not want to try to force in a shim that was too thick. Seemed like there was an oil layer that might affect it as well.
Intake ( spec 6 - 10 mil): 1 - 4mil, 2 - 5mil, 3 - 6mil, 4 - 6mil, 5 - 6mil, 6 - 5mil
Exhaust ( spec 14-18 mil): 1 - 12mil, 2 - 13mil, 3 - 13mil, 4 - 13mil, 5 - 13mil, 6 - 11mil

Below is a synopsis of what i have done so far:
It had low mileage (120,000km) and mainly had a few issues do to sitting (slow sticky power windows, corroded ac condenser, frozen transmission kickdown cable, bad shocks and inoperable fan clutch). It did great on my 2000 mile roadtrip from to bring it back from GA to Ca. So far i have done the following, as i go through the truck to make sure i can trust it for back country camping and long trips with the family:
  • LubriMoly flush of fuel injectors/pump
  • Replaced all fluids/filters, shocks, tires and wheels (17" from 2005 seqouia)
  • Checked/greased all wheel bearings, u-joints, birfs, and replaced axle seals
  • Replaced Timing belt/tensioner
  • Replaced cooling water houses, thermostat, and fan clutch
  • Replaced AC condenser, drier and compressor (had leaky o-rings and some corrosion)
  • Replaced turbo water and oil hoses (going to replace hard lines also when i have it off as i already have them)
  • Cleaned up contacts on Neutral start switch, hazard switch and 24 V isolater relay
  • Replaced passenger window regulator
  • Swapped in shoulder strap seat belts for the lap belts
Future items:
  • Plan on replacing Big End Bearings this weekend if possible (i have a wife, 3 year old and 2 month old daughter that get jealous of my time)
  • Check injector timing, pull injectors and service if needed
  • Larger disc brakes, Lockers, Lift/coil springs, 3" exhaust, EGT probe and gauge, install 3rd row seats
 
Last edited:
Joined
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Turbo is the victim. Engine is the problem.
Smoke can be valve seals etc, but turbo seals leaking is caused by crankcase pressure climbing.

What is the compression test spec for those?
 
Joined
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Messages
56
Location
Southern California
Turbo is the victim. Engine is the problem.
Smoke can be valve seals etc, but turbo seals leaking is caused by crankcase pressure climbing.

What is the compression test spec for those?

That was my thought originally, but the compression #s looked very good. I still need to check it warm, but in my experience with marine diesels is compression usually just gets better at the once warm. Will try and get some warm numbers soon also.

Is there any way that exhaust gases can make their way from the turbine housing into the oil return hose of the turbo? If the seal on the turbine side was bad....

Compression pressure: 1HD-T
35.0 kg/cm2 (498 psi, 3,432 kPa) or more
Minimum pressure: 1HD-T
25.0 kg/cm2 (356 psi, 2,452 kpa) or more Difference between each cylinder:
5.0 kg/cm2 (71 psi, 490 kPa) or less
 
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The turbo seals we refer to are nothing more than piston rings. Circular metal rings that fit in a groove on the turbine shaft and compress a bit as they fit into the housing. A gap in the seal is always present to allow for expansion. It seals as sloppy as a piston ring. It cannot be a positive seal as the turbine runs at 150k rpm while the seal, which is a fraction of a mm away from it, doesn't move at all. A small bit of exhaust always does make its way from the turbine past the turbine seal into the bearing housing. That's bennifical actually as it constantly pushes the small bit of oil that collects around the seal back into the bearing section. The bearing section has the lowest pressure compared to the compressor side and the turbine side. The problem comes when excessive blowby increases crankcase pressure which backs up the turbo oil drain and in turn pressurizes the turbo bearing housing. This begins to lessen the pressure differential and the flow of gasses can even reverse and cause the gas flow to go from bearings section outward through the compressor seal and the turbine seal. Oil then can begin to migrate through the seal and out of the bearing housing. This can be somewhat dimished by increasing boost to restore the differential on the compressor side but nothing can be done on the turbine side.

