Hard to Diagnose P0300 Fixed

[Majkmichael]

A few months ago my CEL came on for a P0300(random cylinder misfire). Truck ran ok but it'd shake on startup so I thought it was probably fuel related or maybe a coil packs causing a misfire on both sides of the engine. I replaced the wires since they were original but not the plugs since I did them about 3k miles ago. I also replaced my PCV valve and it ran a little better but still CEL. I noticed I was ever so slowly losing coolant and my radiator hose was not holding pressure so I realized it was my head gasket. It was a very minor leak so I got some K Seal head gasket fix and poured it in the radiator and within a day my CEL was gone, truck ran great and radiator held pressure. This could have easily costed me hundreds if I threw parts at it.

 

[sweet88gt]

A few months ago my CEL came on for a P0300(random cylinder misfire). Truck ran ok but it'd shake on startup so I thought it was probably fuel related or maybe a coil packs causing a misfire on both sides of the engine. I replaced the wires since they were original but not the plugs since I did them about 3k miles ago. I also replaced my PCV valve and it ran a little better but still CEL. I noticed I was ever so slowly losing coolant and my radiator hose was not holding pressure so I realized it was my head gasket. It was a very minor leak so I got some K Seal head gasket fix and poured it in the radiator and within a day my CEL was gone, truck ran great and radiator held pressure. This could have easily costed me hundreds if I threw parts at it.

How long has it been since you did the K seal ? How many miles have you put on the truck since the install ?

 

[Captsolo]

Good post. I have 2005 SR5 with 150,000 miles. I would try blue devel or the K seal you used if I thought (like you did) my HG had small leak.

Do you have any white smoke out your exhaust.? How about the oil fill cap? Ang evidence of water (white foam)?

I've heard 4runners can go 3000 miles and years with blue devel or a good HG sealer - according to Scotty Kilmer(steel seal).

Scotty Kilmer(blue steel). - Bing video :vader:

 

[Dieselchessy]

I used that stuff on a 3.4 head gasket. Some type of gel with brass powder and white fuzz in it. Primarily all it did was clog up my radiator.
It sealed for a few months and then started leaking again.
The worse part is back flushing the stuff out of the front and rear heater cores when you finally fix the motor. I ended up just replacing the radiator. No way to get that stuff out. It’s amazing how much brass powder is in one of those bottles.
Like trying to clean up glitter.

I recommend draining some fluid so you can see the top of the radiator core and then inspecting with a flashlight to see if the channels are now clogged.

 

[sweet88gt]

I used that stuff on a 3.4 head gasket. Some type of gel with brass powder and white fuzz in it. Primarily all it did was clog up my radiator.
It sealed for a few months and then started leaking again.
The worse part is back flushing the stuff out of the front and rear heater cores when you finally fix the motor. I ended up just replacing the radiator. No way to get that stuff out. It’s amazing how much brass powder is in one of those bottles.
Like trying to clean up glitter.

I recommend draining some fluid so you can see the top of the radiator core and then inspecting with a flashlight to see if the channels are now clogged.

Not the correct fix by any means but in some cases worth a try.
Never priced out a head gasket replacement but I'm guessing its a fair amount.

 

[Thebeastlives]

Head gasket sealant is a good fix a short term fix that is. Eventually they will fail and when they do generally speaking it won't work again and the radiator will need to be replaced as well. I like to use the stuff if I can't get around to getting the head gasket fixed immediately.

 

[Takeo77]

Not the correct fix by any means but in some cases worth a try.
Never priced out a head gasket replacement but I'm guessing its a fair amount.

Had this error for a good while. Head gasket blew a few miles from home, and was overheating before I noticed. Two cracked heads, I sourced a new(er) engine to fix the problem.

Deal with it properly before it gets worse. Replace that head gasket.

 

[sweet88gt]

Had this error for a good while. Head gasket blew a few miles from home, and was overheating before I noticed. Two cracked heads, I sourced a new(er) engine to fix the problem.

Deal with it properly before it gets worse. Replace that head gasket.

I have been chasing that code for 3 months. Bought a new Jeep JL and parked the 4runner in the back yard.

 

[Majkmichael]

Good post. I have 2005 SR5 with 150,000 miles. I would try blue devel or the K seal you used if I thought (like you did) my HG had small leak.

Do you have any white smoke out your exhaust.? How about the oil fill cap? Ang evidence of water (white foam)?

I've heard 4runners can go 3000 miles and years with blue devel or a good HG sealer - according to Scotty Kilmer(steel seal).

Scotty Kilmer(blue steel). - Bing video :vader:

No smoke no oil just a loss of coolant and no pressure in the radiator hose. Scotty's a smart guys, i like his videos. Blue devil is supposed to be good too except some people said they had issues with it clogging their cooling system so i opted for K Seal. Could be bs but I chose not to risk it

 

[Majkmichael]

How long has it been since you did the K seal ? How many miles have you put on the truck since the install ?

