Blown Head Gasket....LX450 Refresh

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KINGCM

KINGCM

10 Year 15 Year
Joined
Sep 29, 2009
Threads
15
Messages
103
Location
Phoenix, AZ
Need a little help diagnosing something from you experts on Mud. My LX450 has about 241k miles and just the other day I was driving it on the freeway and noticed the temp started to spike near the redline after just a mile or two of driving. I immediately got off the interstate and limped it back home luckily only a couple of miles making sure it didn't overheat anymore than it had. In addition when I got home check engine light came with what resulted in a cylinder 1 misfire. Let it cool and checked the coolant and I was obviously low near the top of the cooling fins when i looked into the radiator cap. Previous to this the coolant system had been flushed at maintaining the same level for past 6 months. Performed a combustion leak check and it failed. Did a pressure test and all cylinders actually tested decent at between 180 and 193. Cylinder one with the misfire actually had one of the higher pressures at 190. Number 1 plug had also obviously been exposed to red coolant. Scoped it and its obvious that coolant has somehow made its way into the cylinder due to the red coolant observed.

I intend to replace the head gasket, but before I open up everything in preparation, are there any other possibilities here? Why would cylinder one with the misfire pressure test so high. Is there any other failure methods that could cause this? Cracked block?

I recently replaced the clutch fan fluid with a 15k cst fluid in attempt to increase cooling for the ac and motor as I live in the Phoenix area. Not sure if that would have caused this? As in it cooled too quickly? Also, when I do the squareness/flatness test on the head, are there any suggestions for a machine shops in the Phx area that are familiar with the 1FZ?

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Don't run it. You've done your diagnosis, and decided it needs a head gasket.

Could be a leak that opens up when the engine is up to temperature.
For now it looks dry, but keep running it you risk hydrolocking the engine which can bend rods, crack crankshaft etc.

When you tear it down, if the head gasket isn't obviously compromised around cylinder 1, inspect the head and cylinder walls for cracks. Cracked head or block can leak coolant intermittently when everything gets hot and expands. Cracks are going to typically leak small amounts of coolant that gets boilled off as steam in the combustion cycle.
Pushing hard to get into the motorway at speed is a good example of when a crack can cause an overheat situation. Combustion gas under high load situation can oak pay coolant pressure and cause radiator to boil over. Normal driving, there's not enough constant pressure for a significant amount of gas to push past coolant pressure.

Upgrading fan silicone oil is not going to cause the engine to cool too quickly. You still have a massive slab of iron and metal, and gallons of coolant that all have a high thermal mass aka they hold onto heat well.
No matter how powerful, a fan is not going to drop temperature instantly enough to cause an issue.
If you had the engine at the top of is operating range, and plunged into an icy river, maybe you'd create a thermal shock, but unlikely
 
mudgudgeon said:
Don't run it. You've done your diagnosis, and decided it needs a head gasket.

Could be a leak that opens up when the engine is up to temperature.
For now it looks dry, but keep running it you risk hydrolocking the engine which can bend rods, crack crankshaft etc.

When you tear it down, if the head gasket isn't obviously compromised around cylinder 1, inspect the head and cylinder walls for cracks. Cracked head or block can leak coolant intermittently when everything gets hot and expands. Cracks are going to typically leak small amounts of coolant that gets boilled off as steam in the combustion cycle.
Pushing hard to get into the motorway at speed is a good example of when a crack can cause an overheat situation. Combustion gas under high load situation can oak pay coolant pressure and cause radiator to boil over. Normal driving, there's not enough constant pressure for a significant amount of gas to push past coolant pressure.

Upgrading fan silicone oil is not going to cause the engine to cool too quickly. You still have a massive slab of iron and metal, and gallons of coolant that all have a high thermal mass aka they hold onto heat well.
No matter how powerful, a fan is not going to drop temperature instantly enough to cause an issue.
If you had the engine at the top of is operating range, and plunged into an icy river, maybe you'd create a thermal shock, but unlikely
Click to expand...
Thanks for the response. As you have stated I was already going to replace the HG but was wondering how my cylinder pressures all tested within spec including cylinder 1 where it has obviously ruptured? I figured that it wouldve showed a very low pressure. I wouldn't have thought the fan clutch a possible cause either, but with the dissimilar metals in head and block it was just a guess.
 
i'm taking it off hopefully tonight, if my pain killers work;);).
she was full blown, filling up #6 with coolant quickly. just bought it for a great price, new about it.
 
KINGCM said:
Why would cylinder one with the misfire pressure test so high.
Click to expand...
I'd sleep well attributing this to the coolant that's sitting in the cylinder. First, because that's going to seal real nice around your compression ring (think wet vs dry compression tests). Second, the space it occupies means less compressible volume in the cylinder. And on top of that, as @mudgudgeon was saying, if you did the test cold there's a good chance you're not even loosing pressure to the leak site.

The blocks on these are pretty resilient. Have your machine shop magniflux the head before they do work on it and you should be good. If you can't find a good local shop I can recommend one in northern Utah if you need.
 
Mine started with running slightly warmer. This quickly transitioned into harder starting and I noticed the coolant level was low. Learn from my mistakes and listen to others.

My blown headgasket happened in the most inconvenient time. We were out at dinner one night after experiencing the issues listed above. It ran fine but after dinner, there was a loud clank when I tried to start the engine. I knew immediately it was hydrolocked with coolant. I tried again and got another loud clank but the engine was running. I reversed out of the parking lot and drove as fast as I could home.
It was a 30 mile trip and initially the temps stayed around 179 to 183 and I thought I was lucky. 20 miles from home and the temps spiked to 200 and kept rising. Racing the engine would lower the temp but only temporarily, however I finally made it home by the skin of my teeth and shutoff the engine at 231 degrees.

