Builds Another Prado in Montana

[AirheadNut]

Thinking back on pulling and reinstalling the rear driveshaft something was bugging me, so I downloaded a driveline angle calculator app from Tremec and had a closer look at my u-joint angles. I haven't been able to get a decent measurement on the rear pinion flange without unbolting the driveshaft again, but some preliminary measurements of the top of the valve cover and the driveshaft show that the angle between the t-case output flange and the driveshaft is pretty near 0º, with an angle of 2-3º between the driveshaft and rear pinion flange. I'm no expert, but everything I've seen says this is a recipe for vibrations, so I may have found my problem: it looks like the engine/transmission is at too steep an angle. Initially I think I will try adding shims under the transmission mount to change the transfer case angle relative to the rear pinion and see if I can get it any better.

Also, this morning I noticed a small puddle of oil gathering under the bell housing area. I traced it up the back of the engine to the rear end of the cylinder head. For a moment I had terrible thoughts of head gasket failures, but it turns out that I had forgotten to put in one of the three bolts that holds the vacuum pump on, and as a result the seal was seeping some oil. A trip to a hardware store for 68 cents worth of bolt and washer solved that leak.

 

[fjdiesel]

You need that tiny one the back of the head to pipe into the return. without it flowing you can get hot spots and or trap air in the head over time. Im sure you had that plug off when you filled the system correct? The one good thing about it leaking is it let any trapped air out.

That is what I was told when I did my swap. That is why I used the factory VW expansion tank. It had the extra fittings for all the lines. I can get a few pics if you want to see how I did mine.

Really interested in seeing how your tunes go. I am running hotter than I would like on the EGT scale too...

 

[GTSSportCoupe]

I think you're onto something with your driveshaft angle possible causing vibrations. I hope that is it.

When I went to 4" lift springs I put caster correction bushings in my rear radius arms to correct the angle a bit. Wasn't really having problems, but decided it couldn't hurt.

 

[Blomdala]

This may be a little bit more expensive option, but you could also add a double cardan join in the rear shaft if you aren't quite able to get your angles where you want them with shims. When I added a transferase doubler in my 4runnner, I pointed my rear pinion flange at the new location of the output flange, and added a double join into the drive shaft. Silky smooth with that setup. Never had a vibration.

Edit: This site has a nice explanation, Driveline Geometry 101 - https://4xshaft.com/blogs/general-tech-info-articles/driveshaft-angles

 

[AirheadNut]

I dropped the transmission crossmember today and added a stack of 1/2” washers on each stud of the transmission mount in an attempt to lift the transfer case and change the u-joint angle. The vibration is less noticeable between 80 and 95 km/h, and pretty much goes away around 100km/h, but comes back at 110+km/h. Definitely a change for the better, now I just need to figure out how to get even more angle on the output flange. I have about maxed out the length of the studs on the transmission mount, and don’t have much more clearance above the transmission.

 

[AirheadNut]

You need that tiny one the back of the head to pipe into the return. without it flowing you can get hot spots and or trap air in the head over time. Im sure you had that plug off when you filled the system correct? The one good thing about it leaking is it let any trapped air out.

I must have let some air in when I changed out the plug, because I had a couple of temperature spikes today. I haven't been able to find any fittings that allow me to plumb that little hose into one of the radiator hoses, but I should be able to get a reducer tee that I can put inline in one of the heater hoses higher up in the system, which should help bleed off any trapped air that's in there.

 

[AirheadNut]

That is what I was told when I did my swap. That is why I used the factory VW expansion tank. It had the extra fittings for all the lines. I can get a few pics if you want to see how I did mine.

Really interested in seeing how your tunes go. I am running hotter than I would like on the EGT scale too...

Still no luck with the tune, but the removal of the RTT dropped EGT's by 100-200ºF at highway speeds. I think part of my problem is a small, restrictive downpipe, but there is also a problem either with my injectors or the tune that is causing loads of black smoke. Hopefully I'll be able to get the problem solved without having to pull the injectors out again.

 

[Motohead1]

I must have let some air in when I changed out the plug, because I had a couple of temperature spikes today. I haven't been able to find any fittings that allow me to plumb that little hose into one of the radiator hoses, but I should be able to get a reducer tee that I can put inline in one of the heater hoses higher up in the system, which should help bleed off any trapped air that's in there.

I used the rear plastic flange that already had a small connector on top. I cannot remember the part number. so I have a short 1/4 hose thats like 5 inches at a 90 bend. works great for the last 100k miles. Knowing what I know now I would use an aluminum flange and just tap and weld it the way i want.

 

[AirheadNut]

I put on a plastic coolant flange as well, but it must be a slightly different part. Mine only has one smaller port on the bottom, it feeds the oil cooler and heater core. The other two ports are for full size radiator hoses; I only have one hooked up.

