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2004 Dodge Grand Caravan SXT 3.8L
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On your coil pack, switch 4 &


Welcome to the forum.

No, replacing radiator will not help if the problem is the thermostat. First culprit will always be the thermostat, then radiator fans and lastly the radiator.

That little hose between radiator and overflow bottle is the correct size for the application, any larger and it might not work.

It will never clog in a well maintained engine, shouldn't be any rust ay all.

Seems like your cooling system was badly neglected.
Thanks. I wasn't thinking at all to replace the hose with a larger diameter. If anything, I would possibly only be looking at drilling the inside diameter of the reservoir inlet to be slightly larger just to minimize chances of it getting clogged with rust again. I have a background in mechanical engineering. I would guess it was like an 1/8 of an inch in diameter max, if not smaller. But yeah, My first van. I bought it 2 years ago and I did see that some work/maintenance was to be needed and did not think to check much since I bought it, since it was running like a champ as of a few weeks ago. The cooling system was badly neglected. Leaves me wondering where the rust usually comes from, the upper engine coolant cavities since the coolant level was always low the past 2 years? Also, I've read elsewhere the coolant level in the radiator when cold should be visible and 1/2" to an inch below the radiator cap.
 

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Went to remove the hose that connects at the radiator cap and goes to the reservoir. Sure enough it was deeply clogged with rust. Used a wire clothes hanger to punch through carefully and ran pressurized water through the hose. Also took the reservoir off and I found some rust residue settled at the bottom. Rinsed out vigorously and reinstalled hose and reservoir.
The inlet inside diameter where the hose connects to the reservoir is so tiny it can easily get clogged up again so I'll be checking for more rust and clogging again soon. I've read up on these forums that people replace the radiator and makes me wonder did they ever check that hose from radiator to reservoir. The color of the old thermostat you show in the pictur indicates some rust buildup.
I will be draining the radiator next, my van still runs really hot after radiator cap and thermostat change. Is the hood prop being extremely hot to the touch a surefire way to tell if van is still running too hot? or is this normal? Also, two of my relays in the fusebox are extremely hotter to the touch than the rest, namely Fuel pump relay and EATX transmission safety relay
Proper coolant prevents corrosion. Are you sure what you are seeing isn't some overdosing using a poor quality "stop leak"? The corrosion you are describing is unheard of normally.
Radiators get replaced mostly because they leak.
Your temperature gauge tells you how hot the coolant system is running. Hood prop, not so much. Where is the needle on the gauge?
What coolant are you using?
 
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It will never clog in a well maintained engine, shouldn't be any rust ay all.

Seems like your cooling system was badly neglected.
Yes +1

Using the correct antifreeze coolant is not only for low temperature but also corrosion control (rust)
AND, even so, it must be replaced on a calendar schedule, too.

HOAT Hybrid Organic Acid Technology is the original formula. Mixing coolants is not a good idea also.

Flush your system, refill with distilled water and run with straight distilled water for a good drive, then drain.
Perhaps do this fill / drain a few times.

Then look up the full volume for your cooling system, measure how much you drain out, then calculate how much distilled water remains in your van when 'completely' drained. Then you need to add at least that much concentrate coolant to get a 50/50 mix.

This is just an example for purpose of the discussion: \
lets say you fill the Yugo of water and then you measure how much gets drained when you open the radiator. You get two gallons of water out and the Yugo holds three gallons total (one gallon of distilled water remains in the Yugo).

So, to make a 50/50 mix you need to add 1 gallon of concentrate coolant to mix with the one gallon of distilled water that is still in the Yugo. Then, to complete the fill of the cooling system, you will need to add one gallon of 50/50 mix of the same antifreeze. You can buy a second gallon of concentrate and add 1/2 gallon and 1/2 gallon of distilled water OR most all of the flavor antifreeze also sell a convenient 50/50 mix. Just use that to fill the radiator and fill the reservoir to "cold".

