so after I got my car (1970 delta 88 455 motor) running this week, after test driving for about 10 min it will overflow about half the coolant when I park the car. while driving the temp gets up to 210 which I assume is overheating at that point. I did a coolant flush and replaced the radiator cap this afternoon. and filled it up. the radiator only took 7.5 L of 50/50 coolant. and didn't go down when the temp hit 190. I looked up the capacity and its apparently 16.5 L. I'm guessing my thermostat is stuck closed. just figured I'd check with you guys first to make sure I'm on the right path. I was just going to buy a 180 degree thermostat, which I think is stock? I live in Baltimore, so hot summers, freezing winters. also I've seen a few people saying to keep the stock housing, so I plan on doing that. so I'll just need a thermostat and gasket right? thanks!

 

I doubt you drained all of the coolant out of the block, so when refilling it took only the amount that was drained and not the total amount. This is very typical.

 

Keep in mind that total of 16 quarts is a dry system. You still have water or coolant in the system when you drain it.

When I've flushed mine, I'm only able to get about 7 quarts back in before its full. You are probably just fine.

 

If you want to completely drain the system, remove the block plugs.

 

The reason it may be puking out the overflow after you turn it off could be a weak radiator car and/or its overfilled. The level should be about an inch or so down below the neck. There is a marking on the back side of the radiator.

If you start the car cold with the cap removed and let it idle, initially you won't see any flow while watching the coolant through the neck. As the engine approaches being warmed up (180-195* depending on thermostat rating) you'll see the level drop a little and the coolant will start to flow. Don't rev the engine when its warmed up while the cap is off.

 

so I used a flush and fill kit with a hose attachment to flush the system. I don't know if this would get into the block or not? where are the block plugs? I feel like I should drain the whole system if I can because when it started overflowing it would overflow about half of the coolant out of the radiator. at least a gallon every time. down to about the bottom line. then I would fill it back up to the fill line. and it would do it again after driving for about 10 min. so it was mostly water when I flushed it today with the kit. I still feel like something is going on with the thermostat... the car used to run at 190 fully warmed up. now it gets to 210 + and shoots most of the coolant out. also when I filled the radiator after draining it prettymuch nothing happened when the thermostat should have started opening. at 190 degrees the coolant level only dropped about 1/4 of an inch and nothing looked like it was moving.

 

Well its easy and cheap to replace the thermostat if you think yours is bad. The block drains are at the bottom of the block, 2 on each side, one in front of the motor mount and one may be behind the motor mount... but in that area. Theres 3 motor mount bolt holes on each side of the block, so im not sure which 2 your model uses. It is possible to get an air lock when filling up the block which can cause over heating/hot spots. Maybe you can bounce the front of the car when filling. If you do change the tstat you can fill the block directly when the tstat is out, just keep the level below the gasket surface so you can get a good dry seal with silicone, then fill the rest at the cap.

 

awesome. thanks! I ordered a thermostat today anyway so I'm going to change it and see what happens ( also so i know how to do it) I didn't think about filling at the thermostat. that's a good idea if it looks low in there. I was going to burp the system once it was full too just to make sure. I just went out now and drove around for 15 min. and it still gets up to 210 which has me worried. but it didn't dump coolant this time. that might have just been the original cap, which did look pretty bad

 

I agree, it sounds like a thermostat.

180° or 195° should be good, you can get them all day long at the local auto parts store, though I'd recommend the Robertshaw-type high-flow thermostat (usually $9 instead of $5) over the "standard" type.

- Eric

 

210 degrees is not an overheating engine. The temperature rating of the thermostat (180, 195, etc) is the temperature at which the thermostat opens, not the temperature at which the engine runs when fully warmed up.

 

Here's a photo of the coolant temp gauge on a '76 Chevy Caprice. Note that it doesn't consider the temperature to be too high until it gets above 260 degrees, and 210 is way to the cold end of the dial. I'm not saying that a Chevy Caprice is an Olds Delta 88, although they're not dissimilar in weight and engine size. What I am saying is that 210 degrees is nothing to be concerned about for any normal engine. At least, Chevy didn't think so.

 

True, but boiling half of the coolant out of the radiator is not quite within the normal design parameters.

- Eric

 

I didn't say the man doesn't have a problem as certainly coolant should not be boiling out. I'm just saying that 210 degrees is not an overheating engine, and, absent any other problem, it would be no cause for concern.

 

Ok. That's at least good to know that I shouldn't be too worried about the 210. It usually doesn't go much over that.... But it has been dumping coolant again. I'm going to put the new thermostat in when it comes and re-assess from there. Thanks guys!!!

 

Before taking it apart and installing a thermostat. Remove the radiator cap, start the car and observe what temp the coolant flow starts inside the radiator. You may just have a bad cap.

 

I've replaced the cap, and I've looked to see the coolant flow a few times. The car will get to 200 and nothing moves in there. Seems like the coolant isn't going anywhere but out of the overflow.

 

Well then, sounds like its time for a thermostat. I like Stant Superstats, they can be found at your local parts store.

 

awesome. that's the exact one I ordered!