P0306 did I cause from flushing heater core

[jeepop]

So I flushed the heater core because the heat was not getting hot. Two days later I am getting a P0306. Did I mess up the plug and ignition coil.

What should I do to approach this?

 

[tjkj2002]

Most likely got water down into #6 plug well,pull coil and blow out the plug well with air and dry coil.

Apply a little dielectric grease to the coils o-ring and re-install.


By the way the design of heater cores for the last 20 years prevents any meaningful results from "flushing" or "back flushing".It's a very short term band aid for needing to replace the heater core.

 

[djtimyd]

By the way the design of heater cores for the last 20 years prevents any meaningful results from "flushing" or "back flushing".It's a very short term band aid for needing to replace the heater core.

Why is that? I don't have issues with the heater core in either of the jeeps I own. However, after a quick google search, I can find many articles, tips, suggestions, and procedures for flushing a heater core (including ones specific to jeeps) and its benefits, but I can't find any other mentions of flushing being ineffective - quite the opposite actually. So I am curious as to what the reasons are against core flushing.

I would think that, since the heater core is basically a small radiator, it would benefit from the same flushing that is done for the entire cooling system, radiator, engine and heater core all as one. My thinking, and of course I could be wrong here, is that if a flush is ineffective for a heater core, then wouldn't it also be ineffective for a radiator? I know that there are differences and that I am clearly not the most knowledgeable on internals. That is why I am asking for the reasoning behind your suggestion.

 

[tjkj2002]

Why is that? I don't have issues with the heater core in either of the jeeps I own. However, after a quick google search, I can find many articles, tips, suggestions, and procedures for flushing a heater core (including ones specific to jeeps) and its benefits, but I can't find any other mentions of flushing being ineffective - quite the opposite actually. So I am curious as to what the reasons are against core flushing.

I would think that, since the heater core is basically a small radiator, it would benefit from the same flushing that is done for the entire cooling system, radiator, engine and heater core all as one. My thinking, and of course I could be wrong here, is that if a flush is ineffective for a heater core, then wouldn't it also be ineffective for a radiator? I know that there are differences and that I am clearly not the most knowledgeable on internals. That is why I am asking for the reasoning behind your suggestion.

It's how the heater cores are made and where the inlet/outlet pipes are.

Our heater cores have both the inlet and outlet on the same side so flushing it doesn't do much besides clearing the path between the inlet and outlet and miss the other 90% of the heater core.

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[jeepop]

Before I flushed the heater core there was a noticeable difference in temp in the inlet and outlet hoses from the firewall. I first flushed outlet in, then inlet, then outlet again. Second time I did the outlet side a goop of slime came out of the inlet side. After this the jeep interior gets hot.

Regarding my P0306, we are rolling again with a smooth idle and no hesitation, but the code has not cleared.

I pulled the ignition coils from 4 and 6, sprayed with contact cleaner, and reinstalled. I also agitated the fuel injectors and spayed the contacts on them after messing with the ignition coils did nothing to help. That seemed to do the trick.

I do plan to pull and replace the plugs really soon.

Do you all replace the ignition coils too, or wait for them to go bad?

 

[tommudd]

Before I flushed the heater core there was a noticeable difference in temp in the inlet and outlet hoses from the firewall. I first flushed outlet in, then inlet, then outlet again. Second time I did the outlet side a goop of slime came out of the inlet side. After this the jeep interior gets hot.

Regarding my P0306, we are rolling again with a smooth idle and no hesitation, but the code has not cleared.

I pulled the ignition coils from 4 and 6, sprayed with contact cleaner, and reinstalled. I also agitated the fuel injectors and spayed the contacts on them after messing with the ignition coils did nothing to help. That seemed to do the trick.

I do plan to pull and replace the plugs really soon.

Do you all replace the ignition coils too, or wait for them to go bad?

Seems most wait for them to go bad
and then replace with cheap , then replace with good ones! LOL
The 04 got hers replaced 3 times in 221,000 miles , the 03 I replaced when I bought it at 78,000 miles, the 05 is still original at 98,000 . Maybe overkill to some but they lose power over time as well IMO
plugs, NGK copper core of course

 

[jeepop]

Who makes the good ones?

I can get two delphi or standard motor in the Standard Replacement section at Rockauto for one duralast one from Autozone.

 

[tjkj2002]

Who makes the good ones?

I can get two delphi or standard motor in the Standard Replacement section at Rockauto for one duralast one from Autozone.

The dealership,worth the extra few bucks.

 

[jeepop]

P0306 cleared yesterday on its own.

 

[tommudd]

Who makes the good ones?

I can get two delphi or standard motor in the Standard Replacement section at Rockauto for one duralast one from Autozone.

AUTOZONE=AIR FRESHENERS
not much else

 

[JasonJ]

AUTOZONE=AIR FRESHENERS
not much else

I get washer solvent there when it's on sale.

That's saying something, as I worked there as a parts monkey for 7 years. I was one of the rare guys who actually knew what he was doing, however. Aren't many of those anymore.

 

[tommudd]

I get washer solvent there when it's on sale.

That's saying something, as I worked there as a parts monkey for 7 years. I was one of the rare guys who actually knew what he was doing, however. Aren't many of those anymore.

Thats the biggest issue right there, not many that actually know what a dipstick even is any more . Then trying to sell you something you don't even want LOL
There are a few people out there yet that know which end is up, sadly not many.

They brought a Zone into a small area I used to live, ran in one weekend since NAPA was closed and there is this cute chick, nails/ hair done nice etc
Told her what I needed and right away she starts asking all the right questions without using the computer, almost fell over . She was great!

 

[JasonJ]

Thats the biggest issue right there, not many that actually know what a dipstick even is any more . Then trying to sell you something you don't even want LOL
There are a few people out there yet that know which end is up, sadly not many.

They brought a Zone into a small area I used to live, ran in one weekend since NAPA was closed and there is this cute chick, nails/ hair done nice etc
Told her what I needed and right away she starts asking all the right questions without using the computer, almost fell over . She was great!

Wow.. sometimes they hire a good one! When I was there, we even had real ASE training and certifications; it took 2 solid weeks of parts knowledge and automotive basics training and testing before they even let you be at the parts counter by yourself.

 

[jeepop]

They brought a Zone into a small area I used to live, ran in one weekend since NAPA was closed and there is this cute chick, nails/ hair done nice etc
Told her what I needed and right away she starts asking all the right questions without using the computer, almost fell over . She was great!

If she did not have a dipstick tucked down below you should have married that one.

 

[tommudd]

If she did not have a dipstick tucked down below you should have married that one.

Trust me I tried :happy175:
even went out a few times ( and no dipstick tucked away )
Was even single at the time
but alas it was not to be.....
Contract ended where I was working and she was happy where she was, so I moved on