Lj78 rough idle at start (1 Viewer)

[Holdfast]

Hello,

I have had this truck for a couple of months and still learning diesel and wanted to know if a rough idle at start, for about 10 -15 seconds is normal for the 2.4td after it has sat for a few days? Fires right up, and smooths out nicely after initial shakes. Not noticed any smoke.

It is not cold now, summer, so concerned it will be much worse when winter comes? What would be the first think to look at? Thanks.

Truck is a 1992 Prado lj78 2.4td (head has been done)

 

[Gun Runner 5]

On occasion my LJ78 did the exact same thing however if you shut it off and went through another start cycle there would be no rough idle on the second go around.

 

[Holdfast]

Thanks- did you ever figure out why it was rough on first go?

 

[Gun Runner 5]

Thanks- did you ever figure out why it was rough on first go?

I never did figure out why it had the rough idle and it didn't occur often enough to be an issue. I no longer own the Cruiser.
Sorry I couldn't help.

 

[NGray]

I had periodic rough starts with my bj73, it would shake sputter and stall if I gave it any throttle. It was air getting in from the old seals in the top portion of the rotary pump. Before I got it fixed it would eventually work the air out and run fine. Probably not the culprit for you, but just a thought.

 

[Holdfast]

Thanks for your feedback.

 

[GTSSportCoupe]

It's most likely the glow plugs are not cycling long enough. When its a bit cooler out, I cycle mine twice. The factory glow cycle just doesnt go long enough. Many people put in a manual glow switch. However, what you can do is just listen for the relay when it opens (about 4-5sec), turn the key off, and glow it one more time (another 4-5 sec), then start. I bet you'll get a perfect start. If it's really cold out (freezing), do it three times.

Where are you located? If you want some hints on preserving your 2lte (heads are suseptible to cracking when engine gets too hot) and getting a lot more power/economy, let me know and I can point you in the right direction. Are you familiar with working on your own vehicles?

 

[Holdfast]

Great - will try that. I am in Ontario (updated profile) - I have been reading on maintaining cooling system. Right now temp gauge sits at 1/4 and only moves to half if going up long hill around 80km. I am prepping the truck for my family and i to drive across canada next two summers (Tofino is one stop), so yes, tips on economy are welcomed. Previous owner just did plugs last year and new head done several years ago. He said he never had overheating issues.

I can do general maint., and normally have my mech. friend come over for more involved jobs.

 

[GTSSportCoupe]

Sounds like your Prado is running well and in good shape. They are great little rigs, and can be reliable and last with the right modifications/maintenance and driving style.

Something to be aware of is that even the new heads can crack under the right conditions; so even though it's been replaced, it is good to remain vigilant. My temp guage also sits at about 1/4. It only moves up to about 1/3 under hard driving up long summits. I have read that you should start being concerned when the gauge gets to about 1/2; so definitely take it easy when you see it get up there. A lot of people recommend getting an aftermarket coolant temp gauge so you can get an accurate temperature reading.

I wrote a large post on how to improve the 2lte. Here is the link: https://forum.ih8mud.com/threads/ideas-for-improving-the-2lte.680759/ I need to do a bit of updating on it, and will try to get to it in the next few days.

In a nut shell, make sure all your maintenance is up to date. Install an Pyrometer and Water Temp gauge so you can at least monitor the condition of your engine. Remove the factory emissions systems (EGR, PCV). The items that completely transformed my engine were the intercooler and larger exhaust. These two items allowed the engine to make a lot more power with far lower temperatures. It is like a whole new beast. Unfortunetely, not cheap to do though.

Keep the RPMs up on the hills, as this will move more air through the engine and keep it cooler. Don't be afraid to rev this little diesel; it seems to like it.

Anyhow, I could go on and on, but that is the best advice I can give.

