1986 2L-T still a bit hot on highway - what should I do next?

Joined
May 13, 2013
Messages
123
Dear all,

I've tried to follow as much of the forum's advice as possible as I've made investments in my LJ70 intended to make it a reliable daily driver and expedition vehicle. It has been an expensive journey so far as I live overseas and have had to rely on other mechanics instead of my preferred DIY. After my last nearly $$$$$ repair bill covering the clutch system, swivel ball rebuild, injection pump rebuild, alignment, other front suspension work, and other odds and ends (thanks Beno for parts assistance), I need to get a lot smarter about my repairs until I move back to the US in the fall and can DIY again. Not using the truck during my remaining leaves with my 16 yo son is not an option and we have a busy summer planned!

There is a good chance that my expectations for what I can safely get out of the 2L-T, especially with 170k miles on it, are too high. The truck lives in NC and most of my recreational use requires long highway segments between off-roading and camping sites. On my last extended trip in late April, I was unable to maintain 60-65 MPH on rolling terrain in mid and western NC on the interstate without the temp needle creeping up over half way on its way to much hotter. I think I had to go to 2nd gear climbing the mountains headed west on the steepest part of I40 and couldn't push more than 2500 rpm if I wanted to keep temps at or under the mid-line. I ended up driving by the boost gauge, which I installed because of the nearly always lit overboost light (waste gate doesn't open until 15 psi for whatever reason), needing to stay at 10psi to keep the temps down. I'm used to driving by EGTs in my previous 1.6TD conversion VW Westies but I haven't installed one yet on the LJ. I haven't messed with the fuel delivery but it smokes a bit more since the pump rebuild, though power and heat weren't noticeably affected.

Here is what I've done so far: new radiator, water pump, hoses, t-stat, viscous fan clutch (with at least 50% 10k fluid and lower temp lock-up adjustment as truck immediately overheated on any grade with factory fluid and settings); added Redline to coolant; installed new 2.5" exhaust (need to cut it off and re-route in front of rear passenger tire); removed a/c system, which is going back on soon; and installed snorkel. Rubber mud guards on side of lower engine compartment are gone.

Truck is heavily loaded with a full-length ARB roof rack and TJM bull bar. I'm running the tall skinny tire size listed on the door sticker and have very heavy Radar commercial off-road tires, which are inflated over 30 psi for on-road. Gears are stock. 2" Ironman lift. Winch and refrigerator are going on next and I would like to add a RTT and/or pull a small camping trailer, all of which will add more weight and wind resistance. The viscous fan clutch mod made a huge difference but I think it also reduced my fuel mileage a bit.

The cheapest option is just slowing down but being able to run with traffic and avoid extended 50-55 MPH stints seem like good safety goals. Based on my research, I have a few more options in order of expense before I give up on this engine: go back into the viscous clutch and replace all of the fluid with 10K; try to get a 3" or bigger exhaust; use special coolant, which introduces potential complications on trips far from home; and install an intercooler, which will be top mount so I can keep the a/c.

I don't mind dropping the money on an intercooler if I can be sure that it will make a noticeable difference. Is air-to-air sufficient or is it only worth it with water cooling? How to people feel about using the special coolant far from home and where it won't be readily available? I've only seen one or two people on the forum who seem to use it. Would an auxiliary electric water pump help? Are there larger or more efficient aftermarket radiators than factory I should install? Would an auxiliary oil cooler help or at least be a good investment (always installed one on my diesel Westies)? Would an electric engine fan move more air with less drag than the factory fan and clutch setup? Should I look at the turbo even though it apparently generates plenty of boost? Should I consider rebuilding my existing engine though it starts easily and burns less than a quart between 5000 mile oil changes or is the 2L-T just not going to do it? If so, would a compression test be the defining data point? I also don't mind re powering if my goals are just beyond what this engine can do reliably. I'm planning a Patagonia expedition in the next two years and will move back overseas to Africa after that so I will want to pick whatever engine is best for ROW maintenance and parts availability (American V-8?).

Sorry for the long post and thanks for any and all suggestions for what I should try next.
Cheers,
Rich
 

GTSSportCoupe

2LTE whisperer
Joined
Mar 23, 2012
Messages
5,656
Location
Victoria, BC, Canada
Hi Rich, sounds like you've done a lot to your truck and you are definitely on the right track. You should not be seeing heat problems with regular driving based on what you have done. But there may be just a couple minor things happening that could be improved. Sounds to me like one of the main things you need to do is get the tuning right. Reduce boost and fuel.

Is it the mechanical injection or electronic injection engine? Is it manual or auto transmission? This will really help me answer your questions. I'm assuming you're probably mechanical injection being an '86.

