Hi every one.
Last week I had a curious problem with the Cockroach radiator. A N/A MANUAL transmission XFire

Resume for lazy asses: My radiator blew up after being driven for 10-15 mins with a check coolant light (whereas having the reservoir full) and the A/C on max cold and max fan force.
For fixing it I should've bought the N/A manual trans radiator A202 500 77 03, and I ended buying the AUTOMATIC transmission A202 500 78 03, hence having two additional holes for the automatic tranny oil cooling.
Now I'm wondering about using them for MOTOR oil cooling.
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Chapter one: "to blow hot, blow cold"
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​​​​The car had been parked in the street without moving it for two months or more.
I had to pass the vehicle technical inspection*, so I called my car insurance company, since I have an included driver service for taking the car to the inspection .​​​​​​

Then, when I was going to start it for the guy to pick it up, battery was completely dry, not even digital clock, dashboard, nothing.
Not having jump cables at that moment, I called for a roadside assistance to jumpstart the car.
And TBH I couldn't fully watch it, but I think the tow truck driver put the cables in reverse position (pos to negative), so I told him to re check the polarity and I believe he changed the cables again.

This point is important because when I started the car, two weird things happened:
1.:the windshield wipers were moving WITH STICK IN OFF POSITION. I could only make it faster, but not stopping. After a minute or so, it "recalibrated"?? And stopped by itself. That led me to the 2nd issue
2.: A YELLOW LIGHT came on in the dashboard, one that at first glance I thought it was the windshield wiper low water sign...but later (too late in fact) I recall it was the LOW COOLANT LIGHT (or the "whatever problem with cooling system" light, to be more -un-precise)

I didn't give it much credit since I know these cars throw a bunch of sensor errors whenever out of battery or jumpstarted (happened before), but since I hadn't the code reader in that moment, I couldn't check it. Only thing I can recall is that coolant level was OK in the reservoir, and that there was NOT any coolant leak on the floor when I finally moved the car.

Sooo long story short, the guy departed in the car to the inspection, and 10-15 minutes later he calls me, from the very queue of the place, telling me that he heard a loud BANG and the motor started to white smoke like a chimney. (He just drove 10-15 minutes road to the tech inspection site, from cold start, and he was driving with the air con on max cooling, it was a very hot day).
Car towed to my house, that's how the radiator looked:
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A whole rectangle patch of plastic flew off, there you can see the internal fins of the radiator, with the coolant massively leaking



Driver side, just next to the left vent tube.

​​​​Chapter two: "when Mopar God closes a door, he opens a window"

So, there was I, stood with a foolish look on my face, seeing all the coolant flushing away from the radiator, and hoping that calamity happened because a bad sensor or thermostat or bad function of the cooling system or whatever (tell me what you think, please, that could be even possible because a bad sensor signal due to jumpstart??) and praying to the motor God for not having a head gasket issue that could've lead to a overpressure in the cooling system.

When I finally install the radiator, I'll investigate further in the coolant warning light issue, but AFAIK the fan was working properly (or at least running) both when the guy left and came back.
BTW I can tell reservoir was full because it leaked A LOT onto the floor, like 9-10 Qts.


​​​​So, I tried to search for the MB Serial Nē, but was partially erased (supposedly by the steam bath it had few minutes earlier) and the other etiquette with the serial was just on the part that blew off. I lately found it was A202 500 77 03
Then I searched for a crossfire radiator on ebay, and Bingo! There was an used one for about 70bucks, so I directly purchased it (given that the next option was at near 200$, it was a no brainer)
AND HERE COMES THE ERROR, EITHER POSSIBLE OPPORTUNITY, AND MY MAIN QUESTION for the wise people in this marvelous forum:
​​​​​​I purchased a radiator for an AUTOMATIC Transmission XF, serial number A202 500 78 03.
That menas it has two additional holes for the tranny oil cooling, in the passenger side.

So, here comes the question: assuming that's a SEPARATE part in the radiator (an individual compartment inside the main core, obviously because otherwise it would result in an instant sludge) CAN I USE THAT AS AN OIL COOLER for the motor oil in Manual cars, without throwing in am additional oil cooler-radiator? Anyone though about/tried something like that?
(I plan it as future project, if possible, thus I don't have intentions of tracking the car in the near future.)

