2002 Toyota 4Runner Engine Help

[jwkiss0]

I'm not entirely convinced your head gaskets are ruined. I have also overheated my engine and has been fine for years. The radiator has to be fixed either way and the repair has little overlap with the head gasket so it's not like you are saving time by doing both together. Fix what you know is broken or have the shop do it if space and tools is an issue.

I have definitely decided I am fixing it. Do you know the difference between the 2 different priced radiators at Toyota? One is like $125 and the other is at least double that, maybe closer to $400, I don't remember.

The only thing that gets me is why did it not want to run immediately after it overheated and why did it run rough when it finally did run? That seems like coolant got on the plugs and had to burn off?

 

[jwkiss0]

The fact the engine was running poorly after the radiator failed isn't a good sign. The question is, did the radiator fail because the engine got too hot, or did the engine overheat because the radiator sprung a leak?

Anyway, you're going to need a radiator regardless so I'd start with that. After you get the radiator replaced and coolant refilled, I'd give the engine a start and see where you're at. If it's still running rough or spewing smoke out the tail pipe, you either cracked one of both of your heads and blew one or both of the head gaskets.

As a diagnostic tool, I'm not a fan of relying solely on those combustion gas detector kits. With by buddy Sean's rig, we confirmed he had coolant getting into the #3 cylinder using a leak down tester in conjunction with a cooling system pressure tester and the combustion leak detector didn't confirm the issue.


Here's our Radiator Replacement Video which includes installing a trans cooler.

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If you'd like an upgrade over the OEM radiator, Koyorad makes a nice one.

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Here's the video of [MENTION=102606]infamousRNR[/MENTION] (Sean) and I made confirming coolant was getting into the #3 cylinder.

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Finally, here's Part 1 of our Head Gasket video series. I unfortunately think you're going to need it.

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Good luck! If you need further help, you can contact me on this forum or on my Timmy the Toolman YouTube channel.

I appreciate it greatly! I have already watched the videos for replacing the heads and gaskets and really liked the info from the machine shop. Do you happen to know the difference between the 2 radiators Toyota is offering? One is much more than the other.

When I got it home (towed from mechanic) I had to start it to move it up in the driveway. It ran fine! You would not have known it had an issue. The only thing puzzling to me is the rough run after the overheat issue. I knew the radiator needed replacing and I had planned to do it this week. I know the radiator was weak and the coolant on the hood and engine suggests it was the cause of the overheat. The big question for me is why did it run roughly on the restart? I assumed coolant got on the plugs and had to burn off? Is there any other possible explanation? I will plan on the radiator and see if the diagnosis changes after replacing the radiator. Thank you and everyone else who has provided excellent input.

 

[Jakeepoo3]

Thank you for the link. I have watched his videos before. I used them to fix the door lock actuator. He does a great job. Do you know of a good source for the radiator?

Look at your oil fill cap and dipstick. The cap will have frothy looking crap on it and the oil will look brownish like milk chocolate if gasket is blown. Spark plugs are a good indicator also, the leak test to make extra sure.

 

[jwkiss0]

Look at your oil fill cap and dipstick. The cap will have frothy looking crap on it and the oil will look brownish like milk chocolate if gasket is blown. Spark plugs are a good indicator also, the leak test to make extra sure.

I checked the oil, not milky or frothy looking at all. Looks like normal oil. Guy at the shop said it smelled sweet smelling when they ran it, but I’m not sure I can smell that. The guy also wants to buy it so I don’t know if I trust him.

 

[Jakeepoo3]

I checked the oil, not milky or frothy looking at all. Looks like normal oil. Guy at the shop said it smelled sweet smelling when they ran it, but I’m not sure I can smell that. The guy also wants to buy it so I don’t know if I trust him.

Head gasket is fine which is why he wants it. Coolant does smell sweet so what. I've been forced to overheat mine petty good to get out of a little mishap with my radiator in the middle of my local national forest. I had to get off a gnarly trail to where a I could get a trailer out there and get it home. From reading your thread it was only overheated for a short period. I'd still do the leak test anyways it's free and will ease your mind.

 

[jwkiss0]

Head gasket is fine which is why he wants it. Coolant does smell sweet so what. I've been forced to overheat mine petty good to get out of a little mishap with my radiator in the middle of my local national forest. I had to get off a gnarly trail to where a I could get a trailer out there and get it home. From reading your thread it was only overheated for a short period. I'd still do the leak test anyways it's free and will ease your mind.

I’m going to get a new radiator and test it out and see what happens. I will be be very mad and happy if it checks out good.