 

[VI Cruzer]

Hey there I just had a read of all the great tips for the LJ78. I have owned mine for almost 7 years and am quite pleased with it! I have not many/any of the mods but do baby drive the thing (Still does what I need it to!). I will soon be needing to replace some or all of my exhaust and I was wanting to upsize the pipes and possibly go to stainless (so I won't have to keep doing it). I was reading about the dump after the turbo and didn't quite get the operation of that. Thought that maybe you could explain that if you didn't mind.
I've a 1992 with manual xmsn. Fixed up the clutch fan (world of difference), got some OME suspension. If I am just driving around Nanaimo, the cooling system runs OK, but if I tow our trailers or pop over to Port Alberni, then I have to make sure that the coolant gets back in the system as it goes out when I load it but does not all come back (not sure why just yet). So I'm looking to solve the issues and I know the mods as posted will probably solve most of the operational issues, but I would like to figure why the water does not get sucked back in. I lose a little too and have to add sometimes ( not always) so thought it could be disappearing in the turbo cooling jacket. There's nothing in the oil and wouldn't I see other problems if it was in the head?

Any advice on any of this would be greatly appreciated
Mark

 

[GTSSportCoupe]

Hey there I just had a read of all the great tips for the LJ78. I have owned mine for almost 7 years and am quite pleased with it! I have not many/any of the mods but do baby drive the thing (Still does what I need it to!). I will soon be needing to replace some or all of my exhaust and I was wanting to upsize the pipes and possibly go to stainless (so I won't have to keep doing it). I was reading about the dump after the turbo and didn't quite get the operation of that. Thought that maybe you could explain that if you didn't mind.
I've a 1992 with manual xmsn. Fixed up the clutch fan (world of difference), got some OME suspension. If I am just driving around Nanaimo, the cooling system runs OK, but if I tow our trailers or pop over to Port Alberni, then I have to make sure that the coolant gets back in the system as it goes out when I load it but does not all come back (not sure why just yet). So I'm looking to solve the issues and I know the mods as posted will probably solve most of the operational issues, but I would like to figure why the water does not get sucked back in. I lose a little too and have to add sometimes ( not always) so thought it could be disappearing in the turbo cooling jacket. There's nothing in the oil and wouldn't I see other problems if it was in the head?

Any advice on any of this would be greatly appreciated
Mark

Sounds like you have a nice rig there. I often wish my Prado was manual transmission, and might try to pick one up some day.

An upgrade to 2.5" exhaust will make your engine very happy. It dropped my maximum EGT's by 150F when I did mine. It'll also help the turbo spool faster and operate more efficiently, as there is less back pressure it has to work against. I went with aluminized piping, and it has stood up well to the elements; so might be a cheaper option than stainless if you are on a budget. Go with as free a flow muffler as possible (the ones you can see through are perfect). Exhaust will still be quiet as the turbo reduces most of the noise.

The dump pipe is the cast iron part that bolts onto the turbine housing and is the transition to the exhaust piping. At this point the exhaust gasses are the hottest and need the most room. When you go to 2.5" exhaust, the dump pipe will be the major remaining restriction, as it is about 2" internal diameter if I remember correctly. I did my best to port mine out (with a die grinder air tool), but ideally it is best to replace it with a custom large diameter piece. They are availble after market for the Surf's with the 2LTE, but I don't think that pipe will fit in the Prado, as the Prado has much less space between the turbo and firewall. Anyhow, even if you just do the exhaust, it will help a lot.

I would be quite concerned about your cooling system issue if I were you. It almost sounds like you might have a minor crack in the cylinder head which is where you are both loosing fluid and pressurizing your cooling system on a hard drive. If you have no external leaks, then it is a likely scenario. Next time you notice the problem, check your coolant overflow to see if there are any small bubbles coming up while the engine is hot. You can also get the coolant tested to see if there are any indications of cylinder gases in the coolant. A small crack can cause significant damage over time by eroding the piston/cylinder/head.

