LJ78 cracked head symptoms

[Sd1975]

Hey guys, so I'm planning on picking up a 1991 LJ78 Prado this Saturday. Been communicating with seller constantly for about 3 weeks. Have lots of pics and videos of it running and a drive around the block. Seems to be very tight, but was wondering what symptoms if any show from a cracked head, or anything to look for when I go.
TIA

 

[GTSSportCoupe]

- First thing is, when the engine is cold, open the coolant fill, and see if the coolant is right up to the lid, or if there is lots of air in there. Air is a bad sign. But it's not a sure sign (as air can also be drawn in if there is an external coolant leak somewhere).

- Next, start the engine, and feel the upper rad hose. If it gets really hard right away, that is a bad sign (system being pressurized). Again, this can happen if there is air in the system from an external coolant leak, but the pressure will dissipate after a bit.

- Allow the engine to keep warming up, and carefully remove the cap off the coolant reservoir keeping the tube inside immersed in the coolant. Move the lid to the side a bit so you can see in, and watch around the tube in the coolant. Look to see if bubbles are coming out. If there was just a bit of air in the system, you may see a couple bubbles. But if the bubbles keep coming, it's a head problem.

- Take it for a drive. Load the engine by going up a hill on the highway or similar. Watch the temperature gauge carefully - make sure it only goes to 1/3 of the scale and does not jump around or go higher. Stop somewhere shortly after (leaving the engine idling) and take a look at the coolant reservoir. Make sure the level has gone up just a little bit. If the reservoir is full or overflowing, it's a sure sign of a head problem. You can also feel the upper rad hose again, and check for bubbles in the overflow reservoir again. Careful not to burn yourself. A hard rad hose and bubbles still coming is a sure sign of a head problem.

A bad head is not the end of the world if you are mechanically capable. You can use it to get the truck really cheap, and put a new head on yourself. Then you'll have good confidence afterwards anyhow.

 

[Sd1975]

Thank you so much for the info! Very detailed and specific so thank you! I'll check all this Saturday when I go to look at it!

 

[Sd1975]

I sent seller your reply. He sent me this pic along with 2 videos of soft pliable hose on cold start up and video of coolant in fill tube with lid off while running. Also he has been driving it to work for 2 weeks, 45 miles round trip says temp stays at one third and doesnt fluctuate at all

 

[GTSSportCoupe]

From the sounds of it, it's probably fine.

 

[Sd1975]

I'm excited lol

 

[OGBeno]

Always remember this: You are buying a used car from a used car salesman. Your used car just happens to be one that is a gray market, non-US Land Cruiser.

I would keep that in mind when the head gasket does go and the head does crack.

Good looking truck by the way.

 

[Postoy]

What GTssport said.

When my head cracked it pumped coolant through the coolant reservoir, the entire coolant system pressurized right away do to exhaust gas escaping into the coolant passages.

Sweet cruiser, I want those wheels!

 

[Sd1975]

What GTssport said.

When my head cracked it pumped coolant through the coolant reservoir, the entire coolant system pressurized right away do to exhaust gas escaping into the coolant passages.

Sweet cruiser, I want those wheels!

Yeah, first things I'm gonna do asap is install pyrometer, change to a waterless coolant, snorkel and exhaust. Hopefully she'll breath better, cooler and I can keep an eye on it better

 

[GTSSportCoupe]

Yeah, first things I'm gonna do asap is install pyrometer, change to a waterless coolant, snorkel and exhaust. Hopefully she'll breath better, cooler and I can keep an eye on it better

Good plan. A couple of the other first things I'd recommend doing are servicing the clutch fan and install a Tridon high flow t-stat. Those two items help with the cooling more than anything else (assuming regular maintenance has been kept up).

 

[Sd1975]

Good plan. A couple of the other first things I'd recommend doing are servicing the clutch fan and install a Tridon high flow t-stat. Those two items help with the cooling more than anything else (assuming regular maintenance has been kept up).

Okay will do, thank you. When you say service clutch fan what all does that entail

 

[GTSSportCoupe]

Okay will do, thank you. When you say service clutch fan what all does that entail

Do what the original poster in this thread did: Blue fan clutch mod

 

[Sd1975]

Do what the original poster in this thread did: Blue fan clutch mod

What would you recommend for exhaust, 2.5? I'm assuming any reputable shop can do this or is there anything special they need to do

 

[GTSSportCoupe]

2.5" is plenty large enough if it's well made with mandrel bends. Go with a quality free flowing muffler like the Aeroturbine 2525XL.

 

[Sd1975]

2.5" is plenty large enough if it's well made with mandrel bends. Go with a quality free flowing muffler like the Aeroturbine 2525XL.

Okay thanks. May be tricky around here finding a shop that does mandrel bent exhaust. Most still just use a pipe bender that puts the little crinkles in it. I'll have to search around

 

[GTSSportCoupe]

Okay thanks. May be tricky around here finding a shop that does mandrel bent exhaust. Most still just use a pipe bender that puts the little crinkles in it. I'll have to search around

You can buy a universal exhaust kit with all the mandrel bends you could ever need. I actually shared a kit with a friend as the kit had enough for both of us. Then it's just cutting and welding... Flowmaster/Magnaflow make these kits. Just google it.

 

[Sd1975]

You can buy a universal exhaust kit with all the mandrel bends you could ever need. I actually shared a kit with a friend as the kit had enough for both of us. Then it's just cutting and welding... Flowmaster/Magnaflow make these kits. Just google it.

Well hell yeah then! I've bought a couple flowmaster kits in past, never a universal though

 

[Lomoski]

What GTS said. When my head cracked on my KZJ78 one of the other symptoms was hard starting when warm and a large puff of blueish white smoke when it did run.

The fan mod is key as mentioned prior as well.

That LJ looks like it's in good shape. Same colour as mine.

You'll definitely want a EGT probe. These things get HOT very easily under load. You're going down the right path though with intercooler/exhaust. That's next on my list once it gets a little warmer here and I can work on the truck again (currently -25c).