 

[mtbtim]

Head gasket is fine which is why he wants it. Coolant does smell sweet so what. I've been forced to overheat mine petty good to get out of a little mishap with my radiator in the middle of my local national forest. I had to get off a gnarly trail to where a I could get a trailer out there and get it home. From reading your thread it was only overheated for a short period. I'd still do the leak test anyways it's free and will ease your mind.

It's premature to say the head gasket or head itself is fine. The OP needs to get the radiator swapped and drive it to see what happens. If he starts mysteriously losing coolant with no obvious leak and cold starts produce a rough idle and white smoke out the tail pipe, he's not ok.

All it takes is one short overheating to do damage.

 

[jgue467]

...

All it takes is one short overheating to do damage.

Tru dat - mine 'only' overheated to 212 once or twice for a minute or two and just as you describe, loosing coolant with no leak, puffs of smoke for a few seconds on startup and bam both heads cracked, these engines are very intolerant of excess head heat. Luck all.

 

[jwkiss0]

Anyone have any information on the 2 different radiators Toyota sells? One is around $125 or so and the other one is $400. That's a big difference.

 

[subzjc]

If I had to take a guess on the rough running after the overheating
I would say the fuel got hot.

 

[Jakeepoo3]

It's premature to say the head gasket or head itself is fine. The OP needs to get the radiator swapped and drive it to see what happens. If he starts mysteriously losing coolant with no obvious leak and cold starts produce a rough idle and white smoke out the tail pipe, he's not ok.

All it takes is one short overheating to do damage.

I agree, just being positive. Going by the info provided in his comments there's no sign of coolant besides sprayed all over the bay. I reckon it's possible all the coolant sprayed out then the gasket could have blown. Oil is said to be clear and clean. And if the radiator lost all it's fluid in an explosive manner the driver I assume noticed and shut the vehicle off. We haven't been told how long it was driven like that. Im not certain but pretty sure the 3rd gen has a limp/fail safe mode.. in his case the extreme difference in ECT and IAT would enter fail safe mode to protect the vitals if being driven. And the system is designed to shut the truck off after so long to prevent major damage. I drove mine with little to no coolant about five miles on nasty trail and it entered the first stage of fail safe mode right as I got to an accessible path thankfully. No damage occured and runs perfect. Maybe I got lucky who knows.

 

[brillo_76]

Anyone have any information on the 2 different radiators Toyota sells? One is around $125 or so and the other one is $400. That's a big difference.

They are similar. I have been using the denso cheaper ones for years without issues. The Toyota oem will say Toyota on it instead of denso.

Could be slightly better quality, but then again, it may not as some of Toyota parts are 2 lines. One part number better quality. The other part number the economy line. Oil filters and air filters are this way. I hope this answers your question.

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[brillo_76]

I must have been lucky when my one went to white on the dash gauge. I hit the heater and got it back down to the middle. I first stopped and checked for leaks. Were none. So I replaced the thermostat 20 to 30k ago and am still kicking along. No coolant consumption at all. Heads never off at 290k now.

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[jwkiss0]

I agree, just being positive. Going by the info provided in his comments there's no sign of coolant besides sprayed all over the bay. I reckon it's possible all the coolant sprayed out then the gasket could have blown. Oil is said to be clear and clean. And if the radiator lost all it's fluid in an explosive manner the driver I assume noticed and shut the vehicle off. We haven't been told how long it was driven like that. Im not certain but pretty sure the 3rd gen has a limp/fail safe mode.. in his case the extreme difference in ECT and IAT would enter fail safe mode to protect the vitals if being driven. And the system is designed to shut the truck off after so long to prevent major damage. I drove mine with little to no coolant about five miles on nasty trail and it entered the first stage of fail safe mode right as I got to an accessible path thankfully. No damage occured and runs perfect. Maybe I got lucky who knows.

I don't know that it was driven at all while overheating. It was noticed to be getting hot while sitting still and the CEL came on. We never drove it all after that. I suppose it could have been hot while driving and we didn't notice, but I don't think so. There is also no smoke in the exhaust when we start it. The coolant it lost was very minimal. it was only the amount in the overflow tank. Maybe a quart at best. The restart when I got it home showed no signs of any issue and ran fine. I think the radiator replacement will help me determine the extent of the damage if any. Based on all the great comments, I don't think I can do anything until I replace the radiator anyways.

 

[Jakeepoo3]

I must have been lucky when my one went to white on the dash gauge. I hit the heater and got it back down to the middle. I first stopped and checked for leaks. Were none. So I replaced the thermostat 20 to 30k ago and am still kicking along. No coolant consumption at all. Heads never off at 290k now.

