LJ78 Prado Valve stem seals replacement

[gatier]

Hello!
I am on the way to replace the Valve stem seals. I have a terrible morning starts (smoke) when the engine is cold. After 2 min it runs just fine. Also later starts durring the day are not such a problem. It looks like the oil drops through the seals into the chambers and than it burns till it get more pressure, heat.
Did anybody have an experience replacing those seals? Is it necessary to remove the head? Any special tools required?
Thanks!

 

[SimonInAustralia]

Sounds like a glow plug problem.

 

[Scud1373]

do you get white smoke? black smoke?

I had the issue of rough starts in the morning where I would get a lean smoke which was due to air getting into the system. And this would not happen at all during the course of the day till the engine sits overnight.

The problem for me was the injector pump leaking.

 

[gatier]

Glow plugs are new and checked. Thats fine.
Smoke is white (little black) and I loose also oil because of this. No significant leaking under the car.

 

[Radd Cruisers]

It's a known 2LTE issue. Many of these engines smoke badly on start up.

I doubt very highly that it's valve stem seals.

Check your valves first, before you do this job. The engine must be totally cold - not run for 18 to 24 hours.

Also, using the values for the main temp sensor, check the values on a higher end DVOM or lab scope to make sure the values for any given temperature are within spec.

Furthermore, check the intake throttle plate and EGR throttle valve are not totally shut at start up. Opening them a little (and resetting the TPS) will help in some cases.

With the Mitsubishis, replacing the seal in the front of the injection pump makes a big difference as air enters the pump when it's resting over night creating a harder start and smoke. Haven't tried that yet with a 2LTE.

If you're going to attempt the valve guide seals: It may be possible to do the job with the head in place: you'll need a glow plug adapter to supply shop air to the cylinder you're working on to keep the valves up in place. Expect LOTS of leakdown, so a large-ish shop compressor will be needed to keep the pressure up.

The cam will have to come out, which means the timing belt will need to be taken off. Once the cam is out of the way, remove the valve shims and buckets to expose the top of the valve stem. You'll have to come up with a valve spring compressor that will work in place to tease the spring down to remove the retainers etc. to access the valve guide seals. There are all kinds of valve spring compression tools on the market, and if you do a search you may find one that will work with that head.

Good luck with it, but I would be willing to place a pretty substantial bet that it's not the valve guide seals... and takers?


~John

 

[gatier]

Hi John,
but where comes the smoke from? Air comes into the injection pump and?
Why does this happen? Mine is loosing oil.
Thanks, Tom

 

[SimonInAustralia]

I thought white smoke was usually unburnt diesel.

 

[Radd Cruisers]

Note that I added lots of info to my last post while in "edit" mode.

Where the smoke comes from? I have no idea, I suspect it's related to the spill control valve being a little to conservative on the spill volume, and the engine being overly choked by the throttle plates (opening the gap does help a little in some cases). The smoke is from incomplete combustion of diesel in a cold engine (probably related to fuel over-delivery).

I have spent dozens of hours on these engines with very little success in solving the smoking issues. I don't have any really good answers for you, sorry.


~John

 

[gatier]

I really appreciate your help John!
I'll try to check as much as possible before I start. The valve seals are on the way though.
The head was changed once before by the previous owner. But this guy sold me the car with this smoke problem explaining- not a big deal. He didn't repair any of the easier stuff and that made me sure about the valve stem seals.
Another thing- does the leaking injection pump has something to do with burning oil?
thanks!
t.

 

[gatier]

SimonInAustralia: Its black, than white and blue in the end

 

[SimonInAustralia]

Sounds like you got it all goin' on.

White might be unburnt diesel, blue would be oil.

 

[Radd Cruisers]

I really appreciate your help John!
I'll try to check as much as possible before I start. The valve seals are on the way though.
The head was changed once before by the previous owner. But this guy sold me the car with this smoke problem explaining- not a big deal. He didn't repair any of the easier stuff and that made me sure about the valve stem seals.
Another thing- does the leaking injection pump has something to do with burning oil?
thanks!
t.

Valve guide seals would have been done with the head work.

Leaking diesel is due to bad seals in the pump, usually the top cover. These can be replaced quite easily.

Engine oil burning and diesel leakage at the pump will be unrelated.


~John

 

[gatier]

Valve guide seals would have been done with the head work.

-THIS MIGHT BE TRUE, I JUST DON'T BELIEVE HE TOUCHED THEM.

Leaking diesel is due to bad seals in the pump, usually the top cover. These can be replaced quite easily.

-I'LL CHECK THIS ONE TOO

Engine oil burning and diesel leakage at the pump will be unrelated.

-SO WHY DOES IT BURN OIL AT COLD STARTS ONLY?

THANKS!

 

[Radd Cruisers]

The 2LTE does not suffer from head gasket failures, rather it is the head that fails. Any machine shop that would have installed the cam and valves would have put new valve guide seals in place. The kits that are supplied for repairing these engines would have come with all the parts to do the job - including the valve guide seals.

The smoke is most likely not engine oil. Is there any evidence of the oil level dropping more than one might normally expect (a litre or less between changes).

There is no engine oil lubrication in these injection pumps, they are strictly diesel lubricated. The smoke will most likely be from excess diesel not burning properly. This kind of smoke is grey-ish to black-ish with a hint of blue. Engine oil smoke is predominantly blue and does not smell like diesel.

~John

 

[gatier]

1. Ok, I didn't know...
2. I lost 1L on 2000km on last trip.
3. I'll take the cover off and see what's in there. I'll try to take some pictures

 

[gatier]

I also changed the boost by adding the spacers. The problem is, I don't feel any difference. Maybe I hear the turbo working harder (turning faster) but thats it.
Any ideas on this?
thx

 

[prado t]

Bad valve guide seals will in some cases will keep the motor running even after you shut it off, knock, knock capow-capow.
Remember the way the mid 70s GM products would "diesel" when shut off, kinda like that but different.

P.S. Also your oil consumption would go up. If I can remember right I was always adding oil to the 2lte.

These motors do smoke bad during start-up.

 

[pradocruzer]

I'am under a conclusion that the valve stem seals more then likely are not your main problem. Mostly People complain of oil burning smell and blue smoke under deceleration on the way down or at the bottom of hills. That will be valve seals or bad guides. If they ripped your head apart the valve seals usually fall apart from being hard and brittle and are not reusable but who knows what job they did. The start up problem is one thing but the loss of oil could be another. My 2lte starts with no stumble or blue smoke. take your turbo pipe off and check for abnormal oil in the pipe. little amounts are ok but if it pours out, your turbo may be at fault and also look to see if you are leaking oil out of your intake manifold gasket due to the oil bypassing the seal and gathering in the manifold. The more boost you add will put more pressure on the turbo seal causing more oil to leak by. When I rebuilt my turbo I switched to a dynamic seal instead of the carbon seal and all seems well.

Take Care

 

[gatier]

I had actually problem downhill with gear in. On the way back from 2000km trip, it started to smoke using engine brake. There was 1l less oil, than it should be. After change everything is good except for bad starts.
With 250 tkm, the turbo (seals) might be bad too.
Thanks guys!
t.

 

[Radd Cruisers]

I had actually problem downhill with gear in. On the way back from 2000km trip, it started to smoke using engine brake. There was 1l less oil, than it should be. After change everything is good except for bad starts.
With 250 tkm, the turbo (seals) might be bad too.
Thanks guys!
t.

That can point to EGR system faults as well as the throttle plates being too tightly closed at the idle throttle setting.

I mentioned this before...


~John