Yes or no..?

[jdirty]

Hey guys!
I recently found out that my radiator got smashed by a rock when i was on my way home the other night. I already had a bad feeling about it so i just sped home and hoped the electric fan and air cooling would help keep the temps down since this happened not that far from my house. Got home, popped the hood, steam coming from the end tank where plastic meets aluminum. No heat in the cabin, but rad hoses were hot. And within temp reading since i pulled out an infrared temp gun to check different spots. If anything it was actually cooler than normal.. which i kinda found strange versus the temp reading on my cluster at the time. it was showing 3/4.

Hoping that my head isn't warped and that my head gasket's intact, is it pretty straight forward swapping out the rad on m42 powered cars? Never done a rad swap on anything really. lol

So.. drain, disconnect hoses, sensor, unmount my elec fan (aftermarket), mount new rad, connect hoses and sensor, refill, bleed the system, cuss alot, bleed the system again?

[bmwman91]

If the temp gauge only got to 3/4, and only for a few minutes your are probably fine. Swap radiators and that should be it.

[jdirty]

If the temp gauge only got to 3/4, and only for a few minutes your are probably fine. Swap radiators and that should be it.

Thanks for confirming. So far so good since i left the rad to drain overnight the coolant was pretty clear. No oil or what not. I'll get to swapping when my replacement rad gets delivered later.

[roguetoaster]

I wouldn't worry about it until you see an actual problem.

For instance, last week I apparently forgot to change my antifreeze percentage and my coolant was at least partially froze. I foolishly didn't notice the temp gauge pegged in red until I was on the highway and then was unable to stop for about 2.5 minutes at highway speeds as the shoulders were not plowed and I had just passed an exit. So, I refilled with antifreeze, bled it and continued on to work. After much consternation and many foul oaths on the day of the overheat there have been no apparent issues, granted it was near 0 degrees that day and I was on the highway at the time.

So, here's hoping your M42 survived without damage.

[jdirty]

I wouldn't worry about it until you see an actual problem..

..So, here's hoping your M42 survived without damage.

Thanks dude. I'm glad yours was a trooper! haha


Last night I was able to easily put in the new rad and mount my e-fan and fill up the car. I probably suck at bleeding the system even though I've done it before several times. But I tried to last night, with the exception of revving the engine. I completely forgot about that step. Since I live in an uptight community, I couldn't rev the engine. Instead I tried waiting for it to be in running/operational temperature by trusting that the temp gauge was showing something somewhat accurate, 1/2 reading. So i crack open the bleeder screw and nothing came out. No air no hissing no nothing. The top and lower rad hoses were warm but not that warm. I could probably hold it all night if i wasn't worried that the temp gauge was already creeping past 1/2 and nearing 3/4 so i cut the engine off. Waited for it to be below half then drove out of the community, and gunned it outside. Since it was kinda cold last night even though the temp reading was at 1/2 i could easily get it down by gunning the car. Anyway, i stopped and cracked the bleeder valve again and nothing. No air, no hissing, nothing. So i'm starting to get worried and just head back home.

Since i couldn't really rev the engine while being safe and stationary in my garage, i just jacked up the front of the car and left it overnight with the tank cap off. Whatever. I'm really not a fan of bleeding this shit. I really should've just gotten a mishimoto with an external m20 tank. Oh well.

This morning, I started the car, with the cap still off and the bleeder screw a full turn open, and let the car rev to 3k for like 5 minutes. Temp reading really didn't get anywhere. It was still showing cold. Since I was running late for work.. I had to leave everything where it was and hope I can get somewhere later if I get home early. I'll probably grab my temp reading gun later and check different spots. From what i remember i have an 88 thermostat. So i'm assuming that the head and hoses should be somewhere near that?

tl;dr
this will probably be another one of those m42 cooling system bleeding whining/figuring out shit/ properly bleeding the system thread. I have the other threads open.. and will more than do each one of them.. over and over.

[roguetoaster]

You can always take extra coolant with you, fill the system to max, crack the bleeder screw, drive a short distance, add more coolant, drive more (repeat as necessary) all while leaving the bleeder open until you get somewhere you can rev it when you of course do the final bleed.

By this time most of the air may be gone, the car will be up to temp and the only real negative is that you spray antifreeze on your hood insulation, engine bay and the roads. Sort of bleeding on the go I have done when I cannot rev the engine at home.

[jdirty]

You can always take extra coolant with you, fill the system to max, crack the bleeder screw, drive a short distance, add more coolant, drive more (repeat as necessary) all while leaving the bleeder open until you get somewhere you can rev it when you of course do the final bleed.

I was thinking of doing that but i was just a bit hesitant due to the nearest possible place to do it was although a couple of miles away, involved being on surface streets where i could get stuck at.

