1HDT Valve Guide Failure

[oztec2007]

Hi all
I've had a good run the last year on veg until now.

Performance problems a thing of the past since adjusting IP presets.
It has more power on veg than diesel!

I've developed a big problem on start up while hot I disappear in a cloud of whitish smoke smelling of engine oil for the first minute, attracting a few comments and funny looks. After that everything is fine and there is no smoke on the open road operating at any performance level.

I have the turbo and the exhaust manifold off and have discovered the source of the burning engine oil is not the turbo I first suspected but is in number 3 cylinder exhaust port. thick black engine oil is all over the inside of the port and the valve.

taking the rocker cover off reveals the oil has drained into the port down the valve stem as it is the only one showing a lack of pooled oil against the cam plunger.


Iv'e decided the most likely cause is the exhaust valve stem seal cooked.
Hope my valve guide is OK?

Has anybody had experience replacing a seal without taking the head off?
Mark

[Qwarla]

Re: 1HDT valve stem seals?

I have seen a method used on petrol engines, where the cam and rocker gear is removed. Spark plug removed and screwed in an adaptor to which a hose is connected from the compressed air supply.
The air keeps the valves pushed shut and stops them falling into the cylinder when you remove the retainers and valve springs.
It's obviously very important to ensure the air supply remains on.

I would think the same sort of thing should work on a diesel. Glow plug holes may be a better choice than the injector holes.

Just remember that when pressurizing the cylinder the engine is going to want to turn until that piston is at the bottom of it's stroke.

[Johnnojack]

Re: 1HDT valve stem seals?

You should be able to see the seals under the springs. If you see none there are none. If your engine has seals you should also be able to feel if they are hard and therefore not sealing anymore. Apart from the compressor method another which I have used with success on a petrol engine is to fill the space above the piston with thin (new and clean) nylon rope by feeding it into the spark plug hole (Injector hole?) If it is indirect injection this may be difficult. Then hand crank the piston upwards to jam the valves against the head so the springs can be removed 2 at a time. When each cylinders valves are fixed crank piston back down, remove rope and then repeat for the next cylinder.

[Nuddy]

Re: 1HDT valve stem seals?

1HDT is DI so rope trick should work. Good luck. Nothing to lose, if it doesn't work you simply have to take the head off.

[Tony From West Oz]

Re: 1HDT valve stem seals?

An alternative is to remove the injector / GP and turn the engine feeling the air expelled from the hole into the combustion chamber. The piston will be at TDC or close to it.
As these diesels are "interference" engines (if a valve is open it will contact the piston at or before TDC). Thus the valve cannot drop into the cylinder. This can be verified by trying to push the valve down when that piston is @ TDC. If the valve doesn't go down very far (1 or 2 mm) then you can do what you like to that cylinder's valves and not fear dropping a valve into the cylinder.

I wish you an uneventful repair.

Happy new Year,

Tony

[BrianW]

Re: 1HDT valve stem seals?

I would go with Tony on this one since the clearance is minimal and getting some rope through the 6mm hole at the bottom of the injector slot is going to be a challenge. The valves go straight down so you should not bend the end and the piston tops are plenty thick enough. Just don't go hitting the center of the valves to test how strong they are.

So it should work and I hope it does, but I am not convinced on the diagnosis. These are bucket over valve setups and being able to say it is the problem is a big call. If you have the cam and buckets off already then you may be right. Check if the guide has gone hard or not since if it hasn't the guide may be worn out.

My money is on low compression though. I would start with a compression check and try have a look at you piston tops with an endoscope. My tke on your problems is that once it starts to boost the low compression is not an issue - then heat is generated and you don't see it until next startup.

For me, on my 80, the 1HDT is coming out and a 12HT is going in. After running mine on vege for quite some time I have decided they are not well suited. The 12HT has many advantages over the 1HDT for WVO and I am embracing them.

Good luck
Brian

[oztec2007]

Re: 1HDT valve stem seals?

Thanks for all your suggestions sofar

I have been able to order a valve stem seal individually from toyota $13.95 it will arrive in the new year.The fact that they are available individually seems to suggest that they are aware of the need to replace the odd one here and there. Hope so?