Keeping your revs too low on these motors under load is not necessarily a good thing. I find my EGT's really spike at low rpms with high load. Flowing more air through the motor helps keep it cooler.

15psi is a little much without an intercooler, and will introduce extra heat into the motor. If you want to keep running that boost, I think you should go with an intercooler. Otherwise, figure out what is wrong with your waste gate and run closer to 12psi.

If ou intercool, go with an air/air intercooler. It is much simpler and cheaper. Just as efficient on the highway. The only reason some of us went air/water is because with the A/C system, it is too tight to run air charge pipes. But PLEASE only go with a front mount setup, NOT top mount.

If you do keep running the high boost, you can get an adjustable bleed valve to keep from getting the overboost error.

I do highly recommend the Evans Waterless Coolant to all IDI turbo diesel engine owners. The 2LT/2LTE motors especially really benefit from this. It gives a lot more headroom with coolant temps. You can hit 3/4 or more on the factory temp gauge and be well within the safety margin of the motor/coolant. It does mix with water, so on a long trip, if for some reason you loose coolant and have no extra Evans, you can just top up with regular water. The only draw back is you loose the extra benefits of the waterless coolant, and it just changes to regular coolant.

If yours is the early 2LT, the thermostats are very restrictive. They are even restrictive on the later 2LTE. Please consider a highflow Tridon thermostat in either case. They are truly excellent and will have a big impact on your temp control

Not sure which fan you're running, but the fans that came on the 2LTE are crappy. There are other Toyota fans out there which pull a lot more air. Might be worth an upgrade?

Bigger exhaust will make no difference at all. 2.5" is plenty for these motors.

If I were you I'd start with correcting the boost/fuel issues, then changing to a Tridon thermostat and changing out your cooling fan for a better one (assuming you have the 2LTE style one).

The original 2LT was sold up here in Canada in Toyota pick-up trucks. I've known a few guys that have owned them, and had no issues at all even at 400,000km on the original motors. The early 2LT generally has less issues than the 2LTE with heat and head cracking etc. So I think your issues are solve-able for sure.

Just my two cents...
 
Last edited:
Joined
Oct 2, 2015
Messages
476
Location
Las Vegas
Rich,

I can't add much more than what Nick has just stated, but I would NEVER try to go over 60mph on flat terrain if you are concerned about the longevity of this motor. I had a very tired 2L-T that I just swapped out and the temp gauge would routinely go over half way on flat terrain at 60-65. I just put in a "newer" motor, and I don't plan on going over 60 mph, ever, no matter how hard the people honk behind me. (There are a lot of 6% grades between my house and Moab, and she was damn near 80% pegged at times). I learned a lesson the hard way.

I think she will be fine on a Latin American Expedition, since people don't drive that fast down there.

FYI, the Izusu Rodeo Aisin Fan will bolt right up to the 2L-TII Clutch and is much bigger. Not sure which 2L motor you are running, but with a custom fan shroud, this could provide some additional cooling.
 
Joined
May 13, 2013
Messages
123
Hi Nick,

Your previous threads on keeping your 2LTE cool have been very helpful. To answer your questions below, my truck is mechanical injection and a 5-speed manual. In terms of the boost, I didn't modify to put out 15 psi, that was how I received it. I don't push the boost over 10 psi when I'm driving. Any more and it heats up quickly. I would love to spin the engine faster but 4th gear at highway speeds requires more boost, which increases the heat and thus results in lower speeds.

So besides potentially lowering the fuel supply, although the pump was just rebuilt and shouldn't be too overfueled, the answer seems to be more air - both over the radiator and through the intake. I want to keep my a/c so I'm not sure how to install a front mount intercooler. Do you know if the Isuzu fan will bolt right on to the blue fan clutch in my 2L-T (not II) and if it will clear the shroud? I don't mind buying new parts instead of scrounging for used stuff if I know it will fit.

I've ordered a Tridon t-stat as well and will go with the Evans coolant as well.

Cheers, Rich
 
Joined
Oct 2, 2015
Messages
476
Location
Las Vegas
Rick,
The viscous oil filled clutch is different on the 2LT and 2LT2.

The fans look identical, but the hub is smaller on the older 2L model.

I would get the entire shooting match, clutch and fan since you can't mix and match. I don't have part numbers since I pulled them from the salvage yard.

Just remember this Rodeo fan is wider than then your stock shroud. You will need to fab a new shroud.

Cheers
Don
 

kbushnz

 
Joined
Aug 21, 2006
Messages
787
Location
Auckland, New Zealand
Before you start chasing your tail have you put in a proper temp gauge. The Toyota factory ones are not that accurate.
Your temps may be just fine?
 
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