Replacing the head gasket is a great learning opportunity and IMO very necessary to do the work yourself if you plan on keeping the Cruiser long term.

I'm 6'2" but this made it easier to work on.
1779833512718.webp

Failure at cylinder 6.
1779833531705.webp

ARP studs going in.
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Running like a champ today.
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Last edited:
Devils Paw 80 said:
How did the original look when you did this?
Click to expand...
Pretty clean...no scarring. Bottom end is "like new". Replaced what i can while its out for resurfacing.
New:
Valve stems
Valve job
ARP studs
Throttle body cleaning
Idler pulley
Pulley bearings
EGR cleaning
Thermostat
Spark pugs
Fuel Injectors set
Knock sensors
Ignition wire set
Exhaust studs
Vacuum switch Valve
Fuel filter
PHH hoses
Rewrapped engine harness
 
lumbee1 said:
Mine started with running slightly warmer. This quickly transitioned into harder starting and I noticed the coolant level was low. Learn from my mistakes and listen to others.

My blown headgasket happened in the most inconvenient time. We were out at dinner one night after experiencing the issues listed above. It ran fine but after dinner, there was a loud clank when I tried to start the engine. I knew immediately it was hydrolocked with coolant. I tried again and got another loud clank but the engine was running. I reversed out of the parking lot and drove as fast as I could home.
It was a 30 mile trip and initially the temps stayed around 179 to 183 and I thought I was lucky. 20 miles from home and the temps spiked to 200 and kept rising. Racing the engine would lower the temp but only temporarily, however I finally made it home by the skin of my teeth and shutoff the engine at 231 degrees.

Replacing the head gasket is a great learning opportunity and IMO very necessary to do the work yourself if you plan on keeping the Cruiser long term.

I'm 6'2" but this made it easier to work on.
View attachment 4147404
Failure at cylinder 6.
View attachment 4147405
ARP studs going in.
View attachment 4147406
Running like a champ today.
View attachment 4147411
Click to expand...
did you have any clearance issues getting the head over the ARP studs
?? looks pretty tight by the firewall
 
lumbee1 said:
Mine started with running slightly warmer. This quickly transitioned into harder starting and I noticed the coolant level was low. Learn from my mistakes and listen to others.

My blown headgasket happened in the most inconvenient time. We were out at dinner one night after experiencing the issues listed above. It ran fine but after dinner, there was a loud clank when I tried to start the engine. I knew immediately it was hydrolocked with coolant. I tried again and got another loud clank but the engine was running. I reversed out of the parking lot and drove as fast as I could home.
It was a 30 mile trip and initially the temps stayed around 179 to 183 and I thought I was lucky. 20 miles from home and the temps spiked to 200 and kept rising. Racing the engine would lower the temp but only temporarily, however I finally made it home by the skin of my teeth and shutoff the engine at 231 degrees.

Replacing the head gasket is a great learning opportunity and IMO very necessary to do the work yourself if you plan on keeping the Cruiser long term.

I'm 6'2" but this made it easier to work on.
View attachment 4147404
Failure at cylinder 6.
View attachment 4147405
ARP studs going in.
View attachment 4147406
Running like a champ today.
View attachment 4147411
Click to expand...

Similar to my experience, however, my hydrolocked motor resulted in a cracked crank shaft, and a whole ordeal afterward
 
60 toy ota said:
I'd sleep well attributing this to the coolant that's sitting in the cylinder. First, because that's going to seal real nice around your compression ring (think wet vs dry compression tests). Second, the space it occupies means less compressible volume in the cylinder. And on top of that, as @mudgudgeon was saying, if you did the test cold there's a good chance you're not even loosing pressure to the leak site.

The blocks on these are pretty resilient. Have your machine shop magniflux the head before they do work on it and you should be good. If you can't find a good local shop I can recommend one in northern Utah if you need.
Click to expand...
Thanks 60, I guess I didn't think about the incompressibility factor of the coolant inside the head, or the fact is was helping to possibly seal. See that's why I ask these questions.

Now i've gone down a rabbit hole of buying parts because it would be nice to get her shiny and new as much as possible. Replacing the thermostat, fuel filter, power steering pump, PHH with PP clamps, and timing chain kit with all new parts. Any reason to replace water pump? I've read they're robust, but why take a chance with a new one if the one I've had has been rock solid? I've recently replaced the oil pump seal, and fwd crank shaft seal. I've read a bunch of the HG threads on here, but maybe missed something. I'll take another crack at the search fu, but if you think of something I missed, send it!!
 
60 toy ota said:
Have your machine shop magniflux the head before they do work on it and you should be good. If you can't find a good local shop I can recommend one in northern Utah if you need.
Click to expand...
My plan was to pressure test the head first to check for cracks. Was told that's about $150 from a couple a local machine shops. Is magnafluxing a head cheaper? If it test good, then I was planning on getting it decked and cleaned and lastly a valve job. All told three separate machine shops quoted me around $650-800 to complete the work. One shop was going to vacuum test the valves first to see if they needed the valve job. Is it common to pass the test where the valve lapping can be skipped? Or just do it and get it over with.
 
KINGCM said:
My plan was to pressure test the head first to check for cracks. Was told that's about $150 from a couple a local machine shops. Is magnafluxing a head cheaper? If it test good, then I was planning on getting it decked and cleaned and lastly a valve job. All told three separate machine shops quoted me around $650-800 to complete the work. One shop was going to vacuum test the valves first to see if they needed the valve job. Is it common to pass the test where the valve lapping can be skipped? Or just do it and get it over with.
Click to expand...
Do it while its already apart. Valve job, decked and vacuum test it and your good for the next 200k miles. Thats what i did and slap a Cruisers and Co Turbo on it😎
 
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