That sounds good using TDC for that piston and a rope if needed.

I had a tappet rattle for a long time even before going veg which was slowly getting worse these last few weeks. I think there would be a carbon build up on the valve seat from all this burnt engine oil which would be causing it not to seal properly for any reliable compression test at this stage. It may also be the cause of the tappet rattle which seemed a little temperamental over the years.

Anyway it's a bit of guess work, that's for sure.

I'll get the cam off over the new years break and investigate further

Thanks for all the help

Mark

[Nuddy]

Re: 1HDT valve stem seals?

For me, on my 80, the 1HDT is coming out and a 12HT is going in. After running mine on vege for quite some time I have decided they are not well suited. The 12HT has many advantages over the 1HDT for WVO and I am embracing them.

Good luck
Brian

Brian,
please elaborate on the advantages of 12HT over 1HDT for WVO.
I for one am very interested.
thanks,
Paul

[Tim-HJ61]

Re: 1HDT valve stem seals?

Nuddy,

Before I start, Brian has pulled his 1HD-t apart several times and is very knowledgeable about the internals of the engine. He doesn't make that so clear in his posting, not one to blow his own trumpet.

Brian,
please elaborate on the advantages of 12HT over 1HDT for WVO.
I for one am very interested.
thanks,
Paul

I'm familiar with Brian's 1HDT and his 12H-T project. I also have been running my 12H-t for 70K on vege without apparent problems.

As background:
These engines are both direct injection factory turbo. The 12H-t started in about 1985 in the Landcruiser 60 series and ceased in 1989 when the 60 series finished.

It is a build up of the 2H engine with similar or same bottom end and different top end. One addition over the 2H bottom end are oil squirters that fire coolish oil onto the bottom of the pistons. They are highly regarded as being powerful, simple and reliable with 500k being the norm. They do however suffer from piston ring groove wear that becomes excessive at 300k and making new pistons with steel ring groove inserts a beneficial upgrade at that time. They keep going for an extra 200k even with the wear, so maybe it's not so much of a problem but it sure looks bad when the ring groove is twice as wide as the ring itself!!

The 1HDT is a build up of, I'm not so clear about this, a 1HZ motor. The 1HZ is the stock diesel for Toyota and has been installed in them for 20 years. Not sure what the 1HZ standard output is.

The 12H-t has an inline injection pump incorporating a separate lift pump that supplies pressurised fuel to the IP.
The injectors are single stage.
It starts when you turn it over and stops via a choking butterfly on the intake. There are no electronics. Simple and effective.
Standard output is 100kw

The 1HD-T produces more in standard form - 120Kw I think.
It has a VE injection pump with integral lift pump and highly complex internals.
It has dual stage injectors that are more complex and expensive to repair/replace/clean.
It has stronger conrods than the 12H-t and revs higher.
It is more modern and appeared in the 80 series Landcruiser in the 1990's.

Being DI, both are eminently suitable for getting more power by increasing fuel and boost, bigger turbo's, intercoolers and the normal go faster adjustments available on diesel engines.

IMHO, purging effectively at the injectors is the most critical thing with a DI. My inline pump is much stronger in standard form than the VE pump and with less internal complexity and can be purged more easily. I need to be less concerned with purging the IP than Brian with his VE pump, but we both need to be concerned with purging our injectors correctly.

You may recall my rather complex setup on my 12H-t which has proved very reliable and suitable for this engine and in part is what Brian is chasing. I utilise the existence of the separate lift pump of the 12H-t, not possible on VE pumps. On purge, I feed the IP with a separate electric fuel pump at high flow and high pressure that purges the IP in 3 seconds (determined by colour of fuel exiting IP). I routinely shut down after a 1 minute purge, which I know ensures the injectors are also clear as I get black smoke on a blip of the accelerator and the diesel rattle comes back.

Easy purging is also critical for Brian as his vehicle is the family hack and gets used for suburban travel. Having an effective one minute purge is much more suited to this use.