And, till I have the time to think about the in/out ways for the oil (I read some posts in the forum about an auxiliary oil cooler) IN THE MEANTIME, CAN I JUST LEAVE THOSE HOLES OPENED to the air, OR BETTER CLOSED WITH BOLTS? (I believe these are M14 taps, I'll check tomorrow when I can buy the bolts)


Aside of my questions, I hope this case report would be useful for someone, remember guys, when jumpstarted, chech and erase errors on you cars prior to driving like stolen.

Thanks in advance to whoever that can answer my questions.
Have a good and safe drive people.
​​​​​Red.
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(*): Ive been struggling through some health problems whereby I wasn't able to drive it to the state technical inspection (here is mandatory for using the vehicle to pass an annual -in my case, +10yr old car- technical inspection, where they check various compliances including lights, emissions test, wheels, motor, active and passive safety devices, etcetera), so I asked my assurance company for a service driver to go pass it. Thereby I wasn't in the car at the moment the radiator blown up, neither can tell how it was driven, only it was about 10-15 minutes drive to the tech inspection site, from cold start, and that he was driving with the air con on max cooling, it was a very hot day.

 

Close the holes, you certainly do not want any dirt getting in there. Before installing the radiator test it to be certain it can hold pressure; It being used you do not know it's condition. Test both the main radiator core and the "transmission" sections. Take it to a radiator repair shop if you can't test it yourself. Better safe than sorry. I would be concerned about the head gaskets. You mentioned white smoke coming from the exhaust; That is a sign of a leaking head gasket. Unscrew and look at the cap on the valve cover where you would add more oil. If you see a brownish foam on that cap it indicates a bad head gasket. There are other methods to determine a blown gasket, so if your "New" radiator checks out OK then install it, get a new reservoir cap and drive it straight to a trusted repair shop and have them run ( there are several different methods they can use to test for a bad head gasket) a test for bad head gasket.
Now to your question about cooling the oil through the radiator. The thermostat on the Crossfire opens st 86C, the water temp shouldn't go much above 105C ( the water is under pressure and the boiling point is increased above 100C because of the pressure cap on the reservoir). The sump temperature of engine oil is about 115C, so you are not doing much in the way of cooling should you run the oil lines through the radiator; That is why you see oil coolers exposed to the air. I do not know what the normal pressure of the transmission lines that run through the radiator would be, but the pressure of the oil may be up to 60 psi, so that is also something to consider.

PS Your English is much better than many Americans who post here.

 

Hi Zip! Thanks a lot for the detailed response and your kind words!!

• Pressure testing the radiator is a very good advice that I didn't thought about (I just did a visual inspection of the "new"-used- radiator, and a water flush, checking if it was somehow watertight, and called it a day),
In fact I can recall pressurizing the system it's described as a test for cooling leaks in the service manual.

I'll try to ask in a shop, alas being august (normally all of them 'round here are closed due to vacation, the few that aren't, are up to their ears with work).
Either that or buying myself a pressure tester for radiators/cooling system, those with a hand pump and a set of cap adaptors.

• In regard to the possibility of "bad omen oil sludge", that's the very first thing I checked when being told about the exploded radiator. I looked to the cap and oil stick too, both seemed clear, foam or sludge free, and when I drained the cooling lines and radiator prior to substitution, there wasn't any oil neither sludge in the refrigerant.
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When I have the radiator installed, I'll check the system with a head gasket CO2 chemical detector that I have, those with a little 2 chamber ampoule and the blue liquid reactive.

Hopefully may not be a head gasket leak, I wish Lemmy hear my prayers (being from Motorhead... sorry couldn't avoid the bad joke)

• About the white smoke, I may not explained myself correctly, the steam came from the motor compartment (due to the ruptured lateral of the radiator thus provoking a massive leak), NOT the exhaust tail. In fact, I don't remember seeing white smoke out the exhaust when I started the car for getting it off the tow truck.But, having dismantled already filter box, fan, old radiator...

I'll grab the opportunity to take out sparkplugs and look for an abnormally clean cylinder/sparkplug (I have a little smartphone borescope, bad quality image but enough to tell if the cylinder head is black or clean white).
Also I'll do a compression test in all the cylinders, or pressure testing with compressed air as stated in the service manual, looking for bubbling in the reservoir.

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• I'll follow straight away your tip about a new reservoir cap, certainly it may also be an additional cause for the blow up, not opening and releasing pressure when it should.
In fact, the reservoir area was dry, thus I can conclude if there was any pressure, the cap didn't release any drop of it.