About 5 days, everything's working perfect. I agree with you if it were a huge leak, that would constitute a rebuild but the main reason this happened is because I've been using mostly water and green coolant. The toyota red coolant has additives that fill small leaks when they're exposed to heat and oxygen. Very few people know about this and it was next to impossible to find online.

 

[Majkmichael]

I used that stuff on a 3.4 head gasket. Some type of gel with brass powder and white fuzz in it. Primarily all it did was clog up my radiator.
It sealed for a few months and then started leaking again.
The worse part is back flushing the stuff out of the front and rear heater cores when you finally fix the motor. I ended up just replacing the radiator. No way to get that stuff out. It’s amazing how much brass powder is in one of those bottles.
Like trying to clean up glitter.

I recommend draining some fluid so you can see the top of the radiator core and then inspecting with a flashlight to see if the channels are now clogged.

Good idea, dilluting it with water helped a lot. It's not overheating or anything but I'll give it a look.

 

[Bad Luck]

About 5 days, everything's working perfect. I agree with you if it were a huge leak, that would constitute a rebuild but the main reason this happened is because I've been using mostly water and green coolant. The toyota red coolant has additives that fill small leaks when they're exposed to heat and oxygen. Very few people know about this and it was next to impossible to find online.

Hard to find because it isn't true. You can find anything you want on the internet, but that doesn't make it true. Funniest thing I've read all month. Thank you

 

[Majkmichael]

Hard to find because it isn't true. You can find anything you want on the internet, but that doesn't make it true. Funniest thing I've read all month. Thank you

Straight from a 30 year old automotive textbook. I do not care if you believe me or not. If you look it up it gives you a general explanation of how red coolant works but doesn't really tell you what it's purpose is. That is because they don't want the average person to know this, it does not look good on them. Morons will say coolant color is only used differentiate between auto manufacturers but it's not. Toyota and General Motors both understand that it's impossible to perfect small tolerances while in production, that is the reason they use red coolant.

 

[Bad Luck]

Straight from a 30 year old automotive textbook. I do not care if you believe me or not. If you look it up it gives you a general explanation of how red coolant works but doesn't really tell you what it's purpose is. That is because they don't want the average person to know this, it does not look good on them. Morons will say coolant color is only used differentiate between auto manufacturers but it's not. Toyota and General Motors both understand that it's impossible to perfect small tolerances while in production, that is the reason they use red coolant.

How do you explain all the failed head gaskets from toyota motors that are using toyota red coolant? How do you explain why a water pump leaking through the weep hole doesn't seal itself?

I've got a great book that also tells me that the earth is flat and the sun revolves around us. What's great about information is it constantly gets updated with correct information. You sound like you've been watching Scotty Kilmer on loop.

 

[Majkmichael]

How do you explain all the failed head gaskets from toyota motors that are using toyota red coolant? How do you explain why a water pump leaking through the weep hole doesn't seal itself?

I've got a great book that also tells me that the earth is flat and the sun revolves around us. What's great about information is it constantly gets updated with correct information. You sound like you've been watching Scotty Kilmer on loop.

The organic additives in red antifreeze is not made to stop a huge leak. It is purely made to prolong the life of gaskets and seals in the cooling system. If you have a huge head gasket leak the coolant will not save you obviously. It is only supposed to fill microscopic leaks in these engines when they come out of the factory and as they age.

 

[Bad Luck]

The organic additives in red antifreeze is not made to stop a huge leak. It is purely made to prolong the life of gaskets and seals in the cooling system. If you have a huge head gasket leak the coolant will not save you obviously. It is only supposed to fill microscopic leaks in these engines when they come out of the factory and as they age.

Interesting theory. Still doesn't explain how toyota motors with toyota red coolant are getting head gasket leaks. :snacker:

 

[Dieselchessy]

Toyota red is just a low/no silicates OAT coolant. It’s corrosion inhibitors last longer, but you still need to maintain your cooling system at least every 5 years or so.

Head gaskets die from corrosion, heat cycling, and being sandwiched between dissimilar metals.
That, and if you overheat your engine it’s really hard on them.

OAT coolants aren’t miracle potions. OEM’s just like them better in aluminum and plastic systems.

 

[Majkmichael]

Toyota red is just a low/no silicates OAT coolant. It’s corrosion inhibitors last longer, but you still need to maintain your cooling system at least every 5 years or so.

Head gaskets die from corrosion, heat cycling, and being sandwiched between dissimilar metals.
That, and if you overheat your engine it’s really hard on them.

OAT coolants aren’t miracle potions. OEM’s just like them better in aluminum and plastic systems.

Exactly, they do prolong the life of gaskets though

 

[Dieselchessy]

Exactly, they do prolong the life of gaskets though

Like any coolant of any color it attempts to prolong the life of the engine components by attempting to keep corrosion at bay. It just does it in a different method than green coolant.

I’ve never heard of that “it plugs small holes” stuff you were saying.

 

[Takeo77]

My opinion is that you downgraded. Jeeps break down far more.