Please understand that I am not talking down to anyone in particular, rather if I had to explain this to my teenager, I feel I need to explain in detail. (me thinks mother dropped it on its head)
 

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Thanks. I wasn't thinking at all to replace the hose with a larger diameter. If anything, I would possibly only be looking at drilling the inside diameter of the reservoir inlet to be slightly larger just to minimize chances of it getting clogged with rust again. I have a background in mechanical engineering. I would guess it was like an 1/8 of an inch in diameter max, if not smaller. But yeah, My first van. I bought it 2 years ago and I did see that some work/maintenance was to be needed and did not think to check much since I bought it, since it was running like a champ as of a few weeks ago. The cooling system was badly neglected. Leaves me wondering where the rust usually comes from, the upper engine coolant cavities since the coolant level was always low the past 2 years? Also, I've read elsewhere the coolant level in the radiator when cold should be visible and 1/2" to an inch below the radiator cap.

We have many members here who claims that kind of backround but their posts suggests otherwise.

Again, no need to modify that reservoir inlet, you're better off properly maintaing your cooling system. Bigger inlet diameter might break off vacuum needed to suck coolant from overflow bottle back to radiator.
 

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On your coil pack, switch 4 &
sulkinator, Levy makes a great point here... for test purposes at the ignition coil, swap the wire positions (disconnect the spark plug wire at #4 position and connect it at the #1 position and vice versa).

So, at the coil, swap the middle front and middle rear wires going to the spark plugs.

58689
 

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Discussion Starter #26
OP, not to rain on your parade, but don't spend any money on 'fluff' for the van until you get a feeling for the health of the engine. Maybe overheated too many times? Also, the thermostat looked like there was oil in the coolant.

For now, you can clean up the headlights with any type of car polish and a little elbow grease. Remember, they don't need to be perfect, and anything would be better than what they are now.
That’s fair, just got excited is all. I removed the new thermostat and checked and there is no oil in the coolant, at least at the moment.
 

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Discussion Starter #27
UPDATE: Last night I was working on the van, I decided to take the valve cover back off and look at the fuel injectors again. I looked at the cylinder 4 injector port (Whatever proper term is) and the gaasket from the old injector was in there still! I removed it and it appears my misfire is gone! Now its not perfect, pretty sure I need engine mounts.
 

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Discussion Starter #28
UPDATE: Last night I was working on the van, I decided to take the valve cover back off and look at the fuel injectors again. I looked at the cylinder 4 injector port (Whatever proper term is) and the gaasket from the old injector was in there still! I removed it and it appears my misfire is gone! Now its not perfect, pretty sure I need engine mounts.
UPDATE 2: I’ve driven it around a bit, it does not feel like it’s misfiring. i disconnected the battery to clear the codes and the misfire cylinder 4 code came back. While it was running i unplugged the spark plug wire and could clearly hear a difference, it’s definitely firing. Do i need to just keep driving it to have it clear the codes on its own?
 

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UPDATE 2: I’ve driven it around a bit, it does not feel like it’s misfiring. i disconnected the battery to clear the codes and the misfire cylinder 4 code came back. While it was running i unplugged the spark plug wire and could clearly hear a difference, it’s definitely firing. Do i need to just keep driving it to have it clear the codes on its own?
And you say that you A) installed a new injector (just one, not a whole set) and B) installed all new spark plugs and #4 appeared to be dry whiteish in color indicating that it was firing lean.

I wonder if there is a knock sensor for each cylinder and perhaps yo have a poor cylinder.

What I would have encouraged you to do would be to move fuel injectors (the old #4 injector to the #2 cylinder and vice versa) see if the fault then moved to the #2 cylinder and the #4 cylinder code cleared.

Where did you get this new #4 fuel injector, if you don't mind me asking?
 

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If you should choose to accept the mission...

go to auto zone and they will 'lend' you a compression tester. If you bring a spark plug socket, you can test this right in the parking lot.

You remove the three spark plugs that are easy to get to. #2,4,6 and perform the compression test on those three cylinders. The back three are hard to get to unless you learn how to remove the wiper cowl (it is easy after you learn it, and really the only way to go.)
Carefully disconnect and number the back three spark plug wires at the coil, mark them so you know how to get them back on the right post.
You screw the hose into the each cylinder and crank it four or five revolutions. As high as you can get it, and record the pressure values. Post them here.
 

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It might still be leaking through injector #4 seal if you didn't remove the injector(s) to properly remove the old gasket. Classic vacuum leak (running lean on that cylinder?). Spray something flammable around that injector while running to see if it smooths out when sprayed. If it does, it's just a vacuum leak.
 

