Hello fellow Z owners! My name is Noah and I am a first (Sort of second.) time Z car owner. I recently, after swooning for years, purchased my first Z from a Gentleman in Erie, PA. I payed the measly price of 500 dollars for a running 1978 280z. Yes, it has cancer. Yes, it has an automatic transmission. Yes, it is old and tired. But, it is a Z car, and it was within my price range. I live 30 miles from where I purchased the car and I really needed to get it home to my garage so I could begin attempting to restore it, or at least bring it to working order. The journey home took its toll on my car, and on me. I was worried about the trip because the car hadn't really been worked in 6 years. I'll skip some of the not-important parts and go to the juicy spots. At about 6:00 pm, I rolled into my driveway and killed the engine. Steam hissed from the radiator and it smelled HOT. Call me what you will, but I did not have much of a choice other than to drive the beauty home. I popped the hood slightly to investigate the hissing and BAM, the main coolant line exploded giving me second degree burns to my chest and abdomen. After a horrible ride to the ER and a few pain killers, I was discharged and could finally get a look at the damage. Mind you all, other than extensive bondo and fiberglass work, some suspension and basic engine component knowledge, all I have to offer a car is passion. This is why I bought the z in the first place. It's a BEAUTIFUL car and I intend to fully restore it to its former glory. That being said, when i opened the thermostat housing, i found no thermostat in the vehicle. The heater had been removed and the coolant line re-routed directly into the head. I think this might be the source of my over-heating. And, since the main coolant line blew up, I can only assume that coolant was not circulating properly and caused pressure to build in the cooling system. Any information regarding this realm of thinking would be greatly appreciated. Like I said, I'm new at this and I'm prone to rookie mistakes. Attached is a photo of "Brutus," the killer Datsun, sporting 15x10 Wheel Vintiques smoothies on the rear.

Wow! what a 1st experience with the Zs. I'm guessing your OK by the kindly worded post. Read this post by a guy with a '78 too, http://www.classiczcars.com/forums/misc-s30/52438-steam-powered-z.html He's had a problem with over heating. Especially look at post #29, it'll show why you've ran hot. You'll get a lot of help here, welcome to this forum.

Loosen the bottom radiator hose and put a hose pipe in the top and flush the radiator the best you can. Then take the drain **** out of the bottom of the radiator and put the hose back in the top. Crank your car and let it run, adjust the flow of water to match what comes out the drain hole.

Edited June 23, 201410 yr by siteunseen

While the coolant line being looped would cause overheating (along with the missing thermostat), improper coolant circulation would not cause a pressure build up. That was caused by the radiator cap. It has a pressure rating. Once pressure builds, there is the potential for the weak spot to be found. You found it. Who knows how old and rotten those hoses were?

I assure you that bad brakes or a passenger compartment that in an accident could crumple like an empty beer can will probably kill you faster than 220 degree coolant. It's good to hear you didn't get badly scalded.

If you're planning on driving it any more before you take it apart, start looking for other old rubber pieces that are ready to give way (brake hoses, fuel hoses, etc.), and give the car a good once-over to look for any other repair kludges the previous owner might have performed.

Thanks very much, siteunseen! I can only home that my block doesn't house what that block had in it. So should i actually let water run through my engine while it runs? And let it flush out of the radiator? Also I'm wondering about my heater being MIA. I'll try to post up pics at a later date. The coolant line was kinked and I couldn't find the heater core. Thank you for your response!

Maybe post a picture of the water hoses, so we'll know exactly how it's hooked up. At least it ran 30 miles, wow.

You can run cold water through the motor after first starting it up- maybe for a few minutes after. But cold water and a hot block are not a good combination. As stated above, in addition to the fluids you should change all 4 brake lines so you don't get surprised at speed.

Thank you to everyone for your inputs. I plan on re-introducing the heater into the coolant circulation equation and replacing all coolant hoses before I go out or any sort of joy riding. I purchased a thermostat and a water pump for safe measure and will MOST ASSUREDLY replace the brake lines before too long. Other than the overheating, which doesn't surprise me out of a car that has been taking a break for 6 years, I haven't found a serious mechanical issue yet. Tomorrow the radiator comes out and the water pump goes in and I will get a new radiator cap. Again, thank you guys for the help. This is the first forum I've had to become a part of and it looks as though it won't disappoint.

I hope your wheel bearings hold. Basically all moving parts that have been standing still for a couple of years can seize upon usage again.

Be extra careful with your water pump bolts, they'll be rusted and easily brake off. Keep note of which ones go into which hole, they're different lengths and sizes.

Yes I definitely will. I've already broken a ton of bolts off. Well, two bolts, but still.

Overheating from bypassing the heater core was demonstrated by Tony D on zcar.com a couple of years ago (data seems to be deleted now). Apparently, with no restriction between the head outlet and the water pump inlet, the water pump ends up re-circulating too much coolant from the back of the block, instead of running it through the head and the thermostat. Basically reduces the total flow through the head. If you don't get a heater core soon, just block both holes and the coolant will flow through the head like it's supposed to.

The coolant line is just routed into the 90 degree bend t the rear of the head. The hose is kinked though which, along with a faulty radiator cap, is why I'm assuming the pressure built up after it had overheated. So i think both holes have been plugged up. I will just replace the heater core I think and re install the heater thing (Not sure what it's called. It looks like a horn.) on the firewall and put it back together like it is supposed to be. I wanna make sure everything actually works. But, since the coolant should have been circulating, could that mean the channels for coolant that run through the engine could have been blocked up? Thanks again.

The port at the back right of the head is only for the heater core supply. It actually affects flow in a negative way when coolant flows out at that point. It's a necessary evil to keep the people in the cabin warm. Some other car models used what's called the block drain plug port, under the manifolds, as the source for heater core supply.

Here's a diagram of the coolant flow. Notice that the heater core supply is not even shown. Coolant flows through the block, up in to the head and forward to the thermostat housing, then out to the top of the radiator.