In short......oil is always present imediately at the seal and the seal always leaks.
The question is: which way is it leaking.
 
Joined
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Messages
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Gerg, Thanks for the explanation, that was helpful.

I am still not really sure where to go with this, so anyone with advice is appreciated.
Can i measure the crankcase pressure and how much blow by is excessive (i will take a video of what is coming out of the oil cap tomorrow)?
Can you have excessive blow by even if the compression test is good (valves, sticky rings ect..)?
Would a leak test tell me anything more than the compression test?
Given how much this truck sat the past few years, i am sure it is all sludged up. Is it worth trying a decarbonizing engine flush (sea foam or lubrimoly)? Any tips on doing this (Pours some seafoam in the glow plug holes and let i soak over night)??
Could my slightly off valve timing cause blow by?
Given the play i measured in the turbo shaft, am i due for a rebuild?

I really don't have a feel for the 1hdt as to how much smoke, blow by and oil consumption are reasonable. My main experience is with older perkins marine diesels and they always blow a bit of smoke :) I will try to get some videos of the exhaust smoke, i would consider just barely noticable at idle increasing to very light at ~2000rpm.
 
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Weird, that means your compression numbers are perfect. Which pretty much never happens. Do you trust the tester? Is a leak-down test available?
 
Joined
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I know... It is a brand new high quality gauge that had excellent reviews.
below is the adapter (has check valve in the tip)

If i can find an adapter i could check it against a high pressure gauge at work...
I don't have a leak down tester, but could try to find one if it can provide a more useful diagnosis.

The compression #'s were ~20 psi lower if i did not crank for several revolutions. I got very consistent results once i timed the amount i cranked by the number of pulses (4 or 8 revolutions i think). I am also near sea level, so that may help as well.
 
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Been down this road. Before you throw money at it, vent your valve cover to atmosphere for a few days of driving and see if it helps. Also with the compression test, how many times are you cranking it over?
-edit-
Now I see... I think 4 revolutions for each cyl is what my mechanic did.
 
Joined
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Been down this road. Before you throw money at it, vent your valve cover to atmosphere for a few days of driving and see if it helps. Also with the compression test, how many times are you cranking it over?
-edit-
Now I see... I think 4 revolutions for each cyl is what my mechanic did.
Yeah i wasn't sure if it was 4 compression cycles or 4 crank shaft revolutions?? I didn't have a helper so i just did it by sound, but with the glow plugs out you can hear the compression pretty well. I may have been doing 8 crank shaft revolutions. When i did less cranking time it resulted in ~10-20 psi lower compression... Still great #'s and very little variation between the different cylinders.

I vented the valve cover breather to atm (an open container) a few weeks ago before i cleaned out intake tract the first time. Didn't change the smoke, but reduced the oil in the air cleaner to turbo section. Oil still re-appeared in the cross over pipe, although much less (not sure if this due to the breather or it just not being run long enough to build up again).
 
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Your compression numbers are far better than mine but it looks like the core symptoms are similar. I replaced pretty much everything but the engine and that is going under the knife later this year. Might be a combination of issues in your case. Either way the turbos in these are not the greatest in efficiency so if you planned on replacing it anyway its probably a good place to start. I just wouldn't expect smoke-free operation until you eliminate whatever is coming from the breather.
 

GTSSportCoupe

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It generally runs great, but has some minor white smoke (most noticeable when warm after a long highway run or when merging onto the freeway at night and looking back in rearview mirror. I am not sure if the smoke is white-grey (burnt oil) or white (raw diesel in exhaust). Smells like diesel to me. It also has consumed ~1.5 quarts of oil in 5000km. No leaks that i know of. Some blowby present when warm and removing the oil fill cap (it does not make the cap dance or blow like a steam engine). Mileage has been lower than i expect (17-20 mpg on freeway, running 60-70 mph). So i have been checking everything over.

