Major overheating issue caused coolant system to "explode"

[David T]

Could have been a stuck thermostat. Years ago during a club event we were driving through Provincetown RI and, stuck in traffic, a radiator blew on one of the cars. When you suddenly release hot coolant under pressure it flashes into steam and makes an impressive cloud. The liquid on the passenger side could be condensate leaking from the A/C.

Put the system back together, fill with water, pressurize to see if it holds and run the motor to cycle the fans. I would replace the thermostat just because and the rad cap too. When you get the system leak-tight drain the water and fill with anti-freeze. if you are very lucky you didn't get the motor hot enough to pop the head gaskets.

[bfloyd]

Started the process of putting this all back together.

Put the rear up on ramps and drained about a quart of oil from the pan to check for water. The oil that came out did not have any water in it. Maybe I got lucky here.
Ordered a new thermostat and otterstat yesterday and those should be here in a couple of days.

Pulled the seat and carpet from the passenger side on Monday and got that mess cleaned up. Hung the carpet on the back yard fence and pressure-washed the coolant and crud out of it. I was surprised to see so much SOAP come out of the carpet.


Since its fairly obvious that the heat core blew out, I pulled both hoses from the core and installed a 5/8" 180 degree "Heater Core Bypass Hose" with two 5/8" barbed fittings from my local Autozone. Since I don't really drive the car during the winter months, having no heat really isn't going to be an issue. Next time I take the car to DMC-Midwest, I'll let them replace the core while it's there.


I'll put the pressure tester on the system on Saturday and check for leaks anywhere else in the system.

[81dmc]

Worse case scenario I know, but I wonder if your head gasket just started to let go. It is a possibility that can't be ruled out.

Before I pulled my original PRV, I was beginning to see temps creeping up to 220 even with a 160 thermostat and excellent fans. After talking to Stephen at DMCH, he seemed convince that my head gasket was beginning to let go, even though there were no obvious signs in oil or coolant.

Test your fans and also test your thermostat in a pot of boiling water to determine the actual cause.

[bfloyd]

Worse case scenario I know, but I wonder if your head gasket just started to let go. It is a possibility that can't be ruled out.

Very true possible scenario, and really won't be able to tell anything until I put the pressure tester on the system. However, I can tell you than back in May when my wife and I took the car on a 4 day trip to the mountains of northern Georgia, every now and then we'd get a whiff of antifreeze smell coming out of the center vents. Nothing really strong, but it was obvious it was there. It's also entirely possible I didn't get the system completely bled after I replaced the radiator and cooling fans back in April.

My fans were indeed working when this happened. I had been running with the A/C set on MAX COOL and my indicator lights showed both fans on, and they were both running when I pulled it up on the trailer to get it home.
I'm replacing both the thermostat and the otterstat as soon as they get here. I ordered them yesterday afternoon, so they should be here by the weekend or Monday.

[Parzival]

Man that is a scary story! That over flow hose must have been clogged or the cap was stuck and the pressure went above 15PSI, then the hose popped off from over pressure, or the cap finally opened up and all the extra pressure pushed the hose off.
DMC Midwest can replace the heater core. When I had my AC evaporator replaced DMC FL also changed the heater core since the hard work was done. Before that I had a coolant hose break, I saw my temp start to peak over 220, and it was engine off for me, then coasted to a stop. I was pretty pissed but it was my fault for not changing a hose I knew was old.
I'm interested in your over flow cap. The coolant system pressure checkers you can rent at auto zone have attachment for testing the caps. Check it and see if your cap is holding up to 15PSI and then releasing anything over that.

[AirmanPika]

heh this reminds me of a couple decades ago when the radiator hose blew on my mom's car. It wasn't overheating. It just came off catastrophically. Water and noise everywhere.

[bfloyd]

From what I can tell I may end up being the luckiest Delorean owner alive.

Got my new parts in from DMC-Midwest over the weekend and got everything put back together. Ran a pressure tester on the system and found one small leak at the top radiator hose connection on the drivers side.


Replaced the clamp with a new one and it now holds pressure without any leakdown.

Refilled the system with antifreeze last night and let it idle in the garage for about 45 minutes, bleeding the system twice in the process. No leaks anywhere. No water or steam coming out of the exhaust pipes. Temperatures holding steady right where they should, and both fans are engaging when they should.


Still have to put the interior back together, but that's not a huge issue.

[Col Bennett]

From what I can tell I may end up being the luckiest Delorean owner alive.

Phew! Great news.

[bfloyd]

In regards to the coolant tank radiator cap. My pressure tester has an adapter to test the cap. I hooked it up the other night and if I pumped it up anywhere over 15psi it would just open up and release the air behind it. Fairly confident it's working like it should.

All that's really left to do is reinstall the carpet and interior pieces. It needs a really good bath. I don't think this car has been this sticky and dirty since mid-summer of 2015.

[Riley88]

Good to hear! Awesome progress man