Being a more basic IP, there are more adjustments that can be made more easily to increase power. Brian is chasing more power in his 12H-T and will install various go faster bits to bring the 12H-t performance close to his 1HD-T. And besides all of this, he just wants one!

I hope that clarifies.

Tim

[Matt]

Re: 1HDT valve stem seals?

Welcome to Land Cruiser Owners On Line (LCOOL)

I gather this is an 80 series not a 100 series 1Hz?

1Hz output is about 50kW at the wheels on mineral diesel about 46/47 on bio. In my opinion it was as good as if not better that the older 12HT not as peaky but a good motor when well tuned, extractors would help even on veg or bio. Larger exhaust makes a world of difference.

Matt

Hi all
I've had a good run the last year on veg until now.

Performance problems a thing of the past since adjusting IP presets.
It has more power on veg than diesel!

I've developed a big problem on start up while hot I disappear in a cloud of whitish smoke smelling of engine oil for the first minute, attracting a few comments and funny looks. After that everything is fine and there is no smoke on the open road operating at any performance level.

I have the turbo and the exhaust manifold off and have discovered the source of the burning engine oil is not the turbo I first suspected but is in number 3 cylinder exhaust port. thick black engine oil is all over the inside of the port and the valve.

taking the rocker cover off reveals the oil has drained into the port down the valve stem as it is the only one showing a lack of pooled oil against the cam plunger.


Iv'e decided the most likely cause is the exhaust valve stem seal cooked.
Hope my valve guide is OK?

Has anybody had experience replacing a seal without taking the head off?
Mark

[oztec2007]

Re: 1HDT valve stem guide failure?

Hi all
Well one thing leads to another and I have the head off and the offending valve in my hand.
I just kept going after I found that it was a little more than the valve stem seal.
After taking the bucket and spring off you could see that the protruding top of the valve stem guide had separated ( valve stem seal intact).
The remaining valve stem guide hole had worn nearly 2mm larger than original.
You could wiggle the valve from side to side.
This meant taking the head off.

The valve stem is rough in the area that was inside to stem guide, this must have worn it very quickly just recently.

All other valves, piston tops, heads and cylinders seem as normal as you'd expect though the one with the crook valve has alot of engine oil over everything.

The valve seat appears to have divots here and there probably from the bits of metal worn out of the valve guide.

Still wondering whether to just fix the problem or get the whole head done

Here's a pic I've added later after the dust settled or should I say mud?

Mark

[oztec2007]

Re: 1HDT valve stem guide failure?

Hi all
Here are some pics.
This is how I spent new years day in between rain showers.

The last image is the broken piece of stem guide with seal intact.

Happy new year all.
Mark

[oztec2007]

On the road again

Hi All
Decided to fix it
All is running well for a couple of days now.
It cost me around $600 and two weeks diy all up.
More than half of that cost was the gaskets.
The valve turned out to be bent. It only cost $12.95
I took the head up to a place called Retorqe in tamworth to get the valve guide replaced and reseated. Same day service. Long lunch in maccas and a visit to super cheap for a gasket scraper and a wire brush and it's ready.
They were very good at short notice particularly this time of year it's hard to find a business open and able to fit you in.
The parts I needed arrived the next day.
It took a little longer to put back together due to weather conditions as I'm in it. The mud and rain.
ie in between storms packing up and setting up then trying to dry the engine parts to put back together and finally hot days getting sunburnt.
I'll get a shed one day?
I fired it up on saturday and took it for a test drive.
Any way for the first 25km it was a little smokey. All that unburnt oil still on the inside of the turbo and exhaust system and a bubbling sound from the coolant in the hoses when I stopped due to air locks.
The turbo had a different note at first.
Iv'e done a couple hundred km now and it's settled down and running fine.
Even that tappet rattle has gone.
Thanks for all your help.
Back on veg.
Keep me fingers crossed.
Mark

[Tony From West Oz]

Re: On the road again

Mark,
Well done!
I am sure that the veggie oil caused the valve to bend, I just can't figure out how it did it??

Best wishes,

Tony

[Tim-HJ61]

Re: On the road again

I am sure that the veggie oil caused the valve to bend, I just can't figure out how it did it??

Sardine bones Tony