White/grey exhaust smoke visible at night while accelerating is perfectly normal. All these old diesels without emissions control are like that. I don't think this is a problem.

It's also normal to have some postive pressure at the oil cap. Diesels are very high compression, and some air will get past the rings. Yours sounds fine to me, but compare it to videos of other 1HD/1HZ on youtube to get a better feeling for it.

The mileage you're getting sounds spot on also. I have a friend with a HDJ81, and his mileage is identical to yours. They're big/heavy trucks, and the AWD system doesn't help either.



Checked the turbine while on truck:
No signs of damage to the compressor wheel or housing. Some noticeable play in the shaft (more radial then axial). I tried to measure it on the truck using a dial indicator for axial and feeler gauges (measure the change in gap between the wheel and housing). Both measurements were suspect and real reliable but i got:
Axial ~4-6 mils (FSM spec <5.1 mils)
Radial ~10-12mils (FSM spec <7.1 mils)
I am not sure if it really is this far out of spec or if it is just my bad measurement setup. I would need to get it on the bench with access to both ends of the shaft and a dial indicator through the oil port to do any better.

It's normal for these turbo's to have some radial play. This is the clearance that the oil fills in the journal bearing when the engine is running. If the compressor is getting close to the housing, then the turbo might be getting close to rebuild time.


Performed a compression check:
Cold: 1- 505psi, 2 - 500psi, 3 - 500psi, 4 - 505psi, 5- 510psi, 6 - 510psi
Cold test looked good (it can be a better sign of problems), ran out of time but will redo it warm when i get time. It is a pita because the adapter hose is a pain to get on and i have to remove the crosser pipe, glow plug rail, and injector return piping.
FSM spec:
Nominal Compression pressure: > 498 psi
Minimum pressure: 356 psi or more
Difference between each cylinder: 71 psi or less

That's excellent compression; I don't think you have any worries there.

Checked for oil in the intake. It was fairly wet between the air cleaner and turbo inlet, starting at the breather fitting from the valve cover. The crossover pipe also had some oil present (mostly around the turbo outlet/flex coupling and some at the manifold gasket. The breather tabs inside the valve cover were open to ~15mm, so bend them down to ~4mm gap and I removed breather and vented it into a open bottle temporarily. I cleaned the air intake and crossover pipe up with parts cleaner and wiped them dry as possible, put it back together and drove it to see if the smoke/oil in intake was coming from the breather. In the past 10 days since doing this i drove it maybe 5 times and the smoke did not change. when i re-opened the crossover pipe it again had some oil present (although less than before).

Every single one of these old Toyota diesel's has oil from the PCV breather in the intake system of the engine. Most all of us disconnect this and use some form of catch can, or just vent it under the truck with a long hose like the older landcruiser diesels do.

Also checked valve clearances (have not ordered new shims yet): A couple were outside the fsm specification range by 1-3 mils. Not sure how much of an effect this might have. My measurements may be 1 mil thin as i did not want to try to force in a shim that was too thick. Seemed like there was an oil layer that might affect it as well.
Intake ( spec 6 - 10 mil): 1 - 4mil, 2 - 5mil, 3 - 6mil, 4 - 6mil, 5 - 6mil, 6 - 5mil
Exhaust ( spec 14-18 mil): 1 - 12mil, 2 - 13mil, 3 - 13mil, 4 - 13mil, 5 - 13mil, 6 - 11mil

I'd say these are as expected given normal wear of the motor. Don't think they're tight enough yet to cause issues.