..only real negative is that you spray antifreeze on your hood insulation, engine bay and the roads.

My car's usually filthy so that's not a problem! lol

[brads2002]

If you have most of the coolant in there might to drive it with the bleeder closed for a bit and refill again once it cools down. The air usually makes it to the expansion tank in the times I have tried it this way. Will save you some antifreeze. Stuff is spendy these days. Make sure the heat is on.

[jdirty]

The air usually makes it to the expansion tank in the times..

..that someone is lucky. lol

Make sure the heat is on.

Yup. I was waiting for the slightest hint of heat since it was a bit chilly last night.

Hope I finally get the system completely bled tonight because my backup is an e34 without any cabin heat!

[jdirty]

I thought I was done after I had been sitting on 3k at the Walmart parking lot and heat coming back in the cabin and the temp gauge reading half.. So I headed to the gas station To fill up.. Started the car back up and bam! Climbed right up to 3/4 approaching red really friggin quick so I cut it right away!!

Moved the car aside and waited for it to get cold again. Soon as it went down to halfway I started the car again and revved it to 3k and out of nowhere the temp gauge red 1/4. Lol wtf? So I continue bleeding by going to a nearby autozone(parts place) because I know they have an inclined on their parking lot.

So I'm sitting here and now have heat in the cabin again.. And I'm just scratching my head. Lol I crack the bleed valve and hiss lots of relieved pressure. The most I've seen so far.. So that must be good right. Lol we'll see..

Edit: One thing that I do notice though.. Higher rpm = more heat and feels like the heat intensity is lessened at lower rpm. Never really noticed this before

Edit: sometimes the temp gauge goes up and I rev the engine.. The temp gauge goes down. Wtf

Edit: durrr should've checked my coolant level again. While the car was running, I opened the expansion tank and loosened up the bleeder valve. Dumped coolant in until full then revved the engine using the throttle cable. Until coolant spilled out. Then, while still revving I shut the bleeder valve and then later the expansion tank. Now I have heat even at idle. Now I'm just running too cold as per the temp gauge I'm only at 1/4. Revving nor leaving the car idling isn't really getting the temp up that quick and I shut off my Efan btw. Car's pretty cool still.

Edit: I'm sleepy and going home. I'll report if the temp changes when I get home. Or if I notice any change.

[jdirty]

On the way home I did a bit of hooning around since the streets were eerily empty and on the first turn I kicked the rear end out real hard and would you look at that.. Temp gauge went dead center. It was still flickering a needle before or after the 1/2 mark.. But I got home and cracked the bleeder open for until all the hissing stopped and called it a night. I'll find out tomorrow when I use it commuting to work.

[bmwman91]

Adventures in bleeding lol. HOPEFULLY you got the bulk of the air out and that's that. Worst case, the head warped or cracked and you are getting combustion gases in your cooling system. You'd probably get white smoke on warm-starts in that case though, and find yourself losing coolant. Anyway, it is pretty unlikely that you messed up the head in the first place if you only for to the 3/4 mark.

[jdirty]

Worst case, the head warped or cracked and you are getting combustion gases in your cooling system. You'd probably get white smoke on warm-starts in that case though, and find yourself losing coolant..

nononononononooooo i really hope not. I already have trouble getting m42 specific parts here in Vegas as it is.

--

Drove the car to work today and it was running okay. My efan was set to trigger too soon though which is more than likely why my temp gauge the whole time was between 1/4 and 1/2.

I'll try to tweak my efan later and figure out when it needs to fire. My efan isn't actually wired to any OEM temp sensor, it's hooked up to a primitive temp lead that's in my upper rad hose and there's an external switch to toggle the temp range when to turn the fan on.

Another thing I noticed was the temp switch/connector on the passenger side of the rad (the plug that goes into part #10).. the chassis side plug cracked so it's like three separate things versus one solid plastic piece and I don't really know which goes where. From what i understand this controls the aux fan up front?

[roguetoaster]

Quite the adventure, glad you got it sorted (hopefully).

As to the temp plug on the side of the radiator, which controls the aux fan, the original connector always seems to fall apart after 20+ years. However, if you look at the bends in the wires you can often discern where they were plugged in to begin with.

[jdirty]

Quite the adventure, glad you got it sorted (hopefully).

Oh yeah! I need new tires now too actually. lol Hopefully it's done being bled.

As to the temp plug on the side of the radiator, which controls the aux fan, the original connector always seems to fall apart after 20+ years. However, if you look at the bends in the wires you can often discern where they were plugged in to begin with.

Got it. So it is the aux fan. I wasn't sure if mine even turns on since my efan is so loud. lol About the connectors.. I only know one for sure.. since it fits only in one of the holes unlike the other two that can easily interchange. I'm terrible at electircal stuff. I need to try and find an old thread over at m42club about ohm values to figure out which wire was which.