• Last but not least many thanks for the detailed breakdown about the working temperatures and the oil coolers!!
Certainly, I didn't thought about the difference in working pressures, either different densities between ATF and motor oil. According to service manual, the motor oil pressure at 3000rpm could be in-between 45-105psi, so don't knowing how much pressure that particular radiator transmission circuit could handle, and considering as you pointed that wouldn't do much in terms of cooling down the motor oil, I'll just plug the holes untill my next cooling whacky idea

• BTW for whoever reading this, these transmission oil holes are M14 in diameter, but 1 or 1.5mm thread, I know because I bought regular M14 bolts for the task, I believe 2mm thread, and can screw them just 2 turns until the point it would start crossthreading the hole, but for my purpose that's only to close the holes preventing dirt to get in, that's suffucient. I thought about printing plugs with the 3D printer, but I haven't ABS, just PETG that has its glass transition point/ loss of strength at ą85ēC/185F, so it wouldn't be a feasible or reliable option for the radiator.

Thanks for the help, I'll update whenever possible.
Red.

 

Hi all!
I must post the due update.
Thus i didn't pressure check the "new" radiator yet, I installed all the cooling tubing and just started the car.
Seems it builds normal pressure on the cooling tubes, and couldn't see any leaking, nothing in the floor or the plastic bottom cover.
No white smoke from exhaust nor motor cage, not even when revving. Neither slumpy goo on the coolant, oil cap or oil rod. Not smoke column off the oil cap hole, not a big drop of revs at idle. Good signs so far, thanks God.
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After some clicking of a bad lifter without oil, it behaved just fine. I drove it around the block for +20mins and seems fine, just only downside, the dashboard temp indicator was a little hair above the middle line. Probably due to the next very problem:

When car's idling, if I turn on the A/C, fan won't start over. Not after a few minutes either. It cools ok though, so the A/C compressor is working properly (also the heat). It DOESN'T stop, slow down or do anything funky, just works and cools as it should do.

The obnoxious cooling system light is just from the beginning every time I put the key in, so I was afraid problem wasn't of the radiator fan, but of some of the sensors or the FCM (fan control module).
So I hotwired the fan motor from the battery, and started right away at the very moment I energized it.

I didn't had the time to check the 50Amps fuse, maybe tomorrow.
But I'm already looking for a used FCM, seems that mine's another of those fried fan control module cases

Alos didn't check the voltage of the reservoir sensor, nor the FCM, maybe I'm skinning the cat before have hunted it.
I'll update on that therm too whenever possible.

​​​​​BTW!! I also performed a head gasket coolant leak with the small 2ampoule blue chemical tester.
After idling 15 minutes of bubbling in the ampoules, reactive liquid remained blue as a mother f*ing Smurf!!!, so seems no head gasket at all (at least leaking inside the cooling system).
Thanks Mr. Kilmister, you heard my prayers. May you ride free in the sky.

​​​​So, keep in mind fellas, seems that FCM can cause your radiator goes bang bang.
Or better said, running your car in a hot day with a non working radiator fan, thanks to the marvelous reliability of the FCM
Only solace, I know that wasn't entirely my fault, I would haven't let the guy drive it without checking on that warning light if I could've had the choice.

I hope this helps someone at least to clarify some points of the diagnosis of a coolant light.

Red.

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Hi peoples!!
That's the final update I think. In the final tests I ran, I saw that the 50Amp midi fuse hadn't continuity (open circuit, when tested with the multimeter), so I unmounted and visually inspected it, it was blown.
TURNS OUT A DEAD FUSE CAN END UP IN A RADIATOR EXPLOSION 💥 by shutting off the fan thus overheating the radiator.
And a friendly reminder about starting with a jump starter, beware about electronics, if possible is better to just charge the battery (with an external charger), if possible.

So just changed it and fan worked like a charm, I also checked the voltages and activation with a Launch cps 129 that I have (the last day couldn't read nothing because FCM was not energized)
I also performed a full test, no overheating, no leaking neither overpressuring (though I still have to purchase a new cap; thanks Zip for the tip and the help!!), ran some minutes at 3000rpms with no overheating or warning light whatsoever.
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Here you have a photo if the service manual is not enough. Sorry for the dirt in the motor compartment tho

That's the little m*therfu**er that caused everything. That's the fuse referred in other posts. The black one is the substitute.

Filament clearly broken

So beware folks, at first glance of the obnoxious coolant light, check fuses firstly, that, and the motor fan testing and the A/C triggering the fan are the fastest diagnostic tests you can perform whenever you see the light . That and obviously checking for coolant level.

Ride fast and safe guys!!

Red.
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