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You dang right! I used the heater trick too and luckily it was freezing cold out. Nearly froze to death had to sleep in the truck that's why I love going solo. The adrenaline. The motors are tough as heck. Also I having an engineering background I'm fairly sure their mechanical engineers and metallurgists know aluminum and steel expand at different rates and accounted for that factor within it's structure design.

 

[Jakeepoo3]

I don't know that it was driven at all while overheating. It was noticed to be getting hot while sitting still and the CEL came on. We never drove it all after that. I suppose it could have been hot while driving and we didn't notice, but I don't think so. There is also no smoke in the exhaust when we start it. The coolant it lost was very minimal. it was only the amount in the overflow tank. Maybe a quart at best. The restart when I got it home showed no signs of any issue and ran fine. I think the radiator replacement will help me determine the extent of the damage if any. Based on all the great comments, I don't think I can do anything until I replace the radiator anyways.

You should be fine. Crazy sh1t happens though so we'll cross our fingers for you!

 

[brillo_76]

You dang right! I used the heater trick too and luckily it was freezing cold out. Nearly froze to death had to sleep in the truck that's why I love going solo. The adrenaline. The motors are tough as heck. Also I having an engineering background I'm fairly sure their mechanical engineers and metallurgists know aluminum and steel expand at different rates and accounted for that factor within it's structure design.

I wasnt that lucky.. Mid July, August when i had to ride around with the windows down ac on full blast till a swapped that thermostat..:lookout:

 

[Jakeepoo3]

I wasnt that lucky.. Mid July, August when i had to ride around with the windows down ac on full blast till a swapped that thermostat..:lookout:

That thing has ac! Fancy! Looks like we have some sh1t in common. This is my dirt truck aka "back up b1tch" I've had for twenty years. I've deleted everything out of it including AC. Not to mention every body panel I love the looks people give me and that it'll smoke pretty much anything that wants to give it a try.

 

[mtbtim]

I have definitely decided I am fixing it. Do you know the difference between the 2 different priced radiators at Toyota? One is like $125 and the other is at least double that, maybe closer to $400, I don't remember.

The only thing that gets me is why did it not want to run immediately after it overheated and why did it run rough when it finally did run? That seems like coolant got on the plugs and had to burn off?

There is a very detectable quality difference between the two. The more expensive one is an equal replacement to the original one from Japan. The more affordable one looks and feels cheaper. I've installed the more expensive one in my 2000 4runner and the cheaper one in my 1998 4runner.

 

[mtbtim]

I agree, just being positive. Going by the info provided in his comments there's no sign of coolant besides sprayed all over the bay. I reckon it's possible all the coolant sprayed out then the gasket could have blown. Oil is said to be clear and clean. And if the radiator lost all it's fluid in an explosive manner the driver I assume noticed and shut the vehicle off. We haven't been told how long it was driven like that. Im not certain but pretty sure the 3rd gen has a limp/fail safe mode.. in his case the extreme difference in ECT and IAT would enter fail safe mode to protect the vitals if being driven. And the system is designed to shut the truck off after so long to prevent major damage. I drove mine with little to no coolant about five miles on nasty trail and it entered the first stage of fail safe mode right as I got to an accessible path thankfully. No damage occured and runs perfect. Maybe I got lucky who knows.

Well, design and the result of that design can be very different things, right? And, what was the engineers design goal, to not seize the engine and it be a total loss? All I know is it doesn't take that much to blow a head gasket or crack a head on one of these engines. People have head gasket failures and cracked heads and they never overheated the engine once.

The OP is going to have to see what happens after he gets the new radiator swapped in. If he wants to find out the answer sooner rather than later, he will perform a compression check of all cylinders and follow that up with a leak down test of any cylinders with a low value. Or, he just drives it and sees what happens over time. A head gasket failure or cracked head doesn't always fail between the cylinder and a coolant jacket. It can also fail between the cylinder and an oil gallery, or it can fail at the seal between neighboring cylinders. With these engines, the common failure is a crack between the valves. The crack eventually migrates to a coolant jacket and coolant leaks into the combustion chamber.

Since the OP has a 2002, his engine had the superior MLS (Multi Layer Steel) head gaskets. Those are not known to fail like the older composite gaskets. If the OP's engine ends up eating coolant, it's most likely due to a cracked head.

OP, instead of just hoping you're all good, I suggest doing the compression and leak down test so you don't spend a lot of energy worrying about it.


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