Below is a synopsis of what i have done so far:
It had low mileage (120,000km) and mainly had a few issues do to sitting (slow sticky power windows, corroded ac condenser, frozen transmission kickdown cable, bad shocks and inoperable fan clutch). It did great on my 2000 mile roadtrip from to bring it back from GA to Ca. So far i have done the following, as i go through the truck to make sure i can trust it for back country camping and long trips with the family:
  • LubriMoly flush of fuel injectors/pump
  • Replaced all fluids/filters, shocks, tires and wheels (17" from 2005 seqouia)
  • Checked/greased all wheel bearings, u-joints, birfs, and replaced axle seals
  • Replaced Timing belt/tensioner
  • Replaced cooling water houses, thermostat, and fan clutch
  • Replaced AC condenser, drier and compressor (had leaky o-rings and some corrosion)
  • Replaced turbo water and oil hoses (going to replace hard lines also when i have it off as i already have them)
  • Cleaned up contacts on Neutral start switch, hazard switch and 24 V isolater relay
  • Replaced passenger window regulator
  • Swapped in shoulder strap seat belts for the lap belts
Future items:
  • Plan on replacing Big End Bearings this weekend if possible (i have a wife, 3 year old and 2 month old daughter that get jealous of my time)
  • Check injector timing, pull injectors and service if needed
  • Larger disc brakes, Lockers, Lift/coil springs, 3" exhaust, EGT probe and gauge, install 3rd row seats

In summary I'd say your motor is no different than any other 1HDT with the same number of km's. The oil consumption is perhaps a bit on the high side however. Does it have any oil leaks? It's possible this oil is mostly exiting the PCV breather. Using a catch can will confirm this. I doubt your oil is being lost past the rings or valve guides. I have seen a CT26 turbo spurt oil out the compressor housing outlet when the motor was revved, but it turned out the turbo had been rebuilt incorrectly allowing oil past the seals.

You're definitely on the right track with the maintenance and upgrades.
 

IanB

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A visible haze in the rearview mirrors with headlights behind you under acceleration at night is normal with these old diesels, there's no emissions equipment to clean up the exhaust. That being said, 1.5qt of oil disappearing over 5000kms is quite a bit. Now that you are collecting the blow by in a bottle, are you getting enough there that it makes sense that's where most of it is going?

If you are running stock boost level (~10psi) then you'll be maxing out boost at about 100km/h, to go faster than that you're just dumping in more fuel, there is no more air available. Your fuel consumption figures seem pretty normal to me. Upping the boost to 15psi makes the truck much happier on the highway.
 
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Thanks everyone for the input.

I haven’t been running the breather into bottle long enough to gauge how much oil is coming out. So far it’s only captured a small amount of oil, but I will keep an eye on it and see whether it accumulates in the crossover pipe over the next few weeks.

I’m still concerned that the turbo radial play was so out of spec but I won’t know for sure until I pull it off and measure it properly. I was set on rebuilding the turbo or upgrading, but I will do some more troubleshooting before I do anything major. It hasn’t helped matters reading a few horror stories of turbo failure causing runaway...

I am running stock boost, but I haven’t measured it as I don’t have a boost gauge or EGT. Future upgrades hopefully. At minimum I was thinking of swapping in a 1hdfte turbo (if I can find a low km/cost) and use either a modified Supra or mamba built to fit compressor housing. Was thinking that with a 3” exhaust would give me a good combination of drivability and reliability.
 
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EGT gauge should be your first priority. If your turbo grenades - there goes your motor. Unfortunately speaking from experience.

Not based on experience - was reading that a Cummins guy placed the turbo oil return line in a bucket of water with motor running to check for crankcase pressurization.
 
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There is actually a Cummins device that has a restrictor and a manometer you attach to the blowby tube and at certain rpms of no load it will give you different pressure readings indicating volume of blowby. Pretty cool.
 

mudgudgeon

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White/grey exhaust smoke visible at night while accelerating is perfectly normal. All these old diesels without emissions control are like that. I don't think this is a problem.

It's also normal to have some postive pressure at the oil cap. Diesels are very high compression, and some air will get past the rings. Yours sounds fine to me, but compare it to videos of other 1HD/1HZ on youtube to get a better feeling for it.