 

[VI Cruzer]

Thanks for the reply! I'm not really surprised at the suggestion, as I have been wondering about that myself! I've probably been in denial since it runs OK except for the uphill/loaded runs. I can definitely check for the bubbles, I guess the local radiator shop can check the coolant. I've always said that if the head goes, I might just consider a new engine, but that comes with it's own set of headaches. I read in a post somewhere that someone installed an aftermarket head from the UK that was supposed to fix a lot of the troubles, have you heard about this?
In the meantime, I would like to look into removing the emission systems stuff, and then if I am feeling ambitous after all the yard projects are done for the season, I may feel like tackling some of the other ideas.
The prospect of changing the head seems a little daunting right now, I think I would like to get the improvements done before I shell out for a head replacement.

A quick question about the dump pipe. Does the flange that is part of the turbo unit have a smaller hole or just the pipe that is attached to it? Did you you expand the hole on the turbo as well as the dump pipe? Did you have a new dump pipe fabricated or rework the existing one?

Yes it is nice to have a manual transmission, I imported my own truck and just watched the auctions till the truck I wanted came up. Came with 60,000K orig, was in mint condition. I think it was past the date when toyota put in the somewhat improved head (that's what I had read at the time anyway).

The only major thing I would one day like to add to the truck is a rear locker, either the stock prado one or the ARB version. I thought that the stock one might be easier as the truck is likely wired for it already. Do you have the stock locking diff?

 

[GTSSportCoupe]

Thanks for the reply! I'm not really surprised at the suggestion, as I have been wondering about that myself! I've probably been in denial since it runs OK except for the uphill/loaded runs. I can definitely check for the bubbles, I guess the local radiator shop can check the coolant. I've always said that if the head goes, I might just consider a new engine, but that comes with it's own set of headaches. I read in a post somewhere that someone installed an aftermarket head from the UK that was supposed to fix a lot of the troubles, have you heard about this?
In the meantime, I would like to look into removing the emission systems stuff, and then if I am feeling ambitous after all the yard projects are done for the season, I may feel like tackling some of the other ideas.
The prospect of changing the head seems a little daunting right now, I think I would like to get the improvements done before I shell out for a head replacement.

A quick question about the dump pipe. Does the flange that is part of the turbo unit have a smaller hole or just the pipe that is attached to it? Did you you expand the hole on the turbo as well as the dump pipe? Did you have a new dump pipe fabricated or rework the existing one?

Yes it is nice to have a manual transmission, I imported my own truck and just watched the auctions till the truck I wanted came up. Came with 60,000K orig, was in mint condition. I think it was past the date when toyota put in the somewhat improved head (that's what I had read at the time anyway).

The only major thing I would one day like to add to the truck is a rear locker, either the stock prado one or the ARB version. I thought that the stock one might be easier as the truck is likely wired for it already. Do you have the stock locking diff?

I haven't been through the head replacement thing myself (on a 2lte that is), so am just speaking from what I've read. Some people seem to think that some replacement heads are better than others; but personally I don't think there is that much difference. The geometry of the head is what it is, and the little coolant passage between the valves is going to be pretty similar even if there are other minor differences. I think the big key is just to prevent the heat in the first place. If the head on mine went, I'd just shop for the best priced head and go with it. As far as cylinder head jobs go, the 2lte really is a pretty simple engine with lots of room to work. If you could do the job yourself, you'd save a huge wack of $$.

The part of the turbo that the dump pipe bolts to is plenty large, so nothing needs to be done there. You can buy dump pipe flanges for the CT20 off ebay (I have one sitting in my shop), and could have a talented welder/fabricator make you a custom dump pipe using the flange. Like I said, I just bored out my oem dump pipe with a die grinder. It is still pretty small though, and I'd eventually like to make a custom one; just havent had the time yet.

I do have the factory locking rear diff, and absolutely love it. It makes all the difference while wheeling. Haha, and I wish I had a Prado with the factory winch and manual transmission. The LJ78's are really cheap in Japan now apparently. Maybe I'll import a dream one someday.

You should check out the Vancouver Island Landcruiser part of the website. We have regular meets in the south island, and do trips etc. https://forum.ih8mud.com/forums/ca-bc-vancouver-island-cruisers.104/

 

[VI Cruzer]

Thanks for the advice, I think I'll start with the exhaust and the EGR/PCV. That's a bit of a handful to start with anyway. I'll post again if I run into any trouble.