Major overheating issue caused coolant system to "explode"

[bfloyd]

Just like the title says... My cooling system literally exploded today coming home from a car show. Cruising down the highway at speeds of 60-70 mph everything was working perfectly. Temp gauge was sitting right where it always does at just a hair north of the white line between the 100 and the 220 mark on the gauge. As I got closer in towards town, traffic started getting congested and the temps started creeping up. It got to the 220 mark but I wasn't real worried yet. As I got to the center of town I got stopped at a red light and the gauge crept up to the 240 mark. I was worried now, as it's never gotten that high before. Light turned green and I drove less than a quarter mile through the town square and it pegged at 260. Windows started steaming up inside. With buildings right next to the street in the center of town I had nowhere to pull off. Drove it about two more blocks and everything just kinda "exploded". It blew the overflow hose off the stainless steel coolant tank. It blew the hose off connecting the down pipe to straight pipe behind the right rear tire, steam and antifreeze everywhere. It looked like Thomas the F'ing Tank Engine. Immediately pulled off the road into a convenience store parking lot and turned the engine off. As soon as I turned off the engine steam started pouring out of all the interior cabin vents.

Found a guy to load me up on a trailer and take me the two miles the rest of the way home. We let it cool down for about 20 minutes before I started the engine and drove it up onto the trailer. Got it home and drove it off the trailer and into the garage. There is water standing in a puddle behind the passenger seat - but it does not smell or feel like antifreeze. Have no clue where that came from?

Cannot figure out what exactly happened? Heater core blow? Thermostat stuck? Air pocket trapped in the system? It seemed like one small problem built into another and it kept growing from there. I haven't checked the oil yet to see if I blew a head gasket. I'm hoping I didn't.

I've got all new hoses (DMCH hose and clamp kit) and water pump (2015), stainless coolant tank, new DPI (Delorean Europe) aluminum radiator, and Delorean GO fans and shroud, and Toby's bleeders on the front and rear.

[Michael]

Water pump hose/belt still attached? I'm thinking you lost the waterpump or coolant flow due to thermostat or busted hose and boiled the coolant out.


For future reference to anyone reading this thread, if it overheats, stop right then and there.

[bfloyd]

Water pump hose still attached?

As far as I can see yes. I saw no coolant coming from anywhere near the valley and both side hoses are still attached. I'll have to get my endoscope camera to look under the intake.

[Michael]

Also, if you are sure the cooling system is OK, make sure your fans are working properly.

[DMCMW Dave]

It's all a guessing game until you clean it all up and find the leak. My guess at this point based on your writeup? ….. Fans failed (anything from the otterstat to the fan relay or just wiring issues) (so it was fine on the highway and overheated right away afterwards) and then a defective/failed/incorrect radiator cap allowing the pressure to get way past 15lb. This blew the heater core and then the other stuff. I've never seen a system do this, typically with an overheat it blows out through the radiator cap and into that short hose that is aimed at the ground at the back of the engine compartment. You mention that the overflow hose blew off - could that have been plugged or kinked? It's pretty weird because you'd expect that the first failure (the heater core?) would relieve the pressure (unfortunately into your interior) and nothing else would fail.

Keep in mind that there is slight possibility that the first failure was one of the two small heater core hoses. That connection is very close to the drain hole for the plenum, so a sudden release of steam/hot coolant would get pulled in via that drain hole that is right above the fuel pump and into your interior. Most of it would be going on the ground, but assuming you had the A/C on fresh air (not recirc) and the fan on high you could pull quite a bit into the system and into your car. Long shot. Since it kept steaming after you turned off the car (and the blower) this is probably not the case.

My suggestion would be to hose everything off, bypass the heater core (i.e. tie the two small hoses that go to the heater core together). Replacing the heater core is a huge pain and you probably don't drive the car in cold weather. You can fix that later.

Fix the other obvious leaks. Put coolant (water is fine for the moment) back in the system and see what else is leaking. Check your engine oil for coolant contamination (a good way to do this is slowly loosen the drain plug and see if anything other than oil comes out, no need to dump the whole pan yet). If you see any antifreeze in the oil, you're done for a while.

Now for the bad part. This sort of overheat is very hard on the head gaskets. That is what you are looking for with the oil drain test.

I can guarantee that if it wasn't an otterstat (fan temp switch) failure, the otterstat is bad now. They don't take overheats well. So during this test phase just jumper it out so the fans run all the time. If the fans don't run with the otterstat jumpered, you've found the rood cause and need to fix that.

BTW message to anyone - if you see it hit that sort of temp, i.e. much above 220, shut it off NOW unless its a truly dangerous place to stop.

[bfloyd]

Dave..

Fans failed (anything from the otterstat to the fan relay or just wiring issues) (so it was fine on the highway and overheated right away afterwards)

Both fans were still running as the A/C system was set on MAX. When I drove it up on to the trailer - both fans were running.

then a defective/failed/incorrect radiator cap allowing the pressure to get way past 15lb. This blew the heater core and then the other stuff. I've never seen a system do this, typically with an overheat it blows out through the radiator cap and into that short hose that is aimed at the ground at the back of the engine compartment. You mention that the overflow hose blew off - could that have been plugged or kinked?

The radiator cap was securely fastened, and the "blowing out through the radiator cap into that short hose" part did work. However it came out with so much pressure that the hose blew off and it sprayed all over the engine bay and inside face of the rear fascia.

I'll check the oil when I get home tonight.

[DMC-81]

Oh man, sorry that happened.

You've got good advice here so far. I'll add also checking for a thermostat failed in the closed position (mentioned by Michael). I had that scenario occur 3 times on 2 non-D vehicles, and the temperature gauge climbed fast all three times.

[bfloyd]

Just got home from the theatre (2:05am) and went out to the garage to check on the car.

Checked the oil via the dip stick and its a nice pure amber color, and doesn't seem to have any other smell to it than just oil. I just changed it out in mid-May, and have only driven the car a few short trips around town.

As expected, the coolant bottle is presently bone dry. The entire passenger side floor board and carpets are completely soaked and standing in water. Seems like the heater core blew.

I'll bypass those hose like Dave mentioned and put a pressure tester on the system and see what happens.

[Michael]

Just got home from the theatre (2:05am) and went out to the garage to check on the car.

Checked the oil via the dip stick and its a nice pure amber color, and doesn't seem to have any other smell to it than just oil. I just changed it out in mid-May, and have only driven the car a few short trips around town.

The PRV doesn't like to be overheated but if it was a quick "hot flash" and not allowed to stay in the red for long, it may be ok. It is something you will want to keep an eye on, although the oil may not be milky, you can still have oil leaks or oil consumption issues.

[CFI]

I feel your pain. After 4,000+ trouble free miles in 8 months of driving my car finally had to be towed. Temp kept creeping upward. As soon as it went above the half way mark I pulled over. I’ve sat in stop and go traffic for an hour on a 95 degree day and never saw it even get close to half on the temp gauge so I knew something was wrong.

As soon as I opened my door I could smell coolant. There was a massive leak from the water pump area. Reservoir was bone dry. I haven’t heard from the shop yet but I’m guessing the water pump blew a seal.