The mileage you're getting sounds spot on also. I have a friend with a HDJ81, and his mileage is identical to yours. They're big/heavy trucks, and the AWD system doesn't help either.





It's normal for these turbo's to have some radial play. This is the clearance that the oil fills in the journal bearing when the engine is running. If the compressor is getting close to the housing, then the turbo might be getting close to rebuild time.




That's excellent compression; I don't think you have any worries there.



Every single one of these old Toyota diesel's has oil from the PCV breather in the intake system of the engine. Most all of us disconnect this and use some form of catch can, or just vent it under the truck with a long hose like the older landcruiser diesels do.



I'd say these are as expected given normal wear of the motor. Don't think they're tight enough yet to cause issues.



In summary I'd say your motor is no different than any other 1HDT with the same number of km's. The oil consumption is perhaps a bit on the high side however. Does it have any oil leaks? It's possible this oil is mostly exiting the PCV breather. Using a catch can will confirm this. I doubt your oil is being lost past the rings or valve guides. I have seen a CT26 turbo spurt oil out the compressor housing outlet when the motor was revved, but it turned out the turbo had been rebuilt incorrectly allowing oil past the seals.

You're definitely on the right track with the maintenance and upgrades.

Agreed with all of the above 100 %.

At 120k km, it's only just run in.

Vent the PCV to atmosphere for a couple of months and see what happens.
 

mudgudgeon

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If you can find the HD-T, HZ, PZ engine repair manual, there's a page or two in checking turbo shaft play.

A little side to side play is ok, the shaft floats on a film of oil. When you check for play, you'll displace the oil.
play in/out is definitely bad as there's greater chance the compressor could contact the housing
 
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If you can find the HD-T, HZ, PZ engine repair manual, there's a page or two in checking turbo shaft play.

A little side to side play is ok, the shaft floats on a film of oil. When you check for play, you'll displace the oil.
play in/out is definitely bad as there's greater chance the compressor could contact the housing

I have the fsm and am out of spec per my measurements, it’s just that you need to grab both sides of the axle while the dial indicator is inserted through the oil port, so I used feeler gauges between the compressor wheel and housing to measure the change in clearance between the wheel and housing. In order to measure it properly I have to remove it... at that point I will just break it down throw in a rebuild kit as it really isn’t that much more work once it is out.

Anyone have suggestions on which rebuild kit to buy, so that I can have something in hand?

I would just keep it stock until I work out an upgrade path (I have been looking for a low km 1hdfte turbo on gumtree based your posts)


Below are my notes (hidden in that 3 page story)
Checked the turbine while on truck:
No signs of damage to the compressor wheel or housing. Some noticeable play in the shaft (more radial then axial). I tried to measure it on the truck using a dial indicator for axial and feeler gauges (measure the change in gap between the wheel and housing). Both measurements were suspect and not real reliable but i got:
Axial ~4-6 mils (FSM spec <5.1 mils)
Radial ~10-12mils (FSM spec <7.1 mils)
I am not sure if it really is this far out of spec or if it is just my bad measurement setup. I would need to get it on the bench with access to both ends of the shaft and a dial indicator through the oil port to do any better.
 
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Doing BEB this weekend and before I drained it I was able to get warm compression numbers yesterday. Using my previous measure of 8 revolutions they were all within 515-520psi. Interestingly if I timed it for ~4 revolutions they we all within 455-460psi. Either way, respectable numbers very low variation.

Basically cranking to the count of eight or four. I think I settled on eight before as it seemed to level off there and be more repeatable. The fsm doesn’t say anything about how long to crank, only that it be >250rpm. It also says to remove all glow plugs first, which I did. Just want to make sure I am interpreting this correctly, is that what everyone else has been doing?
 

mudgudgeon

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I don't think measuring shaft play at the compressor is necessarily going to give you a good gauge on the condition.

I would crank until compression peaks. If you get more compression after 4 rotations, go 8
 

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