Coolant temps high. Radiator for auto?

[bmwpower603]

Does anyone know where to source a radiator for an auto s4?

My coolant temps go up just over the middle. And the radiator is peeling on the outside. So I’m assuming this is the issue.

I believe this is the part #

8D0121251BD



Here’s a pic. I also noticed that the temp never stays exactly in the middle. It’s either a little before the middle, or when in traffic a little over .. Maybe a coolant temp sensor?

[james 408]

probably just a sensor man. paint peeling has nothing to do with your issue. Damaged fins or leaking would be a bigger issue, but those would have different symptoms.

[bmwpower603]

I’m going to throw a sensor at it.

Both heads were replaced 20k ago. So t stat, and wp are unlikely. And I didn’t see the radiator in the maintenance records. So that’s why I pointed to that.

I haven’t sone a coolant temp sensor on an s4 since like 2011. But I do know it’s common. Hopefully it comes out lol So I can just squeeze the new one in with little to no mess!

[Silverex]

I would log actual water temp so you know exactly where you’re at.

Both fans are turning on?

[RMode]

fwiw, the actual oem radiator is still available to me. Not cheap, but, certainly gettable

But before you toss parts at it, log actual water temp as silverex said

[bmwpower603]

I would log actual water temp so you know exactly where you’re at.

Both fans are turning on?

Both fans are turning on. (Not sure on speeds)

I’ll have to check the water temps. I replaced the coolant temp sensor last night.

When driving his morning I noticed the temp gauge getting up to temp pretty quickly.

Does anyone know where to source a rad for an auto? If it is a radiator.

[Silverex]

Rmode if you want OE, private FS section for a used one, or a cheap aftermarket from RockAuto.

[james 408]

20-30 year old radiator's still work fine usually man, including with peeling paint, including racing.

how fast is it warming up? like 5+ mins is pretty normal... see if your car is actually overheating... if it is check coolant levels, pressure test. radiator really shouldn't be first on your list.

[bmwpower603]

This is the reason I think it’s the rad.

Everything has been done at 216k

Now has 235k

Trying to see if I can find a receipt for the radiator now.

[james 408]

i mean the radiator is just pipes and fins, all metal. if it's not leaking, unless it's rusted to shit, there's just nothing to even break.

what symptoms are you seeing? is it actually overheating? coolant's still full?

[bmwpower603]

i mean the radiator is just pipes and fins, all metal. if it's not leaking, unless it's rusted to shit, there's just nothing to even break.

what symptoms are you seeing? is it actually overheating? coolant's still full?

Coolant still full. I did the heater core over the weekend. Because it was leaking, and I figured air was getting in causing the minor increase in water temps. So there are no water leaks currently. And it’s not overheating.

It’s mainly in traffic when the temps seems to want to go up. (And after I shut off my car, the temps go up)

It sounds like a fan issue ; but the fans seem to be working fine. My previous s4s always had a fan kick on after engine shutdown. I don’t get that with this car.

I’m going to see if my vag 401 tool can activate the fans, as well as check the temps. Coolant still full.

[Silverex]

Like others have said radiator would be last on my list.

Having temps rise while in traffic and after you shut car off is pretty normal if it’s hot out. I’d check your temps and got from there before you chase your tail for nothing.

[CELison]

I agree that the rad is the last thing I would look at as a culprit.

[james 408]

after run temp sensor first; then wiring/relays/fuses. then electric pump itself after that, but i'd think your fans should come on separately. temps climbing after shutoff is normal without it.

retest for a bit, you might have solved your issue with the temp sensor and heater core. Temps climbing in traffic is usually insufficient fans, but, if it's not overheating it's not a problem, yet. Sitting in traffic in the heat is hard even for a functioning system. Just see what symptoms crop up, if any, going forward.

[bmwpower603]

So I just got my car back from an a/c service. (Since doing the heater core over the weekend)

And the tech said that the fan clutch is spinning freely. And thinks it could be due to that.

- - - Updated - - -

I’ll also mention that he checked the other fans. And they are all working properly.