The plan is to get one of these to put inline in one of the heater hoses:

 

[AirheadNut]

The little coolant bypass hose is in, I tee'd it into the outgoing heater hose for now, but at some point will need to redo all my radiator hoses since the inlet and outlet of the radiator are backwards Still trying to get all the air bled out of the system, every so often the coolant temperature will spike up above 205ºF (96ºC) and jump around a bunch. I would also like to tidy up my motley assortment of hose clamps!

I have been working with the tuning company trying to get the fueling/boost issues sorted out, and got a new modified tune last night. I reflashed the ECU today and took it out for a spin, there is definitely an improvement. Ambient temperatures were around 68ºF (20ºC) with a light headwind, and I was still able to cruise at 120km/h with EGT's around 1170-1220ºF (630-660ºC). Reasonably hard acceleration didn't go much over 1400ºF (760ºC). I even set a new speed record on the interstate: max speed recorded on the phone GPS was 132 km/h!

The Prado also passed a milestone today:

Still trying to figure out my driveline angles, and how to get them within spec. Could one of the other LJ78 owners here do me a big favor and measure the angle the engine sits at relative to some flat surface on the vehicle? I think mine is still too steep, but I don't know what the original angle was.

I recently purchased some large accessories, stay tuned for the install!

 

[AirheadNut]

Did a small install this evening:

The running light/brake light portion of the housing is LED, the reverse and turn signal bulbs are stock type incandescent bulbs. Massive difference to the original faded lenses! Very pleased with the way they look, too. Thanks, @87BJ74 !

 

[AirheadNut]

A somewhat bigger install happened too:

The plan is to eventually get some pieces of metal bent to the same profile as the side wings to extend them up as far as the factory mudflaps, and tie them into the frame. For now I'll just have to live with a slightly unfinished look:

The removal of the factory plastic bumper caps revealed something unfortunate though:

Doesn't look like it will be too hard of a fix, and only the LH side has any significant rust. I'm still amazed how little rust this thing has given that it spent the first 15 years of its life in Japan, followed by 10 years in coastal BC.

Next up:

 

[87BJ74]

Next time you come over to my place remind me to look for a patch panel for that spot. I bought some rocker panel patches for mine a couple years ago and am not gonna need them.

That back bumper came out pretty good!

 

[AirheadNut]

Next time you come over to my place remind me to look for a patch panel for that spot. I bought some rocker panel patches for mine a couple years ago and am not gonna need them.

That back bumper came out pretty good!

That would be great, a patch panel would definitely make that a simple fix.

The rear bumper looks and fits great; all the bolt holes lined up perfectly and made for a quick and easy install. Can't wait to get the front one on, it's going to look awesome!

 

[GTSSportCoupe]

I've got some similar rust on mine I've really got to take care of asap also. Really, for 30 years old, these trucks stand up well though. Compared to 40 or 60 series in similar climates.

I like your bumpers. I've been tempted to pull the trigger on something like that. May I ask where you bought them?

 

[AirheadNut]

I picked up the bumpers locally from another Mud member, I wasn't really in the market (yet) but he made me a deal I couldn't pass up. They are both ARB, the front is for the HD models and doesn't bolt straight up, the frame is too short. The plan is to extend the front of the frame by about 3.5", which should give ample room to add a couple of extra bolt holes to the bumper. The rear is an odd one, I have only been able to find a couple of photos of it online and haven't been able to look it up in any of ARB's worldwide catalogues. I really like how it looks though.

 

[fordyota]

Back bumper looks great. Looking forward to seeing how you do mods for front bumper and how that looks. Do you have model # of ARB front bumper you'll be putting on?
Thanks! And Following

Ps...I have that same exact rust hole at same spot.

 

[AirheadNut]

I believe the front bumper is ARB part number 3412130, its the Deluxe winch bar for narrow nose HD 70-series.

 

[SnowVersion]

I wonder if that rust hole is related to a disconnected drain? Seems odd that on an otherwise rust-free vehicle you’d end up with that serious of a rust hole in just one place. My 80 has drains in roughly the same place in both rear fenders.

 

[AirheadNut]

I wonder if that rust hole is related to a disconnected drain? Seems odd that on an otherwise rust-free vehicle you’d end up with that serious of a rust hole in just one place. My 80 has drains in roughly the same place in both rear fenders.

There is a small bracket for the mudflap that screws into the bottom of the rocker there, I think the rust starts in that hole and works its way out. The bracket was completely disconnected on that side.

I was storing the crank rods for my bottle jack in that side pocket, after seeing the size of hole in the bottom I decided they are probably not safe there!