E500/M119 w/Cooling issue
 

I replaced my radiator and all of the cooling hoses (except the short one from the water pump to the manifold). Following the Shops advice and procedures, there were a few bloody knuckles but it went as prescribed. I ran short on time and could not deal with the recommended thermostat replacement (especially since that 3rd bolt is in such a delightful location....) My problem now is that I filled the expansion tank, started the car with heater on, and the radiator idiot light came on. The car then proceeded to get hotter, hotter, etc. I checked the bottom hose between the radiator and the engine - cool as a cucumber. Level in the expansion tank did not go down as expected and there was no requirement to add fluid.

Is my thermostat frozen closed? Do I have an air bubble (not sure what that is exactly or how to deal with it)? Any suggestions are greatly appreciated as this is my daily driver and I have been disabled for two days.

Thanks

anytime the engine gets hot that quick and the lower radiator hose is cold----your thermostat is closed.

Thanks David.

Any idea why it is suddenly frozen? Is there any way to get it to open without replacing it?

You've got an airlock, Steve. This is common when 119s are refilled. Air is either caught in the top of the radiator, the big hose at the top, or top of the block.

* make sure you refill through the balance tank and not the radiator lid
* fill, run the motor (short time), fill some more. It may take 3-4 cycles, just keep adding as the system soaks it up.
* Leave a little bit down, when it's flowing well, add the antifreeze. I suggest you use only Merc branded, my later model 140s use brown

It'll probably gurgle and bubble as the air gets flushed. Suggest you don't run the motor too long with no coolant (2-3 mins max)

Thanks for the air lock info, but let me expand. I filled the expansion tank and started the car - but nothing drained from the tank into the radiator like I thought it would. I then mad a bone head move (perhaps) and took the top radiator hose off and put some coolant in (about 1 pint). My thought was to prime the water pump. Sealed it all back up and got the same results.

Where do I go from here to undo the problem? I really do not want to take that ******* elbow hose off and mess with trying to get the mystery nut off to change the thermostat.

Thanks

I don't really know, Steve. I'm sort of guessing now, but get whatever you've got out of the system by purging it, then do a normal fill through the balance tank. I'd say leave the little therm/connector hose alone, pull the big hose at the manifold, the little hose at the radiator (bottom), and run it for a few secs. You may want to hide around the corner cause it will throw scalding hot water all over the place. 60 secs max!

Let it cool again, seal it all up, make sure it's NOT hot, and start with water again in the overflow tank while it's running. Either measure it so you'll know how much it's absorbed, or wing it with a hose. When it stops going down (the tank will bubble and act up as you're adding water) I'd let it heat cycle then test it again while running - never let the motor run for more than 2-3 mins, allowing at least 30 mins for cool down. If you're comfortable it's full THEN add your AF by either siphoning a small amount out of the overflow, or not putting that much in to start with.

A big word of caution though - I'm sure you know this. That water coming off the motor is scalding HOT, well above boiling. Please be very careful with cooling systems - I've seen the aftermath of a radiator block cracking/bursting into someone’s chest. For this reason I just let the motor cool between fills so I'm never working with a hot motor. And I NEVER fool with the radiator cap. In fact I never take them off.

This is one of those scarier parts of this biz IMHO, I've always had some phobia about the heat a big V8 can produce

You are brilliant!!:)

Followed your advise and drained about one gallon from the bottom of the radiator, pulled the top hose - it sounded like a vacuum cleaner. Started the process over and went very slowly. Now it is full of coolant and no idiot light on.

New problem and maybe it should be a new post, but here goes. When I was done I went around to the back of the car and noticed some moisture on the ground at the exhaust. it is a humid night here (60%) and I started to freak out. Did I blow a head gasket in the process or is it just condensation?

That's ok, all mine do it, especially when cold. Something to do with hydrogen from the gasoline mixing with oxygen from the air and producing water in the exhaust system. Most of the time it's so hot it'll just be steam and you'll never see it. But when the whole exhaust train is cold the vapor will condense before it reaches the outlet - before it warms up.

Thus the old saying that running a big motor like that for short periods of time is awful, as the same thing happens in the crankcase. Water will sit on top of the heads, sit below the oil etc before it has a chance to really come up to op temp and "boils" off. That magic time? Maybe 20 minutes minimum or so, but repeated and regular 5 minute trips will eventually do it in.

Lots of posts out here about repeated minimum run time damage, although I doubt a few isolated short runs are that bad

You were right again Salty - the problem is gone and she is running like a cool champion. I think the main point I did not pick up on earlier was the slow process of refilling and the time and patients required. Just finished a 15 mile run and needed to top off the tank with about 12 oz of MB coolant - no leaks, I think it si the final air bubble getting out of the system. On to my next big issue - the power steering pump.

thanks again for the help.