[spearson]

This might seem stupid obvious, but consider cleaning the exterior of your radiator and ac cooler. It can't cool anything if it's clogged with crap. While taking a break from being bent over replacing spark plugs I peaked between that front fan and the ac cooler and it was packed with shit, and then between the ac cooler and the radiator was also a bunch of shit.

[bmwpower603]

Just an update.

I threw the sensor in last night. (Rein)

Had a/c service done today, after replacing the heater core over the weekend. Drove it around for an hour. All temps seemed to stabilize. Even after turning off the car.


Ty everyone for the help.

Ty Rmode for having ready available radiators!! <3

[bmwpower603]

Still overheating. And the after run fans are working.

So I’m going to replace the fan clutch as the tech recommended. Shop I brought it to wants $430 to do it with parts and labor.

Can the fan clutch come out without front bumper removal? Maybe by moving the front clip out of the way a little, and removing bi pipe ?

[Mirror70]

Subscribing because my 200k mile car does the same thing. About five years ago, I actually stopped driving it in the summer because it would overheat if there were traffic. Never made any progress on resolving that.

[Silverex]

Have you logged actual temp?

Youll have to put it in service mod at the least to do fan clutch.

[bmwpower603]

Pic of Logged temps.

Doesn’t overheat while driving.

It only does it after driving. And letting it sit a bit.

So there’s an aux fan temp sensor on the lower rad hose.

And there’s also a temp sensor on the drivers side of the rear engine coolant pipe; this one communicates with the aux water pump.

If I need to do service mode: I would probably want to replace both of those sensors as well; to go along with the clutch fan replacement.

[Silverex]

That’s not uncommon to see temps like that with car off. What do they stabilize at after idling for a min?

Is the fan running with car off at that temp?

[CELison]

Wait, you’re saying it only “overheats” after shut down?

[bmwpower603]

The car overheated by like 8c during stop and go traffic.

That has now been solved with the new fan clutch. And I was able to do it without removing the front clip, or bumper.

[james 408]

nice, glad you got it.

[AudiWhatee]

So the fan clutch is the official culprit? Or do you think it was a combo of the items you replaced?

[james 408]

So the fan clutch is the official culprit? Or do you think it was a combo of the items you replaced?

it was a combo. both temp sensors were bad, and the fan clutch slipping.

[bmwpower603]

As far as the slight overheating in stop and go traffic; it was absolutely the fan clutch.

The car still goes over temp after shutting off sometimes. But immediately goes back to center when starting. (Before it would take a bit, or even stay over temp)

I am going to change the aux wp sensor, maybe this will help with the shutoff issue. If it doesn’t. I’ll change the aux fan sensor on the lower rad hose. And that should do the trick.

[james 408]

it's always gonna overheat slightly after shutoff if the block's hot. this is true of any car. the lower temp after-run sensor can cycle the coolant longer / more frequently but it's not really a problem. 1 bar over middle isn't going to hurt anything, especially without the engine running -- you don't want it puking up coolant which is what the cycling avoids. The bigger issue is trying not to park the car immediately after ripping it around, doing a cooldown before parking -- think the bigger threat is burning oil, like in the turbo.

I don't think electric fans work the same as mechanical fans in terms of slippage, afaik i've never seen it.

[bmwpower603]

it's always gonna overheat slightly after shutoff if the block's hot. this is true of any car. the lower temp after-run sensor can cycle the coolant longer / more frequently but it's not really a problem. 1 bar over middle isn't going to hurt anything, especially without the engine running -- you don't want it puking up coolant which is what the cycling avoids. The bigger issue is trying not to park the car immediately after ripping it around, doing a cooldown before parking -- think the bigger threat is burning oil, like in the turbo.

I don't think electric fans work the same as mechanical fans in terms of slippage, afaik i've never seen it.

Do you have a link to one of these lower temp after run sensors? Are you referring to the fan afterun; or the Aux wp after run?? Or do they make both in a lower temp afterrun?