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Discussion Starter #32
It might still be leaking through injector #4 seal if you didn't remove the injector(s) to properly remove the old gasket. Classic vacuum leak (running lean on that cylinder?). Spray something flammable around that injector while running to see if it smooths out when sprayed. If it does, it's just a vacuum leak.
I actually had done that, the old gasket was still in there, i had to go back in and remove it. It still shows the misfire code, it probably is misfiring, just not a very bad one at all.
 

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Discussion Starter #33
If you should choose to accept the mission...

go to auto zone and they will 'lend' you a compression tester. If you bring a spark plug socket, you can test this right in the parking lot.

You remove the three spark plugs that are easy to get to. #2,4,6 and perform the compression test on those three cylinders. The back three are hard to get to unless you learn how to remove the wiper cowl (it is easy after you learn it, and really the only way to go.)
Carefully disconnect and number the back three spark plug wires at the coil, mark them so you know how to get them back on the right post.
You screw the hose into the each cylinder and crank it four or five revolutions. As high as you can get it, and record the pressure values. Post them here.
I will go do that today after work!
 

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Does anyone here know if the ECU determines a 'misfire' based on a knock sensor or if it is detected some other way?

Hey sulkinator, spool up to post #25 where I put the picture of the coil and engine block. Note how the wires on the front of the coil are the same as the layout of the cylinders 2, 4, 6 from left to right. Then note how the coil wiring layout is different on the back of the coil [ cylinders 5, 1, 3 ]
*note that most coils will have a number embossed right on the coil plastic to indicate where it is supposed to be routed to.

On a cool engine, try to 'feel' the wires on the back side to determine that they go to the correct spark plugs.
* this is just a whim, but we had a new member last week or two that was 'SURE' that he had a misfire after he washed his engine and then later found that he had installed new wires and spark plugs wrong...

Wouldn't that be grand if you got this $400 gem because someone made a simple mistake. I 'stole' a Porsche like that for a $1000 over a cracked vacuum hose.
 

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From my understanding, misfires are detected by the crank sensor. The rotational speed of the engine changes (probably slows down) compared to what is expected at that RPM when that particular cylinder misfires.
 

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From my understanding, misfires are detected by the crank sensor. The rotational speed of the engine changes (probably slows down) compared to what is expected at that RPM when that particular cylinder misfires.
Yes, thanks... I do remember reading that here recently, as soon as I asked the question actually.
 

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Discussion Starter #37
Does anyone here know if the ECU determines a 'misfire' based on a knock sensor or if it is detected some other way?

Hey sulkinator, spool up to post #25 where I put the picture of the coil and engine block. Note how the wires on the front of the coil are the same as the layout of the cylinders 2, 4, 6 from left to right. Then note how the coil wiring layout is different on the back of the coil [ cylinders 5, 1, 3 ]
*note that most coils will have a number embossed right on the coil plastic to indicate where it is supposed to be routed to.

On a cool engine, try to 'feel' the wires on the back side to determine that they go to the correct spark plugs.
* this is just a whim, but we had a new member last week or two that was 'SURE' that he had a misfire after he washed his engine and then later found that he had installed new wires and spark plugs wrong...

Wouldn't that be grand if you got this $400 gem because someone made a simple mistake. I 'stole' a Porsche like that for a $1000 over a cracked vacuum hose.
I will definitely check that, but the code is for a misfire specifically on cylinder 4.
 

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Discussion Starter #38
From my understanding, misfires are detected by the crank sensor. The rotational speed of the engine changes (probably slows down) compared to what is expected at that RPM when that particular cylinder misfires.
Is there an easy(ish) way to test the crank sensor?
 

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Crank sensor wouldn't cause a single cylinder misfire. Drop some oil in the spark plug hole, just a little. Compression may go up. If it does, it fouled the piston rings.
 

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Crank sensor wouldn't cause a single cylinder misfire. Drop some oil in the spark plug hole, just a little. Compression may go up. If it does, it fouled the piston rings.
Roger that Sienile.

Sulkinator, did you get that?

If your #4 cylinder tests lower, then a cap full of oil or so into that spark plug hole and repeat the compression test.
If the compression comes up, then we know the pressure is leaking past the piston rings.

If the compression does not come up higher on the second test, then we think it to be either the valves or the head gasket.

Post your results and let us know what you find....
 
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